Class AbstractGraph<B>

Object

UIObject

Widget

Panel

SimplePanel

FocusPanel

AbstractGraph<B>

Type Parameters:

B - the type of buffer backing the graph (may be null if the graph does not use a RingBuffer): typically this is double[] but in some cases Color[], String[] or MeshLambertMaterial[] for Pop2D, PopGraph2D or PopGraph3D, respectively.

All Implemented Interfaces:

HasAllDragAndDropHandlers, HasAllFocusHandlers, HasAllGestureHandlers, HasAllKeyHandlers, HasAllMouseHandlers, HasAllTouchHandlers, HasBlurHandlers, HasClickHandlers, HasContextMenuHandlers, HasDoubleClickHandlers, HasDragEndHandlers, HasDragEnterHandlers, HasDragHandlers, HasDragLeaveHandlers, HasDragOverHandlers, HasDragStartHandlers, HasDropHandlers, HasFocusHandlers, HasGestureChangeHandlers, HasGestureEndHandlers, HasGestureStartHandlers, HasKeyDownHandlers, HasKeyPressHandlers, HasKeyUpHandlers, HasMouseDownHandlers, HasMouseMoveHandlers, HasMouseOutHandlers, HasMouseOverHandlers, HasMouseUpHandlers, HasMouseWheelHandlers, HasTouchCancelHandlers, HasTouchEndHandlers, HasTouchMoveHandlers, HasTouchStartHandlers, MouseDownHandler, MouseMoveHandler, MouseOutHandler, MouseUpHandler, MouseWheelHandler, TouchEndHandler, TouchMoveHandler, TouchStartHandler, HasAttachHandlers, EventHandler, HasHandlers, EventListener, AcceptsOneWidget, Focusable, HasFocus, HasOneWidget, HasVisibility, HasWidgets, HasWidgets.ForIsWidget, IsWidget, RequiresResize, SourcesClickEvents, SourcesFocusEvents, SourcesKeyboardEvents, SourcesMouseEvents, SourcesMouseWheelEvents, Iterable<Widget>, ContextMenu.Listener, ContextMenu.Provider, Tooltip.Provider

Direct Known Subclasses:

GenericPopGraph, HistoGraph, LineGraph, ParaGraph, S3Graph

public abstract class AbstractGraph<B>
extends FocusPanel
implements MouseOutHandler, MouseWheelHandler, MouseDownHandler, MouseUpHandler, MouseMoveHandler, TouchStartHandler, TouchEndHandler, TouchMoveHandler, RequiresResize, Tooltip.Provider, ContextMenu.Listener, ContextMenu.Provider

Abstract base class for 2D graphs rendered into a Canvas within the UI.

This class encapsulates common functionality required by a variety of concrete graph implementations: managing the canvas and its high-DPI scaling, calculating drawing bounds, handling user interactions (mouse and touch) for panning and zooming, integrating with shared UI utilities (tooltip and context menu), buffering historical data, and providing a comprehensive set of drawing helpers for frames, axes, ticks, levels, markers and primitive shapes.

Generic parameter

The type parameter <B> denotes the element type stored in an optional RingBuffer used for graphs that maintain historical data (for example time-series or trajectory graphs).

Primary responsibilities

• Allocate and manage a Canvas element and a wrapped 2D rendering context (MyContext2d) tuned for device pixel ratio (retina/high-DPI) support.
• Compute and maintain drawing bounds that leave room for frames, labels, ticks and tick labels while exposing helper methods to draw full graph frames (axes, tick marks, tick labels, grid levels and custom levels).
• Provide a pluggable styling model (GraphStyle) and helpers to render axes labels, graph title, and common primitives (lines, circles, filled paths, rectangles and vertical text).
• Offer a unified interaction model for shifting (panning) and zooming including mouse drag, mouse wheel, single- and multi-touch gestures, pinch-to-zoom, and inertial visual feedback via CSS classes and a scheduled timer.
• Integrate with shared UI widgets: Tooltip (for hover/touch info) and ContextMenu (for buffer size, log-scale and zoom actions). Subclasses and the owning AbstractView can extend and populate the context menu.
• Maintain an optional RingBuffer<B> for historical data and provide a small context menu for configuring buffer capacity. Subclasses may implement exporting of trajectory/history data when relevant.

Interfaces and Extension Points

AbstractGraph provides inner interfaces that concrete graphs and/or their containing view may implement to customize interaction behavior:

• Shifting — marker indicating the graph supports shifting. Implementing classes can provide custom shift behavior by implementing Shifter, and can optionally override mouse/touch handlers if they need finer control.
• Shifter — single method shift(int dx, int dy) used by the base class to move the view corner when panning. The default implementation in AbstractGraph updates the viewCorner constrained to valid extents.
• Zooming — marker indicating the graph supports zooming. It extends Zoomer and MouseWheelHandler. It documents a default ZOOM_INCR and ZOOM_MAX. Implementations can override zoom behaviour; otherwise the base-class provides sensible defaults.
• Zoomer — single method zoom(double zoom, int x, int y) used to apply zoom centered on a particular screen coordinate. Subclasses or the containing view can provide custom coordinate-space or content-level behavior by implementing Zoomer.
• HasLogScaleY — marker for graphs that may support logarithmic Y scaling; the graph will enable/disable the log-y context menu item appropriately.
• HasTrajectory — marker for graphs that can export trajectories; such graphs should implement an exportTrajectory(StringBuilder) routine.

Lifecycle

Typical lifecycle methods:

• onLoad() — allocates the LayoutPanel wrapper and Canvas, obtains shared Tooltip and ContextMenu instances and configures them, and sets the rendering scale based on device pixel ratio.
• onUnload() — removes and nulls references to DOM components and unregisters from shared widgets.
• activate() — attaches mouse and touch handlers for zooming and shifting depending on which interfaces are implemented and on the environment (e.g. special handling for ePub readers).
• deactivate() — removes all registered input handlers, closes tooltip and context menu, and cancels transient state.
• onResize() — closes transient UI (tooltip/context menu), updates the canvas coordinate space and recalculates drawing bounds.

Interaction semantics

• Mouse wheel: zooms with inertia. The wheel delta is converted to a multiplicative zoom factor (ZOOM_INCR ^ -deltaY) and the zoom center is the current mouse position. A CSS class is briefly applied while inertia is present.
• Mouse drag with left button: initiates panning (shifting) of the viewport when the graph implements Shifting. A CSS class is applied to indicate view movement while dragging.
• Touch: short taps and long touches are distinguished. Long single touches allow panning; two-finger long touches initiate pinch-to-zoom with the center of the pinch used as zoom focus. Touch handlers preventDefault() for panning and pinch gestures to avoid scrolling the page when interacting with the graph.
• All interactions are no-ops when a textual message is shown on the graph (hasMessage flag) to avoid conflicting updates.

Canvas & scaling

The canvas coordinate space is scaled by the detected device pixel ratio to support crisp rendering on high-DPI displays. updateCanvas() sets both the CSS pixel size and the coordinate space (scaled) size; note that setting these properties clears the canvas, so callers should repaint after resizing.

Painting and Helpers

Subclasses must implement export(MyContext2d) and typically override paint() to perform actual rendering. AbstractGraph provides:

• Utility primitives for drawing and filling complex paths efficiently (sketch/stroke/fill) with segmentation to avoid freezing the UI.
• Convenience methods for drawing frames, axis labels, ticks, tick labels (including percent/log formatting), grid levels, and custom level lines.
• Primitives for circles, lines, rectangles and vertical text.
• Coordinate conversion helpers to map browser coordinates to scaled [0..1] coordinates relative to the drawing bounds (convertToScaledCoordinates).

