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This sections describes the following display driver enhancements:
 
♦  Transparent Block Transfers
 
♦  Large Icons & Cursors
 
♦  Default System Colors
 
♦  Grabber Extensions
 
♦  Palette Management
 
Transparent Block Transfers
 
In Windows 3.1, display drivers can indicate that they support transparent
block transfers by setting the C1_TRANSPARENT bit in the dpCaps1 member of
the GDIINFO structure. In a transparent block transfer, a driver excludes
source and brush pixels from a BitBlt or StretchBlt operation if those
pixels have the same color as the current background color for the
destination device.
 
If a display driver supports transparent block transfers, the BitBlt
function must check the bkMode member of the lpDrawMode parameter as well as
the Rop3 parameter to determine how to carry out the transfer. If the
bkMode member specifies the background mode TRANSPARENT1, BitBlt must not
transfer source and brush bits that have the same color as the destination's
background color (as specified by the bkColor member of lpDrawMode). In
other words, the corresponding destination bits must be left unchanged.
Other background modes do not affect the transfer.
 
Large Icons & Cursors
 
In Windows 3.1, display drivers can use icons larger than 64-by-64 bits and
cursors larger than 32-by-32 bits. Large icons and cursors can improve
screen readability for high-resolution graphics adapters.
 
Display drivers specify icon and cursor size in the IconXRatio, IconYRatio,
CurXRatio, and CurYRatio members of the CONFIG.BIN resource (that is, the
resource having identifier 1 and type OEMBIN). In Windows 3.1, these members
specify either a width and height in pixels or a compression ratio. In
Windows 3.0, these members only specify compression ratios. For a complete
description of the members, see the ◄CONFIG.BIN► resource.
 
In all cases, each icon or cursor must have the same width and height in
pixels.
 
Display drivers which specify actual widths and heights in the OEMBIN
resource can not be used with Windows 3.0. Drivers which specify compression
factors work with both Windows 3.0 and 3.1. However, drivers cannot
simultaneously specify compression factors and icons/cursors larger than
32-by-32.
 
Default System Colors
 
The CONFIG.BIN resource specifies the default system colors (as well as
several other OEM-specific values). For Windows 3.1, the recommended default
system color values for 16- and 256-color displays are new. In particular,
several system colors that were patterned (dithered) in Windows 3.0 have
been changed to solids to improve performance and visibility on interlaced
displays.
 
In Windows 3.1, the CONFIG.BIN resource has been expanded to include the
clrInactiveCaptionText member. This member specifies the color of the text
in the title bar of an inactive window.
 
For a complete description of the default system colors and the
clrInactiveCaptionText member, see the ◄CONFIG.BIN► resource.
 
Grabber Extensions
 
Windows 3.1 grabber file extensions have been changed to .2GR for
standard-mode grabbers, and .3GR for enhanced-mode grabbers. This change was
necessitated by a new file compression and naming scheme used for the
Windows 3.1 installation diskettes. This change should not affect the
operation or installation of existing display drivers with Windows 3.1.
 
Palette Management
 
Graphics drivers that support color palettes must make sure that the index
for the palette entry that corresponds to black must be the one's complement
of the index for the palette entry for white. Black and white must be
"static" palette entries meaning the driver sets the indexes for these
colors during initialization and does not change the indexes.
 
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