com.sencha.gxt.chart.client.draw.engine

Class Canvas2d

java.lang.Object

com.sencha.gxt.chart.client.draw.Surface

com.sencha.gxt.chart.client.draw.engine.Canvas2d

public class Canvas2d
extends Surface

Canvas-based implementation of the Surface api, using the 2-d context (as opposed to webgl, etc). EXPERIMENTAL, DISABLED BY DEFAULT, AND NOT OFFICIALLY SUPPORTED. This implementation may in some cases be faster than the built-in SVG or VML implementations, and may be configured as an official implementation in the future, but for now purely experimental. Use at your own risk. Known caveats of using Canvas over a DOM-based implementation like SVG or VML:

• Font details aren't managed by the DOM, so TextSprites must have a font size and family set to avoid the browser default.
• Any change requires a full repaint of the entire canvas, presently this is implmenent as a deferred call to wait for any other changes within the current event loop.

Known bugs and missing features:

• Gradients are partially implemented, and do not correctly handle the angle property
• Sprite.setCursor is ignored
• TextSprite.setFontStyle and setFontWeight are ignored
• TextSprite.getBBox() may not be correct
• High density displays (i.e. 'retina') are not correctly supported

Field Summary

Fields inherited from class com.sencha.gxt.chart.client.draw.Surface

backgroundSprite, component, container, height, sprites, surfaceElement, width

Constructor Summary

Constructors

Constructor and Description
Canvas2d()

Method Summary

Modifier and Type	Method and Description
protected void	append(Sprite sprite) In the Canvas2d class, this method does more or less what renderSprite does in SVG and VML - it actually renders the sprite to the dom.
protected void	appendAll()
protected void	appendPath(Context2d ctx, PathSprite sprite)
void	draw() Renders the surface to the DOM as well as any sprites already added.
protected PreciseRectangle	getBBoxText(TextSprite sprite) Calculates the bounding box of the given text sprite.
protected CanvasElement	getCanvas()
protected Context2d	getContext()
protected CanvasGradient	makeGradient(Gradient gradient, PreciseRectangle bbox)
protected void	renderAll() Renders all of the sprites added to the surface using Surface.renderSprite(Sprite).
void	renderSprite(Sprite sprite) Renders the given sprite to the DOM.
void	setCursor(Sprite sprite, String property) Sets the cursor property for the given sprite.
void	setHeight(int height) Sets the height of the surface.
void	setViewBox(double x, double y, double width, double height) Sets the view box of the surface.
void	setWidth(int width) Sets the width of the surface.

Methods inherited from class com.sencha.gxt.chart.client.draw.Surface

add, addGradient, clear, create, create, deleteSprite, getBBox, getComponent, getHeight, getSprites, getSurfaceElement, getWidth, setBackground

Methods inherited from class java.lang.Object

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

Constructor Detail

Canvas2d

public Canvas2d()

Method Detail

draw

public void draw()

Description copied from class: Surface

Renders the surface to the DOM as well as any sprites already added.

Overrides:

draw in class Surface

renderAll

protected void renderAll()

Description copied from class: Surface

Renders all of the sprites added to the surface using Surface.renderSprite(Sprite).

Overrides:

renderAll in class Surface

appendAll

protected void appendAll()

renderSprite

public void renderSprite(Sprite sprite)

Description copied from class: Surface

Renders the given sprite to the DOM.

Specified by:

renderSprite in class Surface

Parameters:

sprite - the sprite to be rendered

append

protected void append(Sprite sprite)

In the Canvas2d class, this method does more or less what renderSprite does in SVG and VML - it actually renders the sprite to the dom.

Parameters:

sprite - the sprite to draw

appendPath

protected void appendPath(Context2d ctx,
                          PathSprite sprite)

setCursor

public void setCursor(Sprite sprite,
                      String property)

Description copied from class: Surface

Sets the cursor property for the given sprite.

Specified by:

setCursor in class Surface

Parameters:

sprite - the sprite to be set

property - the property to use

setViewBox

public void setViewBox(double x,
                       double y,
                       double width,
                       double height)

Description copied from class: Surface

Sets the view box of the surface. The view box scales the sprites in the surface.

Specified by:

setViewBox in class Surface

Parameters:

x - the x coordinate of the viewbox

y - the y coordinate of the viewbox

width - the width of the viewbox

height - the height of the viewbox

getBBoxText

protected PreciseRectangle getBBoxText(TextSprite sprite)

Description copied from class: Surface

Calculates the bounding box of the given text sprite.

Specified by:

getBBoxText in class Surface

Parameters:

sprite - the text sprite to be used in the calculation

Returns:

bounding box of the text sprite

getCanvas

protected CanvasElement getCanvas()

getContext

protected Context2d getContext()

setWidth

public void setWidth(int width)

Description copied from class: Surface

Sets the width of the surface.

Overrides:

setWidth in class Surface

Parameters:

width - the width of the surface.

setHeight

public void setHeight(int height)

Description copied from class: Surface

Sets the height of the surface.

Overrides:

setHeight in class Surface

Parameters:

height - the height of the surface.

makeGradient

protected CanvasGradient makeGradient(Gradient gradient,
                                      PreciseRectangle bbox)