Bounds and layout

calcBounds computes the inner drawing rectangle available for graph content, factoring in style-determined padding, frame width, label space, tick length and tick label widths. adjustBoundsForLabels() and adjustBoundsForTickLabels() are used to reserve space for axis and tick labels. The bounds are used by frame and drawing methods to position elements consistently.

History & buffering

When a RingBuffer<B> is present, hasHistory() returns true and a small buffer-size submenu is added to the context menu to select capacities (5k, 10k, 50k, 100k). Subclasses that maintain historical data should manage insertion into the buffer and may use prependTime2Data helper to attach a timestamp to stored data points.

Tooltips and context menu

A shared Tooltip instance is used to provide hover/touch information. Context menu population is extensible — AbstractGraph populates buffer-size, log-Y toggle and zoom items when applicable and then delegates to the owning AbstractView for additional items.

Messages

displayMessage(String) can be used to show a centered textual message as an overlay on the graph (e.g. "No Data" or "Paused"). When a message is displayed most interaction handlers become inert and painting/updates are suppressed until the message is cleared via clearMessage().

Utilities & Helper classes

• MyContext2d — a thin subclass of Context2d that exposes setLineDash for dashed lines.
• ZoomCommand — small Command implementation used by context menu items to apply zoom factors.

Notes and implementation details

• Drawing very large paths is split into segments (MAX_SEGEMENTS) and periodically closed/stroked to avoid performance bottlenecks and UI freezing.
• Many protected helper methods are provided so subclasses can reuse the standardized rendering behavior and visuals defined by GraphStyle.
• AbstractGraph intentionally separates coordinate-space transforms (via viewCorner and zoomFactor) from content rendering so subclasses can assume painting inside normalized bounds and apply their own content transforms as needed.

Author:

Christoph Hauert

See Also:

• activate()
• deactivate()
• paint()
• zoom()
• shift(int,int)
• AbstractGraph.Shifting
• AbstractGraph.Shifter
• AbstractGraph.Zooming
• AbstractGraph.Zoomer

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	AbstractGraph.HasLogScaleY	Graphs that support logarithmic scaling on the y-axis should implement this interface.
static interface	AbstractGraph.HasTrajectory	Graphs that show trajectories and support exporting their data should implement this interface.
static class	AbstractGraph.MyContext2d	Create custom Context2d that admits drawing dashed lines.
static interface	AbstractGraph.Shifter	Graphs that support shifting of their view should implement this interface.
static interface	AbstractGraph.Shifting	Graphs that support shifting should implement this interface.
class	AbstractGraph.ZoomCommand	The zoom command for the context menu.
static interface	AbstractGraph.Zoomer	Graphs that support zooming should implement this interface.
static interface	AbstractGraph.Zooming	Graphs that support zooming should implement this interface.

Nested classes/interfaces inherited from class UIObject

UIObject.DebugIdImpl, UIObject.DebugIdImplEnabled

Nested classes/interfaces inherited from interface HasWidgets

HasWidgets.ForIsWidget

Field Summary

Fields

Modifier and Type	Field	Description
protected Rectangle2D	bounds	The bounds of the displaying area.
protected RingBuffer<B>	buffer	The buffer to store historical data, if applicable.
private double	cachedMidYTickLabelWidth	Cached width of the midpoint y tick label from the most recent bounds calculation.
protected Canvas	canvas	Handle to the canvas for drawing the graphics.
protected String[]	colors	The array of colors used for drawing the graph.
protected ContextMenu	contextMenu	The reference to the (shared) context menu.
protected static final String	CSS_CURSOR_MOVE_VIEW	The CSS class name for the view movement cursor.
(package private) static final String	CURSOR_GRAB_NODE_CLASS	CSS class applied when the user is grabbing a node.
(package private) static final String	CURSOR_MOVE_NODE_CLASS	CSS class applied when the user is dragging a node.
(package private) static final String	CURSOR_ZOOM_IN_CLASS	CSS class applied when the user is zooming in.
(package private) static final String	CURSOR_ZOOM_OUT_CLASS	CSS class applied when the user is zooming out.
protected static final int	DEFAULT_BUFFER_SIZE	The default buffer size.
(package private) HandlerRegistration	doubleClickHandler	The handler for DoubleClickEvents.
protected Element	element	Handle to the object's underlying DOM element.
protected AbstractGraph.MyContext2d	g	Handle to the graphical context for drawing on the canvas.
protected boolean	hasMessage	Flag to indicate whether the graph displays a message.
protected boolean	hasZoom	The flag to indicate whether the graph supports zoom.
protected boolean	leftMouseButton	The flag to indicate whether the left mouse button is pressed.
protected Logger	logger	Logger for keeping track of and reporting events and issues.
protected String[]	markerColors	The array of colors used for markers.
protected List<double[]>	markers	Markers for decorating the graph.
private static final int	MAX_SEGEMENTS	The maximum number of line segments to draw before returning control to the event loop.
protected String	message	The last message displayed on the graph.
protected static final int	MIN_BUFFER_SIZE	The minimum buffer size.
protected static final double	MIN_CURVATURE_STEP_SQ	Squared minimum normalized step before curvature checks.
protected static final double	MIN_NORM_DELTA	Normalized absolute-difference threshold for max-delta throttling.
protected static final double	MIN_NORM_DIST_SQ	Squared normalized mean-distance threshold for throttling successive samples.
protected Module<?>	module	The module backing the graph.
(package private) HandlerRegistration	mouseDownHandler	The handler for MouseDownEvents.
(package private) HandlerRegistration	mouseMoveHandler	The handler for MouseMoveEvents.
(package private) HandlerRegistration	mouseOutHandler	The handler for MouseOutEvents.
(package private) HandlerRegistration	mouseUpHandler	The handler for MouseUpEvents.
(package private) HandlerRegistration	mouseWheelHandler	The handler for MouseWheelEvents.
protected int	mouseX	The x-coordinate of the previous mouse or tap event.
protected int	mouseY	The y-coordinate of the previous mouse or tap event.
protected double	msgFontSize	Cached font size of the last displayed message.
protected Label	msgLabel	Overlay label used to display graph messages.
protected double	msgLineHeight	Cached line height of the last displayed message.
protected static final double	PIHALF	Constant representing the numerical value of \(\pi/2\)
protected double	pinchDist	The distance between the pinching gesture.
protected int	pinchX	The x-coordinate of the center of the pinching gesture.
protected int	pinchY	The y-coordinate of the center of the pinching gesture.
protected double	scale	The scale of this graph.
(package private) AbstractGraph.Shifter	shifter	The controller for shifting this graph.
protected GraphStyle	style	The style of the graph.
protected Tooltip	tooltip	The reference to the (shared) tooltip.
(package private) BasicTooltipProvider	tooltipProvider	The provider for tooltips.
(package private) HandlerRegistration	touchEndHandler	The handler for TouchEndEvents.
protected double	touchEndTime	The time when the previous touch ended.
(package private) HandlerRegistration	touchMoveHandler	The handler for TouchMoveEvents.
(package private) HandlerRegistration	touchStartHandler	The handler for TouchStartEvents.
protected static final double	TURN_COS_THRESHOLD	Cosine threshold for a turn-angle criterion (\(6^\circ\)).
private static final double	TWOPI	Constant representing the numerical value of \(2 \pi\)
protected final AbstractView<?>	view	The view of this graph.
protected Point2D	viewCorner	The coordinates of the lower left corner visible on the canvas.
(package private) LayoutPanel	wrapper	The wrapper element which displays the canvas.
private static final double	Y_AXIS_LABEL_MIN_GAP	Minimum horizontal gap between y tick labels and the y-axis label.
private static final double	Y_AXIS_LABEL_RESERVED_GAP	Default horizontal gap reserved between y tick labels and the y-axis label.
private static final double	Y_AXIS_LABEL_THICKNESS	Approximate horizontal thickness reserved for the rotated y-axis label.
private static final double	Y_TICK_LABEL_GAP	Horizontal gap between y ticks and their labels.
protected double	yAxisLabelTickSkip	Optional override for the horizontal offset of the y-axis label.
(package private) AbstractGraph.Zoomer	zoomer	The controller for zooming this graph.
protected double	zoomFactor	The current zoom level.
protected Timer	zoomInertiaTimer	The timer to remove the CSS classes .evoludo-cursorZoomIn or .evoludo-cursorZoomIn, respectively, from the graph element after the inertia of zooming has worn off.

