gecko/layout/generic/nsVideoFrame.cpp

634 lines
24 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 <video> element */
#include "nsVideoFrame.h"
#include "nsCOMPtr.h"
#include "nsGkAtoms.h"
#include "mozilla/dom/HTMLVideoElement.h"
#include "nsIDOMHTMLVideoElement.h"
#include "nsIDOMHTMLImageElement.h"
#include "nsDisplayList.h"
#include "nsGenericHTMLElement.h"
#include "nsPresContext.h"
#include "nsContentCreatorFunctions.h"
#include "nsBoxLayoutState.h"
#include "nsBoxFrame.h"
#include "nsImageFrame.h"
#include "nsIImageLoadingContent.h"
#include "nsContentUtils.h"
#include "ImageContainer.h"
#include "ImageLayers.h"
#include "nsContentList.h"
#include <algorithm>
using namespace mozilla;
using namespace mozilla::layers;
using namespace mozilla::dom;
using namespace mozilla::gfx;
nsIFrame*
NS_NewHTMLVideoFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
return new (aPresShell) nsVideoFrame(aContext);
}
NS_IMPL_FRAMEARENA_HELPERS(nsVideoFrame)
nsVideoFrame::nsVideoFrame(nsStyleContext* aContext) :
nsContainerFrame(aContext)
{
}
nsVideoFrame::~nsVideoFrame()
{
}
NS_QUERYFRAME_HEAD(nsVideoFrame)
NS_QUERYFRAME_ENTRY(nsVideoFrame)
NS_QUERYFRAME_ENTRY(nsIAnonymousContentCreator)
NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)
nsresult
nsVideoFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
{
nsNodeInfoManager *nodeInfoManager = GetContent()->GetCurrentDoc()->NodeInfoManager();
nsCOMPtr<nsINodeInfo> nodeInfo;
Element *element;
if (HasVideoElement()) {
// Create an anonymous image element as a child to hold the poster
// image. We may not have a poster image now, but one could be added
// before we load, or on a subsequent load.
nodeInfo = nodeInfoManager->GetNodeInfo(nsGkAtoms::img,
nullptr,
kNameSpaceID_XHTML,
nsIDOMNode::ELEMENT_NODE);
NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
element = NS_NewHTMLImageElement(nodeInfo.forget());
mPosterImage = element;
NS_ENSURE_TRUE(mPosterImage, NS_ERROR_OUT_OF_MEMORY);
// Set the nsImageLoadingContent::ImageState() to 0. This means that the
// image will always report its state as 0, so it will never be reframed
// to show frames for loading or the broken image icon. This is important,
// as the image is native anonymous, and so can't be reframed (currently).
nsCOMPtr<nsIImageLoadingContent> imgContent = do_QueryInterface(mPosterImage);
NS_ENSURE_TRUE(imgContent, NS_ERROR_FAILURE);
imgContent->ForceImageState(true, 0);
// And now have it update its internal state
element->UpdateState(false);
UpdatePosterSource(false);
if (!aElements.AppendElement(mPosterImage))
return NS_ERROR_OUT_OF_MEMORY;
// Set up the caption overlay div for showing any TextTrack data
nodeInfo = nodeInfoManager->GetNodeInfo(nsGkAtoms::div,
nullptr,
kNameSpaceID_XHTML,
nsIDOMNode::ELEMENT_NODE);
NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
mCaptionDiv = NS_NewHTMLDivElement(nodeInfo.forget());
NS_ENSURE_TRUE(mCaptionDiv, NS_ERROR_OUT_OF_MEMORY);
nsGenericHTMLElement* div = static_cast<nsGenericHTMLElement*>(mCaptionDiv.get());
div->SetClassName(NS_LITERAL_STRING("caption-box"));
if (!aElements.AppendElement(mCaptionDiv))
return NS_ERROR_OUT_OF_MEMORY;
}
// Set up "videocontrols" XUL element which will be XBL-bound to the
// actual controls.
