mirror of
https://github.com/python-pillow/Pillow.git
synced 2024-11-11 12:17:14 +03:00
109 lines
3.8 KiB
Plaintext
109 lines
3.8 KiB
Plaintext
====================================================================
|
|
The Photoimage Booster Patch (for Windows 95/NT)
|
|
====================================================================
|
|
|
|
This patch kit boosts performance for 16/24-bit displays. The
|
|
first patch is required on Tk 4.2 (where it fixes the problems for
|
|
16-bit displays) and later versions, with the exception for Tk 8.0b1
|
|
where Sun added something similar themselves, only to remove it in
|
|
8.0b2. By installing both patches, Tk's PhotoImage handling becomes
|
|
much faster on both 16-bit and 24-bit displays. The patch has been
|
|
tested with Tk 4.2 and 8.0.
|
|
|
|
Here's a benchmark, made with a sample program which loads two
|
|
512x512 greyscale PGM's, and two 512x512 colour PPM's, and displays
|
|
each of them in a separate toplevel windows. Tcl/Tk was compiled
|
|
with Visual C 4.0, and run on a P100 under Win95. Image load times
|
|
are not included in the timings:
|
|
|
|
8-bit 16-bit 24-bit
|
|
--------------------------------------------------------------------
|
|
1. original 4.2 code 5.52 s 8.57 s 3.79 s
|
|
2. booster patch 5.49 s 1.87 s 1.82 s
|
|
|
|
speedup None 4.6x 2.1x
|
|
|
|
====================================================================
|
|
|
|
Here's the patches:
|
|
|
|
1. For portability and speed, the best thing under Windows is to
|
|
treat 16-bit displays as if they were 24-bit. The Windows device
|
|
drivers take care of the rest.
|
|
|
|
----------------------------------------------------------------
|
|
If you have Tk 4.1 or Tk 8.0b1, you don't have to apply this
|
|
patch! It only applies to Tk 4.2, Tk 8.0a[12] and Tk 8.0b2.
|
|
----------------------------------------------------------------
|
|
|
|
In win/tkWinImage.c, change the following line in XCreateImage:
|
|
|
|
imagePtr->bits_per_pixel = depth;
|
|
|
|
to
|
|
|
|
/* ==================================================================== */
|
|
/* The tk photo image booster patch -- patch section 1 */
|
|
/* ==================================================================== */
|
|
|
|
if (visual->class == TrueColor)
|
|
/* true colour is stored as 3 bytes: (blue, green, red) */
|
|
imagePtr->bits_per_pixel = 24;
|
|
else
|
|
imagePtr->bits_per_pixel = depth;
|
|
|
|
/* ==================================================================== */
|
|
|
|
|
|
2. The DitherInstance implementation is not good. It's especially
|
|
bad on highend truecolour displays. IMO, it should be rewritten from
|
|
scratch (some other day...).
|
|
|
|
Anyway, the following band-aid makes the situation a little bit
|
|
better under Windows. This hack trades some marginal quality (no
|
|
dithering on 16-bit displays) for a dramatic performance boost.
|
|
Requires patch 1, unless you're using Tk 4.1 or Tk 8.0b1.
|
|
|
|
In generic/tkImgPhoto.c, add the #ifdef section to the DitherInstance
|
|
function:
|
|
|
|
for (; height > 0; height -= nLines) {
|
|
if (nLines > height) {
|
|
nLines = height;
|
|
}
|
|
dstLinePtr = (unsigned char *) imagePtr->data;
|
|
yEnd = yStart + nLines;
|
|
|
|
/* ==================================================================== */
|
|
/* The tk photo image booster patch -- patch section 2 */
|
|
/* ==================================================================== */
|
|
|
|
#ifdef __WIN32__
|
|
if (colorPtr->visualInfo.class == TrueColor
|
|
&& instancePtr->gamma == 1.0) {
|
|
/* Windows hicolor/truecolor booster */
|
|
for (y = yStart; y < yEnd; ++y) {
|
|
destBytePtr = dstLinePtr;
|
|
srcPtr = srcLinePtr;
|
|
for (x = xStart; x < xEnd; ++x) {
|
|
destBytePtr[0] = srcPtr[2];
|
|
destBytePtr[1] = srcPtr[1];
|
|
destBytePtr[2] = srcPtr[0];
|
|
destBytePtr += 3; srcPtr += 3;
|
|
}
|
|
srcLinePtr += lineLength;
|
|
dstLinePtr += bytesPerLine;
|
|
}
|
|
} else
|
|
#endif
|
|
|
|
/* ==================================================================== */
|
|
|
|
for (y = yStart; y < yEnd; ++y) {
|
|
srcPtr = srcLinePtr;
|
|
errPtr = errLinePtr;
|
|
destBytePtr = dstLinePtr;
|
|
|
|
====================================================================
|
|
last updated: 97-07-03/fl
|