gecko-dev/layout/generic/nsHTMLCanvasFrame.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 *   Vladimir Vukicevic <vladimir@pobox.com>
 * Portions created by the Initial Developer are Copyright (C) 2004
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *    Vladimir Vukicevic <vladimir@pobox.com> (original author)
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/* rendering object for the HTML <canvas> element */

#include "nsHTMLParts.h"
#include "nsCOMPtr.h"
#include "nsIServiceManager.h"
#include "nsGkAtoms.h"

#include "nsHTMLCanvasFrame.h"
#include "nsHTMLCanvasElement.h"
#include "nsDisplayList.h"
#include "nsLayoutUtils.h"

#include "nsTransform2D.h"

#include "gfxContext.h"

using namespace mozilla;
using namespace mozilla::layers;

static nsHTMLCanvasElement *
CanvasElementFromContent(nsIContent *content)
{
  nsCOMPtr<nsIDOMHTMLCanvasElement> domCanvas(do_QueryInterface(content));
  return domCanvas ? static_cast<nsHTMLCanvasElement*>(domCanvas.get()) : nsnull;
}

class nsDisplayCanvas : public nsDisplayItem {
public:
  nsDisplayCanvas(nsIFrame* aFrame)
    : nsDisplayItem(aFrame)
  {
    MOZ_COUNT_CTOR(nsDisplayCanvas);
  }
#ifdef NS_BUILD_REFCNT_LOGGING
  virtual ~nsDisplayCanvas() {
    MOZ_COUNT_DTOR(nsDisplayCanvas);
  }
#endif

  NS_DISPLAY_DECL_NAME("nsDisplayCanvas", TYPE_CANVAS)

  virtual PRBool IsOpaque(nsDisplayListBuilder* aBuilder) {
    nsIFrame* f = GetUnderlyingFrame();
    nsHTMLCanvasElement *canvas = CanvasElementFromContent(f->GetContent());
    return canvas->GetIsOpaque();
  }

  virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder) {
    nsHTMLCanvasFrame* f = static_cast<nsHTMLCanvasFrame*>(GetUnderlyingFrame());
    return f->GetInnerArea() + aBuilder->ToReferenceFrame(f);
  }

  virtual already_AddRefed<Layer> BuildLayer(nsDisplayListBuilder* aBuilder,
                                             LayerManager* aManager)
  {
    return static_cast<nsHTMLCanvasFrame*>(mFrame)->
      BuildLayer(aBuilder, aManager, this);
  }
  virtual LayerState GetLayerState(nsDisplayListBuilder* aBuilder,
                                   LayerManager* aManager)
  {
    // XXX we should have some kind of activity timeout here so that
    // inactive canvases can be composited into the background
    return mozilla::LAYER_ACTIVE;
  }
};


nsIFrame*
NS_NewHTMLCanvasFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
  return new (aPresShell) nsHTMLCanvasFrame(aContext);
}

NS_IMPL_FRAMEARENA_HELPERS(nsHTMLCanvasFrame)

nsHTMLCanvasFrame::~nsHTMLCanvasFrame()
{
}

nsIntSize
nsHTMLCanvasFrame::GetCanvasSize()
{
  nsIntSize size(0,0);
  nsHTMLCanvasElement *canvas = CanvasElementFromContent(GetContent());
  if (canvas) {
    size = canvas->GetSize();
  } else {
    NS_NOTREACHED("couldn't get canvas size");
  }

  return size;
}

/* virtual */ nscoord
nsHTMLCanvasFrame::GetMinWidth(nsIRenderingContext *aRenderingContext)
{
  // XXX The caller doesn't account for constraints of the height,
  // min-height, and max-height properties.
  nscoord result = nsPresContext::CSSPixelsToAppUnits(GetCanvasSize().width);
  DISPLAY_MIN_WIDTH(this, result);
  return result;
}

/* virtual */ nscoord
nsHTMLCanvasFrame::GetPrefWidth(nsIRenderingContext *aRenderingContext)
{
  // XXX The caller doesn't account for constraints of the height,
  // min-height, and max-height properties.
  nscoord result = nsPresContext::CSSPixelsToAppUnits(GetCanvasSize().width);
  DISPLAY_PREF_WIDTH(this, result);
  return result;
}

/* virtual */ nsSize
nsHTMLCanvasFrame::GetIntrinsicRatio()
{
  nsIntSize size(GetCanvasSize());
  return nsSize(nsPresContext::CSSPixelsToAppUnits(size.width),
                nsPresContext::CSSPixelsToAppUnits(size.height));
}

/* virtual */ nsSize
nsHTMLCanvasFrame::ComputeSize(nsIRenderingContext *aRenderingContext,
                               nsSize aCBSize, nscoord aAvailableWidth,
                               nsSize aMargin, nsSize aBorder, nsSize aPadding,
                               PRBool aShrinkWrap)
{
  nsIntSize size = GetCanvasSize();

  IntrinsicSize intrinsicSize;
  intrinsicSize.width.SetCoordValue(nsPresContext::CSSPixelsToAppUnits(size.width));
  intrinsicSize.height.SetCoordValue(nsPresContext::CSSPixelsToAppUnits(size.height));

  nsSize intrinsicRatio = GetIntrinsicRatio(); // won't actually be used

  return nsLayoutUtils::ComputeSizeWithIntrinsicDimensions(
                            aRenderingContext, this,
                            intrinsicSize, intrinsicRatio, aCBSize,
                            aMargin, aBorder, aPadding);
}