Fields inherited from class UIObject

DEBUG_ID_PREFIX

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractGraph(AbstractView<?> view, Module<?> module)	Create the base class for graphs.

Method Summary

Modifier and Type	Method	Description
void	activate()	Perform necessary preparations to show the graph in the GUI.
protected void	addClearMenu(ContextMenu menu)	Add a clear-history entry to the context menu when this graph stores history.
HandlerRegistration	addContextMenuHandler(ContextMenuHandler handler)
protected void	addLogScaleMenu(ContextMenu menu)	Add logarithmic scale menu item to context menu if graph supports log scale on y-axis.
protected void	addZoomMenu(ContextMenu menu)	Add zoom menu items to context menu if graph supports zooming.
private void	adjustBoundsForLabels()	Adjust bounds to make room for axes labels.
protected void	adjustBoundsForLegend()	Adjust bounds to make room for an optional legend.
private void	adjustBoundsForTickLabels()	Adjust bounds to make room for tick labels.
private void	adjustBoundsForYSide(double padding)	Adjust bounds to make room for y-axis decorations on the selected side.
void	autoscale(boolean x, boolean y)	Set auto-scaling for horizontal and vertical axes.
protected boolean	calcBounds()	Calculate bounds of drawing area.
void	calcBounds(int width, int height)	Calculate bounds of drawing area.
protected void	clearCanvas()	Clear the canvas.
void	clearGraph()	Clear the graph.
void	clearHistory()	Clear the history of the graph (if there is one).
void	clearMessage()	Clear the message.
private void	closePath(boolean fill)	Helper method to close the path and draw (or fill) it.
private int	computeLinearDigits(double min, double max, int levels, boolean percent, boolean pretty)	Compute the number of decimal digits needed for linear labels so consecutive ticks remain distinct.
private double[]	computeYRange()	Compute the (possibly logarithmic) y-range for tick computations.
private int	computeYTickDigits(int levels)	Compute the number of decimal digits needed for y-axis tick labels.
private double	computeYVal(int n, double frac, double yrange, double ymin)	Compute the y-value for tick number n.
boolean	contains(int x, int y)	Checks if the (browser) coordinates (x, y) are inside this graph.
Point2D	convertToScaledCoordinates(int x, int y)	Convert the (browser) coordinates (x, y) to scaled coordinates in \([0,1]^2\).
Point2D	convertToScaledCoordinates(int x, int y, Point2D dest)	Convert the (browser) coordinates (x, y) to scaled coordinates in \([0,1]^2\) and store in dest.
void	deactivate()	The graph is removed from the GUI.
boolean	displayMessage(String msg)	Display message msg on the graph (no HTML formatting).
boolean	displayMessage(String msg, boolean autoscale)	Display message msg on the graph (no HTML formatting), optionally autoscaling the text to the available width.
private void	drawCustomXLevels(double w, double h)	Draw vertical guide lines at custom x positions.
private void	drawCustomYLevels(double w, double h)	Draw horizontal guide lines at custom y positions.
protected void	drawFrame(int xLevels, int yLevels)	Draw the frame of the graph including axes labels, ticks and tick marks, as applicable.
protected void	drawFrame(int xLevels, int yLevels, double gscale)	Draw the frame of the graph including axes labels, ticks and tick marks, as applicable, after scaling the canvas by gscale.
private void	drawFrameBorder(double w, double h)	Draw the bounding box of the graph frame.
private void	drawGraphLabel(double gscale)	Draw the label shown inside the graph canvas.
private void	drawXAxisLabel(double w, double h)	Draw the x-axis label.
private void	drawXLevels(int xLevels, double w, double h)	Draw regular vertical guide lines, ticks, and labels.
private void	drawYAxisLabel(double w, double h)	Draw the y-axis label, including positioning logic based on tick labels.
private void	drawYLevels(int yLevels, double w, double h)	Draw the y-levels including ticks and tick labels.
private void	drawYTickLabel(double w, double level, int n, double yval, int digits)	Draw the y-axis tick label at the specified screen level.
abstract void	export(AbstractGraph.MyContext2d ctx)	Export the graphical context ctx.
protected void	fill(Path2D path)	Fill the path path.
protected void	fillCircle(double x, double y, double radius)	Fill the circle with the center at (x,y) and radius radius.
protected void	fillCircle(Node2D node)	Draw the filled 2D node.
protected void	fillCircle(Point2D point, double radius)	Draw a filled circle at point with radius.
protected void	fillRect(double x, double y, double w, double h)	Fill the rectangle with origin at (x,y), width w and height h.
protected void	fillTextVertical(String msg, double x, double y)	Draw filled text vertically starting at point (x,y)
private String	formatYTickLabel(double tickValue, int digits)	Format a y-axis tick label using the same pretty formatting as the renderer.
RingBuffer<B>	getBuffer()	Return the RingBuffer<double[]> containing historical data, if applicable.
protected double	getMaxViewCornerX(double zoom)	Get the maximum horizontal view-corner offset for the zoom factor zoom.
protected double	getMaxViewCornerY(double zoom)	Get the maximum vertical view-corner offset for the zoom factor zoom.
Module<?>	getModule()	Get the module that backs the graph.
GraphStyle	getStyle()	Get the graph style.
protected double	getYAxisLabelTickSkip()	Get the horizontal offset to use for the y-axis label.
boolean	hasHistory()	Check whether the graph entertains a buffer with historical data.
boolean	hasMessage()	Check if the graph displays a message.
protected final boolean	hasSignificantTurn(double[] current, double[] last, double[] prev)	Check whether the last two retained segments form a sufficiently strong turn.
void	init()	Initialize the graph.
protected boolean	inside(int x, int y)	Check if the event coordinates are inside the interactive plot area.
protected boolean	keepSample(RingBuffer<double[]> history, double[] current, double[] last)	Decide whether to retain a candidate sample by applying a display-agnostic heuristic: normalized mean squared distance and local curvature.
protected final double	maxDelta(double[] current, double[] last)	Compute the maximum absolute normalized difference between two samples, excluding time.
private double	measureMidYTickLabelWidth(int digits)	Measure the width of the midpoint y-axis tick label using the same pretty formatting as the renderer.
private double	measureYTickLabelWidth(String[] numexp, boolean percent)	Measure the width of a y-axis tick label including exponent and percent.
protected final double	normDelta(double current, double last)	Compute the normalized difference between two values.
protected final double	normDeltaSq(double[] current, double[] last)	Compute the mean squared normalized difference between two samples, excluding time.
protected void	onLoad()
protected void	onMessageCleared()	Hook invoked after a message has been cleared.
protected void	onMessageDisplayed()	Hook invoked after a message has been displayed.
void	onMouseDown(MouseDownEvent event)
void	onMouseMove(MouseMoveEvent event)
void	onMouseOut(MouseOutEvent event)
void	onMouseUp(MouseUpEvent event)
void	onMouseWheel(MouseWheelEvent event)
void	onResize()
void	onTouchEnd(TouchEndEvent event)
void	onTouchMove(TouchMoveEvent event)
void	onTouchStart(TouchStartEvent event)
protected void	onUnload()
void	paint()	Draw the graph.
boolean	paint(boolean force)	Draw the graph.
boolean	parse(String args)	Parse the arguments for the graph.
void	populateContextMenuAt(ContextMenu menu, int x, int y)	Populate context menu menu in listening widget at (relative) position (x,y).
void	populateLocalAxesMenu(ContextMenu menu)	Opportunity for graph subclasses to contribute graph-local entries to the shared axes submenu assembled by the owning view.
protected void	populateZoomMenu(ContextMenu menu)	Populate the zoom submenu with standard zoom actions.
protected double[]	prependTime2Data(double t, double[] data)	Utility method to prepend time to data point.
void	reset()	Reset the graph.
protected void	resetTransforms()	Reset the transformation of the graphics context to the identity transform.
void	setColors(String[] colors)	Assign a list of colors to the graph.
protected void	setFont(String cssfont)	Set the font to cssfont in CSS format for drawing on the canvas.
(package private) void	setLogY(boolean logY)	Set the y-axis to logarithmic scale if logY is true and if yMin &ge; 0.
void	setMarkers(List<double[]> markers)	Assign a list of markers to the graph.
void	setMarkers(List<double[]> markers, String[] colors)	Assign a list of markers with custom colors to the graph.
protected void	setStrokeStyleAt(int node)	Set the stroke colour for node with index node.
void	setTooltipProvider(BasicTooltipProvider tooltipProvider)	Set the provider for tooltips.
void	shift(int dx, int dy)	Shift the (zoomed) graph within the view port by (dx, dy).
private void	sketch(Path2D path, boolean fill)	Draw or fill (if fill == true) the path path.
private void	sketchCircle(double x, double y, double radius)	Helper method to create a path for a circle with the center at (x,y) and radius radius.
protected void	stroke(Path2D path)	Draw the path path.
protected void	strokeCircle(double x, double y, double radius)	Draw the circle with the center at (x,y) and radius radius.
protected void	strokeCircle(Node2D node)	Draw the outline of the 2D node.
protected void	strokeCircle(Point2D point, double radius)	Draw the outline of a circle at point with radius.
protected void	strokeLine(double sx, double sy, double ex, double ey)	Draw a line from point (sx,sy) to (ex,ey).
protected void	strokeLine(Point2D a, Point2D b)	Draw a line from point a to b).
protected void	strokeRect(double x, double y, double w, double h)	Draw the rectangle with origin at (x,y), width w and height h.
private void	updateCanvas()	Update the canvas size and coordinate space dimensions.
void	zoom()	Reset zoom.
void	zoom(double zoom)	Adjust zoom level by the factor zoom.
protected void	zoom(double zoom, double fx, double fy)	Helper method to adjust zoom level with the zoom center at the scaled coordinates (fx, fy), specified as a fraction of the view port in horizontal and vertical directions, respectively.
void	zoom(double zoom, int x, int y)	Adjust zoom level by the factor zoom with the center at coordinates (x,y) (in display coordinates as provided by event listeners).

