Bitmap Styles and Inks (IM: XG)

Inside Macintosh: QuickDraw GX Graphics /: Chapter 5 - Bitmap Shapes / About Bitmap Shapes

Bitmap Styles and Inks
Although bitmap shapes have style objects and ink objects, they do not make full use of the properties of these objects. Of the many properties of the style object, only the style attributes property affects bitmap shapes. In fact, only the gxSourceGridStyle and gxDeviceGridStyle style attributes affect bitmap shapes.
QuickDraw GX ignores the other style attributes and the other style properties when drawing a bitmap shape. You can set the values of these properties and determine the values you have set them to, but they do not affect how the bitmap is drawn.
See Chapter 3, "Geometric Styles," for a description of how the gxSourceGridStyle and gxDeviceGridStyle style attributes affect shapes, including bitmap shapes.
Of the ink object properties, bitmaps use the transfer mode property and ignore the color property. Since bitmap shapes have color information stored in their geometries, they do not need the color information stored in their ink objects. You can set the color of a bitmap shape's ink object, but it does not affect how the bitmap is drawn.
The transfer mode property, on the other hand, does affect the drawing of the bitmap. QuickDraw GX applies the transfer mode as it draws each pixel of the bitmap, as shown in Figure 5-4. You can find a color version of this figure in Plate 1 at the front of this book.
Figure 5-4 The effect of transfer modes on bitmap shapes

The section "Applying Transfer Modes to Bitmaps" beginning on page 5-32 shows you how to apply a transfer mode to a bitmap shape.