gecko-dev/gfx/layers/CopyableCanvasLayer.cpp

/* -*- 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 "mozilla/layers/PLayerTransactionParent.h"
#include "CopyableCanvasLayer.h"
#include "BasicLayersImpl.h"
#include "gfxImageSurface.h"
#include "GLContext.h"
#include "gfxUtils.h"
#include "gfxPlatform.h"
#include "mozilla/Preferences.h"
#include "SurfaceStream.h"
#include "SharedSurfaceGL.h"
#include "SharedSurfaceEGL.h"
#include "GeckoProfiler.h"

#include "nsXULAppAPI.h"

using namespace mozilla::gfx;
using namespace mozilla::gl;

namespace mozilla {
namespace layers {

void
CopyableCanvasLayer::Initialize(const Data& aData)
{
  NS_ASSERTION(mSurface == nullptr, "BasicCanvasLayer::Initialize called twice!");

  if (aData.mSurface) {
    mSurface = aData.mSurface;
    NS_ASSERTION(!aData.mGLContext, "CanvasLayer can't have both surface and GLContext");
    mNeedsYFlip = false;
  } else if (aData.mGLContext) {
    mGLContext = aData.mGLContext;
    mIsGLAlphaPremult = aData.mIsGLAlphaPremult;
    mNeedsYFlip = true;
    MOZ_ASSERT(mGLContext->IsOffscreen(), "canvas gl context isn't offscreen");

    // [Basic Layers, non-OMTC] WebGL layer init.
    // `GLScreenBuffer::Morph`ing is only needed in BasicShadowableCanvasLayer.
  } else if (aData.mDrawTarget) {
    mDrawTarget = aData.mDrawTarget;
    mSurface = gfxPlatform::GetPlatform()->CreateThebesSurfaceAliasForDrawTarget_hack(mDrawTarget);
    mNeedsYFlip = false;
  } else {
    NS_ERROR("CanvasLayer created without mSurface, mDrawTarget or mGLContext?");
  }

  mBounds.SetRect(0, 0, aData.mSize.width, aData.mSize.height);
}

void
CopyableCanvasLayer::UpdateSurface(gfxASurface* aDestSurface, Layer* aMaskLayer)
{
  if (!IsDirty())
    return;
  Painted();

  if (mDrawTarget) {
    mDrawTarget->Flush();
    if (mDrawTarget->GetType() == BACKEND_COREGRAPHICS_ACCELERATED) {
      // We have an accelerated CG context which has changed, unlike a bitmap surface
      // where we can alias the bits on initializing the mDrawTarget, we need to readback
      // and copy the accelerated surface each frame. We want to support this for quick
      // thumbnail but if we're going to be doing this every frame it likely is better
      // to use a non accelerated (bitmap) canvas.
      mSurface = gfxPlatform::GetPlatform()->GetThebesSurfaceForDrawTarget(mDrawTarget);
    }
  }

  if (!mGLContext && aDestSurface) {
    nsRefPtr<gfxContext> tmpCtx = new gfxContext(aDestSurface);
    tmpCtx->SetOperator(gfxContext::OPERATOR_SOURCE);
    CopyableCanvasLayer::PaintWithOpacity(tmpCtx, 1.0f, aMaskLayer);
    return;
  }

  if (mGLContext) {
    if (aDestSurface && aDestSurface->GetType() != gfxASurface::SurfaceTypeImage) {
      MOZ_ASSERT(false, "Destination surface must be ImageSurface type.");
      return;
    }

    nsRefPtr<gfxImageSurface> readSurf;
    nsRefPtr<gfxImageSurface> resultSurf;

    SharedSurface* sharedSurf = mGLContext->RequestFrame();
    if (!sharedSurf) {
      NS_WARNING("Null frame received.");
      return;
    }

    gfxIntSize readSize(sharedSurf->Size());
    gfxImageFormat format = (GetContentFlags() & CONTENT_OPAQUE)
                            ? gfxASurface::ImageFormatRGB24
                            : gfxASurface::ImageFormatARGB32;

    if (aDestSurface) {
      resultSurf = static_cast<gfxImageSurface*>(aDestSurface);
    } else {
      resultSurf = GetTempSurface(readSize, format);
    }
    MOZ_ASSERT(resultSurf);
    if (resultSurf->CairoStatus() != 0) {
      MOZ_ASSERT(false, "Bad resultSurf->CairoStatus().");
      return;
    }

