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#include "stdafx.h"
#include "Png.h"
#include "Exception.h"
#ifndef WINDOWS
#include <png.h>
#endif
namespace graphics {
static Bool CODECALL pngApplicable(IStream *from) {
return checkHeader(from, "\x89PNG", false);
}
static FormatOptions *CODECALL pngCreate(ImageFormat *f) {
return new (f) PNGOptions();
}
ImageFormat *pngFormat(Engine &e) {
const wchar *exts[] = { S("png"), null };
return new (e) ImageFormat(S("Portable Network Graphics"), exts, &pngApplicable, &pngCreate);
}
PNGOptions::PNGOptions() {}
// See ImageWin32.cpp for loading/saving on Windows.
#ifndef WINDOWS
// IO callbacks from libpng.
static void pngRead(png_structp png, byte *to, size_t length) {
IStream *src = (IStream*)png_get_io_ptr(png);
Buffer out = src->fill(length);
if (out.count() > 0)
memcpy(to, out.dataPtr(), out.count());
}
static Image *loadPng(PNGOptions *options, IStream *from, const wchar *&error) {
// Anchor 'from' on the stack so that the GC does not move it.
IStream *volatile anchor = null;
atomicWrite(anchor, from);
png_structp png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
png_infop info = null;
error = S("Failed to initialize libpng");
// Custom error handling:
if (setjmp(png_jmpbuf(png))) {
// Error. Clean up and exit.
png_destroy_read_struct(&png, &info, NULL);
error = S("Internal error in libpng.");
return null;
}
png_set_read_fn(png, (void *)anchor, &pngRead);
if (png) {
info = png_create_info_struct(png);
error = S("Failed to create info struct.");
}
png_uint_32 ok = 0;
png_uint_32 width = 0, height = 0;
int depth = 0, type = 0;
if (info) {
png_read_info(png, info);
ok = png_get_IHDR(png, info, &width, &height, &depth, &type, NULL, NULL, NULL);
error = S("Failed to read PNG header.");
}
Image *output = null;
if (ok) {
int typeNoAlpha = type & ~PNG_COLOR_MASK_ALPHA;
// Fix the format.
if (typeNoAlpha == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb(png);
if (typeNoAlpha == PNG_COLOR_TYPE_GRAY)
png_set_gray_to_rgb(png);
if (png_get_valid(png, info, PNG_INFO_tRNS))
png_set_tRNS_to_alpha(png);
if (depth == 16)
png_set_strip_16(png);
if (depth < 8) {
png_color_8p bit;
if (png_get_sBIT(png, info, &bit))
png_set_shift(png, bit);
}
if (!(type & PNG_COLOR_MASK_ALPHA))
png_set_add_alpha(png, 0xFF, PNG_FILLER_AFTER);
png_read_update_info(png, info);
// Read the PNG file itself!
output = new (from) Image(Nat(width), Nat(height));
// Make sure to pin the internal array by storing a pointer to it on the stack.
byte *volatile buffer = null;
atomicWrite(buffer, output->buffer());
Nat stride = output->stride();
// Create a GcArray where we can store pointers to inside 'buffer'. Note: it is not
// scanned, as that would lead to pointers to the middle of objects. Since the buffer is
// pinned on the stack, it can not move so this should be fine anyway.
GcArray<byte *> *rows = runtime::allocArray<byte *>(output->engine(), &sizeArrayType, height);
for (Nat i = 0; i < height; i++)
rows->v[i] = buffer + stride*i;
png_read_image(png, rows->v);
}
// Clean up any structures we allocated.
png_destroy_read_struct(&png, &info, NULL);
return output;
}
Image *PNGOptions::load(IStream *from) {
const wchar *error;
Image *out = loadPng(this, from, error);
if (!out)
throw new (this) ImageLoadError(error);
return out;
}
static void pngWrite(png_structp png, byte *from, size_t length) {
OStream *dest = (OStream *)png_get_io_ptr(png);
dest->write(buffer(dest->engine(), from, length));
}
static void pngFlush(png_structp png) {
OStream *dest = (OStream *)png_get_io_ptr(png);
dest->flush();
}
void PNGOptions::save(Image *image, OStream *to) {
OStream *volatile anchor = null;
atomicWrite(anchor, to);
const wchar *error = S("Failed to initialize libpng.");
png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
png_infop info = null;
if (!png) {
throw new (image) ImageSaveError(error);
}
if (setjmp(png_jmpbuf(png))) {
// Error. Clean up and exit.
png_destroy_write_struct(&png, &info);
throw new (image) ImageSaveError(S("Internal error in libpng."));
}
info = png_create_info_struct(png);
if (!info)
throw new (image) ImageSaveError(S("Failed to create png info struct."));
png_set_write_fn(png, (void *)anchor, &pngWrite, &pngFlush);
png_set_IHDR(png, info, image->width(), image->height(), 8,
PNG_COLOR_TYPE_RGBA, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
png_write_info(png, info);
// Make sure to pin the internal array by storing a pointer to it on the stack.
byte *volatile buffer = null;
atomicWrite(buffer, image->buffer());
Nat stride = image->stride();
// Create a GcArray where we can store pointers to inside 'buffer'. Note: it is not
// scanned, as that would lead to pointers to the middle of objects. Since the buffer is
// pinned on the stack, it can not move so this should be fine anyway.
GcArray<byte *> *rows = runtime::allocArray<byte *>(image->engine(), &sizeArrayType, image->height());
for (Nat i = 0; i < image->height(); i++)
rows->v[i] = buffer + stride*i;
png_write_image(png, rows->v);
png_write_end(png, NULL);
png_destroy_write_struct(&png, &info);
}
#endif
}
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