/**
* \brief encode an image to RGB(A) PNG format
* \private \memberof mapcache_image_format_png
* \sa mapcache_image_format::write()
*/
mapcache_buffer* _mapcache_imageio_png_encode(mapcache_context *ctx, mapcache_image *img, mapcache_image_format *format) {
png_infop info_ptr;
int color_type;
size_t row;
mapcache_buffer *buffer = NULL;
int compression = ((mapcache_image_format_png*)format)->compression_level;
png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL,NULL,NULL);
if (!png_ptr) {
ctx->set_error(ctx, 500, "failed to allocate png_struct structure");
return NULL;
}
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_write_struct(&png_ptr,
(png_infopp)NULL);
ctx->set_error(ctx, 500, "failed to allocate png_info structure");
return NULL;
}
if (setjmp(png_jmpbuf(png_ptr)))
{
ctx->set_error(ctx, 500, "failed to setjmp(png_jmpbuf(png_ptr))");
png_destroy_write_struct(&png_ptr, &info_ptr);
return NULL;
}
buffer = mapcache_buffer_create(5000,ctx->pool);
png_set_write_fn(png_ptr, buffer, _mapcache_imageio_png_write_func, _mapcache_imageio_png_flush_func);
if(mapcache_image_has_alpha(img))
color_type = PNG_COLOR_TYPE_RGB_ALPHA;
else
color_type = PNG_COLOR_TYPE_RGB;
png_set_IHDR(png_ptr, info_ptr, img->w, img->h,
8, color_type, PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
if(compression == MAPCACHE_COMPRESSION_BEST)
png_set_compression_level (png_ptr, Z_BEST_COMPRESSION);
else if(compression == MAPCACHE_COMPRESSION_FAST)
png_set_compression_level (png_ptr, Z_BEST_SPEED);
png_write_info(png_ptr, info_ptr);
if(color_type == PNG_COLOR_TYPE_RGB)
png_set_filler(png_ptr, 255, PNG_FILLER_AFTER);
png_bytep rowptr = img->data;
for(row=0;row<img->h;row++) {
png_write_row(png_ptr,rowptr);
rowptr += img->stride;
}
png_write_end(png_ptr, info_ptr);
png_destroy_write_struct(&png_ptr, &info_ptr);
return buffer;
}
/**
* \brief encode an image to mixed format
* depending on the transparency of the provided image, use either one
* of the two member encoding formats.
* Intended to be used for creating png when transparency is present, and jpeg
* when fully opaque
* \sa mapcache_image_format::write()
*/
static mapcache_buffer* _mapcache_imageio_mixed_encode( mapcache_context *ctx,
mapcache_image *image, mapcache_image_format *format)
{
mapcache_image_format_mixed *f = (mapcache_image_format_mixed*)format;
if(mapcache_image_has_alpha(image)) {
return f->transparent->write(ctx,image,f->transparent);
} else {
return f->opaque->write(ctx,image,f->opaque);
}
}