Methods inherited from class FocusPanel

addBlurHandler, addClickHandler, addClickListener, addDoubleClickHandler, addDragEndHandler, addDragEnterHandler, addDragHandler, addDragLeaveHandler, addDragOverHandler, addDragStartHandler, addDropHandler, addFocusHandler, addFocusListener, addGestureChangeHandler, addGestureEndHandler, addGestureStartHandler, addKeyboardListener, addKeyDownHandler, addKeyPressHandler, addKeyUpHandler, addMouseDownHandler, addMouseListener, addMouseMoveHandler, addMouseOutHandler, addMouseOverHandler, addMouseUpHandler, addMouseWheelHandler, addMouseWheelListener, addTouchCancelHandler, addTouchEndHandler, addTouchMoveHandler, addTouchStartHandler, getTabIndex, removeClickListener, removeFocusListener, removeKeyboardListener, removeMouseListener, removeMouseWheelListener, setAccessKey, setFocus, setTabIndex

Methods inherited from class SimplePanel

add, getContainerElement, getWidget, iterator, remove, setWidget, setWidget

Methods inherited from class Panel

add, adopt, clear, doAttachChildren, doDetachChildren, orphan, remove

Methods inherited from class Widget

addAttachHandler, addBitlessDomHandler, addDomHandler, addHandler, asWidget, asWidgetOrNull, createHandlerManager, delegateEvent, fireEvent, getHandlerCount, getLayoutData, getParent, isAttached, isOrWasAttached, onAttach, onBrowserEvent, onDetach, removeFromParent, setLayoutData, sinkEvents, unsinkEvents

Methods inherited from class UIObject

addStyleDependentName, addStyleName, ensureDebugId, ensureDebugId, ensureDebugId, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleElement, getStyleName, getStyleName, getStylePrimaryName, getStylePrimaryName, getTitle, isVisible, isVisible, onEnsureDebugId, removeStyleDependentName, removeStyleName, resolvePotentialElement, setElement, setElement, setHeight, setPixelSize, setSize, setStyleDependentName, setStyleName, setStyleName, setStyleName, setStyleName, setStylePrimaryName, setStylePrimaryName, setTitle, setVisible, setVisible, setWidth, sinkBitlessEvent, toString

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface ContextMenu.Listener

getAbsoluteLeft, getAbsoluteTop

Methods inherited from interface HasHandlers

fireEvent

Methods inherited from interface HasTouchCancelHandlers

addTouchCancelHandler

Methods inherited from interface HasTouchEndHandlers

addTouchEndHandler

Methods inherited from interface HasTouchMoveHandlers

addTouchMoveHandler

Methods inherited from interface HasTouchStartHandlers

addTouchStartHandler

Methods inherited from interface Iterable

forEach, spliterator

Methods inherited from interface Tooltip.Provider

getTooltipAt

Field Details

doubleClickHandler

HandlerRegistration doubleClickHandler

The handler for DoubleClickEvents.

mouseOutHandler

HandlerRegistration mouseOutHandler

The handler for MouseOutEvents.

mouseDownHandler

HandlerRegistration mouseDownHandler

The handler for MouseDownEvents.

mouseUpHandler

HandlerRegistration mouseUpHandler

The handler for MouseUpEvents.

mouseMoveHandler

HandlerRegistration mouseMoveHandler

The handler for MouseMoveEvents.

mouseWheelHandler

HandlerRegistration mouseWheelHandler

The handler for MouseWheelEvents.

touchStartHandler

HandlerRegistration touchStartHandler

The handler for TouchStartEvents.

touchEndHandler

HandlerRegistration touchEndHandler

The handler for TouchEndEvents.

touchMoveHandler

HandlerRegistration touchMoveHandler

The handler for TouchMoveEvents.

zoomFactor

protected double zoomFactor

The current zoom level.

viewCorner

protected Point2D viewCorner

The coordinates of the lower left corner visible on the canvas.

view

protected final AbstractView<?> view

The view of this graph.

shifter

AbstractGraph.Shifter shifter

The controller for shifting this graph.

zoomer

AbstractGraph.Zoomer zoomer

The controller for zooming this graph.

contextMenu

protected ContextMenu contextMenu

The reference to the (shared) context menu.

tooltip

protected Tooltip tooltip

The reference to the (shared) tooltip.

tooltipProvider

BasicTooltipProvider tooltipProvider

The provider for tooltips.

scale

protected double scale

The scale of this graph. Used to translate width and height into canvas coordinates. For example, on retina displays the scale is typically 2, i.e. two pixels per unit width or height.

