Package com.google.gwt.canvas.dom.client

Class Context2d

java.lang.Object
com.google.gwt.core.client.JavaScriptObject
com.google.gwt.canvas.dom.client.Context2d
All Implemented Interfaces:
Context
public class Context2d extends JavaScriptObject implements Context
Rendering interface used to draw on a CanvasElement.
See Also:

  • Field Details

    • CONTEXT_ID

      public static final String CONTEXT_ID
      Specifies the context id property used in creating a Context.
      See Also:

  • Constructor Details

    • Context2d

      protected Context2d()

  • Method Details

    • arc

      public final void arc(double x, double y, double radius, double startAngle, double endAngle)
      Draws an arc. If a current subpath exists, a line segment is added from the current point to the starting point of the arc. If endAngle - startAngle is equal to or greater than 2 * Math.Pi, the arc is the whole circumference of the circle.
      Parameters:
      x - the x coordinate of the center of the arc
      y - the y coordinate of the center of the arc
      radius - the radius of the arc
      startAngle - the start angle, measured in radians clockwise from the positive x-axis
      endAngle - the end angle, measured in radians clockwise from the positive x-axis

    • arc

      public final void arc(double x, double y, double radius, double startAngle, double endAngle, boolean anticlockwise)
      Draws an arc. If a current subpath exists, a line segment is added from the current point to the starting point of the arc. If anticlockwise is false and endAngle - startAngle is equal to or greater than 2 * Math.PI, or if anticlockwise is true and startAngle - endAngle is equal to or greater than 2 * Math.PI, then the arc is the whole circumference of the circle.
      Parameters:
      x - the x coordinate of the center of the arc
      y - the y coordinate of the center of the arc
      radius - the radius of the arc
      startAngle - the start angle, measured in radians clockwise from the positive x-axis
      endAngle - the end angle, measured in radians clockwise from the positive x-axis
      anticlockwise - if true, the arc is drawn in an anticlockwise direction

    • arcTo

      public final void arcTo(double x1, double y1, double x2, double y2, double radius)
      Adds an arc to the current subpath, connecting it to the current point with a line segment.
      Parameters:
      x1 - the x coordinate of the starting point of the arc
      y1 - the y coordinate of the starting point of the arc
      x2 - the x coordinate of the ending point of the arc
      y2 - the y coordinate of the ending point of the arc
      radius - the radius of a circle containing the arc

    • beginPath

      public final void beginPath()
      Begins a new path.

    • bezierCurveTo

      public final void bezierCurveTo(double cp1x, double cp1y, double cp2x, double cp2y, double x, double y)
      Draws a cubic Bézier curve from the current point to the point (x, y), with control points (cp1x, cp1y) and (cp2x, cp2y).
      Parameters:
      cp1x - the x coordinate of the first control point
      cp1y - the y coordinate of the first control point
      cp2x - the x coordinate of the second control point
      cp2y - the y coordinate of the second control point
      x - the x coordinate of the end point
      y - the y coordinate of the end point

    • clearRect

      public final void clearRect(double x, double y, double w, double h)
      Clears a rectangle.
      Parameters:
      x - the x coordinate of the rectangle's upper-left corner
      y - the y coordinate of the rectangle's upper-left corner
      w - the width of the rectangle
      h - the height of the rectangle

    • clip

      public final void clip()
      Creates a new clipping region from the current path.

    • closePath

      public final void closePath()
      Closes the current path.

    • createImageData

      public final ImageData createImageData(ImageData imagedata)
      Creates an image data object of the same size as the given object.
      Parameters:
      imagedata - an ImageData object
      Returns:
      a new ImageData object

    • createImageData

      public final ImageData createImageData(int w, int h)
      Creates an image data object of the given size.
      Parameters:
      w - the width of the image
      h - the height of the image
      Returns:
      an ImageData object

    • createLinearGradient

      public final CanvasGradient createLinearGradient(double x0, double y0, double x1, double y1)
      Creates a linear gradient.
      Parameters:
      x0 - the x coordinate of the starting point of the gradient
      y0 - the y coordinate of the starting point of the gradient
      x1 - the x coordinate of the ending point of the gradient
      y1 - the y coordinate of the ending point of the gradient
      Returns:
      a CanvasGradient object

    • createPattern

      public final CanvasPattern createPattern(CanvasElement image, Context2d.Repetition repetition)
      Creates a pattern from another canvas.
      Parameters:
      image - an CanvasElement object
      repetition - a Context2d.Repetition object
      Returns:
      a CanvasPattern object

