1 files changed, 437 insertions, 0 deletions
diff --git a/layout/generic/nsHTMLCanvasFrame.cpp b/layout/generic/nsHTMLCanvasFrame.cpp
new file mode 100644
index 0000000000..bad3a710f8
--- /dev/null
+++ b/layout/generic/nsHTMLCanvasFrame.cpp
@@ -0,0 +1,437 @@
+/* -*- 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/. */
+
+/* rendering object for the HTML <canvas> element */
+
+#include "nsHTMLCanvasFrame.h"
+
+#include "nsGkAtoms.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/dom/HTMLCanvasElement.h"
+#include "nsDisplayList.h"
+#include "nsLayoutUtils.h"
+#include "nsStyleUtil.h"
+#include "ImageLayers.h"
+#include "Layers.h"
+#include "ActiveLayerTracker.h"
+
+#include <algorithm>
+
+using namespace mozilla;
+using namespace mozilla::dom;
+using namespace mozilla::layers;
+using namespace mozilla::gfx;
+
+/* Helper for our nsIFrame::GetIntrinsicSize() impl. Takes the result of
+ * "GetCanvasSize()" as a parameter, which may help avoid redundant
+ * indirect calls to GetCanvasSize().
+ *
+ * @param aCanvasSizeInPx The canvas's size in CSS pixels, as returned
+ *                        by GetCanvasSize().
+ * @return The canvas's intrinsic size, as an IntrinsicSize object.
+ */
+static IntrinsicSize
+IntrinsicSizeFromCanvasSize(const nsIntSize& aCanvasSizeInPx)
+{
+  IntrinsicSize intrinsicSize;
+  intrinsicSize.width.SetCoordValue(
+    nsPresContext::CSSPixelsToAppUnits(aCanvasSizeInPx.width));
+  intrinsicSize.height.SetCoordValue(
+    nsPresContext::CSSPixelsToAppUnits(aCanvasSizeInPx.height));
+
+  return intrinsicSize;
+}
+
+/* Helper for our nsIFrame::GetIntrinsicRatio() impl. Takes the result of
+ * "GetCanvasSize()" as a parameter, which may help avoid redundant
+ * indirect calls to GetCanvasSize().
+ *
+ * @param aCanvasSizeInPx The canvas's size in CSS pixels, as returned
+ *                        by GetCanvasSize().
+ * @return The canvas's intrinsic ratio, as a nsSize.
+ */
+static nsSize
+IntrinsicRatioFromCanvasSize(const nsIntSize& aCanvasSizeInPx)
+{
+  return nsSize(nsPresContext::CSSPixelsToAppUnits(aCanvasSizeInPx.width),
+                nsPresContext::CSSPixelsToAppUnits(aCanvasSizeInPx.height));
+}
+
+class nsDisplayCanvas : public nsDisplayItem {
+public:
+  nsDisplayCanvas(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)
+    : nsDisplayItem(aBuilder, 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 nsRegion GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
+                                   bool* aSnap) override {
+    *aSnap = false;
+    nsHTMLCanvasFrame* f = static_cast<nsHTMLCanvasFrame*>(Frame());
+    HTMLCanvasElement* canvas =
+      HTMLCanvasElement::FromContent(f->GetContent());
+    nsRegion result;
+    if (canvas->GetIsOpaque()) {
+      // OK, the entire region painted by the canvas is opaque. But what is
+      // that region? It's the canvas's "dest rect" (controlled by the
+      // object-fit/object-position CSS properties), clipped to the container's
+      // content box (which is what GetBounds() returns). So, we grab those
+      // rects and intersect them.