See Also:

• NativeJS.getDevicePixelRatio()
• Canvas.setCoordinateSpaceWidth(int)
• Canvas.setCoordinateSpaceHeight(int)

wrapper

LayoutPanel wrapper

The wrapper element which displays the canvas. Subclasses may use this to add further elements to the graph such as labels.

msgLabel

protected Label msgLabel

Overlay label used to display graph messages.

logger

protected Logger logger

Logger for keeping track of and reporting events and issues.

element

protected Element element

Handle to the object's underlying DOM element.

canvas

protected Canvas canvas

Handle to the canvas for drawing the graphics.

g

protected AbstractGraph.MyContext2d g

Handle to the graphical context for drawing on the canvas.

colors

protected String[] colors

The array of colors used for drawing the graph.

markers

protected List<double[]> markers

Markers for decorating the graph.

markerColors

protected String[] markerColors

The array of colors used for markers.

module

protected Module<?> module

The module backing the graph.

bounds

protected Rectangle2D bounds

The bounds of the displaying area. This excludes any frames and/or axes labels.

style

protected GraphStyle style

The style of the graph. Includes labels, fonts, etc.

Y_TICK_LABEL_GAP

private static final double Y_TICK_LABEL_GAP

Horizontal gap between y ticks and their labels.

See Also:

• Constant Field Values

Y_AXIS_LABEL_MIN_GAP

private static final double Y_AXIS_LABEL_MIN_GAP

Minimum horizontal gap between y tick labels and the y-axis label.

See Also:

• Constant Field Values

Y_AXIS_LABEL_RESERVED_GAP

private static final double Y_AXIS_LABEL_RESERVED_GAP

Default horizontal gap reserved between y tick labels and the y-axis label. This exceeds Y_AXIS_LABEL_MIN_GAP so modest tick-label width changes can be absorbed without moving the axis label.

See Also:

• Constant Field Values

Y_AXIS_LABEL_THICKNESS

private static final double Y_AXIS_LABEL_THICKNESS

Approximate horizontal thickness reserved for the rotated y-axis label.

See Also:

• Constant Field Values

yAxisLabelTickSkip

protected double yAxisLabelTickSkip

Optional override for the horizontal offset of the y-axis label. When this is not set, the offset is derived from the cached y-axis tick-label width and the configured label gap.

cachedMidYTickLabelWidth

private double cachedMidYTickLabelWidth

Cached width of the midpoint y tick label from the most recent bounds calculation.

buffer

protected RingBuffer<B> buffer

The buffer to store historical data, if applicable.

MIN_BUFFER_SIZE

protected static final int MIN_BUFFER_SIZE

The minimum buffer size.

See Also:

• Constant Field Values

DEFAULT_BUFFER_SIZE

protected static final int DEFAULT_BUFFER_SIZE

The default buffer size. Must be at least MIN_BUFFER_SIZE.

See Also:

• Constant Field Values

CURSOR_GRAB_NODE_CLASS

static final String CURSOR_GRAB_NODE_CLASS

CSS class applied when the user is grabbing a node.

See Also:

• Constant Field Values

CURSOR_MOVE_NODE_CLASS

static final String CURSOR_MOVE_NODE_CLASS

CSS class applied when the user is dragging a node.

See Also:

• Constant Field Values

CURSOR_ZOOM_IN_CLASS

static final String CURSOR_ZOOM_IN_CLASS

CSS class applied when the user is zooming in.

See Also:

• Constant Field Values

CURSOR_ZOOM_OUT_CLASS

static final String CURSOR_ZOOM_OUT_CLASS

CSS class applied when the user is zooming out.

See Also:

• Constant Field Values

MIN_NORM_DIST_SQ

protected static final double MIN_NORM_DIST_SQ

Squared normalized mean-distance threshold for throttling successive samples.

See Also:

• Constant Field Values

MIN_NORM_DELTA

protected static final double MIN_NORM_DELTA

Normalized absolute-difference threshold for max-delta throttling.

See Also:

• Constant Field Values

MIN_CURVATURE_STEP_SQ

protected static final double MIN_CURVATURE_STEP_SQ

Squared minimum normalized step before curvature checks.

See Also:

• Constant Field Values

TURN_COS_THRESHOLD

protected static final double TURN_COS_THRESHOLD

Cosine threshold for a turn-angle criterion (\(6^\circ\)).

hasZoom

protected boolean hasZoom

The flag to indicate whether the graph supports zoom. The default is no support.

TWOPI

private static final double TWOPI

Constant representing the numerical value of \(2 \pi\)

See Also:

• Constant Field Values

PIHALF

protected static final double PIHALF

Constant representing the numerical value of \(\pi/2\)

See Also:

• Constant Field Values

MAX_SEGEMENTS

private static final int MAX_SEGEMENTS

The maximum number of line segments to draw before returning control to the event loop.

See Also:

• Constant Field Values

hasMessage

protected boolean hasMessage

Flag to indicate whether the graph displays a message.

message

protected String message

The last message displayed on the graph.

msgFontSize

protected double msgFontSize

Cached font size of the last displayed message.

msgLineHeight

protected double msgLineHeight

Cached line height of the last displayed message.

leftMouseButton

protected boolean leftMouseButton

The flag to indicate whether the left mouse button is pressed.

mouseX

protected int mouseX

The x-coordinate of the previous mouse or tap event.

mouseY

protected int mouseY

The y-coordinate of the previous mouse or tap event.

CSS_CURSOR_MOVE_VIEW

protected static final String CSS_CURSOR_MOVE_VIEW

The CSS class name for the view movement cursor.

See Also:

• Constant Field Values

touchEndTime

protected double touchEndTime

The time when the previous touch ended.

pinchX

protected int pinchX

The x-coordinate of the center of the pinching gesture.

pinchY

protected int pinchY

The y-coordinate of the center of the pinching gesture.

pinchDist

protected double pinchDist

The distance between the pinching gesture.

zoomInertiaTimer

protected Timer zoomInertiaTimer

The timer to remove the CSS classes .evoludo-cursorZoomIn or .evoludo-cursorZoomIn, respectively, from the graph element after the inertia of zooming has worn off.

Constructor Details

AbstractGraph

protected AbstractGraph(AbstractView<?> view,
 Module<?> module)

Create the base class for graphs. Allocates the canvas, retrieves the shared tooltip and context menu. Use the CSS class evoludo-Canvas2D for custom formatting of the canvas element.

Parameters:

view - the view of this graph

module - the module backing the graph

Method Details

setTooltipProvider

public void setTooltipProvider(BasicTooltipProvider tooltipProvider)

Set the provider for tooltips.

Parameters:

tooltipProvider - the provider for tooltips

getBuffer

public RingBuffer<B> getBuffer()

Return the RingBuffer<double[]> containing historical data, if applicable.

