[giv] Added png plugin.

[Dov Grobgeld <dov src gnome org>]

commit 325eaa220c2ea022f6294834ba209912a38768ce
Author: Dov Grobgeld <dov grobgeld gmail com>
Date:   Wed Apr 6 22:20:31 2011 +0300

    Added png plugin.

 ChangeLog              |    2 +
 TODO                   |    3 +
 src/plugins/SConscript |    6 ++
 src/plugins/png.c      |  157 ++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 168 insertions(+), 0 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 4849c09..94a20e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2011-04-06  Dov Grobgeld  <dov grobgeld gmail com>
 
+        * plugins/png.c : png plugin with support for 16-bit png files.
+
         * plugins/dcmtk/dcmdata/libsrc/SConscript: Turned of autogeneration of dcdictbi.cc.
 
         * tiff.c, giv_image.c, giv_image.h : Added support for 16 bit tiff images.
diff --git a/TODO b/TODO
index 4e328bc..968591d 100644
--- a/TODO
+++ b/TODO
@@ -17,3 +17,6 @@ List of things to do.
 * Fix annoying resize bugs on reload. Fix flickering!
 * Add 3d support to npy plugin.
 * Add zoom of histogram.
+* Add option for setting the number of decimals to show
+* Add optional grid for high zoom in.
+* Make png plugin support backgrounds.
diff --git a/src/plugins/SConscript b/src/plugins/SConscript
index ea1f1bd..3a08ae3 100644
--- a/src/plugins/SConscript
+++ b/src/plugins/SConscript
@@ -32,6 +32,12 @@ if not env['SBOX']:
                       LIBPATH=['..','../gtkimageviewer','../agg','../pcre','../plis'] + env['LIBPATH'],
                       LIBS=['libtiff','giv-image']+env['LIBS'],
                       )
+
+    env.SharedLibrary('png',
+                      ['png.c'],
+                      LIBPATH=['..','../gtkimageviewer','../agg','../pcre','../plis'] + env['LIBPATH'],
+                      LIBS=['png','z','giv-image']+env['LIBS'],
+                      )
     
     SConscript('dcmtk/SConscript',
                exports='env')
diff --git a/src/plugins/png.c b/src/plugins/png.c
new file mode 100644
index 0000000..8235679
--- /dev/null
+++ b/src/plugins/png.c
@@ -0,0 +1,157 @@
+//======================================================================
+//  png.c - Load 8-bit and 16-bit png images
+//
+//  Dov Grobgeld <dov grobgeld gmail com>
+//  Wed Apr  6 18:49:17 2011
+//----------------------------------------------------------------------
+#include <string.h>
+#include <stdlib.h>
+#include "../givimage.h"
+#include "../givplugin.h"
+#include <glib.h>
+#include <math.h>
+#include "png.h"
+
+static giv_plugin_support_t png_support = {
+    TRUE,
+    0,
+    "\211PNG",
+    TRUE,
+    "png"
+};
+
+giv_plugin_support_t giv_plugin_get_support()
+{
+    return png_support;
+}
+
+gboolean giv_plugin_supports_file(const char *filename,
+                                  guchar *start_chunk,
+                                  gint start_chunk_len)
+{
+    return !png_sig_cmp(start_chunk, 0, start_chunk_len);
+}
+
+GivImage *giv_plugin_load_file(const char *filename,
+                               GError **error)
+{
+    GivImage *img=NULL;
+    FILE *fp = fopen(filename, "rb");
+    if (!fp) 
+        return NULL;
+    
+    // Check again that this is a png file
+    const int number = 8;
+    guchar header[9];
+    fread(header, 1, number, fp);
+    gboolean is_png = !png_sig_cmp(header, 0, number);
+    if (!is_png) {
+        return NULL;
+    }
+    
+    png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,NULL,NULL);
+    if (!png_ptr)
+        return NULL;
+
+    // Comments may be stored in the beginning or the end so create
+    // a structure for both.
+    png_infop info_ptr = png_create_info_struct(png_ptr);
+    if (!info_ptr) {
+        png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
+        return NULL;
+    }
+
+    png_infop end_info = png_create_info_struct(png_ptr);
+    if (!end_info) {
+        png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
+        return NULL;
+    }
+
+    png_uint_32 width, height;
+    int bit_depth, color_type, interlace_type, compression_type, filter_method;
+
+    png_init_io(png_ptr, fp);
+    png_set_sig_bytes(png_ptr, 8);
+    png_read_info(png_ptr, info_ptr);
+
+    png_get_IHDR(png_ptr, info_ptr, &width, &height,
+       &bit_depth, &color_type, &interlace_type,
+       &compression_type, &filter_method);
+
+    printf("width height bit_depth color_type = %d %d %d %d\n",
+           (int)width, (int)height,
+           bit_depth, color_type);
+
+    
+    if (color_type == PNG_COLOR_TYPE_PALETTE)
+        png_set_palette_to_rgb(png_ptr);
+
+    if (color_type == PNG_COLOR_TYPE_GRAY &&
+        bit_depth < 8) png_set_gray_1_2_4_to_8(png_ptr);
+
+    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
+        png_set_tRNS_to_alpha(png_ptr);
+
+    if (bit_depth == 16)
+        png_set_swap(png_ptr);
+
+    // Reread info
+    png_read_update_info(png_ptr, info_ptr);
+    png_get_IHDR(png_ptr, info_ptr, &width, &height,
+       &bit_depth, &color_type, &interlace_type,
+       &compression_type, &filter_method);
+    
+    GivImageType image_type;
+    if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth <= 8)
+        image_type = GIVIMAGE_U8;
+    else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth == 16)
+        image_type = GIVIMAGE_U16;
+    else if (color_type == PNG_COLOR_TYPE_RGB && bit_depth == 16)
+        image_type = GIVIMAGE_RGB_U16;
+    else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA && bit_depth == 16)
+        image_type = GIVIMAGE_RGBA_U16;
+    else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA && bit_depth == 8)
+        image_type = GIVIMAGE_RGBA_U8;
+    else
+        image_type = GIVIMAGE_RGB_U8;
+
+    img = giv_image_new(image_type, width, height);
+
+    int png_transforms = PNG_TRANSFORM_PACKING;
+    png_bytep *row_pointers = (png_bytep*)g_new0(gpointer, height);
+
+    guchar *dst_buf = img->buf.buf;
+    int dst_row_stride = img->row_stride;
+    int row_idx;
+    for (row_idx=0; row_idx<(int)height; row_idx++)
+        row_pointers[row_idx] = dst_buf + dst_row_stride * row_idx;
+
+    png_read_image(png_ptr, row_pointers);
+
+    png_timep mod_time;
+    if (png_get_tIME(png_ptr, info_ptr, &mod_time)) {
+      gchar *mod_time_str = g_strdup_printf("%04d-%02d-%02d %02d:%02d:%02d",
+                                            mod_time->year,
+                                            mod_time->month,
+                                            mod_time->day,
+                                            mod_time->hour,
+                                            mod_time->minute,
+                                            mod_time->second);
+      giv_image_set_attribute(img, "mod_time", mod_time_str);
+      g_free(mod_time_str);
+    }
+
+    png_textp png_text;
+    int num_text;
+    if (png_get_text(png_ptr, info_ptr, &png_text, &num_text)) {
+        int i;
+        for (i=0; i<num_text; i++) 
+            giv_image_set_attribute(img, png_text[i].key, png_text[i].text);
+    }
+
+    png_read_end(png_ptr, NULL);
+    g_free(row_pointers);
+    png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+
+    return img;
+}