    MOZ_ASSERT(sharedSurf->APIType() == APITypeT::OpenGL);
    SharedSurface_GL* surfGL = SharedSurface_GL::Cast(sharedSurf);

    if (surfGL->Type() == SharedSurfaceType::Basic) {
      SharedSurface_Basic* sharedSurf_Basic = SharedSurface_Basic::Cast(surfGL);
      readSurf = sharedSurf_Basic->GetData();
    } else {
      if (resultSurf->Format() == format &&
          resultSurf->GetSize() == readSize)
      {
        readSurf = resultSurf;
      } else {
        readSurf = GetTempSurface(readSize, format);
      }

      // Readback handles Flush/MarkDirty.
      mGLContext->Screen()->Readback(surfGL, readSurf);
    }
    MOZ_ASSERT(readSurf);

    bool needsPremult = surfGL->HasAlpha() && !mIsGLAlphaPremult;
    if (needsPremult) {
      gfxImageSurface* sizedReadSurf = nullptr;
      if (readSurf->Format()  == resultSurf->Format() &&
          readSurf->GetSize() == resultSurf->GetSize())
      {
        sizedReadSurf = readSurf;
      } else {
        readSurf->Flush();
        nsRefPtr<gfxContext> ctx = new gfxContext(resultSurf);
        ctx->SetOperator(gfxContext::OPERATOR_SOURCE);
        ctx->SetSource(readSurf);
        ctx->Paint();

        sizedReadSurf = resultSurf;
      }
      MOZ_ASSERT(sizedReadSurf);

      readSurf->Flush();
      resultSurf->Flush();
      gfxUtils::PremultiplyImageSurface(readSurf, resultSurf);
      resultSurf->MarkDirty();
    } else if (resultSurf != readSurf) {
      // Didn't need premult, but we do need to blit to resultSurf
      readSurf->Flush();
      nsRefPtr<gfxContext> ctx = new gfxContext(resultSurf);
      ctx->SetOperator(gfxContext::OPERATOR_SOURCE);
      ctx->SetSource(readSurf);
      ctx->Paint();
    }

    // stick our surface into mSurface, so that the Paint() path is the same
    if (!aDestSurface) {
      mSurface = resultSurf;
    }
  }
}

void
CopyableCanvasLayer::PaintWithOpacity(gfxContext* aContext,
                                      float aOpacity,
                                      Layer* aMaskLayer,
                                      gfxContext::GraphicsOperator aOperator)
{
  if (!mSurface) {
    NS_WARNING("No valid surface to draw!");
    return;
  }

  nsRefPtr<gfxPattern> pat = new gfxPattern(mSurface);

  pat->SetFilter(mFilter);
  pat->SetExtend(gfxPattern::EXTEND_PAD);

  gfxMatrix m;
  if (mNeedsYFlip) {
    m = aContext->CurrentMatrix();
    aContext->Translate(gfxPoint(0.0, mBounds.height));
    aContext->Scale(1.0, -1.0);
  }

  // If content opaque, then save off current operator and set to source.
  // This ensures that alpha is not applied even if the source surface
  // has an alpha channel
  gfxContext::GraphicsOperator savedOp;
  if (GetContentFlags() & CONTENT_OPAQUE) {
    savedOp = aContext->CurrentOperator();
    aContext->SetOperator(gfxContext::OPERATOR_SOURCE);
  }

  AutoSetOperator setOperator(aContext, aOperator);
  aContext->NewPath();
  // No need to snap here; our transform is already set up to snap our rect
  aContext->Rectangle(gfxRect(0, 0, mBounds.width, mBounds.height));
  aContext->SetPattern(pat);

  FillWithMask(aContext, aOpacity, aMaskLayer);
  // Restore surface operator
  if (GetContentFlags() & CONTENT_OPAQUE) {
    aContext->SetOperator(savedOp);
  }  

  if (mNeedsYFlip) {
    aContext->SetMatrix(m);
  }
}

}
}