In com.lowagie.text.Image#getInstance(Image, Color, boolean), there is
code that tries to detect an image with binary transparency. It assumes
that if the only alpha values are 0 and 255, the color of the first
pixel with transparency 0 is fully transparent throughout the
image. While this works for GIFs and images with pre-multiplied alpha,
it is possible to have a PNG image where the rgb values of fully
transparent pixels differ.
I've attached a patch that ensures that the color values of all
transparent pixels are the same. If they differ, it falls back on using
a full alpha channel.
Thanks,
Chris
*** Image.java.~1.95.~ Wed Jan 26 23:10:50 2005
--- Image.java Sun Jan 30 00:53:49 2005
***************
*** 576,593 ****
}
}
else {
smask = new byte[w * h];
boolean shades = false;
for (int j = 0; j < size; j++) {
byte alpha = smask[j] = (byte)((pixels[j] >> 24) & 0xff);
! if (alpha != 0 && alpha != -1)
! shades = true;
! if (transparency == null) {
! if (alpha == 0) {
! transparency = new int[6];
! transparency[0] = transparency[1] = (pixels[j] >>
16) & 0xff;
! transparency[2] = transparency[3] = (pixels[j] >>
8) & 0xff;
! transparency[4] = transparency[5] = pixels[j] &
0xff;
}
}
pixelsByte[index++] = (byte) ((pixels[j] >> 16) & 0xff);
--- 576,599 ----
}
}
else {
+ int transparentPixel = 0;
smask = new byte[w * h];
boolean shades = false;
for (int j = 0; j < size; j++) {
byte alpha = smask[j] = (byte)((pixels[j] >> 24) & 0xff);
! if (!shades) {
! if (alpha != 0 || alpha != -1) {
! shades = true;
! } else if (transparency == null) {
! if (alpha == 0) {
! transparentPixel = pixels[j] & 0xffffff;
! transparency = new int[6];
! transparency[0] = transparency[1] =
(transparentPixel >> 16) & 0xff;
! transparency[2] = transparency[3] =
(transparentPixel >> 8) & 0xff;
! transparency[4] = transparency[5] =
transparentPixel & 0xff;
! }
! } else if ((pixels[j] & 0xffffff) !=
transparentPixel) {
! shades = true;
}
}
pixelsByte[index++] = (byte) ((pixels[j] >> 16) & 0xff);
