optimization to opengl drawing

modules/juce_graphics/native/juce_RenderingHelpers.h

@@ -1553,6 +1553,12 @@ namespace ClipRegions
         virtual Ptr clipToImageAlpha (const Image&, const AffineTransform&, Graphics::ResamplingQuality) = 0;
         virtual void translate (Point<int> delta) = 0;
 
+        // Check whether the supplied rectangle can be drawn clipped inside a single
+		// rectangle.
+        // Pessimistic check; only used for optimization - returning false is always
+        // a correct choice, though it might lead to a slower path in the rasterizer.
+        virtual bool trimRectangularClip(Rectangle<int> requestedDrawRect, Rectangle<int>& trimmedDrawRect) const = 0;
+
         virtual bool clipRegionIntersects (Rectangle<int>) const = 0;
         virtual Rectangle<int> getClipBounds() const = 0;
 
@@ -1669,6 +1675,11 @@ namespace ClipRegions
             edgeTable.translate ((float) delta.x, delta.y);
         }
 
+        bool trimRectangularClip(Rectangle<int>, Rectangle<int>&) const override
+        {
+            return false;
+        }
+
         bool clipRegionIntersects (Rectangle<int> r) const override
         {
             return edgeTable.getMaximumBounds().intersects (r);
@@ -1793,6 +1804,15 @@ namespace ClipRegions
         bool clipRegionIntersects (Rectangle<int> r) const override   { return clip.intersects (r); }
         Rectangle<int> getClipBounds() const override                 { return clip.getBounds(); }
 
+        bool trimRectangularClip(Rectangle<int> requestedDrawRect, Rectangle<int>& trimmedDrawRect) const override
+        {
+			if (clip.getNumRectangles() != 1) return false;
+
+			Rectangle<int> rect = clip.getRectangle(0);
+			trimmedDrawRect = rect.getIntersection(requestedDrawRect);
+			return !trimmedDrawRect.isEmpty();
+        }
+
         void fillRectWithColour (SavedStateType& state, Rectangle<int> area, PixelARGB colour, bool replaceContents) const override
         {
             SubRectangleIterator iter (clip, area);

modules/juce_opengl/opengl/juce_OpenGLGraphicsContext.cpp

@@ -1713,6 +1713,41 @@ struct SavedState final : public RenderingHelpers::SavedStateBase<SavedState>
           previousTarget (createCopyIfNotNull (other.previousTarget.get()))
     {}
 
+    void drawImage (const Image& sourceImage, const AffineTransform& trans)
+    {
+        auto t = transform.getTransformWith (trans);
+        auto alpha = fillType.colour.getAlpha();
+
+        // If we're only translating, and if the target image can be drawn with a
+		// clip that can be reduced to a single rectangle, we can just add a single
+		// quad to the queue and dispatch a draw call.
+        if (isOnlyTranslationAllowingError (t, 0.002f))
+        {
+            auto targetRect = Rectangle<int>{
+                (int)t.getTranslationX(),
+                (int)t.getTranslationY(),
+                sourceImage.getWidth(),
+                sourceImage.getHeight(),
+            };
+			Rectangle<int> trimmedTargetRect;
+
+            if (clip->trimRectangularClip(targetRect, trimmedTargetRect))
+            {
+                state->shaderQuadQueue.flush();
+                state->setShaderForTiledImageFill (state->cachedImageList->getTextureFor (sourceImage), t, 0, nullptr, false);
+
+                state->shaderQuadQueue.add (trimmedTargetRect, PixelARGB ((uint8) alpha, (uint8) alpha, (uint8) alpha, (uint8) alpha));
+                state->shaderQuadQueue.flush();
+
+                state->currentShader.clearShader (state->shaderQuadQueue);
+
+                return;
+            }
+        }
+
+        BaseClass::drawImage(sourceImage, trans);
+    }
+
     SavedState* beginTransparencyLayer (float opacity)
     {
         auto* s = new SavedState (*this);