+      nsRect constraintRect = GetBounds(aBuilder, aSnap);
+
+      // Need intrinsic size & ratio, for ComputeObjectDestRect:
+      nsIntSize canvasSize = f->GetCanvasSize();
+      IntrinsicSize intrinsicSize = IntrinsicSizeFromCanvasSize(canvasSize);
+      nsSize intrinsicRatio = IntrinsicRatioFromCanvasSize(canvasSize);
+
+      const nsRect destRect =
+        nsLayoutUtils::ComputeObjectDestRect(constraintRect,
+                                             intrinsicSize, intrinsicRatio,
+                                             f->StylePosition());
+      return nsRegion(destRect.Intersect(constraintRect));
+    }
+    return result;
+  }
+
+  virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder,
+                           bool* aSnap) override {
+    *aSnap = true;
+    nsHTMLCanvasFrame* f = static_cast<nsHTMLCanvasFrame*>(Frame());
+    return f->GetInnerArea() + ToReferenceFrame();
+  }
+
+  virtual already_AddRefed<Layer> BuildLayer(nsDisplayListBuilder* aBuilder,
+                                             LayerManager* aManager,
+                                             const ContainerLayerParameters& aContainerParameters) override
+  {
+    return static_cast<nsHTMLCanvasFrame*>(mFrame)->
+      BuildLayer(aBuilder, aManager, this, aContainerParameters);
+  }
+  virtual LayerState GetLayerState(nsDisplayListBuilder* aBuilder,
+                                   LayerManager* aManager,
+                                   const ContainerLayerParameters& aParameters) override
+  {
+    if (HTMLCanvasElement::FromContent(mFrame->GetContent())->ShouldForceInactiveLayer(aManager))
+      return LAYER_INACTIVE;
+
+    // If compositing is cheap, just do that
+    if (aManager->IsCompositingCheap() ||
+        ActiveLayerTracker::IsContentActive(mFrame))
+      return mozilla::LAYER_ACTIVE;
+
+    return LAYER_INACTIVE;
+  }
+};
+
+
+nsIFrame*
+NS_NewHTMLCanvasFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsHTMLCanvasFrame(aContext);
+}
+
+NS_QUERYFRAME_HEAD(nsHTMLCanvasFrame)
+  NS_QUERYFRAME_ENTRY(nsHTMLCanvasFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)
+
+NS_IMPL_FRAMEARENA_HELPERS(nsHTMLCanvasFrame)
+
+void
+nsHTMLCanvasFrame::Init(nsIContent*       aContent,
+                        nsContainerFrame* aParent,
+                        nsIFrame*         aPrevInFlow)
+{
+  nsContainerFrame::Init(aContent, aParent, aPrevInFlow);
+
+  // We can fill in the canvas before the canvas frame is created, in
+  // which case we never get around to marking the content as active. Therefore,
+  // we mark it active here when we create the frame.
+  ActiveLayerTracker::NotifyContentChange(this);
+}
+
+nsHTMLCanvasFrame::~nsHTMLCanvasFrame()
+{
+}
+
+nsIntSize
+nsHTMLCanvasFrame::GetCanvasSize()
+{
+  nsIntSize size(0,0);
+  HTMLCanvasElement *canvas =
+    HTMLCanvasElement::FromContentOrNull(GetContent());
+  if (canvas) {
+    size = canvas->GetSize();
+    MOZ_ASSERT(size.width >= 0 && size.height >= 0,
+               "we should've required <canvas> width/height attrs to be "
+               "unsigned (non-negative) values");
+  } else {
+    NS_NOTREACHED("couldn't get canvas size");
+  }
+
+  return size;
+}
+
+/* virtual */ nscoord
+nsHTMLCanvasFrame::GetMinISize(nsRenderingContext *aRenderingContext)
+{
+  // XXX The caller doesn't account for constraints of the height,
+  // min-height, and max-height properties.
+  bool vertical = GetWritingMode().IsVertical();
+  nscoord result = nsPresContext::CSSPixelsToAppUnits(
+    vertical ? GetCanvasSize().height : GetCanvasSize().width);
+  DISPLAY_MIN_WIDTH(this, result);
+  return result;
+}
+
+/* virtual */ nscoord
+nsHTMLCanvasFrame::GetPrefISize(nsRenderingContext *aRenderingContext)
+{
+  // XXX The caller doesn't account for constraints of the height,
+  // min-height, and max-height properties.
