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    copied!<p>The <a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html" rel="nofollow">CGAffineTransform</a> data structure represents a matrix used for affine transformations. A transformation specifies how points in one coordinate system map to points in another coordinate system. An affine transformation is a special type of mapping that preserves parallel lines in a path but does not necessarily preserve lengths or angles. Scaling, rotation, and translation are the most commonly used manipulations supported by affine transforms, but skewing is also possible.</p> <p>Quartz provides functions that create, concatenate, and apply affine transformations using the CGAffineTransform data structure. For information on how to use affine transformation functions, see <a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/Introduction/Introduction.html#//apple_ref/doc/uid/TP30001066" rel="nofollow">Quartz 2D Programming Guide</a>.</p> <p>You typically do not need to create an affine transform directly—<a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGContext/index.html#//apple_ref/doc/uid/TP30000950" rel="nofollow">CGContext Reference</a> describes functions that modify the current affine transform. If you don’t plan to reuse an affine transform, you may want to use <a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGContext/index.html#//apple_ref/c/func/CGContextScaleCTM" rel="nofollow">CGContextScaleCTM</a>, <a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGContext/index.html#//apple_ref/c/func/CGContextRotateCTM" rel="nofollow">CGContextRotateCTM</a>, <a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGContext/index.html#//apple_ref/c/func/CGContextTranslateCTM" rel="nofollow">CGContextTranslateCTM</a>, or <a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGContext/index.html#//apple_ref/c/func/CGContextConcatCTM" rel="nofollow">CGContextConcatCTM</a>.</p> <p><strong>Functions</strong></p> <p><strong>Creating an Affine Transformation Matrix</strong></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/macro/CGAffineTransformMake" rel="nofollow">CGAffineTransformMake</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformMakeRotation" rel="nofollow">CGAffineTransformMakeRotation</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformMakeScale" rel="nofollow">CGAffineTransformMakeScale</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformMakeTranslation" rel="nofollow">CGAffineTransformMakeTranslation</a></p> <p><strong>Modifying Affine Transformations</strong></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformTranslate" rel="nofollow">CGAffineTransformTranslate</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformScale" rel="nofollow">CGAffineTransformScale</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformRotate" rel="nofollow">CGAffineTransformRotate</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformInvert" rel="nofollow">CGAffineTransformInvert</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformConcat" rel="nofollow">CGAffineTransformConcat</a></p> <p><strong>Applying Affine Transformations</strong></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/macro/CGPointApplyAffineTransform" rel="nofollow">CGPointApplyAffineTransform</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/macro/CGSizeApplyAffineTransform" rel="nofollow">CGSizeApplyAffineTransform</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGRectApplyAffineTransform" rel="nofollow">CGRectApplyAffineTransform</a></p> <p><strong>Evaluating Affine Transforms</strong></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformIsIdentity" rel="nofollow">CGAffineTransformIsIdentity</a></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/func/CGAffineTransformEqualToTransform" rel="nofollow">CGAffineTransformEqualToTransform</a></p> <p><strong>Data Types</strong></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/c/tdef/CGAffineTransform" rel="nofollow">CGAffineTransform</a></p> <p><strong>Constants</strong></p> <p><a href="https://developer.apple.com/library/prerelease/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/index.html#//apple_ref/doc/constant_group/CGAffineTransformIdentity" rel="nofollow">CGAffineTransformIdentity</a></p>
 

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