    • createPattern

      public final CanvasPattern createPattern(CanvasElement image, String repetition)
      Creates a pattern from another canvas.
      Parameters:
      image - an CanvasElement object
      repetition - the repetition type as a String
      Returns:
      a CanvasPattern object

    • createPattern

      public final CanvasPattern createPattern(ImageElement image, Context2d.Repetition repetition)
      Creates a pattern from an image.
      Parameters:
      image - an ImageElement object
      repetition - a Context2d.Repetition object
      Returns:
      a CanvasPattern object

    • createPattern

      public final CanvasPattern createPattern(ImageElement image, String repetition)
      Creates a pattern from an image.
      Parameters:
      image - an ImageElement object
      repetition - the repetition type as a String
      Returns:
      a CanvasPattern object

    • createRadialGradient

      public final CanvasGradient createRadialGradient(double x0, double y0, double r0, double x1, double y1, double r1)
      Creates a radial gradient.
      Parameters:
      x0 - the x coordinate of the center of the start circle of the gradient
      y0 - the y coordinate of the center of the start circle of the gradient
      r0 - the radius of the start circle of the gradient
      x1 - the x coordinate of the center of the end circle of the gradient
      y1 - the y coordinate of the center of the end circle of the gradient
      r1 - the radius of the end circle of the gradient
      Returns:
      a CanvasGradient object

    • drawImage

      public final void drawImage(CanvasElement image, double dx, double dy)
      Draws an image.
      Parameters:
      image - an CanvasElement object
      dx - the x coordinate of the upper-left corner of the destination rectangle
      dy - the y coordinate of the upper-left corner of the destination rectangle

    • drawImage

      public final void drawImage(CanvasElement image, double dx, double dy, double dw, double dh)
      Draws a scaled image.
      Parameters:
      image - an CanvasElement object
      dx - the x coordinate of the upper-left corner of the destination rectangle
      dy - the y coordinate of the upper-left corner of the destination rectangle
      dw - the width of the destination rectangle
      dh - the height of the destination rectangle

    • drawImage

      public final void drawImage(CanvasElement image, double sx, double sy, double sw, double sh, double dx, double dy, double dw, double dh)
      Draws a scaled subset of an image.
      Parameters:
      image - an CanvasElement object
      sx - the x coordinate of the upper-left corner of the source rectangle
      sy - the y coordinate of the upper-left corner of the source rectangle
      sw - the width of the source rectangle
      sh - the width of the source rectangle
      dx - the x coordinate of the upper-left corner of the destination rectangle
      dy - the y coordinate of the upper-left corner of the destination rectangle
      dw - the width of the destination rectangle
      dh - the height of the destination rectangle

    • drawImage

      public final void drawImage(ImageElement image, double dx, double dy)
      Draws an image.
      Parameters:
      image - an ImageElement object
      dx - the x coordinate of the upper-left corner of the destination rectangle
      dy - the y coordinate of the upper-left corner of the destination rectangle

    • drawImage

      public final void drawImage(ImageElement image, double dx, double dy, double dw, double dh)
      Draws a scaled image.
      Parameters:
      image - an ImageElement object
      dx - the x coordinate of the upper-left corner of the destination rectangle
      dy - the y coordinate of the upper-left corner of the destination rectangle
      dw - the width of the destination rectangle
      dh - the height of the destination rectangle

    • drawImage

      public final void drawImage(ImageElement image, double sx, double sy, double sw, double sh, double dx, double dy, double dw, double dh)
      Draws a scaled subset of an image.
      Parameters:
      image - an ImageElement object
      sx - the x coordinate of the upper-left corner of the source rectangle
      sy - the y coordinate of the upper-left corner of the source rectangle
      sw - the width of the source rectangle
      sh - the width of the source rectangle
      dx - the x coordinate of the upper-left corner of the destination rectangle
      dy - the y coordinate of the upper-left corner of the destination rectangle
      dw - the width of the destination rectangle
      dh - the height of the destination rectangle

    • drawImage

      public final void drawImage(VideoElement image, double dx, double dy)
      Draws a video's current frame.
      Parameters:
      image - a VideoElement object
      dx - the x coordinate of the upper-left corner of the destination rectangle
      dy - the y coordinate of the upper-left corner of the destination rectangle

