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colorize-alpha: only recolor if source alpha is > 0 to avoid overpainted background - refs #1371

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This commit is contained in:
Dane Springmeyer 2012-08-03 14:48:02 -07:00
parent 9284c6369d
commit b43697fd5d
1 changed files with 30 additions and 23 deletions
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53
deps/agg/include/agg_pixfmt_rgba.h vendored
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@ -1468,31 +1468,38 @@ namespace agg
// source rgb
unsigned sr, unsigned sg, unsigned sb,
// source alpha and opacity
unsigned sa, unsigned cover) {
if (cover < 255) {
unsigned sa, unsigned cover)
{
if(cover < 255)
{
sr = (sr * cover + 255) >> 8;
sg = (sg * cover + 255) >> 8;
sb = (sb * cover + 255) >> 8;
sa = (sa * cover + 255) >> 8;
}
p[Order::R] = (value_type)(((0 + base_mask) >> base_shift));
p[Order::G] = (value_type)(((0 + base_mask) >> base_shift));
p[Order::B] = (value_type)(((0 + base_mask) >> base_shift));
p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
// http://en.wikipedia.org/wiki/File:HSV-RGB-comparison.svg
if (p[Order::A] < 64) {
p[Order::G] = ((p[Order::A] - 64) * 4);
p[Order::B] = 255;
}
if (p[Order::A] >= 64 && p[Order::A] < 128) {
p[Order::G] = 255;
p[Order::B] = 255 - ((p[Order::A] - 64) * 4);
}
if (p[Order::A] >= 128 && p[Order::A] < 192) {
p[Order::R] = ((p[Order::A] - 128) * 4);
p[Order::G] = 255;
}
if (p[Order::A] >= 192) {
p[Order::R] = 255;
p[Order::G] = 255 - ((p[Order::A] - 192) * 4);
if (sa > 0)
{
p[Order::R] = (value_type)(((0 + base_mask) >> base_shift));
p[Order::G] = (value_type)(((0 + base_mask) >> base_shift));
p[Order::B] = (value_type)(((0 + base_mask) >> base_shift));
p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
// http://en.wikipedia.org/wiki/File:HSV-RGB-comparison.svg
if (p[Order::A] < 64) {
p[Order::G] = ((p[Order::A] - 64) * 4);
p[Order::B] = 255;
}
if (p[Order::A] >= 64 && p[Order::A] < 128) {
p[Order::G] = 255;
p[Order::B] = 255 - ((p[Order::A] - 64) * 4);
}
if (p[Order::A] >= 128 && p[Order::A] < 192) {
p[Order::R] = ((p[Order::A] - 128) * 4);
p[Order::G] = 255;
}
if (p[Order::A] >= 192) {
p[Order::R] = 255;
p[Order::G] = 255 - ((p[Order::A] - 192) * 4);
}
}
}
};