New image functions:

* invert
 * flip_horizontal
 * flip_vertical
 * rotate

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@1472 0fc631ac-6414-0410-93d0-97cfa31319b6

src/gfx/image_effects.cpp

@@ -60,3 +60,13 @@ void saturate(Image& image, double amount) {
 		}
 	}
 }
+
+// ----------------------------------------------------------------------------- : Color inversion
+
+void invert(Image& img) {
+	Byte* data = img.GetData();
+	int n = 3 * img.GetWidth() * img.GetHeight();
+	for (int i = 0 ; i < n ; ++i) {
+		data[i] = 255 - data[i];
+	}
+}