Returns:

the buffer with historical data or null

onLoad

protected void onLoad()

Overrides:

onLoad in class Widget

onUnload

protected void onUnload()

Overrides:

onUnload in class Widget

parse

public boolean parse(String args)

Parse the arguments for the graph. Default implementation does nothing.

Parameters:

args - the arguments for the graph

Returns:

true if parsing was successful

activate

public void activate()

Perform necessary preparations to show the graph in the GUI. Attaches mouse and touch handlers for graphs that implement AbstractGraph.Zooming or AbstractGraph.Shifting interfaces.

See Also:

• deactivate()

deactivate

public void deactivate()

The graph is removed from the GUI. Opportunity for some clean up. Removes all mouse and touch handlers from graph.

See Also:

• activate()

onResize

public void onResize()

Specified by:

onResize in interface RequiresResize

updateCanvas

private void updateCanvas()

Update the canvas size and coordinate space dimensions. IMPORTANT: Setting the canvas size or the coordinate space dimensions clears the canvas (even with no actual changes)!

reset

public void reset()

Reset the graph. Clear canvas and messages.

init

public void init()

Initialize the graph. Do not clear graph.

paint

public void paint()

Draw the graph.

getModule

public Module<?> getModule()

Get the module that backs the graph.

Returns:

the module

paint

public boolean paint(boolean force)

Draw the graph. For re-drawing the graph, set force to true.

Parameters:

force - true to force re-drawing of graph

Returns:

true if painting skipped

setMarkers

public void setMarkers(List<double[]> markers)

Assign a list of markers to the graph.

Parameters:

markers - the list of markers

setMarkers

public void setMarkers(List<double[]> markers,
 String[] colors)

Assign a list of markers with custom colors to the graph.

Parameters:

markers - the list of markers

colors - the list of custom colors

setColors

public void setColors(String[] colors)

Assign a list of colors to the graph.

Parameters:

colors - the list of colors

hasHistory

public boolean hasHistory()

Check whether the graph entertains a buffer with historical data.

Returns:

true if the graph stores the data history

clearHistory

public void clearHistory()

Clear the history of the graph (if there is one).

prependTime2Data

protected double[] prependTime2Data(double t,
 double[] data)

Utility method to prepend time to data point.

Parameters:

t - the time

data - the data

Returns:

the new data array including time

keepSample

protected boolean keepSample(RingBuffer<double[]> history,
 double[] current,
 double[] last)

Decide whether to retain a candidate sample by applying a display-agnostic heuristic: normalized mean squared distance and local curvature.

Parameters:

history - ring buffer holding retained samples (latest first)

current - candidate sample including prepended time

last - most recently retained sample including prepended time

Returns:

true if sample should be kept

normDelta

protected final double normDelta(double current,
 double last)

Compute the normalized difference between two values.

Parameters:

current - the current value

last - the reference value

Returns:

the normalized difference

maxDelta

protected final double maxDelta(double[] current,
 double[] last)

Compute the maximum absolute normalized difference between two samples, excluding time.

Parameters:

current - current sample including prepended time

last - reference sample including prepended time

Returns:

the maximum absolute normalized difference, or Double.POSITIVE_INFINITY if the samples are invalid or contain non-finite entries

normDeltaSq

protected final double normDeltaSq(double[] current,
 double[] last)

Compute the mean squared normalized difference between two samples, excluding time.

Parameters:

current - current sample including prepended time

last - reference sample including prepended time

Returns:

the mean squared normalized difference, or Double.POSITIVE_INFINITY if the samples are invalid or contain non-finite entries

hasSignificantTurn

protected final boolean hasSignificantTurn(double[] current,
 double[] last,
 double[] prev)

Check whether the last two retained segments form a sufficiently strong turn.

Parameters:

current - candidate sample including prepended time

last - most recently retained sample including prepended time

prev - previous retained sample before last including prepended time

Returns:

true if local turn angle exceeds threshold

populateContextMenuAt

public void populateContextMenuAt(ContextMenu menu,
 int x,
 int y)

Populate context menu menu in listening widget at (relative) position (x,y).

Adds buffer size menu and queries the view to add further functionality.

Specified by:

populateContextMenuAt in interface ContextMenu.Provider

Parameters:

menu - context menu entries are added here

x - horizontal coordinate (relative to listening widget)

y - horizontal coordinate (relative to listening widget)

See Also:

• AbstractView.populateContextMenu(ContextMenu)

populateLocalAxesMenu

public void populateLocalAxesMenu(ContextMenu menu)

Opportunity for graph subclasses to contribute graph-local entries to the shared axes submenu assembled by the owning view.

Parameters:

menu - the axes submenu to populate

addClearMenu

protected void addClearMenu(ContextMenu menu)

Add a clear-history entry to the context menu when this graph stores history.

Parameters:

menu - the context menu to populate

addLogScaleMenu

protected void addLogScaleMenu(ContextMenu menu)

Add logarithmic scale menu item to context menu if graph supports log scale on y-axis.

Parameters:

menu - the context menu to populate

addZoomMenu

protected void addZoomMenu(ContextMenu menu)

Add zoom menu items to context menu if graph supports zooming.

Parameters:

menu - the context menu to populate

populateZoomMenu

protected void populateZoomMenu(ContextMenu menu)

Populate the zoom submenu with standard zoom actions.

Parameters:

menu - the zoom submenu to populate

setLogY

void setLogY(boolean logY)

Set the y-axis to logarithmic scale if logY is true and if yMin ≥ 0. If yMin == 0 it is increased to 0.01 * yMax. If yMin < 0 logarithmic scale requests are ignored.

Parameters:

logY - true to set logarithmic scale on y-axis

contains

public boolean contains(int x,
 int y)

Checks if the (browser) coordinates (x, y) are inside this graph. This is useful for controllers that may manage several graphs.

Parameters:

x - the x-coordinate to check

y - the y-coordinate to check

Returns:

true if (x, y) is inside graph

convertToScaledCoordinates

public Point2D convertToScaledCoordinates(int x,
 int y)

Convert the (browser) coordinates (x, y) to scaled coordinates in \([0,1]^2\).

Parameters:

x - the x-coordinate to convert

y - the y-coordinate to convert

Returns:

the converted coordinates

convertToScaledCoordinates

public Point2D convertToScaledCoordinates(int x,
 int y,
 Point2D dest)

Convert the (browser) coordinates (x, y) to scaled coordinates in \([0,1]^2\) and store in dest.

Parameters:

x - the x-coordinate to convert

y - the y-coordinate to convert

dest - the point to save the converted coordinates

Returns:

the converted coordinates

export

public abstract void export(AbstractGraph.MyContext2d ctx)

Export the graphical context ctx.

Parameters:

ctx - the graphical context to export

calcBounds

protected boolean calcBounds()

Calculate bounds of drawing area. If element has never been visible its size is not yet known.

Returns:

true if bounds are successfully calculated.

calcBounds

public void calcBounds(int width,
 int height)

Calculate bounds of drawing area.

Parameters:

width - the width of the drawing area

height - the height of the drawing area

adjustBoundsForLabels

private void adjustBoundsForLabels()

Adjust bounds to make room for axes labels.

adjustBoundsForTickLabels

private void adjustBoundsForTickLabels()

Adjust bounds to make room for tick labels.

adjustBoundsForYSide

private void adjustBoundsForYSide(double padding)

Adjust bounds to make room for y-axis decorations on the selected side.

Parameters:

padding - the horizontal padding to reserve

adjustBoundsForLegend

protected void adjustBoundsForLegend()

Adjust bounds to make room for an optional legend.