NS_IMETHODIMP
nsHTMLCanvasFrame::Reflow(nsPresContext*           aPresContext,
                          nsHTMLReflowMetrics&     aMetrics,
                          const nsHTMLReflowState& aReflowState,
                          nsReflowStatus&          aStatus)
{
  DO_GLOBAL_REFLOW_COUNT("nsHTMLCanvasFrame");
  DISPLAY_REFLOW(aPresContext, this, aReflowState, aMetrics, aStatus);
  NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
                  ("enter nsHTMLCanvasFrame::Reflow: availSize=%d,%d",
                  aReflowState.availableWidth, aReflowState.availableHeight));

  NS_PRECONDITION(mState & NS_FRAME_IN_REFLOW, "frame is not in reflow");

  aStatus = NS_FRAME_COMPLETE;

  aMetrics.width = aReflowState.ComputedWidth();
  aMetrics.height = aReflowState.ComputedHeight();

  // stash this away so we can compute our inner area later
  mBorderPadding   = aReflowState.mComputedBorderPadding;

  aMetrics.width += mBorderPadding.left + mBorderPadding.right;
  aMetrics.height += mBorderPadding.top + mBorderPadding.bottom;

  if (GetPrevInFlow()) {
    nscoord y = GetContinuationOffset(&aMetrics.width);
    aMetrics.height -= y + mBorderPadding.top;
    aMetrics.height = NS_MAX(0, aMetrics.height);
  }

  aMetrics.mOverflowArea.SetRect(0, 0, aMetrics.width, aMetrics.height);
  FinishAndStoreOverflow(&aMetrics);

  if (mRect.width != aMetrics.width || mRect.height != aMetrics.height) {
    Invalidate(nsRect(0, 0, mRect.width, mRect.height));
  }

  NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
                  ("exit nsHTMLCanvasFrame::Reflow: size=%d,%d",
                  aMetrics.width, aMetrics.height));
  NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aMetrics);
  return NS_OK;
}

// FIXME taken from nsImageFrame, but then had splittable frame stuff
// removed.  That needs to be fixed.
nsRect 
nsHTMLCanvasFrame::GetInnerArea() const
{
  nsRect r;
  r.x = mBorderPadding.left;
  r.y = mBorderPadding.top;
  r.width = mRect.width - mBorderPadding.left - mBorderPadding.right;
  r.height = mRect.height - mBorderPadding.top - mBorderPadding.bottom;
  return r;
}

already_AddRefed<Layer>
nsHTMLCanvasFrame::BuildLayer(nsDisplayListBuilder* aBuilder,
                              LayerManager* aManager,
                              nsDisplayItem* aItem)
{
  nsRect area = GetContentRect() + aBuilder->ToReferenceFrame(GetParent());
  nsHTMLCanvasElement* element = static_cast<nsHTMLCanvasElement*>(GetContent());
  nsIntSize canvasSize = GetCanvasSize();

  if (canvasSize.width <= 0 || canvasSize.height <= 0 || area.IsEmpty())
    return nsnull;

  CanvasLayer* oldLayer = static_cast<CanvasLayer*>
    (aBuilder->LayerBuilder()->GetLeafLayerFor(aBuilder, aManager, aItem));
  nsRefPtr<CanvasLayer> layer = element->GetCanvasLayer(oldLayer, aManager);
  if (!layer)
    return nsnull;

  element->MarkContextClean();

  nsPresContext* presContext = PresContext();
  gfxRect r = gfxRect(presContext->AppUnitsToGfxUnits(area.x),
                      presContext->AppUnitsToGfxUnits(area.y),
                      presContext->AppUnitsToGfxUnits(area.width),
                      presContext->AppUnitsToGfxUnits(area.height));

  // Transform the canvas into the right place
  gfxMatrix transform;
  transform.Translate(r.pos);
  transform.Scale(r.Width()/canvasSize.width, r.Height()/canvasSize.height);
  layer->SetTransform(gfx3DMatrix::From2D(transform));
  layer->SetFilter(nsLayoutUtils::GetGraphicsFilterForFrame(this));

  return layer.forget();
}

NS_IMETHODIMP
nsHTMLCanvasFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                    const nsRect&           aDirtyRect,
                                    const nsDisplayListSet& aLists)
{
  if (!IsVisibleForPainting(aBuilder))
    return NS_OK;

  nsresult rv = DisplayBorderBackgroundOutline(aBuilder, aLists);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = aLists.Content()->AppendNewToTop(new (aBuilder) nsDisplayCanvas(this));
  NS_ENSURE_SUCCESS(rv, rv);

  return DisplaySelectionOverlay(aBuilder, aLists,
                                 nsISelectionDisplay::DISPLAY_IMAGES);
}

nsIAtom*
nsHTMLCanvasFrame::GetType() const
{
  return nsGkAtoms::HTMLCanvasFrame;
}

// get the offset into the content area of the image where aImg starts if it is a continuation.
// from nsImageFrame
nscoord 
nsHTMLCanvasFrame::GetContinuationOffset(nscoord* aWidth) const
{
  nscoord offset = 0;
  if (aWidth) {
    *aWidth = 0;
  }

  if (GetPrevInFlow()) {
    for (nsIFrame* prevInFlow = GetPrevInFlow() ; prevInFlow; prevInFlow = prevInFlow->GetPrevInFlow()) {
      nsRect rect = prevInFlow->GetRect();
      if (aWidth) {
        *aWidth = rect.width;
      }
      offset += rect.height;
    }
    offset -= mBorderPadding.top;
    offset = NS_MAX(0, offset);
  }
  return offset;
}

#ifdef ACCESSIBILITY
already_AddRefed<nsAccessible>
nsHTMLCanvasFrame::CreateAccessible()
{
  return nsnull;
}
#endif

#ifdef DEBUG
NS_IMETHODIMP
nsHTMLCanvasFrame::GetFrameName(nsAString& aResult) const
{
  return MakeFrameName(NS_LITERAL_STRING("HTMLCanvas"), aResult);
}
#endif