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PNG: Inform inflate about expected output size for extra speed.

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This commit is contained in:
Jeroen van Rijn
2021-06-27 13:57:12 +02:00
parent eaf88bcc4d
commit 064516bf0b
1 changed files with 29 additions and 27 deletions
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56
core/image/png/png.odin
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@@ -668,39 +668,41 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
return img, E_PNG.IDAT_Missing;
}
/*
Calculate the expected output size, to help `inflate` make better decisions about the output buffer.
We'll also use it to check the returned buffer size is what we expected it to be.
Let's calcalate the expected size of the IDAT based on its dimensions, and whether or not it's interlaced.
*/
expected_size: int;
if header.interlace_method != .Adam7 {
expected_size = compute_buffer_size(int(header.width), int(header.height), int(img.channels), int(header.bit_depth), 1);
} else {
/*
Because Adam7 divides the image up into sub-images, and each scanline must start
with a filter byte, Adam7 interlaced images can have a larger raw size.
*/
for p := 0; p < 7; p += 1 {
x := (int(header.width) - ADAM7_X_ORIG[p] + ADAM7_X_SPACING[p] - 1) / ADAM7_X_SPACING[p];
y := (int(header.height) - ADAM7_Y_ORIG[p] + ADAM7_Y_SPACING[p] - 1) / ADAM7_Y_SPACING[p];
if x > 0 && y > 0 {
expected_size += compute_buffer_size(int(x), int(y), int(img.channels), int(header.bit_depth), 1);
}
}
}
buf: bytes.Buffer;
zlib_error := zlib.inflate(idat, &buf);
zlib_error := zlib.inflate(idat, &buf, false, expected_size);
defer bytes.buffer_destroy(&buf);
if zlib_error != nil {
return {}, zlib_error;
} else {
/*
Let's calcalate the expected size of the IDAT based on its dimensions,
and whether or not it's interlaced
*/
expected_size: int;
buf_len := len(buf.buf);
}
if header.interlace_method != .Adam7 {
expected_size = compute_buffer_size(int(header.width), int(header.height), int(img.channels), int(header.bit_depth), 1);
} else {
/*
Because Adam7 divides the image up into sub-images, and each scanline must start
with a filter byte, Adam7 interlaced images can have a larger raw size.
*/
for p := 0; p < 7; p += 1 {
x := (int(header.width) - ADAM7_X_ORIG[p] + ADAM7_X_SPACING[p] - 1) / ADAM7_X_SPACING[p];
y := (int(header.height) - ADAM7_Y_ORIG[p] + ADAM7_Y_SPACING[p] - 1) / ADAM7_Y_SPACING[p];
if x > 0 && y > 0 {
expected_size += compute_buffer_size(int(x), int(y), int(img.channels), int(header.bit_depth), 1);
}
}
}
if expected_size != buf_len {
return {}, E_PNG.IDAT_Corrupt;
}
buf_len := len(buf.buf);
if expected_size != buf_len {
return {}, E_PNG.IDAT_Corrupt;
}
/*