gecko/gfx/layers/basic/BasicThebesLayer.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 "BasicThebesLayer.h"
#include "gfxUtils.h"
#include "nsIWidget.h"
#include "RenderTrace.h"
#include "GeckoProfiler.h"

#include "prprf.h"

using namespace mozilla::gfx;

namespace mozilla {
namespace layers {

static nsIntRegion
IntersectWithClip(const nsIntRegion& aRegion, gfxContext* aContext)
{
  gfxRect clip = aContext->GetClipExtents();
  clip.RoundOut();
  nsIntRect r(clip.X(), clip.Y(), clip.Width(), clip.Height());
  nsIntRegion result;
  result.And(aRegion, r);
  return result;
}

static void
SetAntialiasingFlags(Layer* aLayer, gfxContext* aTarget)
{
  if (!aTarget->IsCairo()) {
    RefPtr<DrawTarget> dt = aTarget->GetDrawTarget();

    if (dt->GetFormat() != FORMAT_B8G8R8A8) {
      return;
    }

    const nsIntRect& bounds = aLayer->GetVisibleRegion().GetBounds();
    gfx::Rect transformedBounds = dt->GetTransform().TransformBounds(gfx::Rect(Float(bounds.x), Float(bounds.y),
                                                                     Float(bounds.width), Float(bounds.height)));
    transformedBounds.RoundOut();
    IntRect intTransformedBounds;
    transformedBounds.ToIntRect(&intTransformedBounds);
    dt->SetPermitSubpixelAA(!(aLayer->GetContentFlags() & Layer::CONTENT_COMPONENT_ALPHA) ||
                            dt->GetOpaqueRect().Contains(intTransformedBounds));
  } else {
    nsRefPtr<gfxASurface> surface = aTarget->CurrentSurface();
    if (surface->GetContentType() != gfxASurface::CONTENT_COLOR_ALPHA) {
      // Destination doesn't have alpha channel; no need to set any special flags
      return;
    }

    const nsIntRect& bounds = aLayer->GetVisibleRegion().GetBounds();
    surface->SetSubpixelAntialiasingEnabled(
        !(aLayer->GetContentFlags() & Layer::CONTENT_COMPONENT_ALPHA) ||
        surface->GetOpaqueRect().Contains(
          aTarget->UserToDevice(gfxRect(bounds.x, bounds.y, bounds.width, bounds.height))));
  }
}

void
BasicThebesLayer::PaintThebes(gfxContext* aContext,
                              Layer* aMaskLayer,
                              LayerManager::DrawThebesLayerCallback aCallback,
                              void* aCallbackData,
                              ReadbackProcessor* aReadback)
{
  PROFILER_LABEL("BasicThebesLayer", "PaintThebes");
  NS_ASSERTION(BasicManager()->InDrawing(),
               "Can only draw in drawing phase");
  nsRefPtr<gfxASurface> targetSurface = aContext->CurrentSurface();

  if (!mContentClient) {
    // we pass a null pointer for the Forwarder argument, which means
    // this will not have a ContentHost on the other side.
    mContentClient = new ContentClientBasic(nullptr, BasicManager());
  }

  nsTArray<ReadbackProcessor::Update> readbackUpdates;
  if (aReadback && UsedForReadback()) {
    aReadback->GetThebesLayerUpdates(this, &readbackUpdates);
  }
  //TODO: This is going to copy back pixels that we might end up
  // drawing over anyway. It would be nice if we could avoid
  // this duplication.
  mContentClient->SyncFrontBufferToBackBuffer();

  bool canUseOpaqueSurface = CanUseOpaqueSurface();
  ContentType contentType =
    canUseOpaqueSurface ? gfxASurface::CONTENT_COLOR :
                          gfxASurface::CONTENT_COLOR_ALPHA;
  float opacity = GetEffectiveOpacity();
  
  if (!BasicManager()->IsRetained()) {
    NS_ASSERTION(readbackUpdates.IsEmpty(), "Can't do readback for non-retained layer");

    mValidRegion.SetEmpty();
    mContentClient->Clear();

    nsIntRegion toDraw = IntersectWithClip(GetEffectiveVisibleRegion(), aContext);

