About Transfer Modes
Basically, ink objects exist to specify two important characteristics of a shape: its color and the transfer mode to draw it with. Colors are described in the chapter "Colors and Color-Related Objects" in this book. Transfer modes are described here.Transfer modes specify how a shape's color is transferred onto a device. The color of a shape to be drawn (the source color) interacts with the existing color (the destination color) on the device it is drawn to. The color that results from that interaction is called the result color. The result color is the color of the destination after the drawing occurs.
Note that colors from different color spaces can be used. The source and destination colors are converted to the transfer mode's color space, and the resulting color is then reconverted to the destination color space.
QuickDraw GX allows you to influence the transfer mode operation in very flexible and powerful ways. By manipulating different parts of the transfer mode structure, you can specify
- Bitmaps and the ink object
- A bitmap shape does not use the color in its ink object, but it does use the ink's transfer mode. Transfer modes work the same for the pixels of bitmaps as they do for colors in ink objects. For more information, see the bitmap shapes chapter of Inside Macintosh: QuickDraw GX Graphics.
The rest of this section discusses these five aspects of transfer modes. The section concludes with a summary diagram (Figure 5-18 on page 5-37) of the transfer mode process.
- the type of transfer mode to apply to each color component
- the color space in which to perform the transfer-mode calculations
- limits on the values of color components that can be permitted in the source, destination, or result colors
- values for the source, destination, or result matrices that can allow you to perform sophisticated transformations within and across color components
- values for flags that affect several aspects of the transfer mode operation
Subtopics
- Transfer Mode Types
- Transfer Mode Color Space
- Color Limits
- Transfer Mode Matrices
- Flags
- Summary of Transfer Mode Operation