PNG reading support

2014-08-04 00:09:46 +01:00
parent 594b7258cc
commit d11fc3c7c8
6 changed files with 132 additions and 6 deletions
--- a/rdpng.c
+++ b/rdpng.c
@@ -0,0 +1,116 @@
+
+#include "cdjpeg.h"   /* Common decls for cjpeg/djpeg applications */
+
+#ifdef PNG_SUPPORTED
+
+#include <png.h>      /* if this fails, you need to install libpng-devel */
+
+
+typedef struct png_source_struct {
+    struct cjpeg_source_struct pub;
+    png_structp  png_ptr;
+    png_infop    info_ptr;
+    JDIMENSION   current_row;
+} png_source_struct;
+
+
+METHODDEF(void)
+finish_input_png (j_compress_ptr cinfo, cjpeg_source_ptr sinfo);
+
+METHODDEF(JDIMENSION)
+get_pixel_rows_png (j_compress_ptr cinfo, cjpeg_source_ptr sinfo);
+
+METHODDEF(void)
+start_input_png (j_compress_ptr cinfo, cjpeg_source_ptr sinfo);
+
+
+GLOBAL(cjpeg_source_ptr)
+jinit_read_png(j_compress_ptr cinfo)
+{
+    png_source_struct *source = (*cinfo->mem->alloc_small)((j_common_ptr) cinfo, JPOOL_IMAGE, sizeof(png_source_struct));
+
+    memset(source, 0, sizeof(*source));
+
+    /* Fill in method ptrs, except get_pixel_rows which start_input sets */
+    source->pub.start_input = start_input_png;
+    source->pub.finish_input = finish_input_png;
+
+    return &source->pub;
+}
+
+METHODDEF(void) error_input_png(png_structp png_ptr, png_const_charp msg) {
+    j_compress_ptr cinfo = png_get_error_ptr(png_ptr);
+    ERREXITS(cinfo, JERR_PNG_ERROR, msg);
+}
+
+METHODDEF(void)
+start_input_png (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
+{
+    png_source_struct *source = (png_source_struct *)sinfo;
+
+    source->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, cinfo, error_input_png, NULL);
+    source->info_ptr = png_create_info_struct(source->png_ptr);
+
+    if (!source->png_ptr || !source->info_ptr) {
+        ERREXITS(cinfo, JERR_PNG_ERROR, "Can't create read/info_struct");
+        return;
+    }
+
+    png_set_palette_to_rgb(source->png_ptr);
+    png_set_expand_gray_1_2_4_to_8(source->png_ptr);
+    png_set_strip_alpha(source->png_ptr);
+    png_set_interlace_handling(source->png_ptr);
+
+    png_init_io(source->png_ptr, source->pub.input_file);
+    png_read_info(source->png_ptr, source->info_ptr);
+
+    png_uint_32 width, height;
+    int bit_depth, color_type;
+    png_get_IHDR(source->png_ptr, source->info_ptr, &width, &height,
+                 &bit_depth, &color_type, NULL, NULL, NULL);
+
+    if (color_type == PNG_COLOR_TYPE_GRAY) {
+        cinfo->in_color_space = JCS_GRAYSCALE;
+        cinfo->input_components = 1;
+    } else {
+        cinfo->in_color_space = JCS_RGB;
+        cinfo->input_components = 3;
+    }
+    cinfo->data_precision = 8;
+    cinfo->image_width = width;
+    cinfo->image_height = height;
+
+    double gamma = 0.45455;
+    if (!png_get_valid(source->png_ptr, source->info_ptr, PNG_INFO_sRGB)) {
+        png_get_gAMA(source->png_ptr, source->info_ptr, &gamma);
+    }
+    cinfo->input_gamma = gamma;
+    sinfo->get_pixel_rows = get_pixel_rows_png;
+
+    png_read_update_info(source->png_ptr, source->info_ptr);
+
+    png_size_t rowbytes = png_get_rowbytes(source->png_ptr, source->info_ptr);
+
+    source->pub.buffer = (*cinfo->mem->alloc_sarray)((j_common_ptr)cinfo, JPOOL_IMAGE, (JDIMENSION)rowbytes, 1);
+    source->pub.buffer_height = 1;
+}
+
+METHODDEF(JDIMENSION)
+get_pixel_rows_png (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
+{
+    png_source_struct *source = (png_source_struct *)sinfo;
+
+    png_read_row(source->png_ptr, source->pub.buffer[0], NULL);
+    return 1;
+}
+
+METHODDEF(void)
+finish_input_png (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
+{
+    png_source_struct *source = (png_source_struct *)sinfo;
+
+    png_read_end(source->png_ptr, source->info_ptr);
+    png_destroy_read_struct(&source->png_ptr, &source->info_ptr, NULL);
+}
+
+#endif