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amend 2d0bd726c3 - patch from @lightmare - refs #1557

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This commit is contained in:
Dane Springmeyer 2012-11-08 16:33:18 -05:00
parent 2d0bd726c3
commit 53c5933dbd
1 changed files with 29 additions and 18 deletions
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47
include/mapnik/png_io.hpp
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@ -361,8 +361,9 @@ void save_as_png8_oct(T1 & file,
unsigned alphaHist[256];//transparency histogram
unsigned semiCount = 0;//sum of semitransparent pixels
unsigned meanAlpha = 0;
if (trans_mode == 0) {
alphaHist[255] = width * height;
if (trans_mode == 0)
{
meanAlpha = 255;
}
else
@ -376,10 +377,6 @@ void save_as_png8_oct(T1 & file,
for (unsigned x = 0; x < width; ++x)
{
unsigned val = U2ALPHA((unsigned)image.getRow(y)[x]);
if (trans_mode==0)
{
val=255;
}
alphaHist[val]++;
meanAlpha += val;
if (val>0 && val<255)
@ -394,21 +391,24 @@ void save_as_png8_oct(T1 & file,
// transparency ranges division points
unsigned limits[MAX_OCTREE_LEVELS+1];
limits[0] = 0;
limits[1] = (alphaHist[0]>0)?1:0;
limits[1] = (trans_mode!=0 && alphaHist[0]>0)?1:0;
limits[TRANSPARENCY_LEVELS] = 256;
unsigned alphaHistSum = 0;
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
for(unsigned j=2; j<TRANSPARENCY_LEVELS; j++)
{
limits[j] = limits[1];
}
for(unsigned i=1; i<256; i++)
if (trans_mode != 0)
{
alphaHistSum += alphaHist[i];
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
unsigned alphaHistSum = 0;
for(unsigned i=1; i<256; i++)
{
if (alphaHistSum<semiCount*(j)/4)
alphaHistSum += alphaHist[i];
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
{
limits[j] = i;
if (alphaHistSum<semiCount*(j)/4)
{
limits[j] = i;
}
}
}
}
@ -429,12 +429,23 @@ void save_as_png8_oct(T1 & file,
// estimated number of colors from palette assigned to chosen ranges
unsigned cols[MAX_OCTREE_LEVELS];
// count colors
for(unsigned j=1; j<=TRANSPARENCY_LEVELS; j++)
if (trans_mode == 0)
{
cols[j-1] = 0;
for(unsigned i=limits[j-1]; i<limits[j]; i++)
for (unsigned j=0; j<TRANSPARENCY_LEVELS; j++)
{
cols[j-1] += alphaHist[i];
cols[j] = 0;
}
cols[TRANSPARENCY_LEVELS-1] = width * height;
}
else
{
for (unsigned j=0; j<TRANSPARENCY_LEVELS; j++)
{
cols[j] = 0;
for (unsigned i=limits[j]; i<limits[j+1]; i++)
{
cols[j] += alphaHist[i];
}
}
}