Bug 1232576 (part 1) - Move the reference |cairo_t*| from gfxContext to DrawTarget (as user data). r=jfkthame.

--HG--
extra : rebase_source : 5f4be8b9cb4a24527ee95468239ff6ff26d4a279

gfx/layers/client/TiledContentClient.cpp

@@ -55,6 +55,7 @@ static void DrawDebugOverlay(mozilla::gfx::DrawTarget* dt, int x, int y, int wid
   ss << x << ", " << y;
 
   // Draw text using cairo toy text API
+  // XXX: this drawing will silently fail if |dt| doesn't have a Cairo backend
   cairo_t* cr = c.GetCairo();
   cairo_set_font_size(cr, 25);
   cairo_text_extents_t extents;

gfx/thebes/gfxContext.cpp

@@ -1,5 +1,6 @@
-/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
- * This Source Code Form is subject to the terms of the Mozilla Public
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
 
@@ -68,7 +69,6 @@ PatternFromState::operator mozilla::gfx::Pattern&()
 gfxContext::gfxContext(DrawTarget *aTarget, const Point& aDeviceOffset)
   : mPathIsRect(false)
   , mTransformChanged(false)
-  , mRefCairo(nullptr)
   , mDT(aTarget)
   , mOriginalDT(aTarget)
 {
@@ -98,9 +98,6 @@ gfxContext::ContextForDrawTarget(DrawTarget* aTarget)
 
 gfxContext::~gfxContext()
 {
-  if (mRefCairo) {
-    cairo_destroy(mRefCairo);
-  }
   for (int i = mStateStack.Length() - 1; i >= 0; i--) {
     for (unsigned int c = 0; c < mStateStack[i].pushedClips.Length(); c++) {
       mDT->PopClip();
@@ -132,25 +129,38 @@ gfxContext::CurrentSurface(gfxFloat *dx, gfxFloat *dy)
   return nullptr;
 }
 
+static void
+DestroyRefCairo(void* aData)
+{
+  cairo_t* refCairo = static_cast<cairo_t*>(aData);
+  MOZ_ASSERT(refCairo);
+  cairo_destroy(refCairo);
+}
+
 cairo_t *
 gfxContext::GetCairo()
 {
+  // DrawTargets that don't use a Cairo backend can be given a 1x1 "reference"
+  // |cairo_t*|, stored in the DrawTarget's user data, for doing font-related
+  // operations.
+  static UserDataKey sRefCairo;
+
+  cairo_t* refCairo = nullptr;
   if (mDT->GetBackendType() == BackendType::CAIRO) {
-    cairo_t *ctx =
-      (cairo_t*)mDT->GetNativeSurface(NativeSurfaceType::CAIRO_CONTEXT);
-    if (ctx) {
-      return ctx;
+    refCairo = static_cast<cairo_t*>
+      (mDT->GetNativeSurface(NativeSurfaceType::CAIRO_CONTEXT));
+    if (refCairo) {
+      return refCairo;
     }
   }
 
-  if (mRefCairo) {
-    // Set transform!
-    return mRefCairo;
+  refCairo = static_cast<cairo_t*>(mDT->GetUserData(&sRefCairo));
+  if (!refCairo) {
+    refCairo = cairo_create(gfxPlatform::GetPlatform()->ScreenReferenceSurface()->CairoSurface());
+    mDT->AddUserData(&sRefCairo, refCairo, DestroyRefCairo);
   }
 
-  mRefCairo = cairo_create(gfxPlatform::GetPlatform()->ScreenReferenceSurface()->CairoSurface()); 
-
-  return mRefCairo;
+  return refCairo;
 }
 
 void

gfx/thebes/gfxContext.h

@@ -548,8 +548,6 @@ private:
   AzureState &CurrentState() { return mStateStack[mStateStack.Length() - 1]; }
   const AzureState &CurrentState() const { return mStateStack[mStateStack.Length() - 1]; }
 
-  cairo_t *mRefCairo;
-
   RefPtr<DrawTarget> mDT;
   RefPtr<DrawTarget> mOriginalDT;
 };

gfx/thebes/gfxFT2FontBase.cpp

@@ -178,8 +178,6 @@ gfxFT2FontBase::GetGlyphWidth(DrawTarget& aDrawTarget, uint16_t aGID)
 bool
 gfxFT2FontBase::SetupCairoFont(gfxContext *aContext)
 {
-    cairo_t *cr = aContext->GetCairo();
-
     // The scaled font ctm is not relevant right here because
     // cairo_set_scaled_font does not record the scaled font itself, but
     // merely the font_face, font_matrix, font_options.  The scaled_font used
@@ -212,6 +210,6 @@ gfxFT2FontBase::SetupCairoFont(gfxContext *aContext)
     // what is set here.  It's too late to change things here as measuring has
     // already taken place.  We should really be measuring with a different
     // font for pdf and ps surfaces (bug 403513).
-    cairo_set_scaled_font(cr, cairoFont);
+    cairo_set_scaled_font(aContext->GetCairo(), cairoFont);
     return true;
 }