1 files changed, 102 insertions, 0 deletions
diff --git a/test/write_png.c b/test/write_png.c
new file mode 100644
index 000000000..2ea29d062
--- /dev/null
+++ b/test/write_png.c
@@ -0,0 +1,102 @@
+/*
+ * Copyright © 2003 USC, Information Sciences Institute
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without
+ * fee, provided that the above copyright notice appear in all copies
+ * and that both that copyright notice and this permission notice
+ * appear in supporting documentation, and that the name of the
+ * University of Southern California not be used in advertising or
+ * publicity pertaining to distribution of the software without
+ * specific, written prior permission. The University of Southern
+ * California makes no representations about the suitability of this
+ * software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ *
+ * THE UNIVERSITY OF SOUTHERN CALIFORNIA DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE UNIVERSITY OF
+ * SOUTHERN CALIFORNIA BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+ * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+ * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Author: Carl D. Worth <cworth@isi.edu>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <png.h>
+
+#include "write_png.h"
+
+static void
+unpremultiply_data (png_structp png, png_row_infop row_info, png_bytep data)
+{
+    int i;
+
+    for (i = 0; i < row_info->rowbytes; i += 4) {
+        unsigned char *b = &data[i];
+        unsigned int pixel;
+        unsigned char alpha;
+
+	memcpy (&pixel, b, sizeof (unsigned int));
+	alpha = (pixel & 0xff000000) >> 24;
+        if (alpha == 0) {
+	    b[0] = b[1] = b[2] = b[3] = 0;
+	} else {
+            b[0] = (((pixel & 0x0000ff) >>  0) * 255) / alpha;
+            b[1] = (((pixel & 0x00ff00) >>  8) * 255) / alpha;
+            b[2] = (((pixel & 0xff0000) >> 16) * 255) / alpha;
+	    b[3] = alpha;
+	}
+    }
+}
+
+void
+write_png_argb32 (char *buffer, char *filename,
+		  int width, int height, int stride)
+{
+    FILE *f;
+    int i;
+    png_struct *png;
+    png_info *info;
+    png_byte **rows;
+    png_color_16 white;
+    
+    f = fopen (filename, "w");
+    rows = malloc (height * sizeof(png_byte*));
+
+    for (i = 0; i < height; i++) {
+	rows[i] = buffer + i * stride;
+    }
+
+    png = png_create_write_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+    info = png_create_info_struct (png);
+
+    png_init_io (png, f);
+    png_set_IHDR (png, info,
+		  width, height, 8,
+		  PNG_COLOR_TYPE_RGB_ALPHA, 
+		  PNG_INTERLACE_NONE,
+		  PNG_COMPRESSION_TYPE_DEFAULT,
+		  PNG_FILTER_TYPE_DEFAULT);
+
+    white.red = 0xff;
+    white.blue = 0xff;
+    white.green = 0xff;
+    png_set_bKGD (png, info, &white);
+
+    png_set_write_user_transform_fn (png, unpremultiply_data);
+    png_set_bgr (png);
+
+    png_write_info (png, info);
+    png_write_image (png, rows);
+    png_write_end (png, info);
+
+    png_destroy_write_struct (&png, &info);
+
+    free (rows);
+    fclose (f);
+}