nodeInfo = nodeInfoManager->GetNodeInfo(nsGkAtoms::videocontrols,
nullptr,
kNameSpaceID_XUL,
nsIDOMNode::ELEMENT_NODE);
NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
NS_TrustedNewXULElement(getter_AddRefs(mVideoControls), nodeInfo.forget());
if (!aElements.AppendElement(mVideoControls))
return NS_ERROR_OUT_OF_MEMORY;
return NS_OK;
}
void
nsVideoFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
uint32_t aFliter)
{
aElements.MaybeAppendElement(mPosterImage);
aElements.MaybeAppendElement(mVideoControls);
aElements.MaybeAppendElement(mCaptionDiv);
}
void
nsVideoFrame::DestroyFrom(nsIFrame* aDestructRoot)
{
nsContentUtils::DestroyAnonymousContent(&mCaptionDiv);
nsContentUtils::DestroyAnonymousContent(&mVideoControls);
nsContentUtils::DestroyAnonymousContent(&mPosterImage);
nsContainerFrame::DestroyFrom(aDestructRoot);
}
bool
nsVideoFrame::IsLeaf() const
{
return true;
}
// Return the largest rectangle that fits in aRect and has the
// same aspect ratio as aRatio, centered at the center of aRect
static gfxRect
CorrectForAspectRatio(const gfxRect& aRect, const nsIntSize& aRatio)
{
NS_ASSERTION(aRatio.width > 0 && aRatio.height > 0 && !aRect.IsEmpty(),
"Nothing to draw");
// Choose scale factor that scales aRatio to just fit into aRect
gfxFloat scale =
std::min(aRect.Width()/aRatio.width, aRect.Height()/aRatio.height);
gfxSize scaledRatio(scale*aRatio.width, scale*aRatio.height);
gfxPoint topLeft((aRect.Width() - scaledRatio.width)/2,
(aRect.Height() - scaledRatio.height)/2);
return gfxRect(aRect.TopLeft() + topLeft, scaledRatio);
}
already_AddRefed<Layer>
nsVideoFrame::BuildLayer(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
nsDisplayItem* aItem,
const ContainerLayerParameters& aContainerParameters)
{
nsRect area = GetContentRect() - GetPosition() + aItem->ToReferenceFrame();
HTMLVideoElement* element = static_cast<HTMLVideoElement*>(GetContent());
nsIntSize videoSize;
if (NS_FAILED(element->GetVideoSize(&videoSize)) || area.IsEmpty()) {
return nullptr;
}
nsRefPtr<ImageContainer> container = element->GetImageContainer();
if (!container)
return nullptr;
// Retrieve the size of the decoded video frame, before being scaled
// by pixel aspect ratio.
mozilla::gfx::IntSize frameSize = container->GetCurrentSize();
if (frameSize.width == 0 || frameSize.height == 0) {
// No image, or zero-sized image. No point creating a layer.
return nullptr;
}
// Compute the rectangle in which to paint the video. We need to use
// the largest rectangle that fills our content-box and has the
// correct aspect ratio.