    RenderTraceInvalidateStart(this, "FFFF00", toDraw.GetBounds());

    if (!toDraw.IsEmpty() && !IsHidden()) {
      if (!aCallback) {
        BasicManager()->SetTransactionIncomplete();
        return;
      }

      aContext->Save();

      bool needsClipToVisibleRegion = GetClipToVisibleRegion();
      bool needsGroup =
          opacity != 1.0 || GetOperator() != gfxContext::OPERATOR_OVER || aMaskLayer;
      nsRefPtr<gfxContext> groupContext;
      if (needsGroup) {
        groupContext =
          BasicManager()->PushGroupForLayer(aContext, this, toDraw,
                                            &needsClipToVisibleRegion);
        if (GetOperator() != gfxContext::OPERATOR_OVER) {
          needsClipToVisibleRegion = true;
        }
      } else {
        groupContext = aContext;
      }
      SetAntialiasingFlags(this, groupContext);
      aCallback(this, groupContext, toDraw, nsIntRegion(), aCallbackData);
      if (needsGroup) {
        BasicManager()->PopGroupToSourceWithCachedSurface(aContext, groupContext);
        if (needsClipToVisibleRegion) {
          gfxUtils::ClipToRegion(aContext, toDraw);
        }
        AutoSetOperator setOperator(aContext, GetOperator());
        PaintWithMask(aContext, opacity, aMaskLayer);
      }

      aContext->Restore();
    }

    RenderTraceInvalidateEnd(this, "FFFF00");
    return;
  }

  {
    uint32_t flags = 0;
#ifndef MOZ_WIDGET_ANDROID
    if (BasicManager()->CompositorMightResample()) {
      flags |= ThebesLayerBuffer::PAINT_WILL_RESAMPLE;
    }
    if (!(flags & ThebesLayerBuffer::PAINT_WILL_RESAMPLE)) {
      if (MayResample()) {
        flags |= ThebesLayerBuffer::PAINT_WILL_RESAMPLE;
      }
    }
#endif
    if (mDrawAtomically) {
      flags |= ThebesLayerBuffer::PAINT_NO_ROTATION;
    }
    PaintState state =
      mContentClient->BeginPaintBuffer(this, contentType, flags);
    mValidRegion.Sub(mValidRegion, state.mRegionToInvalidate);

    if (state.mContext) {
      // The area that became invalid and is visible needs to be repainted
      // (this could be the whole visible area if our buffer switched
      // from RGB to RGBA, because we might need to repaint with
      // subpixel AA)
      state.mRegionToInvalidate.And(state.mRegionToInvalidate,
                                    GetEffectiveVisibleRegion());
      nsIntRegion extendedDrawRegion = state.mRegionToDraw;
      SetAntialiasingFlags(this, state.mContext);

      RenderTraceInvalidateStart(this, "FFFF00", state.mRegionToDraw.GetBounds());

      PaintBuffer(state.mContext,
                  state.mRegionToDraw, extendedDrawRegion, state.mRegionToInvalidate,
                  state.mDidSelfCopy,
                  aCallback, aCallbackData);
      MOZ_LAYERS_LOG_IF_SHADOWABLE(this, ("Layer::Mutated(%p) PaintThebes", this));
      Mutated();

      RenderTraceInvalidateEnd(this, "FFFF00");
    } else {
      // It's possible that state.mRegionToInvalidate is nonempty here,
      // if we are shrinking the valid region to nothing. So use mRegionToDraw
      // instead.
      NS_WARN_IF_FALSE(state.mRegionToDraw.IsEmpty(),
                       "No context when we have something to draw, resource exhaustion?");
    }
  }

  if (BasicManager()->IsTransactionIncomplete())
    return;

  gfxRect clipExtents;
  clipExtents = aContext->GetClipExtents();

  // Pull out the mask surface and transform here, because the mask
  // is internal to basic layers
  AutoMaskData mask;
  gfxASurface* maskSurface = nullptr;
  const gfxMatrix* maskTransform = nullptr;
  if (GetMaskData(aMaskLayer, &mask)) {
    maskSurface = mask.GetSurface();
    maskTransform = &mask.GetTransform();
  }

  if (!IsHidden() && !clipExtents.IsEmpty()) {
    AutoSetOperator setOperator(aContext, GetOperator());
    mContentClient->DrawTo(this, aContext, opacity, maskSurface, maskTransform);
  }

  for (uint32_t i = 0; i < readbackUpdates.Length(); ++i) {
    ReadbackProcessor::Update& update = readbackUpdates[i];
    nsIntPoint offset = update.mLayer->GetBackgroundLayerOffset();
    nsRefPtr<gfxContext> ctx =
      update.mLayer->GetSink()->BeginUpdate(update.mUpdateRect + offset,
                                            update.mSequenceCounter);
    if (ctx) {
      NS_ASSERTION(opacity == 1.0, "Should only read back opaque layers");
      ctx->Translate(gfxPoint(offset.x, offset.y));
      mContentClient->DrawTo(this, ctx, 1.0, maskSurface, maskTransform);
      update.mLayer->GetSink()->EndUpdate(ctx, update.mUpdateRect + offset);
    }
  }
}

already_AddRefed<ThebesLayer>
BasicLayerManager::CreateThebesLayer()
{
  NS_ASSERTION(InConstruction(), "Only allowed in construction phase");
  nsRefPtr<ThebesLayer> layer = new BasicThebesLayer(this);
  return layer.forget();
}

}
}