+  bool vertical = GetWritingMode().IsVertical();
+  nscoord result = nsPresContext::CSSPixelsToAppUnits(
+    vertical ? GetCanvasSize().height : GetCanvasSize().width);
+  DISPLAY_PREF_WIDTH(this, result);
+  return result;
+}
+
+/* virtual */ IntrinsicSize
+nsHTMLCanvasFrame::GetIntrinsicSize()
+{
+  return IntrinsicSizeFromCanvasSize(GetCanvasSize());
+}
+
+/* virtual */ nsSize
+nsHTMLCanvasFrame::GetIntrinsicRatio()
+{
+  return IntrinsicRatioFromCanvasSize(GetCanvasSize());
+}
+
+/* virtual */
+LogicalSize
+nsHTMLCanvasFrame::ComputeSize(nsRenderingContext *aRenderingContext,
+                               WritingMode aWM,
+                               const LogicalSize& aCBSize,
+                               nscoord aAvailableISize,
+                               const LogicalSize& aMargin,
+                               const LogicalSize& aBorder,
+                               const LogicalSize& aPadding,
+                               ComputeSizeFlags aFlags)
+{
+  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 ComputeSizeWithIntrinsicDimensions(aRenderingContext, aWM,
+                                            intrinsicSize, intrinsicRatio,
+                                            aCBSize, aMargin, aBorder, aPadding,
+                                            aFlags);
+}
+
+void
+nsHTMLCanvasFrame::Reflow(nsPresContext*           aPresContext,
+                          ReflowOutput&     aMetrics,
+                          const ReflowInput& aReflowInput,
+                          nsReflowStatus&          aStatus)
+{
+  MarkInReflow();
+  DO_GLOBAL_REFLOW_COUNT("nsHTMLCanvasFrame");
+  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
+  NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
+                  ("enter nsHTMLCanvasFrame::Reflow: availSize=%d,%d",
+                  aReflowInput.AvailableWidth(), aReflowInput.AvailableHeight()));
+
+  NS_PRECONDITION(mState & NS_FRAME_IN_REFLOW, "frame is not in reflow");
+
+  aStatus = NS_FRAME_COMPLETE;
+
+  WritingMode wm = aReflowInput.GetWritingMode();
+  LogicalSize finalSize(wm,
+                        aReflowInput.ComputedISize(),
+                        aReflowInput.ComputedBSize());
+
+  // stash this away so we can compute our inner area later
+  mBorderPadding   = aReflowInput.ComputedLogicalBorderPadding();
+
+  finalSize.ISize(wm) += mBorderPadding.IStartEnd(wm);
+  finalSize.BSize(wm) += mBorderPadding.BStartEnd(wm);
+
+  if (GetPrevInFlow()) {
+    nscoord y = GetContinuationOffset(&finalSize.ISize(wm));
+    finalSize.BSize(wm) -= y + mBorderPadding.BStart(wm);
+    finalSize.BSize(wm) = std::max(0, finalSize.BSize(wm));
+  }
+
+  aMetrics.SetSize(wm, finalSize);
+  aMetrics.SetOverflowAreasToDesiredBounds();
+  FinishAndStoreOverflow(&aMetrics);
+
+  // Reflow the single anon block child.
+  nsReflowStatus childStatus;
+  nsIFrame* childFrame = mFrames.FirstChild();
+  WritingMode childWM = childFrame->GetWritingMode();
+  LogicalSize availSize = aReflowInput.ComputedSize(childWM);
+  availSize.BSize(childWM) = NS_UNCONSTRAINEDSIZE;
+  NS_ASSERTION(!childFrame->GetNextSibling(), "HTML canvas should have 1 kid");
+  ReflowOutput childDesiredSize(aReflowInput.GetWritingMode(), aMetrics.mFlags);
+  ReflowInput childReflowInput(aPresContext, aReflowInput, childFrame,
+                                     availSize);
+  ReflowChild(childFrame, aPresContext, childDesiredSize, childReflowInput,
+              0, 0, 0, childStatus, nullptr);
+  FinishReflowChild(childFrame, aPresContext, childDesiredSize,
+                    &childReflowInput, 0, 0, 0);
+
+  NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
+                  ("exit nsHTMLCanvasFrame::Reflow: size=%d,%d",
+                   aMetrics.ISize(wm), aMetrics.BSize(wm)));
+  NS_FRAME_SET_TRUNCATION(aStatus, aReflowInput, aMetrics);
+}
+
+// FIXME taken from nsImageFrame, but then had splittable frame stuff
+// removed.  That needs to be fixed.
+// XXXdholbert As in nsImageFrame, this function's clients should probably
+// just be calling GetContentRectRelativeToSelf().