nsPresContext* presContext = PresContext();
gfxRect r = gfxRect(presContext->AppUnitsToGfxUnits(area.x),
presContext->AppUnitsToGfxUnits(area.y),
presContext->AppUnitsToGfxUnits(area.width),
presContext->AppUnitsToGfxUnits(area.height));
r = CorrectForAspectRatio(r, videoSize);
r.Round();
if (r.IsEmpty()) {
return nullptr;
}
IntSize scaleHint(static_cast<int32_t>(r.Width()),
static_cast<int32_t>(r.Height()));
container->SetScaleHint(scaleHint);
nsRefPtr<ImageLayer> layer = static_cast<ImageLayer*>
(aManager->GetLayerBuilder()->GetLeafLayerFor(aBuilder, aItem));
if (!layer) {
layer = aManager->CreateImageLayer();
if (!layer)
return nullptr;
}
layer->SetContainer(container);
layer->SetFilter(nsLayoutUtils::GetGraphicsFilterForFrame(this));
layer->SetContentFlags(Layer::CONTENT_OPAQUE);
// Set a transform on the layer to draw the video in the right place
gfx::Matrix transform;
gfxPoint p = r.TopLeft() + aContainerParameters.mOffset;
transform.Translate(p.x, p.y);
transform.Scale(r.Width()/frameSize.width, r.Height()/frameSize.height);
layer->SetBaseTransform(gfx::Matrix4x4::From2D(transform));
layer->SetVisibleRegion(nsIntRect(0, 0, frameSize.width, frameSize.height));
nsRefPtr<Layer> result = layer.forget();
return result.forget();
}
class DispatchResizeToControls : public nsRunnable
{
public:
DispatchResizeToControls(nsIContent* aContent)
: mContent(aContent) {}
NS_IMETHOD Run() {
nsContentUtils::DispatchTrustedEvent(mContent->OwnerDoc(), mContent,
NS_LITERAL_STRING("resizevideocontrols"),
false, false);
return NS_OK;
}
nsCOMPtr<nsIContent> mContent;
};
NS_IMETHODIMP
nsVideoFrame::Reflow(nsPresContext* aPresContext,
nsHTMLReflowMetrics& aMetrics,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aStatus)
{
DO_GLOBAL_REFLOW_COUNT("nsVideoFrame");
DISPLAY_REFLOW(aPresContext, this, aReflowState, aMetrics, aStatus);
NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
("enter nsVideoFrame::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.ComputedPhysicalBorderPadding();
aMetrics.Width() += mBorderPadding.left + mBorderPadding.right;
aMetrics.Height() += mBorderPadding.top + mBorderPadding.bottom;
// Reflow the child frames. We may have up to two, an image frame
// which is the poster, and a box frame, which is the video controls.
for (nsIFrame *child = mFrames.FirstChild();
child;
child = child->GetNextSibling()) {
if (child->GetContent() == mPosterImage) {
// Reflow the poster frame.
nsImageFrame* imageFrame = static_cast<nsImageFrame*>(child);
nsHTMLReflowMetrics kidDesiredSize(aReflowState.GetWritingMode());
nsSize availableSize = nsSize(aReflowState.AvailableWidth(),
aReflowState.AvailableHeight());
nsHTMLReflowState kidReflowState(aPresContext,
aReflowState,
imageFrame,
availableSize,
aMetrics.Width(),
aMetrics.Height());
uint32_t posterHeight, posterWidth;
nsSize scaledPosterSize(0, 0);
nsSize computedArea(aReflowState.ComputedWidth(), aReflowState.ComputedHeight());
nsPoint posterTopLeft(0, 0);
nsCOMPtr<nsIDOMHTMLImageElement> posterImage = do_QueryInterface(mPosterImage);
NS_ENSURE_TRUE(posterImage, NS_ERROR_FAILURE);
posterImage->GetNaturalHeight(&posterHeight);
posterImage->GetNaturalWidth(&posterWidth);
if (ShouldDisplayPoster() && posterHeight && posterWidth) {
gfxFloat scale =
std::min(static_cast<float>(computedArea.width)/nsPresContext::CSSPixelsToAppUnits(static_cast<float>(posterWidth)),
static_cast<float>(computedArea.height)/nsPresContext::CSSPixelsToAppUnits(static_cast<float>(posterHeight)));
gfxSize scaledRatio = gfxSize(scale*posterWidth, scale*posterHeight);
scaledPosterSize.width = nsPresContext::CSSPixelsToAppUnits(static_cast<float>(scaledRatio.width));
scaledPosterSize.height = nsPresContext::CSSPixelsToAppUnits(static_cast<int32_t>(scaledRatio.height));
}
kidReflowState.SetComputedWidth(scaledPosterSize.width);
kidReflowState.SetComputedHeight(scaledPosterSize.height);
posterTopLeft.x = ((computedArea.width - scaledPosterSize.width) / 2) + mBorderPadding.left;
posterTopLeft.y = ((computedArea.height - scaledPosterSize.height) / 2) + mBorderPadding.top;
ReflowChild(imageFrame, aPresContext, kidDesiredSize, kidReflowState,
posterTopLeft.x, posterTopLeft.y, 0, aStatus);
FinishReflowChild(imageFrame, aPresContext, kidDesiredSize, &kidReflowState,
posterTopLeft.x, posterTopLeft.y, 0);
} else if (child->GetContent() == mVideoControls) {
// Reflow the video controls frame.
