- Object
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- org.freedesktop.bindings.Pointer
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- org.freedesktop.bindings.Proxy
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- org.freedesktop.cairo.Matrix
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public class Matrix extends org.freedesktop.bindings.ProxyA matrix describing an affine transformation.You can apply this transformation to a Cairo Context with its
transform()method as follows:matrix = new Matrix(); matrix.rotate(...); // and/or matrix.scale(...); // and/or matrix.translate(...); cr.transform(matrix);
Calls to therotate(),scale(), andtranslatemethods are cumulative on a given Matrix.Applying a transformation is what take you from device co-ordinates to user-space co-ordinates; you are in fact always working in the later but we tend not to focus on this as the default is naturally no transformation.
Examples
In each of the illustrations below, we draw a box as follows:
cr.setSource(0.7, 0.8, 0.8); cr.rectangle(5, 5, 25, 15); cr.stroke();
We then apply the transform shown, change colour to blue, and then draw the exact same rectangle again:cr.setSource(0.0, 0.0, 1.0); cr.rectangle(5, 5, 25, 15); cr.stroke();
Thus both the original rectangle and the result of the matrix operation are shown.- Since:
- 4.0.10
- Author:
- Andrew Cowie
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Constructor Summary
Constructors Constructor and Description Matrix()Construct a new transformation matrix with the identity (no-op) transform.
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Constructor Detail
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Matrix
public Matrix()
Construct a new transformation matrix with the identity (no-op) transform.- Since:
- 4.0.10
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Method Detail
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rotate
public void rotate(double angle)
Rotate the transformation by the given angle. As with elsewhere in Cairo,angleis in radians.
matrix.rotate(-Math.PI / 4.0); cr.transform(matrix);
A negative angle is used in this example for the same reason as discussed in
arc().- Since:
- 4.0.10
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scale
public void scale(double sx, double sy)Scale bysxhorizontally andsyvertically.
matrix.scale(-0.8, 1.6); cr.transform(matrix);
Note that in this example thesxargument being negative results in a reflection through the y axis. Note also that the line widths are not the same as the original image's were; only scaling by1.0would have left the widths alone.Don't scale by
0.- Since:
- 4.0.10
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translate
public void translate(double tx, double ty)Translate bytxhorizontally andtyvertically.
matrix.translate(5, 10); cr.transform(matrix);
- Since:
- 4.0.10
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