The base implementation is a no-op and serves as a hook for subclasses that render legends.

drawFrame

protected void drawFrame(int xLevels,
 int yLevels)

Draw the frame of the graph including axes labels, ticks and tick marks, as applicable.

Implementation Note:

The top, left corner of the canvas is assumed to be at (0, 0). Flips the direction of the y-axis.

Parameters:

xLevels - the number of vertical levels

yLevels - the number of horizontal levels

See Also:

• GraphStyle

drawFrame

protected void drawFrame(int xLevels,
 int yLevels,
 double gscale)

Draw the frame of the graph including axes labels, ticks and tick marks, as applicable, after scaling the canvas by gscale.

Implementation Note:

After scaling the origin (0, 0) is assumed to be in the bottom, left corner of the canvas.

Parameters:

xLevels - the number of vertical levels

yLevels - the number of horizontal levels

gscale - the scaling applied to the coordinate transformation

drawFrameBorder

private void drawFrameBorder(double w,
 double h)

Draw the bounding box of the graph frame.

Parameters:

w - frame width

h - frame height

drawXLevels

private void drawXLevels(int xLevels,
 double w,
 double h)

Draw regular vertical guide lines, ticks, and labels.

Parameters:

xLevels - number of levels

w - frame width

h - frame height

drawCustomXLevels

private void drawCustomXLevels(double w,
 double h)

Draw vertical guide lines at custom x positions.

Parameters:

w - frame width

h - frame height

drawYLevels

private void drawYLevels(int yLevels,
 double w,
 double h)

Draw the y-levels including ticks and tick labels.

Parameters:

yLevels - the number of horizontal levels

w - the width of the graph

h - the height of the graph

computeYRange

private double[] computeYRange()

Compute the (possibly logarithmic) y-range for tick computations.

Returns:

array {ymin, yrange}

computeYVal

private double computeYVal(int n,
 double frac,
 double yrange,
 double ymin)

Compute the y-value for tick number n.

Parameters:

n - tick index

frac - fractional spacing between ticks

yrange - total y-range (possibly logarithmic)

ymin - minimum y-value (possibly logarithmic)

Returns:

the y-value represented by the tick

drawYTickLabel

private void drawYTickLabel(double w,
 double level,
 int n,
 double yval,
 int digits)

Draw the y-axis tick label at the specified screen level.

Parameters:

w - frame width

level - screen y-position for the tick

n - tick index

yval - y-value represented by the tick

digits - decimal digits for tick label formatting

computeLinearDigits

private int computeLinearDigits(double min,
 double max,
 int levels,
 boolean percent,
 boolean pretty)

Compute the number of decimal digits needed for linear labels so consecutive ticks remain distinct.

Parameters:

min - axis minimum

max - axis maximum

levels - number of tick levels

percent - whether values are percent formatted

pretty - whether to use pretty formatting for duplicates check

Returns:

decimal digits for linear labels

computeYTickDigits

private int computeYTickDigits(int levels)

Compute the number of decimal digits needed for y-axis tick labels.

Parameters:

levels - number of y-axis intervals

Returns:

decimal digits for y tick labels

formatYTickLabel

private String formatYTickLabel(double tickValue,
 int digits)

Format a y-axis tick label using the same pretty formatting as the renderer.

Parameters:

tickValue - the y value represented by the tick

digits - decimal digits for pretty formatting

Returns:

the formatted tick label

measureYTickLabelWidth

private double measureYTickLabelWidth(String[] numexp,
 boolean percent)

Measure the width of a y-axis tick label including exponent and percent.

Parameters:

numexp - the tick label split into base and exponent parts

percent - whether a percent sign is appended

Returns:

the total width in pixels

measureMidYTickLabelWidth

private double measureMidYTickLabelWidth(int digits)

Measure the width of the midpoint y-axis tick label using the same pretty formatting as the renderer. This is the label most likely to interfere with the vertical axis label.

Parameters:

digits - decimal digits for pretty formatting

Returns:

measured midpoint tick label width

drawCustomYLevels

private void drawCustomYLevels(double w,
 double h)

Draw horizontal guide lines at custom y positions.

Parameters:

w - frame width

h - frame height

drawXAxisLabel

private void drawXAxisLabel(double w,
 double h)

Draw the x-axis label.

Parameters:

w - frame width

h - frame height

drawYAxisLabel

private void drawYAxisLabel(double w,
 double h)

Draw the y-axis label, including positioning logic based on tick labels.

Parameters:

w - frame width

h - frame height

getYAxisLabelTickSkip

protected double getYAxisLabelTickSkip()

Get the horizontal offset to use for the y-axis label.

Returns:

the y-axis label offset, including reserved whitespace beyond the y tick labels

drawGraphLabel

private void drawGraphLabel(double gscale)

Draw the label shown inside the graph canvas.

Parameters:

gscale - current canvas scale factor

setFont

protected void setFont(String cssfont)

Set the font to cssfont in CSS format for drawing on the canvas.

Parameters:

cssfont - the font for drawing

setStrokeStyleAt

protected void setStrokeStyleAt(int node)

Set the stroke colour for node with index node.

Parameters:

node - the index of the node

stroke

protected void stroke(Path2D path)

Draw the path path.

Parameters:

path - the path to draw

fill

protected void fill(Path2D path)

Fill the path path.

Parameters:

path - the path to fill

sketch

private void sketch(Path2D path,
 boolean fill)

Draw or fill (if fill == true) the path path.

Implementation notes:

• Drawing too many segments at once becomes very slow (why?).
• Periodically closing and stroking the path is orders of magnitudes faster!
• This simple change renders freezing of the GUI essentially a non issue.
• SVG seems to be a stickler about opening and closing paths or empty paths (see Canvas2SVG.js)

Parameters:

path - the path to draw (or fill)

fill - true to fill path

closePath

private void closePath(boolean fill)

Helper method to close the path and draw (or fill) it.

Parameters:

fill - true to fill path

strokeRect

protected void strokeRect(double x,
 double y,
 double w,
 double h)

Draw the rectangle with origin at (x,y), width w and height h.

Parameters:

x - the x-coordinate of the origin

y - the y-coordinate of the origin

w - the width of the rectangle

h - the height of the rectangle

fillRect

protected void fillRect(double x,
 double y,
 double w,
 double h)

Fill the rectangle with origin at (x,y), width w and height h.

Parameters:

x - the x-coordinate of the origin

y - the y-coordinate of the origin

w - the width of the rectangle

h - the height of the rectangle

strokeCircle

protected void strokeCircle(Node2D node)

Draw the outline of the 2D node.

Parameters:

node - the node to draw

strokeCircle

protected void strokeCircle(Point2D point,
 double radius)

Draw the outline of a circle at point with radius.

Parameters:

point - the node to draw

radius - the radius of the circle

strokeCircle

protected void strokeCircle(double x,
 double y,
 double radius)

Draw the circle with the center at (x,y) and radius radius.

Parameters:

x - the x-coordinate of the center

y - the y-coordinate of the center

radius - the radius of the circle

fillCircle

protected void fillCircle(Node2D node)

Draw the filled 2D node.

Parameters:

node - the node to draw

fillCircle

protected void fillCircle(Point2D point,
 double radius)

Draw a filled circle at point with radius.

Parameters:

point - the node to draw

radius - the radius of the circle

fillCircle

protected void fillCircle(double x,
 double y,
 double radius)

Fill the circle with the center at (x,y) and radius radius.

