gecko/layout/base/FrameLayerBuilder.h
Robert O'Callahan 4ca813ae6e Bug 622072. Part 3: Support empty transactions for canvas layers. r=tnikkel
The basic idea is that whenever a layer transaction updates the window, we clear out the invalidation state for the canvas rendering context,
using a DidTransactionCallback registered on the layer(s) for the canvas, which calls MakeContextClean.

The DidTransactionCallbacks are directed to the user data attached to the Layer, which holds a strong reference to the canvas element. This
ensures that the element lives as long as the layer. Layers are destroyed when the presentation is torn down (including if the frame is destroyed),
so we can't have a leak here. The reference to the canvas element is only strong because the layer might briefly outlive the frame (the layer
won't be destroyed until the next paint of the window).

This patch moves responsibility for calling CanvasLayer::Updated and nsFrame::MarkLayersActive from the canvas context to nsHTMLCanvasElement::InvalidateFrame.
We call Updated on the retained CanvasLayer, if there is one; any other CanvasLayers created for this canvas would only be used once, and have Updated
called on them in BuildLayer when created.
2011-03-28 12:59:47 +13:00

504 lines
18 KiB
C++

/* -*- Mode: C++; tab-width: 20; 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 Corporation code.
*
* The Initial Developer of the Original Code is Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Robert O'Callahan <robert@ocallahan.org>
*
* Alternatively, the contents of this file may be used under the terms of
* either 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
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* 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 ***** */
#ifndef FRAMELAYERBUILDER_H_
#define FRAMELAYERBUILDER_H_
#include "nsTHashtable.h"
#include "nsHashKeys.h"
#include "nsTArray.h"
#include "nsRegion.h"
#include "nsIFrame.h"
#include "Layers.h"
class nsDisplayListBuilder;
class nsDisplayList;
class nsDisplayItem;
class gfxContext;
class nsRootPresContext;
namespace mozilla {
enum LayerState {
LAYER_NONE,
LAYER_INACTIVE,
LAYER_ACTIVE,
// Force an active layer even if it causes incorrect rendering, e.g.
// when the layer has rounded rect clips.
LAYER_ACTIVE_FORCE
};
/**
* The FrameLayerBuilder belongs to an nsDisplayListBuilder and is
* responsible for converting display lists into layer trees.
*
* The most important API in this class is BuildContainerLayerFor. This
* method takes a display list as input and constructs a ContainerLayer
* with child layers that render the contents of the display list. It
* also updates userdata for the retained layer manager, and
* DisplayItemDataProperty data for frames, to record the relationship
* between frames and layers.
*
* That data enables us to retain layer trees. When constructing a
* ContainerLayer, we first check to see if there's an existing
* ContainerLayer for the same frame that can be recycled. If we recycle
* it, we also try to reuse its existing ThebesLayer children to render
* the display items without layers of their own. The idea is that by
* recycling layers deterministically, we can ensure that when nothing
* changes in a display list, we will reuse the existing layers without
* changes.
*
* We expose a GetLeafLayerFor method that can be called by display items
* that make their own layers (e.g. canvas and video); this method
* locates the last layer used to render the display item, if any, and
* return it as a candidate for recycling.
*
* FrameLayerBuilder sets up ThebesLayers so that 0,0 in the Thebes layer
* corresponds to the (pixel-snapped) top-left of the aActiveScrolledRoot.
* It sets up ContainerLayers so that 0,0 in the container layer
* corresponds to the snapped top-left of the display list reference frame.
*/
class FrameLayerBuilder {
public:
typedef layers::ContainerLayer ContainerLayer;
typedef layers::Layer Layer;
typedef layers::ThebesLayer ThebesLayer;
typedef layers::LayerManager LayerManager;
FrameLayerBuilder() :
mRetainingManager(nsnull),
mDetectedDOMModification(PR_FALSE),
mInvalidateAllLayers(PR_FALSE)
{
mNewDisplayItemData.Init();
mThebesLayerItems.Init();
}
void Init(nsDisplayListBuilder* aBuilder);
/**
* Call this to notify that we have just started a transaction on the
* retained layer manager aManager.
*/
void DidBeginRetainedLayerTransaction(LayerManager* aManager);
/**
* Call this just before we end a transaction on aManager. If aManager
* is not the retained layer manager then it must be a temporary layer
* manager that will not be used again.
