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Save_PNG(): use PNG_RESOLUTION_UNKNOWN in pHYs chunk

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Thomas Bernard 2018-03-06 00:01:51 +01:00
parent f9dc86eb87
commit 3bdd69c523
1 changed files with 7 additions and 2 deletions
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9
src/fileformats.c
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@ -6417,16 +6417,21 @@ void Save_PNG(T_IO_Context * context)
opacity[context->Transparent_color]=0;
png_set_tRNS(png_ptr, info_ptr, opacity, (int)1 + context->Transparent_color,0);
}
// if using PNG_RESOLUTION_METER, unit is in dot per meter.
// 72 DPI = 2835, 600 DPI = 23622
// with PNG_RESOLUTION_UNKNOWN, it is arbitrary
switch(Pixel_ratio)
{
case PIXEL_WIDE:
case PIXEL_WIDE2:
png_set_pHYs(png_ptr, info_ptr, 3000, 6000, PNG_RESOLUTION_METER);
png_set_pHYs(png_ptr, info_ptr, 1, 2, PNG_RESOLUTION_UNKNOWN);
break;
case PIXEL_TALL:
case PIXEL_TALL2:
png_set_pHYs(png_ptr, info_ptr, 2, 1, PNG_RESOLUTION_UNKNOWN);
break;
case PIXEL_TALL3:
png_set_pHYs(png_ptr, info_ptr, 6000, 3000, PNG_RESOLUTION_METER);
png_set_pHYs(png_ptr, info_ptr, 4, 3, PNG_RESOLUTION_UNKNOWN);
break;
default:
break;