draw rect optimization

implementations/Crafter.Graphics-Window.cpp

@@ -111,10 +111,27 @@ void Window::AddDirtyRect(ScaleData scale) {
         return;
     }
 
-    //merging logic should work so that no pixel is drawn twice, and that no pixel not marked dirty is drawn.
-    //so lets say there is already an existing horizontal bar and the new rect is a vertical bar making a cross shape, the center of the cross will currently be drawn twice
-    //so we need to turn it into 3 rects, the top part of the vertical bar, the horizontal bar, and the bottom part of the vertical bar
-    //in this way no pixel is drawn twice and no area not marked dirty is included
-    
+    for(ClipRect existing : dirtyRects) {
+        //fully enclosed
+        if(rect.left >= existing.left && rect.right <= existing.right && rect.top >= existing.top && rect.bottom <= existing.bottom) {
+            return;
+        }
+
+        //horizontal line
+        if(rect.top == existing.top && rect.bottom == existing.bottom) {
+            existing.left = std::min(rect.left, existing.left);
+            existing.right = std::max(rect.right, existing.right);
+            return;
+        }
+
+        //vertical line
+        if(rect.left == existing.left && rect.right == existing.right) {
+            existing.top = std::min(rect.top, existing.top);
+            existing.bottom = std::max(rect.bottom, existing.bottom);
+            return;
+        }
+    }
+
+    //no overlap
     dirtyRects.push_back(rect);
 }