Inside Macintosh: QuickDraw GX Graphics /

Chapter 5 - Bitmap Shapes / Bitmap Shapes Reference

Functions / Editing Bitmaps

GXSetShapePixel

You can use the GXSetShapePixel function to change the pixel value of a specific pixel in a bitmap shape.

void GXSetShapePixel(gxShape target, long x, long y, 
                     const gxColor *newColor, long newIndex);

target

A reference to the bitmap shape containing the pixel to change.

x

The index of the column in which the pixel lies.

y

The index of the row in which the pixel lies.

newColor

A pointer to a gxColor structure indicating the new pixel value of the specified pixel. You may specify nil for this parameter if the target bitmap shape has the gxIndexedSpace color space.

newIndex

An index into a color set. You may use this parameter to set the pixel value if the target bitmap shape has the gxIndexedSpace color space.

DESCRIPTION

The GXSetShapePixel function sets the pixel value of a specific pixel in the target bitmap. The pixel is determined by the values you provide in the x and y parameters. The new pixel value is determined by the newColor or newIndex parameter:

• If you provide a color value in the newColor parameter, this function sets the pixel value of the specified pixel to be the closest color available in the color space of the target bitmap shape--even if the target bitmap shape has the gxIndexedSpace color space.
• Alternatively, and only if the target bitmap shape has the gxIndexedSpace color space, you may provide nil for the newColor parameter and provide in the newIndex parameter a new index into the color set of the bitmap shape.

This function posts a functionality_unimplemented error for disk-based bitmaps.

ERRORS, WARNINGS, AND NOTICES

Errors
out_of_memory
shape_is_nil
point_does_not_intersect_bitmap	(debugging only)
functionality_unimplemented	(debugging only)
Warnings
shape_does_not_contain_a_bitmap	(debugging only)

SEE ALSO

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

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

To change more than a single pixel of a bitmap, use the GXSetBitmapParts function, which is described on page 5-75.

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

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