    • drawImage

      public final void drawImage(VideoElement image, double dx, double dy, double dw, double dh)
      Draws a scaled video's current frame.
      Parameters:
      image - a VideoElement object
      dx - the x coordinate of the upper-left corner of the destination rectangle
      dy - the y coordinate of the upper-left corner of the destination rectangle
      dw - the width of the destination rectangle
      dh - the height of the destination rectangle

    • drawImage

      public final void drawImage(VideoElement image, double sx, double sy, double sw, double sh, double dx, double dy, double dw, double dh)
      Draws a scaled subset of a video's current frame.
      Parameters:
      image - a VideoElement object
      sx - the x coordinate of the upper-left corner of the source rectangle
      sy - the y coordinate of the upper-left corner of the source rectangle
      sw - the width of the source rectangle
      sh - the width of the source rectangle
      dx - the x coordinate of the upper-left corner of the destination rectangle
      dy - the y coordinate of the upper-left corner of the destination rectangle
      dw - the width of the destination rectangle
      dh - the height of the destination rectangle

    • fill

      public final void fill()
      Fills the current path.

    • fillRect

      public final void fillRect(double x, double y, double w, double h)
      Fills a rectangle.
      Parameters:
      x - the x coordinate of the rectangle's upper-left corner
      y - the y coordinate of the rectangle's upper-left corner
      w - the width of the rectangle
      h - the height of the rectangle

    • fillText

      public final void fillText(String text, double x, double y)
      Draws filled text.
      Parameters:
      text - the text as a String
      x - the x coordinate of the text position
      y - the y coordinate of the text position

    • fillText

      public final void fillText(String text, double x, double y, double maxWidth)
      Draws filled text squeezed into the given max width.
      Parameters:
      text - the text as a String
      x - the x coordinate of the text position
      y - the y coordinate of the text position
      maxWidth - the maximum width for the text

    • getCanvas

      public final CanvasElement getCanvas()
      Gets this context's canvas.
      Returns:
      a CanvasElement object

    • getFillStyle

      public final FillStrokeStyle getFillStyle()
      Returns the context's fillStyle. In dev mode, the returned object will be wrapped in a JavaScript array.
      Returns:
      a FillStrokeStyle object
      See Also:

    • getFont

      public final String getFont()
      Gets this context's font.
      Returns:
      the font name as a String
      See Also:

    • getGlobalAlpha

      public final double getGlobalAlpha()
      Gets the global alpha value.
      Returns:
      the global alpha value as a double
      See Also:

    • getGlobalCompositeOperation

      public final String getGlobalCompositeOperation()
      Gets the global composite operation.
      Returns:
      the global composite operation as a String
      See Also:

    • getImageData

      public final ImageData getImageData(double sx, double sy, double sw, double sh)
      Returns an image data object for the screen area denoted by sx, sy, sw and sh.
      Parameters:
      sx - the x coordinate of the upper-left corner of the desired area
      sy - the y coordinate of the upper-left corner of the desired area
      sw - the width of the desired area
      sh - the height of the desired area
      Returns:
      an ImageData object containing screen pixel data

    • getLineCap

      public final String getLineCap()
      Gets the current line-cap style.
      Returns:
      the line cap style as a String
      See Also:

    • getLineJoin

      public final String getLineJoin()
      Gets the current line-join style.
      Returns:
      the line join style as a String
      See Also:

    • getLineWidth

      public final double getLineWidth()
      Gets the current line-width.
      Returns:
      the line width as a double
      See Also:

    • getMiterLimit

      public final double getMiterLimit()
      Gets the current miter-limit.
      Returns:
      the miter limit as a double
      See Also:

    • getShadowBlur

      public final double getShadowBlur()
      Gets the current shadow-blur.
      Returns:
      the shadow blur amount as a double
      See Also:

    • getShadowColor

      public final String getShadowColor()
      Gets the current shadow color.
      Returns:
      the shadow color as a String
      See Also:

    • getShadowOffsetX

      public final double getShadowOffsetX()
      Gets the current x-shadow-offset.
      Returns:
      the shadow x offset as a double
      See Also:

    • getShadowOffsetY

      public final double getShadowOffsetY()
      Gets the current y-shadow-offset.
      Returns:
      the shadow y offset as a double
      See Also:

    • getStrokeStyle

      public final FillStrokeStyle getStrokeStyle()
      Returns the context's strokeStyle. In dev mode, the returned object will be wrapped in a JavaScript array.
      Returns:
      the stroke style as a FillStrokeStyle object
      See Also:

    • getTextAlign

      public final String getTextAlign()
      Gets the current text align.
      Returns:
      the text align as a String
      See Also:

    • getTextBaseline

      public final String getTextBaseline()
      Gets the current text baseline.
      Returns:
      the text baseline as a String
      See Also:

    • isPointInPath

      public final boolean isPointInPath(double x, double y)
      Returns true if the given point is in the current path.
      Parameters:
      x - the x coordinate of the point to test.
      y - the y coordinate of the point to test.
      Returns:
      true if the given point is in the current path.