+nsRect 
+nsHTMLCanvasFrame::GetInnerArea() const
+{
+  nsMargin bp = mBorderPadding.GetPhysicalMargin(GetWritingMode());
+  nsRect r;
+  r.x = bp.left;
+  r.y = bp.top;
+  r.width = mRect.width - bp.left - bp.right;
+  r.height = mRect.height - bp.top - bp.bottom;
+  return r;
+}
+
+already_AddRefed<Layer>
+nsHTMLCanvasFrame::BuildLayer(nsDisplayListBuilder* aBuilder,
+                              LayerManager* aManager,
+                              nsDisplayItem* aItem,
+                              const ContainerLayerParameters& aContainerParameters)
+{
+  nsRect area = GetContentRectRelativeToSelf() + aItem->ToReferenceFrame();
+  HTMLCanvasElement* element = static_cast<HTMLCanvasElement*>(GetContent());
+  nsIntSize canvasSizeInPx = GetCanvasSize();
+
+  nsPresContext* presContext = PresContext();
+  element->HandlePrintCallback(presContext->Type());
+
+  if (canvasSizeInPx.width <= 0 || canvasSizeInPx.height <= 0 || area.IsEmpty())
+    return nullptr;
+
+  CanvasLayer* oldLayer = static_cast<CanvasLayer*>
+    (aManager->GetLayerBuilder()->GetLeafLayerFor(aBuilder, aItem));
+  RefPtr<Layer> layer = element->GetCanvasLayer(aBuilder, oldLayer, aManager);
+  if (!layer)
+    return nullptr;
+
+  IntrinsicSize intrinsicSize = IntrinsicSizeFromCanvasSize(canvasSizeInPx);
+  nsSize intrinsicRatio = IntrinsicRatioFromCanvasSize(canvasSizeInPx);
+
+  nsRect dest =
+    nsLayoutUtils::ComputeObjectDestRect(area, intrinsicSize, intrinsicRatio,
+                                         StylePosition());
+
+  gfxRect destGFXRect = presContext->AppUnitsToGfxUnits(dest);
+
+  // Transform the canvas into the right place
+  gfxPoint p = destGFXRect.TopLeft() + aContainerParameters.mOffset;
+  Matrix transform = Matrix::Translation(p.x, p.y);
+  transform.PreScale(destGFXRect.Width() / canvasSizeInPx.width,
+                     destGFXRect.Height() / canvasSizeInPx.height);
+  layer->SetBaseTransform(gfx::Matrix4x4::From2D(transform));
+  if (layer->GetType() == layers::Layer::TYPE_CANVAS) {
+    RefPtr<CanvasLayer> canvasLayer = static_cast<CanvasLayer*>(layer.get());
+    canvasLayer->SetSamplingFilter(nsLayoutUtils::GetSamplingFilterForFrame(this));
+  } else if (layer->GetType() == layers::Layer::TYPE_IMAGE) {
+    RefPtr<ImageLayer> imageLayer = static_cast<ImageLayer*>(layer.get());
+    imageLayer->SetSamplingFilter(nsLayoutUtils::GetSamplingFilterForFrame(this));
+  }
+
+  return layer.forget();
+}
+
+void
+nsHTMLCanvasFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                    const nsRect&           aDirtyRect,
+                                    const nsDisplayListSet& aLists)
+{
+  if (!IsVisibleForPainting(aBuilder))
+    return;
+
+  DisplayBorderBackgroundOutline(aBuilder, aLists);
+
+  uint32_t clipFlags =
+    nsStyleUtil::ObjectPropsMightCauseOverflow(StylePosition()) ?
+    0 : DisplayListClipState::ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT;
+
+  DisplayListClipState::AutoClipContainingBlockDescendantsToContentBox
+    clip(aBuilder, this, clipFlags);
+
+  aLists.Content()->AppendNewToTop(
+    new (aBuilder) nsDisplayCanvas(aBuilder, this));
+
+  DisplaySelectionOverlay(aBuilder, aLists.Content(),
+                          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.GetPhysicalMargin(GetWritingMode()).top;
+    offset = std::max(0, offset);
+  }
+  return offset;
+}
+
+#ifdef ACCESSIBILITY
+a11y::AccType
+nsHTMLCanvasFrame::AccessibleType()
+{
+  return a11y::eHTMLCanvasType;
+}
+#endif
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+nsHTMLCanvasFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("HTMLCanvas"), aResult);
+}
+#endif
+