From 680a8c314f3b597b2ee18d9aae408a9da4f0ca10 Mon Sep 17 00:00:00 2001
From: William Kendrick <wkendrick@users.sourceforge.net>
Date: Mon, 30 Jan 2006 01:24:50 +0000
Subject: [PATCH] Properly handles a variety of PNG formats when loading
 Starter images and turning them into thumbnails.  (Tested with indexed PNGs,
 and PNGs where RGB colors were stored, even where pixels were fully
 transparent.)

---
 docs/CHANGES.txt |  7 ++++++-
 src/tuxpaint.c   | 39 +++++++++++++++++++++++++++++++--------
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/docs/CHANGES.txt b/docs/CHANGES.txt
index f4e1f6fb9..e7900f5e7 100644
--- a/docs/CHANGES.txt
+++ b/docs/CHANGES.txt
@@ -9,7 +9,7 @@ http://www.newbreedsoftware.com/tuxpaint/
 $Id$
 
 
-2006.January.22 (0.9.16)
+2006.January.29 (0.9.16)
   * Interface improvements:
     -----------------------
     * Modified "Text" tool so that it correctly handles the 16-bit unicode
@@ -45,6 +45,11 @@ $Id$
     * Added GetSystemFontDir() and amended WIN32 code so that the system fonts
       option work correctly on Windows.
 
+    * Properly handles a variety of PNG formats when loading Starter images
+      and turning them into thumbnails.  (Tested with indexed PNGs, and
+      PNGs where RGB colors were stored, even where pixels were
+      fully transparent.)
+
 
 2005.November.26 (0.9.15b)
 
diff --git a/src/tuxpaint.c b/src/tuxpaint.c
index d6e045825..dbffa3986 100644
--- a/src/tuxpaint.c
+++ b/src/tuxpaint.c
@@ -1557,6 +1557,8 @@ static SDL_Surface * img_tools[NUM_TOOLS], * img_tool_names[NUM_TOOLS];
 
 static SDL_Surface * thumbnail(SDL_Surface * src, int max_x, int max_y,
 			int keep_aspect);
+static SDL_Surface * thumbnail2(SDL_Surface * src, int max_x, int max_y,
+			int keep_aspect, int keep_alpha);
 
 //////////////////////////////////////////////////////////////////////
 // font stuff
@@ -10285,6 +10287,12 @@ static void draw_none(void)
 
 static SDL_Surface * thumbnail(SDL_Surface * src, int max_x, int max_y,
 			int keep_aspect)
+{
+  return(thumbnail2(src, max_x, max_y, keep_aspect, 1));
+}
+
+static SDL_Surface * thumbnail2(SDL_Surface * src, int max_x, int max_y,
+			int keep_aspect, int keep_alpha)
 {
   int x, y;
   float src_x, src_y, off_x, off_y;
@@ -10398,11 +10406,26 @@ static SDL_Surface * thumbnail(SDL_Surface * src, int max_x, int max_y,
 	      tg = tg / tmp;
 	      ta = ta / tmp;
 
-	      putpixel(s, x + off_x, y + off_y, SDL_MapRGBA(s->format,
-							    (Uint8) tr,
-							    (Uint8) tg,
-							    (Uint8) tb,
-							    (Uint8) ta));
+	      if (keep_alpha == 0 && s->format->Amask != 0)
+	      {
+		tr = ((ta * tr) / 255) + (255 - ta);
+		tg = ((ta * tg) / 255) + (255 - ta);
+		tb = ((ta * tb) / 255) + (255 - ta);
+
+	        putpixel(s, x + off_x, y + off_y, SDL_MapRGBA(s->format,
+							     (Uint8) tr,
+							     (Uint8) tg,
+							     (Uint8) tb,
+							     0xff));
+	      }
+	      else
+	      {
+	        putpixel(s, x + off_x, y + off_y, SDL_MapRGBA(s->format,
+							      (Uint8) tr,
+							      (Uint8) tg,
+							      (Uint8) tb,
+							      (Uint8) ta));
+	      }
 	    }
 #else
 	  src_x = x * xscale;
@@ -14031,9 +14054,9 @@ void do_open(void)
 	      else
 	      {
 	        /* Turn it into a thumbnail: */
-			      
-	        img1 = SDL_DisplayFormat(img);
-	        img2 = thumbnail(img1, THUMB_W - 20, THUMB_H - 20, 0);
+
+	        img1 = SDL_DisplayFormatAlpha(img);
+	        img2 = thumbnail2(img1, THUMB_W - 20, THUMB_H - 20, 0, 0);
 		SDL_FreeSurface(img1);
 			      
 		show_progress_bar();