gecko-dev/gfx/thebes/gfxQuartzNativeDrawing.cpp

/* -*- 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
 * 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 "gfxQuartzNativeDrawing.h"
#include "gfxPlatform.h"
#include "mozilla/gfx/Helpers.h"

using namespace mozilla::gfx;
using namespace mozilla;

gfxQuartzNativeDrawing::gfxQuartzNativeDrawing(DrawTarget& aDrawTarget,
                                               const Rect& nativeRect)
    : mDrawTarget(&aDrawTarget), mNativeRect(nativeRect), mCGContext(nullptr) {}

CGContextRef gfxQuartzNativeDrawing::BeginNativeDrawing() {
  NS_ASSERTION(!mCGContext,
               "BeginNativeDrawing called when drawing already in progress");

  DrawTarget* dt = mDrawTarget;
  if (dt->IsTiledDrawTarget() || dt->GetBackendType() != BackendType::SKIA ||
      dt->IsRecording()) {
    // We need a DrawTarget that we can get a CGContextRef from:
    Matrix transform = dt->GetTransform();

    mNativeRect = transform.TransformBounds(mNativeRect);
    mNativeRect.RoundOut();
    if (mNativeRect.IsEmpty()) {
      return nullptr;
    }

    mTempDrawTarget = Factory::CreateDrawTarget(
        BackendType::SKIA,
        IntSize::Truncate(mNativeRect.width, mNativeRect.height),
        SurfaceFormat::B8G8R8A8);
    if (!mTempDrawTarget) {
      return nullptr;
    }

    transform.PostTranslate(-mNativeRect.x, -mNativeRect.y);
    mTempDrawTarget->SetTransform(transform);

    dt = mTempDrawTarget;
  } else {
    // Clip the DT in case BorrowedCGContext needs to create a new layer.
    // This prevents it from creating a new layer the size of the window.
    // But make sure that this clip is device pixel aligned.
    Matrix transform = dt->GetTransform();

    Rect deviceRect = transform.TransformBounds(mNativeRect);
    deviceRect.RoundOut();
    mNativeRect = transform.Inverse().TransformBounds(deviceRect);
    mDrawTarget->PushClipRect(mNativeRect);
  }

  MOZ_ASSERT(dt->GetBackendType() == BackendType::SKIA);
  mCGContext = mBorrowedContext.Init(dt);

  if (NS_WARN_IF(!mCGContext)) {
    // Failed borrowing CG context, so we need to clean up.
    if (!mTempDrawTarget) {
      mDrawTarget->PopClip();
    }
    return nullptr;
  }

  return mCGContext;
}

void gfxQuartzNativeDrawing::EndNativeDrawing() {
  NS_ASSERTION(mCGContext,
               "EndNativeDrawing called without BeginNativeDrawing");

  mBorrowedContext.Finish();
  if (mTempDrawTarget) {
    RefPtr<SourceSurface> source = mTempDrawTarget->Snapshot();

    AutoRestoreTransform autoRestore(mDrawTarget);
    mDrawTarget->SetTransform(Matrix());
    mDrawTarget->DrawSurface(source, mNativeRect,
                             Rect(0, 0, mNativeRect.width, mNativeRect.height));
  } else {
    mDrawTarget->PopClip();
  }
}