nsBoxLayoutState boxState(PresContext(), aReflowState.rendContext);
nsSize size = child->GetSize();
nsBoxFrame::LayoutChildAt(boxState,
child,
nsRect(mBorderPadding.left,
mBorderPadding.top,
aReflowState.ComputedWidth(),
aReflowState.ComputedHeight()));
if (child->GetSize() != size) {
nsRefPtr<nsRunnable> event = new DispatchResizeToControls(child->GetContent());
nsContentUtils::AddScriptRunner(event);
}
} else if (child->GetContent() == mCaptionDiv) {
// Reflow to caption div
nsHTMLReflowMetrics kidDesiredSize(aReflowState.GetWritingMode());
nsSize availableSize = nsSize(aReflowState.AvailableWidth(),
aReflowState.AvailableHeight());
nsHTMLReflowState kidReflowState(aPresContext,
aReflowState,
child,
availableSize,
aMetrics.Width(),
aMetrics.Height());
nsSize size(aReflowState.ComputedWidth(), aReflowState.ComputedHeight());
size.width -= kidReflowState.ComputedPhysicalBorderPadding().LeftRight();
size.height -= kidReflowState.ComputedPhysicalBorderPadding().TopBottom();
kidReflowState.SetComputedWidth(std::max(size.width, 0));
kidReflowState.SetComputedHeight(std::max(size.height, 0));
ReflowChild(child, aPresContext, kidDesiredSize, kidReflowState,
mBorderPadding.left, mBorderPadding.top, 0, aStatus);
FinishReflowChild(child, aPresContext,
kidDesiredSize, &kidReflowState,
mBorderPadding.left, mBorderPadding.top, 0);
}
}
aMetrics.SetOverflowAreasToDesiredBounds();
FinishAndStoreOverflow(&aMetrics);
NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
("exit nsVideoFrame::Reflow: size=%d,%d",
aMetrics.Width(), aMetrics.Height()));
NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aMetrics);
return NS_OK;
}
class nsDisplayVideo : public nsDisplayItem {
public:
nsDisplayVideo(nsDisplayListBuilder* aBuilder, nsVideoFrame* aFrame)
: nsDisplayItem(aBuilder, aFrame)
{
MOZ_COUNT_CTOR(nsDisplayVideo);
}
#ifdef NS_BUILD_REFCNT_LOGGING
virtual ~nsDisplayVideo() {
MOZ_COUNT_DTOR(nsDisplayVideo);
}
#endif
NS_DISPLAY_DECL_NAME("Video", TYPE_VIDEO)
// It would be great if we could override GetOpaqueRegion to return nonempty here,
// but it's probably not safe to do so in general. Video frames are
// updated asynchronously from decoder threads, and it's possible that
// we might have an opaque video frame when GetOpaqueRegion is called, but
// when we come to paint, the video frame is transparent or has gone
// away completely (e.g. because of a decoder error). The problem would
// be especially acute if we have off-main-thread rendering.
virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder, bool* aSnap)
{
*aSnap = true;
nsIFrame* f = Frame();
return f->GetContentRect() - f->GetPosition() + ToReferenceFrame();
}
virtual already_AddRefed<Layer> BuildLayer(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
const ContainerLayerParameters& aContainerParameters)
{
return static_cast<nsVideoFrame*>(mFrame)->BuildLayer(aBuilder, aManager, this, aContainerParameters);
}
virtual LayerState GetLayerState(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
const ContainerLayerParameters& aParameters)
{
if (aManager->IsCompositingCheap()) {
// Since ImageLayers don't require additional memory of the
// video frames we have to have anyway, we can't save much by
// making layers inactive. Also, for many accelerated layer
// managers calling imageContainer->GetCurrentAsSurface can be
// very expensive. So just always be active when compositing is
// cheap (i.e. hardware accelerated).
return LAYER_ACTIVE;
}
HTMLMediaElement* elem =
static_cast<HTMLMediaElement*>(mFrame->GetContent());
return elem->IsPotentiallyPlaying() ? LAYER_ACTIVE_FORCE : LAYER_INACTIVE;
}
};
void
nsVideoFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsRect& aDirtyRect,
const nsDisplayListSet& aLists)
{
if (!IsVisibleForPainting(aBuilder))
return;
DO_GLOBAL_REFLOW_COUNT_DSP("nsVideoFrame");
DisplayBorderBackgroundOutline(aBuilder, aLists);
DisplayListClipState::AutoClipContainingBlockDescendantsToContentBox
clip(aBuilder, this, DisplayListClipState::ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT);
if (HasVideoElement() && !ShouldDisplayPoster()) {
aLists.Content()->AppendNewToTop(
new (aBuilder) nsDisplayVideo(aBuilder, this));
}
// Add child frames to display list. We expect various children,
// but only want to draw mPosterImage conditionally. Others we
// always add to the display list.
for (nsIFrame *child = mFrames.FirstChild();
child;
child = child->GetNextSibling()) {
if (child->GetContent() != mPosterImage || ShouldDisplayPoster()) {
child->BuildDisplayListForStackingContext(aBuilder,
aDirtyRect - child->GetOffsetTo(this),
aLists.Content());
} else if (child->GetType() == nsGkAtoms::boxFrame) {
child->BuildDisplayListForStackingContext(aBuilder,
aDirtyRect - child->GetOffsetTo(this),
aLists.Content());
}
}
}
nsIAtom*
nsVideoFrame::GetType() const
{
return nsGkAtoms::HTMLVideoFrame;
}
#ifdef ACCESSIBILITY
a11y::AccType
nsVideoFrame::AccessibleType()
{
return a11y::eHTMLMediaType;
}
#endif
#ifdef DEBUG_FRAME_DUMP
NS_IMETHODIMP
nsVideoFrame::GetFrameName(nsAString& aResult) const
{
return MakeFrameName(NS_LITERAL_STRING("HTMLVideo"), aResult);
}
#endif
nsSize nsVideoFrame::ComputeSize(nsRenderingContext *aRenderingContext,
nsSize aCBSize,
nscoord aAvailableWidth,
nsSize aMargin,
nsSize aBorder,
nsSize aPadding,
uint32_t aFlags)
{
nsSize size = GetVideoIntrinsicSize(aRenderingContext);
IntrinsicSize intrinsicSize;
intrinsicSize.width.SetCoordValue(size.width);
intrinsicSize.height.SetCoordValue(size.height);
// Only video elements have an intrinsic ratio.
nsSize intrinsicRatio = HasVideoElement() ? size : nsSize(0, 0);
return nsLayoutUtils::ComputeSizeWithIntrinsicDimensions(aRenderingContext,
this,
intrinsicSize,
intrinsicRatio,
aCBSize,
aMargin,
aBorder,
aPadding);
}
nscoord nsVideoFrame::GetMinWidth(nsRenderingContext *aRenderingContext)
{
nscoord result = GetVideoIntrinsicSize(aRenderingContext).width;
DISPLAY_MIN_WIDTH(this, result);
return result;
}
nscoord nsVideoFrame::GetPrefWidth(nsRenderingContext *aRenderingContext)
{
nscoord result = GetVideoIntrinsicSize(aRenderingContext).width;
DISPLAY_PREF_WIDTH(this, result);
return result;
}
nsSize nsVideoFrame::GetIntrinsicRatio()
{
if (!HasVideoElement()) {
// Audio elements have no intrinsic ratio.
