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support other bit depths of greyscale (hopefully)

This commit is contained in:
Adam D. Ruppe 2019-07-06 12:31:17 -04:00
parent 814875e411
commit 0bbee857c0
1 changed files with 44 additions and 21 deletions
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65
png.d
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@ -162,52 +162,75 @@ void convertPngData(ubyte type, ubyte depth, const(ubyte)[] data, int width, uby
switch(type) {
case 0: // greyscale
case 4: // greyscale with alpha
auto value = consumeOne();
idata[idataIdx++] = value;
idata[idataIdx++] = value;
idata[idataIdx++] = value;
idata[idataIdx++] = (type == 4) ? consumeOne() : 255;
break;
case 3: // indexed
void acceptPixel(ubyte p) {
if(type == 3) {
idata[idataIdx++] = p;
} else {
if(depth < 8) {
if(p == (1 << depth - 1)) {
p <<= 8 - depth;
p |= (1 << (1 - depth)) - 1;
} else {
p <<= 8 - depth;
}
}
idata[idataIdx++] = p;
idata[idataIdx++] = p;
idata[idataIdx++] = p;
}
}
auto b = consumeOne();
switch(depth) {
case 1:
idata[idataIdx++] = (b >> 7) & 0x01;
acceptPixel((b >> 7) & 0x01);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = (b >> 6) & 0x01;
acceptPixel((b >> 6) & 0x01);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = (b >> 5) & 0x01;
acceptPixel((b >> 5) & 0x01);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = (b >> 4) & 0x01;
acceptPixel((b >> 4) & 0x01);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = (b >> 3) & 0x01;
acceptPixel((b >> 3) & 0x01);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = (b >> 2) & 0x01;
acceptPixel((b >> 2) & 0x01);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = (b >> 1) & 0x01;
acceptPixel((b >> 1) & 0x01);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = b & 0x01;
acceptPixel(b & 0x01);
break;
case 2:
idata[idataIdx++] = (b >> 6) & 0x03;
acceptPixel((b >> 6) & 0x03);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = (b >> 4) & 0x03;
acceptPixel((b >> 4) & 0x03);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = (b >> 2) & 0x03;
acceptPixel((b >> 2) & 0x03);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = b & 0x03;
acceptPixel(b & 0x03);
break;
case 4:
idata[idataIdx++] = (b >> 4) & 0x0f;
acceptPixel((b >> 4) & 0x0f);
pixel++; if(pixel == width) break loop;
idata[idataIdx++] = b & 0x0f;
acceptPixel(b & 0x0f);
break;
case 8:
idata[idataIdx++] = b;
acceptPixel(b);
break;
case 16:
assert(type != 3); // 16 bit indexed isn't supported per png spec
acceptPixel(b);
consumeOne(); // discarding the least significant byte as we can't store it anyway
break;
default:
assert(0, "bit depth not implemented");
}
if(type == 0)
idata[idataIdx++] = 255;
else if(type == 4)
idata[idataIdx++] = consumeOne();
break;
case 2: // truecolor
case 6: // true with alpha