*/
void WillEndTransaction(LayerManager* aManager);
/**
* Call this after we end a transaction on aManager. If aManager
* is not the retained layer manager then it must be a temporary layer
* manager that will not be used again.
*/
void DidEndTransaction(LayerManager* aManager);
/**
* Build a container layer for a display item that contains a child
* list, either reusing an existing one or creating a new one. It
* sets the container layer children to layers which together render
* the contents of the display list. It reuses existing layers from
* the retained layer manager if possible.
* aContainer may be null, in which case we construct a root layer.
* This gets called by display list code. It calls BuildLayer on the
* items in the display list, making items with their own layers
* children of the new container, and assigning all other items to
* ThebesLayer children created and managed by the FrameLayerBuilder.
* Returns a layer with clip rect cleared; it is the
* caller's responsibility to add any clip rect. The visible region
* is set based on what's in the layer.
*/
already_AddRefed<ContainerLayer>
BuildContainerLayerFor(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
nsIFrame* aContainerFrame,
nsDisplayItem* aContainerItem,
const nsDisplayList& aChildren);
/**
* Get a retained layer for a display item that needs to create its own
* layer for rendering (i.e. under nsDisplayItem::BuildLayer). Returns
* null if no retained layer is available, which usually means that this
* display item didn't have a layer before so the caller will
* need to create one.
* Returns a layer with clip rect cleared; it is the
* caller's responsibility to add any clip rect and set the visible
* region.
*/
Layer* GetLeafLayerFor(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
nsDisplayItem* aItem);
/**
* Call this during invalidation if aFrame has
* the NS_FRAME_HAS_CONTAINER_LAYER state bit. Only the nearest
* ancestor frame of the damaged frame that has
* NS_FRAME_HAS_CONTAINER_LAYER needs to be invalidated this way.
*/
static void InvalidateThebesLayerContents(nsIFrame* aFrame,
const nsRect& aRect);
/**
* For any descendant frame of aFrame (including across documents) that
* has an associated container layer, invalidate all the contents of
* all ThebesLayer children of the container. Useful when aFrame is
* being moved and we need to invalidate everything in aFrame's subtree.
*/
static void InvalidateThebesLayersInSubtree(nsIFrame* aFrame);
/**
* Call this to force all retained layers to be discarded and recreated at
* the next paint.
*/
static void InvalidateAllLayers(LayerManager* aManager);
/**
* Call this to determine if a frame has a dedicated (non-Thebes) layer
* for the given display item key. If there isn't one, we return null,
* otherwise we return the layer.
*/
static Layer* GetDedicatedLayer(nsIFrame* aFrame, PRUint32 aDisplayItemKey);
/**
* This callback must be provided to EndTransaction. The callback data
* must be the nsDisplayListBuilder containing this FrameLayerBuilder.
*/
static void DrawThebesLayer(ThebesLayer* aLayer,
gfxContext* aContext,
const nsIntRegion& aRegionToDraw,
const nsIntRegion& aRegionToInvalidate,
void* aCallbackData);
#ifdef DEBUG
/**
* Dumps this FrameLayerBuilder's retained layer manager's retained
* layer tree to stderr.
*/
void DumpRetainedLayerTree();
#endif
/******* PRIVATE METHODS to FrameLayerBuilder.cpp ********/
/* These are only in the public section because they need
* to be called by file-scope helper functions in FrameLayerBuilder.cpp.
*/
/**
* Record aItem as a display item that is rendered by aLayer.
*/
void AddLayerDisplayItem(Layer* aLayer, nsDisplayItem* aItem);
/**
* Record aItem as a display item that is rendered by the ThebesLayer
* aLayer, with aClipRect, where aContainerLayerFrame is the frame
* for the container layer this ThebesItem belongs to.
* aItem must have an underlying frame.
*/
struct Clip;
void AddThebesDisplayItem(ThebesLayer* aLayer,
nsDisplayItem* aItem,
const Clip& aClip,
nsIFrame* aContainerLayerFrame,
LayerState aLayerState);
/**
* Given a frame and a display item key that uniquely identifies a
* display item for the frame, find the layer that was last used to
* render that display item. Returns null if there is no such layer.
* This could be a dedicated layer for the display item, or a ThebesLayer
* that renders many display items.
*/
Layer* GetOldLayerFor(nsIFrame* aFrame, PRUint32 aDisplayItemKey);
/**
* A useful hashtable iteration function that removes the
* DisplayItemData property for the frame, clears its
* NS_FRAME_HAS_CONTAINER_LAYER bit and returns PL_DHASH_REMOVE.
