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[supertux.git] / lib / video / screen.cpp

diff --git a/lib/video/screen.cpp b/lib/video/screen.cpp
index 41245ee..1714943 100644 (file)
--- a/lib/video/screen.cpp
+++ b/lib/video/screen.cpp
@@ -42,6 +42,37 @@
 using namespace SuperTux;
 
 /* 'Stolen' from the SDL documentation.
+ * Return the pixel value at (x, y)
+ * NOTE: The surface must be locked before calling this!
+ */
+Uint32 SuperTux::getpixel(SDL_Surface *surface, int x, int y)
+{
+    int bpp = surface->format->BytesPerPixel;
+    /* Here p is the address to the pixel we want to retrieve */
+    Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;
+
+    switch(bpp) {
+    case 1:
+        return *p;
+
+    case 2:
+        return *(Uint16 *)p;
+
+    case 3:
+        if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
+            return p[0] << 16 | p[1] << 8 | p[2];
+        else
+            return p[0] | p[1] << 8 | p[2] << 16;
+
+    case 4:
+        return *(Uint32 *)p;
+
+    default:
+        return 0;       /* shouldn't happen, but avoids warnings */
+    }
+}
+
+/* 'Stolen' from the SDL documentation.
  * Set the pixel at (x, y) to the given value
  * NOTE: The surface must be locked before calling this!
  */