Document Revision History

This table describes the changes to CGContext Reference.

2013-09-18Added deprecation information; removed symbols from the documentation that were removed from the headers. Clarified which functions clear the context's path.
2013-01-28Corrected formula for kCGBlendModePlusDarker.
2011-10-12Moved line constants to the CGPath Reference.
2010-08-03Moved fill rules for paths to the Quartz 2D Programming Guide.
2010-07-01Clarifications on many CGContext functions.

Clarified how the parameters of CGContextDrawTiledImage affect the final result.


CGContextSetAllowsAntialiasing is not part of the graphics state.


Clarified how paths are created and drawn. Some terminology for paths is defined in CGPath Reference.

2010-05-20Documented symbols being made publicly available in iOS 4.0.
2009-05-26Updated function discussions to account for coordinate system differences between iOS and OS X.
2008-04-08Made a minor typographical change.
2007-07-17Updated for OS X v10.5.

All instances of the float data type were changed to the CGFloat data type.


Added the Porter-Duff blend modes to “CGBlendMode”.


Added CGContextDrawLinearGradient, CGContextDrawRadialGradient, CGContextDrawTiledImage, CGContextShowGlyphsAtPositions, and CGContextBeginTransparencyLayerWithRect.


Modified the description of the auxiliaryInfo parameter in CGContextBeginTransparencyLayer.


Added a performance tip to CGContextBeginTransparencyLayer.


Clarified the definition of “inside” for CGContextPathContainsPoint.

2006-01-10 Added information to the discussion for blend mode constants.

Improved wording concerning text clipping in “CGTextDrawingMode.”

2005-11-09Revised information about text space and user space.
2005-04-29 Updated for OS X v10.4.

Added the functions CGContextSetBlendMode, CGContextAddEllipseInRect, CGContextReplacePathWithStrokedPath, CGContextPathContainsPoint, CGContextFillEllipseInRect, CGContextStrokeEllipseInRect, CGContextStrokeLineSegments, CGContextClipToMask, CGContextSetAllowsAntialiasing, CGContextGetUserSpaceToDeviceSpaceTransform, CGContextConvertPointToDeviceSpace, CGContextConvertPointToUserSpace, CGContextConvertSizeToDeviceSpace, CGContextConvertSizeToUserSpace, CGContextConvertRectToDeviceSpace, and CGContextConvertRectToUserSpace.


Added constants for “CGBlendMode”.


Changed the description of what to pass for the components parameter for the functions CGContextSetFillPattern and CGContextSetStrokePattern.


Updated graphics context information and added cross references to conceptual documentation.


First version of this document. An earlier version of this information appeared in Quartz 2D Reference.