File selector: display preview no longer changes GUI colors when the image uses less than 253 colors. Fixes many cases of issue 215, and generally allows much smoother browsing.

git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@1592 416bcca6-2ee7-4201-b75f-2eb2f807beb1

src/loadsave.h

@@ -98,12 +98,17 @@ typedef struct
   short Preview_factor_Y;
   short Preview_pos_X;
   short Preview_pos_Y;
+  byte *Preview_bitmap;
+  byte  Preview_usage[256];
   
   // Internal: returned surface for SDL_Surface case
   SDL_Surface * Surface;
 
 } T_IO_Context;
 
+#define PREVIEW_WIDTH  120
+#define PREVIEW_HEIGHT  80
+
 /// Type of a function that can be called for a T_IO_Context. Kind of a method.
 typedef void (* Func_IO) (T_IO_Context *);