    • lineTo

      public final void lineTo(double x, double y)
      Adds a line from the current point to the point (x, y) to the current path.
      Parameters:
      x - the x coordinate of the line endpoint
      y - the y coordinate of the line endpoint

    • measureText

      public final TextMetrics measureText(String text)
      Returns the metrics for the given text.
      Parameters:
      text - the text to measure, as a String
      Returns:
      a TextMetrics object

    • moveTo

      public final void moveTo(double x, double y)
      Terminates the current path and sets the current path position to the point (x, y).
      Parameters:
      x - the x coordinate of the new position
      y - the y coordinate of the new position

    • putImageData

      public final void putImageData(ImageData imagedata, double x, double y)
      Draws the given image data at the given screen position.
      Parameters:
      imagedata - an ImageData instance to be written to the screen
      x - the x coordinate of the upper-left corner at which to draw
      y - the y coordinate of the upper-left corner at which to draw

    • quadraticCurveTo

      public final void quadraticCurveTo(double cpx, double cpy, double x, double y)
      Draws a quadratic Bézier curve from the current point to the point (x, y), with control point (cpx, cpy).
      Parameters:
      cpx - the x coordinate of the control point
      cpy - the y coordinate of the control point
      x - the x coordinate of the end point
      y - the y coordinate of the end point

    • rect

      public final void rect(double x, double y, double w, double h)
      Creates a new rectangular path.
      Parameters:
      x - the x coordinate of the rectangle's upper-left corner
      y - the y coordinate of the rectangle's upper-left corner
      w - the width of the rectangle
      h - the height of the rectangle

    • restore

      public final void restore()
      Restores the context's state.

    • rotate

      public final void rotate(double angle)
      Applies rotation to the current transform.
      Parameters:
      angle - the clockwise rotation angle, in radians

    • save

      public final void save()
      Saves the context's state.

    • scale

      public final void scale(double x, double y)
      Applies scale to the current transform.
      Parameters:
      x - the scale factor along the x-axis
      y - the scale factor along the y-axis

    • setFillStyle

      public final void setFillStyle(FillStrokeStyle fillStyle)
      Sets the context's fillStyle.
      Parameters:
      fillStyle - the fill style to set.
      See Also:

    • setFillStyle

      public final void setFillStyle(String fillStyleColor)
      Convenience method to set the context's fillStyle to a CssColor, specified in String form.
      Parameters:
      fillStyleColor - the color as a String
      See Also:

    • setFont

      public final void setFont(String f)
      Sets the font.
      Parameters:
      f - the font name as a String
      See Also:

    • setGlobalAlpha

      public final void setGlobalAlpha(double alpha)
      Sets the global alpha value.
      Parameters:
      alpha - the global alpha value as a double
      See Also:

    • setGlobalCompositeOperation

      public final void setGlobalCompositeOperation(Context2d.Composite composite)
      Sets the global composite operation.
      Parameters:
      composite - a Context2d.Composite value
      See Also:

    • setGlobalCompositeOperation

      public final void setGlobalCompositeOperation(String globalCompositeOperation)
      Sets the global composite operation.
      Parameters:
      globalCompositeOperation - the operation as a String
      See Also:

    • setLineCap

      public final void setLineCap(Context2d.LineCap lineCap)
      Sets the line-cap style.
      Parameters:
      lineCap - the line cap style as a Context2d.LineCap value
      See Also:

    • setLineCap

      public final void setLineCap(String lineCap)
      Sets the line-cap style.
      Parameters:
      lineCap - the line cap style as a String
      See Also:

    • setLineJoin

      public final void setLineJoin(Context2d.LineJoin lineJoin)
      Sets the line-join style.
      Parameters:
      lineJoin - the line join style as a Context2d.LineJoin value
      See Also:

