Inside Macintosh: QuickDraw GX Graphics /

Chapter 5 - Bitmap Shapes / Bitmap Shapes Reference

Functions / Editing Bitmaps

GXGetBitmapParts

You can use the GXGetBitmapParts function to extract a rectangular section of pixels from a bitmap.

gxShape GXGetBitmapParts(gxShape source, 
                         const gxLongRectangle *bounds);

source

A reference to the bitmap shape containing the pixels to extract.

bounds

A pointer to a gxRectangle indicating which part of the bitmap to extract.

function result

A reference to a new bitmap shape containing only the extracted section
of the source bitmap shape.

DESCRIPTION

The GXGetBitmapParts function extracts the pixels whose row number and column number fall within the boundaries of the rectangle pointed to by the bounds parameter, encapsulates the extracted pixel image in a new bitmap shape, and returns a reference to the new bitmap shape as the function result.

The returned bitmap shape has the same pixel size as the source bitmap shape. The returned bitmap shape also shares the same color space, color set, and color profile as the source bitmap shape.

The pixel image of the returned bitmap is allocated in QuickDraw GX memory.

ERRORS, WARNINGS, AND NOTICES

Errors
out_of_memory
shape_is_nil
parameter_is_nil
parameter_out_of_range	(debugging only)
point_does_not_intersect_bitmap	(debugging only)
Warnings
shape_does_not_contain_a_bitmap	(debugging only)

SEE ALSO

For examples using this function, see "Editing Part of a Bitmap" beginning on page 5-53.

For information about the gxBitmap structure, see "The Bitmap Geometry Structure" beginning on page 5-62.

For information about the gxLongRectangle structure, see "The Long Rectangle Structure" on page 5-64.

For information about pixels and pixel images, see "Bitmap Geometries" beginning on page 5-5.

To examine a single pixel of a bitmap, use the GXGetShapePixel function, which is described on page 5-71.

To change a section of a bitmap, use the GXSetBitmapParts function, which is described in the next section.

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