Transfer Modes

Transfer Modes defined constants

#include <Quickdraw.h>

This shows the effect of the “source transfer” modes when drawing text on various

patterns; ie, calling TextMode(n ), followed by DrawChar('A'). The same effects

are seen in bit transfer operations, such as CopyBits and CopyMask.

For some reason, there is a separate set of transfer mode constants for

line-drawing and paint operations. At the bit- level, these “pattern transfer”

modes function the same as the source transfer modes. The next figure shows the

effect of using these pattern transfer modes. The samples were created by filling a

rectangle with a background pattern (FillRect), setting the transfer mode via

PenMode(n ), and painting an oval with a brick-work pattern (PaintOval).

The values of the Quickdraw transfer mode constants are:

srcCopy 0 overwrite background entirely

srcOr 1 overwrite where character (or source bitmap) is black

srcXor 2 invert where character (or source bitmap) is black

srcBic 3 force white where character (or source bitmap) is black

notSrcCopy 4 invert character (or source bitmap), then srcCopy

notSrcOr 5 invert character (or source bitmap), then srcOr

notSrcXor 6 invert character (or source bitmap), then srcXor

notSrcBic 7 invert character (or source bitmap), then srcBic

patCopy 8 overwrite background entirely

patOr 9 overwrite where pattern is black

patXor 10 invert where pattern and background are both black

patBic 11 force white where pattern is black

notPatCopy 12 invert pen pattern, then patCopy

notPatOr 13 invert pen pattern, then patOr

notPatXor 14 invert pen pattern, then patXor

notPatBic 15 invert pen pattern, then patBic

When using old-model colors via ForeColor and BackColor, most of these

operations remain intuitive. Instead of forcing white, an operation changes a pixel

to the current background color; instead of forcing black, the operation changes a

pixel to the current foreground color. The effect of an “ invert” operation depends

on the hardware in use.

Referenced by (18):