eu.webtoolkit.jwt
Class WCanvasPaintDevice

java.lang.Object
  eu.webtoolkit.jwt.WObject
      eu.webtoolkit.jwt.WCanvasPaintDevice

All Implemented Interfaces:

WPaintDevice

public class WCanvasPaintDevice
extends WObject
implements WPaintDevice

A paint device for rendering using the HTML 5 <canvas> element.

The WCanvasPaintDevice is used by WPaintedWidget to render to the browser using the HTML 5 <canvas> element. You usually will not use the device directly, but rather rely on WPaintedWidget to use this device when appropriate.

Note: Older browsers do not have text support in <canvas>. Text is then rendered in an overlayed DIV and a consequence text is not subject to rotation and scaling components of the current transformation (but does take into account translation). On most browser you can use the WSvgImage or WVmlImage paint devices which do support text natively.

Nested Class Summary

Nested classes/interfaces inherited from interface eu.webtoolkit.jwt.WPaintDevice

WPaintDevice.ChangeFlag, WPaintDevice.FeatureFlag

Constructor Summary

WCanvasPaintDevice(WLength width, WLength height)
Create a canvas paint device.

WCanvasPaintDevice(WLength width, WLength height, WObject parent)
Create a canvas paint device.

WCanvasPaintDevice(WLength width, WLength height, WObject parent, boolean paintUpdate)
Create a canvas paint device.

Method Summary

void	done() Finishes painting on the device.
void	drawArc(WRectF rect, double startAngle, double spanAngle) Draws an arc.
void	drawImage(WRectF rect, java.lang.String imgUri, int imgWidth, int imgHeight, WRectF sourceRect) Draws an image.
void	drawLine(double x1, double y1, double x2, double y2) Draws a line.
void	drawPath(WPainterPath path) Draws a path.
void	drawText(WRectF rect, java.util.EnumSet<AlignmentFlag> flags, TextFlag textFlag, java.lang.CharSequence text) Draws text.
java.util.EnumSet<WPaintDevice.FeatureFlag>	getFeatures() Returns device features.
WFontMetrics	getFontMetrics() Returns font metrics.
WLength	getHeight() Returns the device height.
WPainter	getPainter() Returns the painter that is currently painting on the device.
WLength	getWidth() Returns the device width.
void	init() Initializes the device for painting.
boolean	isPaintActive() Returns whether painting is active.
WTextItem	measureText(java.lang.CharSequence text) Measures rendered text size.
WTextItem	measureText(java.lang.CharSequence text, double maxWidth) Measures rendered text size.
WTextItem	measureText(java.lang.CharSequence text, double maxWidth, boolean wordWrap) Measures rendered text size.
void	setChanged(java.util.EnumSet<WPaintDevice.ChangeFlag> flags) Indicates changes in painter state.
void	setChanged(WPaintDevice.ChangeFlag flag, WPaintDevice.ChangeFlag... flags) Indicates changes in painter state.
void	setPainter(WPainter painter) Sets the painter.

Methods inherited from class eu.webtoolkit.jwt.WObject

addChild, getId, getObjectName, remove, setObjectName, tr

Methods inherited from class java.lang.Object

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

Constructor Detail

WCanvasPaintDevice

public WCanvasPaintDevice(WLength width,
                          WLength height,
                          WObject parent,
                          boolean paintUpdate)

Create a canvas paint device.

WCanvasPaintDevice

public WCanvasPaintDevice(WLength width,
                          WLength height)

Create a canvas paint device.

Calls this(width, height, (WObject)null, false)

WCanvasPaintDevice

public WCanvasPaintDevice(WLength width,
                          WLength height,
                          WObject parent)

Create a canvas paint device.

Calls this(width, height, parent, false)

Method Detail

getFeatures

public java.util.EnumSet<WPaintDevice.FeatureFlag> getFeatures()

Description copied from interface: WPaintDevice

Returns device features.

Specified by:

getFeatures in interface WPaintDevice

setChanged

public void setChanged(java.util.EnumSet<WPaintDevice.ChangeFlag> flags)

Description copied from interface: WPaintDevice

Indicates changes in painter state.

The flags argument is the logical OR of one or more change flags.

Specified by:

setChanged in interface WPaintDevice

See Also:

WPaintDevice.ChangeFlag

setChanged

public final void setChanged(WPaintDevice.ChangeFlag flag,
                             WPaintDevice.ChangeFlag... flags)

Description copied from interface: WPaintDevice

Indicates changes in painter state.