* aClosure is ignored.
*/
static PLDHashOperator RemoveDisplayItemDataForFrame(nsPtrHashKey<nsIFrame>* aEntry,
void* aClosure)
{
return UpdateDisplayItemDataForFrame(aEntry, nsnull);
}
/**
* Try to determine whether the ThebesLayer aLayer paints an opaque
* single color everywhere it's visible in aRect.
* If successful, return that color, otherwise return NS_RGBA(0,0,0,0).
*/
nscolor FindOpaqueColorCovering(nsDisplayListBuilder* aBuilder,
ThebesLayer* aLayer, const nsRect& aRect);
/**
* Destroy any stored DisplayItemDataProperty for aFrame.
*/
static void DestroyDisplayItemDataFor(nsIFrame* aFrame)
{
aFrame->Properties().Delete(DisplayItemDataProperty());
}
LayerManager* GetRetainingLayerManager() { return mRetainingManager; }
/**
* Returns true if the given item (which we assume here is
* background-attachment:fixed) needs to be repainted as we scroll in its
* document.
* Returns false if it doesn't need to be repainted because the layer system
* is ensuring its fixed-ness for us.
*/
static PRBool NeedToInvalidateFixedDisplayItem(nsDisplayListBuilder* aBuilder,
nsDisplayItem* aItem);
/**
* Returns true if the given display item was rendered directly
* into a retained layer.
* Returns false if it was rendered into a temporary layer manager and then
* into a retained layer.
*/
static PRBool HasRetainedLayerFor(nsIFrame* aFrame, PRUint32 aDisplayItemKey);
/**
* Clip represents the intersection of an optional rectangle with a
* list of rounded rectangles.
*/
struct Clip {
struct RoundedRect {
nsRect mRect;
// Indices into mRadii are the NS_CORNER_* constants in nsStyleConsts.h
nscoord mRadii[8];
bool operator==(const RoundedRect& aOther) const {
if (mRect != aOther.mRect) {
return false;
}
NS_FOR_CSS_HALF_CORNERS(corner) {
if (mRadii[corner] != aOther.mRadii[corner]) {
return false;
}
}
return true;
}
bool operator!=(const RoundedRect& aOther) const {
return !(*this == aOther);
}
};
nsRect mClipRect;
nsTArray<RoundedRect> mRoundedClipRects;
PRPackedBool mHaveClipRect;
Clip() : mHaveClipRect(PR_FALSE) {}
// Construct as the intersection of aOther and aClipItem.
Clip(const Clip& aOther, nsDisplayItem* aClipItem);
// Apply this |Clip| to the given gfxContext. Any saving of state
// or clearing of other clips must be done by the caller.
void ApplyTo(gfxContext* aContext, nsPresContext* aPresContext);
// Return a rectangle contained in the intersection of aRect with this
// clip region. Tries to return the largest possible rectangle, but may
// not succeed.
nsRect ApproximateIntersect(const nsRect& aRect) const;
// Returns false if aRect is definitely not clipped by a rounded corner in
// this clip. Returns true if aRect is clipped by a rounded corner in this
// clip or it can not be quickly determined that it is not clipped by a
// rounded corner in this clip.
bool IsRectClippedByRoundedCorner(const nsRect& aRect) const;
// Intersection of all rects in this clip ignoring any rounded corners.
nsRect NonRoundedIntersection() const;
// Gets rid of any rounded corners in this clip.
void RemoveRoundedCorners();
bool operator==(const Clip& aOther) const {
return mHaveClipRect == aOther.mHaveClipRect &&
(!mHaveClipRect || mClipRect == aOther.mClipRect) &&
mRoundedClipRects == aOther.mRoundedClipRects;
}
bool operator!=(const Clip& aOther) const {
return !(*this == aOther);
}
};
protected:
/**
* We store an array of these for each frame that is associated with
* one or more retained layers. Each DisplayItemData records the layer
* used to render one of the frame's display items.
*/
class DisplayItemData {
public:
DisplayItemData(Layer* aLayer, PRUint32 aKey)
: mLayer(aLayer), mDisplayItemKey(aKey) {}
nsRefPtr<Layer> mLayer;
PRUint32 mDisplayItemKey;
};
static void InternalDestroyDisplayItemData(nsIFrame* aFrame,
void* aPropertyValue,
PRBool aRemoveFromFramesWithLayers);
static void DestroyDisplayItemData(nsIFrame* aFrame, void* aPropertyValue);
/**
* For DisplayItemDataProperty, the property value *is* an
* nsTArray<DisplayItemData>, not a pointer to an array. This works
* because sizeof(nsTArray<T>) == sizeof(void*).