return nsSize(0, 0);
}
return GetVideoIntrinsicSize(nullptr);
}
bool nsVideoFrame::ShouldDisplayPoster()
{
if (!HasVideoElement())
return false;
HTMLVideoElement* element = static_cast<HTMLVideoElement*>(GetContent());
if (element->GetPlayedOrSeeked() && HasVideoData())
return false;
nsCOMPtr<nsIImageLoadingContent> imgContent = do_QueryInterface(mPosterImage);
NS_ENSURE_TRUE(imgContent, false);
nsCOMPtr<imgIRequest> request;
nsresult res = imgContent->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
getter_AddRefs(request));
if (NS_FAILED(res) || !request) {
return false;
}
uint32_t status = 0;
res = request->GetImageStatus(&status);
if (NS_FAILED(res) || (status & imgIRequest::STATUS_ERROR))
return false;
return true;
}
nsSize
nsVideoFrame::GetVideoIntrinsicSize(nsRenderingContext *aRenderingContext)
{
// Defaulting size to 300x150 if no size given.
nsIntSize size(300, 150);
if (!HasVideoElement()) {
if (!mFrames.FirstChild()) {
return nsSize(0, 0);
}
// Ask the controls frame what its preferred height is
nsBoxLayoutState boxState(PresContext(), aRenderingContext, 0);
nscoord prefHeight = mFrames.LastChild()->GetPrefSize(boxState).height;
return nsSize(nsPresContext::CSSPixelsToAppUnits(size.width), prefHeight);
}
HTMLVideoElement* element = static_cast<HTMLVideoElement*>(GetContent());
if (NS_FAILED(element->GetVideoSize(&size)) && ShouldDisplayPoster()) {
// Use the poster image frame's size.
nsIFrame *child = mPosterImage->GetPrimaryFrame();
nsImageFrame* imageFrame = do_QueryFrame(child);
nsSize imgsize;
if (NS_SUCCEEDED(imageFrame->GetIntrinsicImageSize(imgsize))) {
return imgsize;
}
}
return nsSize(nsPresContext::CSSPixelsToAppUnits(size.width),
nsPresContext::CSSPixelsToAppUnits(size.height));
}
void
nsVideoFrame::UpdatePosterSource(bool aNotify)
{
NS_ASSERTION(HasVideoElement(), "Only call this on <video> elements.");
HTMLVideoElement* element = static_cast<HTMLVideoElement*>(GetContent());
if (element->HasAttr(kNameSpaceID_None, nsGkAtoms::poster)) {
nsAutoString posterStr;
element->GetPoster(posterStr);
mPosterImage->SetAttr(kNameSpaceID_None,
nsGkAtoms::src,
posterStr,
aNotify);
} else {
mPosterImage->UnsetAttr(kNameSpaceID_None, nsGkAtoms::poster, aNotify);
}
}
NS_IMETHODIMP
nsVideoFrame::AttributeChanged(int32_t aNameSpaceID,
nsIAtom* aAttribute,
int32_t aModType)
{
if (aAttribute == nsGkAtoms::poster && HasVideoElement()) {
UpdatePosterSource(true);
}
return nsContainerFrame::AttributeChanged(aNameSpaceID,
aAttribute,
aModType);
}
bool nsVideoFrame::HasVideoElement() {
nsCOMPtr<nsIDOMHTMLVideoElement> videoDomElement = do_QueryInterface(mContent);
return videoDomElement != nullptr;
}
bool nsVideoFrame::HasVideoData()
{
if (!HasVideoElement())
return false;
HTMLVideoElement* element = static_cast<HTMLVideoElement*>(GetContent());
nsIntSize size(0, 0);
element->GetVideoSize(&size);
return size != nsIntSize(0,0);
}