Calls setChanged(EnumSet.of(flag, flags))

Specified by:

setChanged in interface WPaintDevice

drawArc

public void drawArc(WRectF rect,
                    double startAngle,
                    double spanAngle)

Description copied from interface: WPaintDevice

Draws an arc.

The arc is defined as in WPainter#drawArc()

The arc must be stroked, filled, and transformed using the current painter settings.

Specified by:

drawArc in interface WPaintDevice

drawImage

public void drawImage(WRectF rect,
                      java.lang.String imgUri,
                      int imgWidth,
                      int imgHeight,
                      WRectF sourceRect)

Description copied from interface: WPaintDevice

Draws an image.

Draws sourceRect from the image with URL imageUri and original dimensions imgWidth and imgHeight to the location, into the rectangle defined by rect.

The image is transformed using the current painter settings.

Specified by:

drawImage in interface WPaintDevice

drawLine

public void drawLine(double x1,
                     double y1,
                     double x2,
                     double y2)

Description copied from interface: WPaintDevice

Draws a line.

The line must be stroked and transformed using the current painter settings.

Specified by:

drawLine in interface WPaintDevice

drawPath

public void drawPath(WPainterPath path)

Description copied from interface: WPaintDevice

Draws a path.

The path must be stroked, filled, and transformed using the current painter settings.

Specified by:

drawPath in interface WPaintDevice

drawText

public void drawText(WRectF rect,
                     java.util.EnumSet<AlignmentFlag> flags,
                     TextFlag textFlag,
                     java.lang.CharSequence text)

Description copied from interface: WPaintDevice

Draws text.

The text must be rendered, stroked and transformed using the current painter settings.

Specified by:

drawText in interface WPaintDevice

measureText

public WTextItem measureText(java.lang.CharSequence text,
                             double maxWidth,
                             boolean wordWrap)

Description copied from interface: WPaintDevice

Measures rendered text size.

Returns the bounding rect of the given text when rendered using the current font.

If maxWidth != -1, then the text is truncated to fit in the width.

If wordWrap = true then text is truncated only at word boundaries. Note that in this case the whitespace at the truncated position is included in the text but not accounted for by the returned width (since usually you will not render the whitespace at the end of a line).

Throws a std::logic_error if the underlying device does not provide font metrics.

Specified by:

measureText in interface WPaintDevice

measureText

public final WTextItem measureText(java.lang.CharSequence text)

Description copied from interface: WPaintDevice

Measures rendered text size.

Returns measureText(text, - 1, false)

Specified by:

measureText in interface WPaintDevice

measureText

public final WTextItem measureText(java.lang.CharSequence text,
                                   double maxWidth)

Description copied from interface: WPaintDevice

Measures rendered text size.

Returns measureText(text, maxWidth, false)

Specified by:

measureText in interface WPaintDevice

getFontMetrics

public WFontMetrics getFontMetrics()

Description copied from interface: WPaintDevice

Returns font metrics.

This returns font metrics for the current font.

Throws a std::logic_error if the underlying device does not provide font metrics.

Specified by:

getFontMetrics in interface WPaintDevice

init

public void init()

Description copied from interface: WPaintDevice

Initializes the device for painting.

This method is called when a WPainter starts painting.

Specified by:

init in interface WPaintDevice

See Also:

WPainter.begin(WPaintDevice device), WPaintDevice.getPainter()

done

public void done()

Description copied from interface: WPaintDevice

Finishes painting on the device.

This method is called when a WPainter stopped painting.

Specified by:

done in interface WPaintDevice

See Also:

WPainter.end()

isPaintActive

public boolean isPaintActive()

Description copied from interface: WPaintDevice

Returns whether painting is active.

Specified by:

isPaintActive in interface WPaintDevice

See Also:

WPaintDevice.init(), WPaintDevice.getPainter()

getWidth

public WLength getWidth()

Description copied from interface: WPaintDevice

Returns the device width.

The device width, in pixels, establishes the width of the device coordinate system.

Specified by:

getWidth in interface WPaintDevice

getHeight

public WLength getHeight()

Description copied from interface: WPaintDevice

Returns the device height.

The device height, in pixels, establishes the height of the device coordinate system.

Specified by:

getHeight in interface WPaintDevice

getPainter

public WPainter getPainter()

Description copied from interface: WPaintDevice

Returns the painter that is currently painting on the device.

Specified by:

getPainter in interface WPaintDevice

See Also:

WPaintDevice.init()

setPainter

public void setPainter(WPainter painter)

Description copied from interface: WPaintDevice

Sets the painter.

Specified by:

setPainter in interface WPaintDevice