ICanvas

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Interface ICanvas

interface ICanvas

Extends com.amazon.apmf.IStandard ICanvas provides an interface for drawing, and how the drawing is clipped and transformed.

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Methods

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concat()

void concat(AffineMatrix* affineMatrix)

This method preconcats the current AffineMatrix of the ICanvas with the specified matrix.

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Parameters

affineMatrix

AffineMatrix* — Required to preconcatenate with the current AffineMatrix of the ICanvas.

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setAffineMatrix()

void setAffineMatrix(AffineMatrix* affineMatrix)

This method sets the current AffineMatrix of the ICanvas to the specified matrix.

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Parameters

affineMatrix

AffineMatrix* — Required to replace with the current AffineMatrix of the ICanvas.

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clipRect()

void clipRect(Rect* rect)

This method performs intersecting clip operation with the current ICanvas using the specified Rect. Resulting clip will be anti-aliased by default.

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Parameters

rect

Rect* — Required The Rect to perform the clip operation with the current clip

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clipRRect()

void clipRRect(RRect* rRect)

This method performs intersecting clip operation with the current ICanvas using the specified RRect. Resulting clip will be anti-aliased by default.

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Parameters

rRect

RRect* — Required The RRect to perform the clip operation with the current clip

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clipPath()

void clipPath(IPath* path)

This method performs intersecting clip operation with the current ICanvas clip using the specified IPath. Resulting clip will be anti-aliased by default.

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Parameters

path

IPath* — Required The IPath to perform the clip operation with the current clip

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drawRect()

void drawRect(Rect* rect, IPaint* paint)

This method draws the specified Rect using the specified IPaint.

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Parameters

rect

Rect* — Required Rect to be drawn

paint

IPaint* — Required IPaint instance to draw the Rect.

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drawRRect()

void drawRRect(RRect* rRect, IPaint* paint)

This method draws the specified RRect using the specified IPaint.

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Parameters

rRect

RRect* — Required RRect to be drawn

paint

IPaint* — Required IPaint instance to draw the RRect.

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drawCircle()

void drawCircle(Point center, float radius, IPaint* paint)

This method draws the circle using the specified IPaint, center and radius.

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Parameters

center

Point — Required center of the circle

radius

float — Required radius of the circle

paint

IPaint* — Required IPaint instance to draw the circle

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drawPath()

void drawPath(IPath* path, IPaint* paint)

This method draws the specified IPath using the specified IPaint.

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Parameters

path

IPath* — Required IPath to be drawn

paint

IPaint* — Required IPaint instance to draw the IPath.

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rotateDegrees()

void rotateDegrees(float degrees, Point pivot)

This method preconcats the current AffineMatrix with the specified rotation about a pivot Point at (pivot.x, pivot.y)

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Parameters

degrees

float — Required The amount to rotate, in degrees

pivot

Point — Required pivot Point to be used for rotation

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save()

u32 save()

This method saves the current AffineMatrix and clip onto a private stack. Subsequent calls to ICanvas::translate, ICanvas::scale, ICanvas::rotateDegrees, ICanvas::concat, ICanvas::clipRect, or ICanvas::clipPath will all operate as usual, but when the balancing call to restore() is made, those calls will be forgotten, and the settings that existed before the save() will be reinstated.

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Returns

u32 depth of saved stack.

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restore()

void restore()

This method balances a previous call to ICanvas::save, and is used to remove all modifications to the matrix/clip state since the last save call.

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Throws

• InvalidOperationError — If it is called more times than ICanvas::save was called.

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restoreToCount()

void restoreToCount(u32 saveCount)

This method is an efficient way to pop any calls to ICanvas::save that happened after the save count reached saveCount. Does nothing if saveCount is greater than state stack count. Restores state to initial values if saveCount is less than or equal to one.

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Parameters

saveCount

u32 — Required The save level to restore to

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getSaveCount()

u32 getSaveCount()

This method returns current save count of the canvas stack

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Returns

u32 saveCount

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scale()

void scale(float scaleX, float scaleY)

This method preconcats the current AffineMatrix with the specified scale.

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Parameters

scaleX

float — Required amount to scale on x-axis

scaleY

float — Required amount to scale on y-axis

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translate()

void translate(Point distance)

This method preconcats the current AffineMatrix with the specified translation

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Parameters

distance

Point — Required distance to translate on both x-axis and y-axis

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drawOval()

void drawOval(Rect* oval, IPaint* paint)

This method draws the specified oval using the specified IPaint. The oval will be filled or framed based on the Style in the IPaint.

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Parameters

oval

Rect* — Required The bounds of oval used to define the shape and size of the oval.

paint

IPaint* — Required IPaint instance to draw.

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saveLayerAlpha()

u32 saveLayerAlpha(Rect* bounds, float alpha)

This method behaves the same as ICanvas::save, but in addition it allocates and redirects drawing to an offscreen rendering target. All drawing calls are directed to a newly allocated offscreen rendering target. Only when the balancing call to ICanvas::restore is made, is that offscreen buffer drawn back to the current target of the ICanvas (which can potentially be a previous layer if these calls are nested).

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Parameters

bounds

Rect* — Required The maximum size the offscreen render target needs to be (in local coordinates)

alpha

float — Required The alpha value to set, specified as a float.

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Returns

u32 saveCount value to pass to restoreToCount() to balance this save().

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