    • setLineJoin

      public final void setLineJoin(String lineJoin)
      Sets the line-join style.
      Parameters:
      lineJoin - the ling join style as a String
      See Also:

    • setLineWidth

      public final void setLineWidth(double lineWidth)
      Sets the line-width.
      Parameters:
      lineWidth - the line width as a double
      See Also:

    • setMiterLimit

      public final void setMiterLimit(double miterLimit)
      Sets the miter-limit.
      Parameters:
      miterLimit - the miter limit as a double
      See Also:

    • setShadowBlur

      public final void setShadowBlur(double shadowBlur)
      Sets the shadow-blur.
      Parameters:
      shadowBlur - the amount of blur as a double
      See Also:

    • setShadowColor

      public final void setShadowColor(String shadowColor)
      Sets the shadow-color.
      Parameters:
      shadowColor - the shadow color as a String
      See Also:

    • setShadowOffsetX

      public final void setShadowOffsetX(double shadowOffsetX)
      Sets the x-shadow-offset.
      Parameters:
      shadowOffsetX - the x shadow offset
      See Also:

    • setShadowOffsetY

      public final void setShadowOffsetY(double shadowOffsetY)
      Sets the y-shadow-offset.
      Parameters:
      shadowOffsetY - the y shadow offset
      See Also:

    • setStrokeStyle

      public final void setStrokeStyle(FillStrokeStyle strokeStyle)
      Sets the context's stroke style.
      Parameters:
      strokeStyle - the stroke style to set
      See Also:

    • setStrokeStyle

      public final void setStrokeStyle(String strokeStyleColor)
      Convenience method to set the context's strokeStyle to a CssColor.
      Parameters:
      strokeStyleColor - the stroke color as a String
      See Also:

    • setTextAlign

      public final void setTextAlign(String align)
      Sets the text alignment.
      Parameters:
      align - the alignment setting as a String
      See Also:

    • setTextAlign

      public final void setTextAlign(Context2d.TextAlign align)
      Sets the text alignment.
      Parameters:
      align - the alignment setting as a Context2d.TextAlign value
      See Also:

    • setTextBaseline

      public final void setTextBaseline(String baseline)
      Sets the text baseline.
      Parameters:
      baseline - the baseline setting as a String
      See Also:

    • setTextBaseline

      public final void setTextBaseline(Context2d.TextBaseline baseline)
      Sets the text baseline.
      Parameters:
      baseline - a the baseline setting as a Context2d.TextBaseline value
      See Also:

    • setTransform

      public final void setTransform(double m11, double m12, double m21, double m22, double dx, double dy)
      Sets the 2D transformation matrix.
      Parameters:
      m11 - the value at position (1, 1) of the matrix
      m12 - the value at position (1, 2) of the matrix
      m21 - the value at position (2, 1) of the matrix
      m22 - the value at position (2, 2) of the matrix
      dx - the x translation value
      dy - the y translation value

    • stroke

      public final void stroke()
      Draws the current path with the current stroke style.

    • strokeRect

      public final void strokeRect(double x, double y, double w, double h)
      Draws the outline of a rectangle with the current stroke style.
      Parameters:
      x - the x coordinate of the rectangle's upper-left corner
      y - the y coordinate of the rectangle's upper-left corner
      w - the width of the rectangle
      h - the height of the rectangle

    • strokeText

      public final void strokeText(String text, double x, double y)
      Draws the text outline.
      Parameters:
      text - the text as a String
      x - the x coordinate of the text position
      y - the y coordinate of the text position

    • strokeText

      public final void strokeText(String text, double x, double y, double maxWidth)
      Draws the text outline, squeezing the text into the given max width by compressing the font.
      Parameters:
      text - the text as a String
      x - the x coordinate of the text position
      y - the y coordinate of the text position
      maxWidth - the maximum width for the text

    • transform

      public final void transform(double m11, double m12, double m21, double m22, double dx, double dy)
      Multiplies the current transform by the given matrix.
      Parameters:
      m11 - the value at position (1, 1) of the matrix
      m12 - the value at position (1, 2) of the matrix
      m21 - the value at position (2, 1) of the matrix
      m22 - the value at position (2, 2) of the matrix
      dx - the x translation value
      dy - the y translation value

    • translate

      public final void translate(double x, double y)
      Applies a translation to the current transform.
      Parameters:
      x - the amount of translation along the x-axis
      y - the amount of translation along the y-axis