Parameters:

x - the x-coordinate of the center

y - the y-coordinate of the center

radius - the radius of the circle

sketchCircle

private void sketchCircle(double x,
 double y,
 double radius)

Helper method to create a path for a circle with the center at (x,y) and radius radius.

Parameters:

x - the x-coordinate of the center

y - the y-coordinate of the center

radius - the radius of the circle

strokeLine

protected void strokeLine(Point2D a,
 Point2D b)

Draw a line from point a to b).

Parameters:

a - the start point

b - the end point

strokeLine

protected void strokeLine(double sx,
 double sy,
 double ex,
 double ey)

Draw a line from point (sx,sy) to (ex,ey).

Parameters:

sx - the x-coordinate of the start point

sy - the y-coordinate of the start point

ex - the x-coordinate of the end point

ey - the y-coordinate of the end point

fillTextVertical

protected void fillTextVertical(String msg,
 double x,
 double y)

Draw filled text vertically starting at point (x,y)

Parameters:

msg - the text to write

x - the x-coordinate of the start point

y - the y-coordinate of the start point

clearGraph

public void clearGraph()

Clear the graph.

clearCanvas

protected void clearCanvas()

Clear the canvas.

Implementation note:

Assumes scaled canvas coordinates, i.e. lower, left corner at (0,0).

resetTransforms

protected void resetTransforms()

Reset the transformation of the graphics context to the identity transform.

displayMessage

public boolean displayMessage(String msg)

Display message msg on the graph (no HTML formatting).

Parameters:

msg - the message to display

Returns:

true if message displayed

displayMessage

public boolean displayMessage(String msg,
 boolean autoscale)

Display message msg on the graph (no HTML formatting), optionally autoscaling the text to the available width.

Parameters:

msg - the message to display

autoscale - true to scale the text to the available width

Returns:

true if message displayed

clearMessage

public void clearMessage()

Clear the message.

onMessageDisplayed

protected void onMessageDisplayed()

Hook invoked after a message has been displayed.

onMessageCleared

protected void onMessageCleared()

Hook invoked after a message has been cleared.

hasMessage

public boolean hasMessage()

Check if the graph displays a message.

Returns:

true if message displayed

zoom

public void zoom()

Reset zoom. Default implementation for graphs that implement Zooming.

See Also:

• AbstractGraph.Zooming.zoom()

zoom

public void zoom(double zoom)

Adjust zoom level by the factor zoom. Default implementation for graphs that implement Zooming.

Parameters:

zoom - the new zoom level

See Also:

• AbstractGraph.Zooming.zoom(double)

zoom

public void zoom(double zoom,
 int x,
 int y)

Adjust zoom level by the factor zoom with the center at coordinates (x,y) (in display coordinates as provided by event listeners). Default implementation for graphs that implement Zooming.

Parameters:

zoom - the new zoom level

x - the x-coordinate of the zoom center

y - the y-coordinate of the zoom center

See Also:

• AbstractGraph.Zoomer.zoom(double, int, int)

zoom

protected void zoom(double zoom,
 double fx,
 double fy)

Helper method to adjust zoom level with the zoom center at the scaled coordinates (fx, fy), specified as a fraction of the view port in horizontal and vertical directions, respectively.

Parameters:

zoom - the new zoom level

fx - the scaled x-coordinate of the zoom center

fy - the scaled y-coordinate of the zoom center

See Also:

• onMouseWheel(MouseWheelEvent)
• onTouchMove(TouchMoveEvent)

getMaxViewCornerX

protected double getMaxViewCornerX(double zoom)

Get the maximum horizontal view-corner offset for the zoom factor zoom.

Parameters:

zoom - the zoom factor

Returns:

the maximum horizontal offset

getMaxViewCornerY

protected double getMaxViewCornerY(double zoom)

Get the maximum vertical view-corner offset for the zoom factor zoom.

Parameters:

zoom - the zoom factor

Returns:

the maximum vertical offset

shift

public void shift(int dx,
 int dy)

Shift the (zoomed) graph within the view port by (dx, dy). Default implementation for graphs that implement Shifting.

Parameters:

dx - the horizontal shift of the graph

dy - the vertical shift of the graph

See Also:

• AbstractGraph.Shifter.shift(int, int)

inside

protected boolean inside(int x,
 int y)

Check if the event coordinates are inside the interactive plot area. Default implementation accepts all coordinates.

Parameters:

x - the x-coordinate relative to the graph element

y - the y-coordinate relative to the graph element

Returns:

true if inside the interactive plot area

onMouseOut

public void onMouseOut(MouseOutEvent event)

If mouse leaves graph while shifting the view stop shifting. Mouse events are no longer received and hence it is impossible to track releasing or pressing mouse buttons.

Specified by:

onMouseOut in interface MouseOutHandler

onMouseDown

public void onMouseDown(MouseDownEvent event)

If a node has been hit by a left-click, remember the node's index and the current mouse coordinates. This information might be used by subsequent MouseMoveEvents.

Specified by:

onMouseDown in interface MouseDownHandler

See Also:

• onMouseMove(MouseMoveEvent)

onMouseUp

public void onMouseUp(MouseUpEvent event)

Cancel all interactions with the graph and reset node and mouse information.

CSS Style Rules

.evoludo-cursorMoveView

removed from graph element.

Specified by:

onMouseUp in interface MouseUpHandler

See Also:

• onMouseMove(MouseMoveEvent)

onMouseMove

public void onMouseMove(MouseMoveEvent event)

If the left mouse-key is pressed the graph is shifted within its viewport. Note this requires that the zoom level of the graph exceeds 1.

CSS Style Rules

.evoludo-cursorMoveView

added to graph element when shifting the view.

Specified by:

onMouseMove in interface MouseMoveHandler

See Also:

• onMouseDown(MouseDownEvent)

onMouseWheel

public void onMouseWheel(MouseWheelEvent event)

Adjusts the zoom level of the graph, while preserving the location of the mouse on the graph. The zooming has inertia.

CSS Style Rules

.evoludo-cursorZoomIn

added to graph element when zooming in and removed when inertia stops.

.evoludo-cursorZoomOut

added to graph element when zooming out and removed when inertia stops.

Specified by:

onMouseWheel in interface MouseWheelHandler

See Also:

• zoom(double, int, int)
• zoomInertiaTimer

onTouchStart

public void onTouchStart(TouchStartEvent event)

The graph reacts to different kinds of touches: short touches or taps (<250 msec) and long touches (>250 msec). Long touches trigger different actions depending on the number of fingers:

Single finger

Initiate shifting the view

Two fingers

Initiate pinching zoom.

Specified by:

onTouchStart in interface TouchStartHandler

See Also:

• onTouchMove(TouchMoveEvent)

onTouchEnd

public void onTouchEnd(TouchEndEvent event)

The number of touches on the graph changed.

Specified by:

onTouchEnd in interface TouchEndHandler

onTouchMove

public void onTouchMove(TouchMoveEvent event)

The graph reacts to different kinds of touch moves:

Move one finger

Shift view

Pinch two fingers

Zoom view

Specified by:

onTouchMove in interface TouchMoveHandler

addContextMenuHandler

public HandlerRegistration addContextMenuHandler(ContextMenuHandler handler)

Specified by:

addContextMenuHandler in interface HasContextMenuHandlers

getStyle

public GraphStyle getStyle()

Get the graph style.

Returns:

the graph style

autoscale

public void autoscale(boolean x,
 boolean y)

Set auto-scaling for horizontal and vertical axes.

Parameters:

x - true to automatically scale the x-axis

y - true to automatically scale the y-axis