PNG reading support

Makefile.am

@@ -115,6 +115,12 @@ cjpeg_LDADD = libjpeg.la
 cjpeg_CFLAGS = -DBMP_SUPPORTED -DGIF_SUPPORTED -DPPM_SUPPORTED \
 	-DTARGA_SUPPORTED
 
+if HAVE_LIBPNG
+cjpeg_CFLAGS += -DPNG_SUPPORTED $(libpng_CFLAGS)
+cjpeg_LDADD += $(libpng_LIBS)
+cjpeg_SOURCES += rdpng.c
+endif
+
 djpeg_SOURCES = cdjpeg.h cderror.h cdjpeg.c djpeg.c rdcolmap.c rdswitch.c \
 	wrbmp.c wrgif.c wrppm.c wrtarga.c
 

cderror.h

@@ -122,6 +122,10 @@ JMESSAGE(JERR_UNKNOWN_FORMAT, "Unrecognized input file format")
 #endif
 JMESSAGE(JERR_UNSUPPORTED_FORMAT, "Unsupported output file format")
 
+#ifdef PNG_SUPPORTED
+JMESSAGE(JERR_PNG_ERROR, "Unable to read PNG file: %s")
+#endif
+
 #ifdef JMAKE_ENUM_LIST
 
   JMSG_LASTADDONCODE

cdjpeg.h

@@ -135,6 +135,7 @@ EXTERN(cjpeg_source_ptr) jinit_read_gif JPP((j_compress_ptr cinfo));
 EXTERN(djpeg_dest_ptr) jinit_write_gif JPP((j_decompress_ptr cinfo));
 EXTERN(cjpeg_source_ptr) jinit_read_jpeg JPP((j_compress_ptr cinfo));
 EXTERN(cjpeg_source_ptr) jinit_read_ppm JPP((j_compress_ptr cinfo));
+EXTERN(cjpeg_source_ptr) jinit_read_png JPP((j_compress_ptr cinfo));
 EXTERN(djpeg_dest_ptr) jinit_write_ppm JPP((j_decompress_ptr cinfo));
 EXTERN(cjpeg_source_ptr) jinit_read_rle JPP((j_compress_ptr cinfo));
 EXTERN(djpeg_dest_ptr) jinit_write_rle JPP((j_decompress_ptr cinfo));

cjpeg.c

@@ -113,6 +113,10 @@ select_file_type (j_compress_ptr cinfo, FILE * infile)
   case 'P':
     return jinit_read_ppm(cinfo);
 #endif
+#ifdef PNG_SUPPORTED
+  case 0x89:
+    return jinit_read_png(cinfo);
+#endif
 #ifdef RLE_SUPPORTED
   case 'R':
     return jinit_read_rle(cinfo);

configure.ac

@@ -95,6 +95,11 @@ fi
 # Checks for libraries.
 AC_CHECK_LIB([m],[pow])
 
+PKG_CHECK_MODULES([libpng], [libpng], [HAVE_LIBPNG=1], [
+  PKG_CHECK_MODULES([libpng], [libpng12], [HAVE_LIBPNG=1], [HAVE_LIBPNG=0])
+])
+AM_CONDITIONAL([HAVE_LIBPNG], [test "$HAVE_LIBPNG" -eq 1])
+
 # Checks for header files.
 AC_HEADER_STDC
 AC_CHECK_HEADERS([stddef.h stdlib.h string.h])

jconfig.txt

@@ -130,11 +130,12 @@ typedef unsigned char boolean;
 
 /* These defines indicate which image (non-JPEG) file formats are allowed. */
 
-#define BMP_SUPPORTED		/* BMP image file format */
-#define GIF_SUPPORTED		/* GIF image file format */
-#define PPM_SUPPORTED		/* PBMPLUS PPM/PGM image file format */
-#undef RLE_SUPPORTED		/* Utah RLE image file format */
-#define TARGA_SUPPORTED		/* Targa image file format */
+#define PNG_SUPPORTED       /* PNG image file format */
+#define BMP_SUPPORTED       /* BMP image file format */
+#define GIF_SUPPORTED       /* GIF image file format */
+#define PPM_SUPPORTED       /* PBMPLUS PPM/PGM image file format */
+#undef RLE_SUPPORTED        /* Utah RLE image file format */
+#define TARGA_SUPPORTED     /* Targa image file format */
 
 /* Define this if you want to name both input and output files on the command
  * line, rather than using stdout and optionally stdin.  You MUST do this if

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