*/
NS_DECLARE_FRAME_PROPERTY_WITH_FRAME_IN_DTOR(DisplayItemDataProperty,
DestroyDisplayItemData)
/**
* We accumulate DisplayItemData elements in a hashtable during
* the paint process, and store them in the frame property only when
* paint is complete. This is the hashentry for that hashtable.
*/
class DisplayItemDataEntry : public nsPtrHashKey<nsIFrame> {
public:
DisplayItemDataEntry(const nsIFrame *key) : nsPtrHashKey<nsIFrame>(key) {}
DisplayItemDataEntry(const DisplayItemDataEntry &toCopy) :
nsPtrHashKey<nsIFrame>(toCopy.mKey), mData(toCopy.mData)
{
NS_ERROR("Should never be called, since we ALLOW_MEMMOVE");
}
PRBool HasContainerLayer();
nsTArray<DisplayItemData> mData;
enum { ALLOW_MEMMOVE = PR_TRUE };
};
/**
* We store one of these for each display item associated with a
* ThebesLayer, in a hashtable that maps each ThebesLayer to an array
* of ClippedDisplayItems. (ThebesLayerItemsEntry is the hash entry
* for that hashtable.)
* These are only stored during the paint process, so that the
* DrawThebesLayer callback can figure out which items to draw for the
* ThebesLayer.
* mItem always has an underlying frame.
*/
struct ClippedDisplayItem {
ClippedDisplayItem(nsDisplayItem* aItem, const Clip& aClip)
: mItem(aItem), mClip(aClip)
{
}
nsDisplayItem* mItem;
Clip mClip;
PRPackedBool mInactiveLayer;
};
/**
* We accumulate ClippedDisplayItem elements in a hashtable during
* the paint process. This is the hashentry for that hashtable.
*/
class ThebesLayerItemsEntry : public nsPtrHashKey<ThebesLayer> {
public:
ThebesLayerItemsEntry(const ThebesLayer *key) : nsPtrHashKey<ThebesLayer>(key) {}
ThebesLayerItemsEntry(const ThebesLayerItemsEntry &toCopy) :
nsPtrHashKey<ThebesLayer>(toCopy.mKey), mItems(toCopy.mItems)
{
NS_ERROR("Should never be called, since we ALLOW_MEMMOVE");
}
nsTArray<ClippedDisplayItem> mItems;
nsIFrame* mContainerLayerFrame;
enum { ALLOW_MEMMOVE = PR_TRUE };
};
void RemoveThebesItemsForLayerSubtree(Layer* aLayer);
static PLDHashOperator UpdateDisplayItemDataForFrame(nsPtrHashKey<nsIFrame>* aEntry,
void* aUserArg);
static PLDHashOperator StoreNewDisplayItemData(DisplayItemDataEntry* aEntry,
void* aUserArg);
/**
* Returns true if the DOM has been modified since we started painting,
* in which case we should bail out and not paint anymore. This should
* never happen, but plugins can trigger it in some cases.
*/
PRBool CheckDOMModified();
/**
* The layer manager belonging to the widget that is being retained
* across paints.
*/
LayerManager* mRetainingManager;
/**
* The root prescontext for the display list builder reference frame
*/
nsRootPresContext* mRootPresContext;
/**
* A map from frames to a list of (display item key, layer) pairs that
* describes what layers various parts of the frame are assigned to.
*/
nsTHashtable<DisplayItemDataEntry> mNewDisplayItemData;
/**
* A map from ThebesLayers to the list of display items (plus
* clipping data) to be rendered in the layer.
*/
nsTHashtable<ThebesLayerItemsEntry> mThebesLayerItems;
/**
* Saved generation counter so we can detect DOM changes.
*/
PRUint32 mInitialDOMGeneration;
/**
* Set to true if we have detected and reported DOM modification during
* the current paint.
*/
PRPackedBool mDetectedDOMModification;
/**
* Indicates that the entire layer tree should be rerendered
* during this paint.
*/
PRPackedBool mInvalidateAllLayers;
};
}
#endif /* FRAMELAYERBUILDER_H_ */