Bug 1317862 - Part 1: Add TextLayer class and basic support for them. r=mstange

gfx/layers/basic/BasicTextLayer.cpp

@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "BasicLayersImpl.h"            // for FillRectWithMask, etc
+#include "Layers.h"                     // for ColorLayer, etc
+#include "BasicImplData.h"              // for BasicImplData
+#include "BasicLayers.h"                // for BasicLayerManager
+#include "gfxContext.h"                 // for gfxContext, etc
+#include "gfxRect.h"                    // for gfxRect
+#include "gfx2DGlue.h"
+#include "mozilla/mozalloc.h"           // for operator new
+#include "nsCOMPtr.h"                   // for already_AddRefed
+#include "nsDebug.h"                    // for NS_ASSERTION
+#include "nsISupportsImpl.h"            // for Layer::AddRef, etc
+#include "nsRect.h"                     // for mozilla::gfx::IntRect
+#include "nsRegion.h"                   // for nsIntRegion
+#include "mozilla/gfx/PathHelpers.h"
+
+using namespace mozilla::gfx;
+
+namespace mozilla {
+namespace layers {
+
+class BasicTextLayer : public TextLayer, public BasicImplData {
+public:
+  explicit BasicTextLayer(BasicLayerManager* aLayerManager) :
+    TextLayer(aLayerManager, static_cast<BasicImplData*>(this))
+  {
+    MOZ_COUNT_CTOR(BasicTextLayer);
+  }
+
+protected:
+  virtual ~BasicTextLayer()
+  {
+    MOZ_COUNT_DTOR(BasicTextLayer);
+  }
+
+public:
+  virtual void SetVisibleRegion(const LayerIntRegion& aRegion) override
+  {
+    NS_ASSERTION(BasicManager()->InConstruction(),
+                 "Can only set properties in construction phase");
+    TextLayer::SetVisibleRegion(aRegion);
+  }
+
+  virtual void Paint(DrawTarget* aDT,
+                     const gfx::Point& aDeviceOffset,
+                     Layer* aMaskLayer) override
+  {
+    if (IsHidden() || !mFont) {
+      return;
+    }
+
+    Rect snapped(mBounds.x, mBounds.y, mBounds.width, mBounds.height);
+    MaybeSnapToDevicePixels(snapped, *aDT, true);
+
+    // We don't currently support subpixel-AA in TextLayers since we
+    // don't check if there's an opaque background color behind them.
+    // We should fix this before using them in production.
+    aDT->SetPermitSubpixelAA(false);
+
+    for (GlyphArray& g : mGlyphs) {
+      GlyphBuffer buffer = { g.glyphs().Elements(), (uint32_t)g.glyphs().Length() };
+      aDT->FillGlyphs(mFont, buffer, ColorPattern(g.color().value()));
+    }
+  }
+
+protected:
+  BasicLayerManager* BasicManager()
+  {
+    return static_cast<BasicLayerManager*>(mManager);
+  }
+};
+
+already_AddRefed<TextLayer>
+BasicLayerManager::CreateTextLayer()
+{
+  NS_ASSERTION(InConstruction(), "Only allowed in construction phase");
+  RefPtr<TextLayer> layer = new BasicTextLayer(this);
+  return layer.forget();
+}
+
+} // namespace layers
+} // namespace mozilla