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add impl for grayscale_to_alpha (e.g. devseed world glass effect) - #609

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This commit is contained in:
Dane Springmeyer 2010-09-24 17:08:12 +00:00
parent 0a300c8be7
commit 5c424d2e7c
1 changed files with 18 additions and 4 deletions
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22
src/graphics.cpp
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@ -93,7 +93,22 @@ image_32::~image_32() {}
void image_32::set_grayscale_to_alpha()
{
for (int y = 0; y < height_; ++y)
{
unsigned int* row_from = data_.getRow(y);
for (int x = 0; x < width_; ++x)
{
unsigned rgba = row_from[x];
unsigned r = rgba & 0xff;
unsigned g = (rgba >> 8 ) & 0xff;
unsigned b = (rgba >> 16) & 0xff;
// magic numbers for grayscale
unsigned a = (int)((r * .3) + (g * .59) + (b * .11));
row_from[x] = (a << 24)| (255 << 16) | (255 << 8) | (255) ;
}
}
}
void image_32::set_color_to_alpha(const color& c)
@ -113,8 +128,7 @@ void image_32::set_alpha(float opacity)
#ifdef MAPNIK_BIG_ENDIAN
unsigned a0 = (rgba & 0xff);
//unsigned a1 = int( (rgba & 0xff) * opacity );
unsigned a1 = opacity;
unsigned a1 = int( (rgba & 0xff) * opacity );
if (a0 == a1) continue;
@ -126,8 +140,8 @@ void image_32::set_alpha(float opacity)
#else
unsigned a0 = (rgba >> 24) & 0xff;
//unsigned a1 = int( ((rgba >> 24) & 0xff) * opacity );
unsigned a1 = opacity;
unsigned a1 = int( ((rgba >> 24) & 0xff) * opacity );
//unsigned a1 = opacity;
if (a0 == a1) continue;
unsigned r = rgba & 0xff;