The Tor Browser: comparison gfx/layers/TiledLayerBuffer.h

--1:000000000000
+:28e13eb835c4
+/* 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/. */
+#ifndef GFX_TILEDLAYERBUFFER_H
+#define GFX_TILEDLAYERBUFFER_H
+// Debug defines
+//#define GFX_TILEDLAYER_DEBUG_OVERLAY
+//#define GFX_TILEDLAYER_PREF_WARNINGS
+#include <stdint.h>                     // for uint16_t, uint32_t
+#include <sys/types.h>                  // for int32_t
+#include "gfxPrefs.h"                   // for gfxPrefs::LayersTileWidth/Height
+#include "nsDebug.h"                    // for NS_ABORT_IF_FALSE
+#include "nsPoint.h"                    // for nsIntPoint
+#include "nsRect.h"                     // for nsIntRect
+#include "nsRegion.h"                   // for nsIntRegion
+#include "nsTArray.h"                   // for nsTArray
+#if defined(MOZ_WIDGET_GONK) && ANDROID_VERSION >= 17
+#include <ui/Fence.h>
+#endif
+namespace mozilla {
+namespace layers {
+// An abstract implementation of a tile buffer. This code covers the logic of
+// moving and reusing tiles and leaves the validation up to the implementor. To
+// avoid the overhead of virtual dispatch, we employ the curiously recurring
+// template pattern.
+//
+// Tiles are aligned to a grid with one of the grid points at (0,0) and other
+// grid points spaced evenly in the x- and y-directions by GetTileSize()
+// multiplied by mResolution. GetScaledTileSize() provides convenience for
+// accessing these values.
+//
+// This tile buffer stores a valid region, which defines the areas that have
+// up-to-date content. The contents of tiles within this region will be reused
+// from paint to paint. It also stores the region that was modified in the last
+// paint operation; this is useful when one tiled layer buffer shadows another
+// (as in an off-main-thread-compositing scenario), so that the shadow tiled
+// layer buffer can correctly reflect the updates of the master layer buffer.
+//
+// The associated Tile may be of any type as long as the derived class can
+// validate and return tiles of that type. Tiles will be frequently copied, so
+// the tile type should be a reference or some other type with an efficient
+// copy constructor.
+//
+// It is required that the derived class specify the base class as a friend. It
+// must also implement the following public method:
+//
+//   Tile GetPlaceholderTile() const;
+//
+//   Returns a temporary placeholder tile used as a marker. This placeholder tile
+//   must never be returned by validateTile and must be == to every instance
+//   of a placeholder tile.
+//
+// Additionally, it must implement the following protected methods:
+//
+//   Tile ValidateTile(Tile aTile, const nsIntPoint& aTileOrigin,
+//                     const nsIntRegion& aDirtyRect);
+//
+//   Validates the dirtyRect. The returned Tile will replace the tile.
+//
+//   void ReleaseTile(Tile aTile);
+//
+//   Destroys the given tile.
+//
+//   void SwapTiles(Tile& aTileA, Tile& aTileB);
+//
+//   Swaps two tiles.
+//
+// The contents of the tile buffer will be rendered at the resolution specified
+// in mResolution, which can be altered with SetResolution. The resolution
+// should always be a factor of the tile length, to avoid tiles covering
+// non-integer amounts of pixels.
+template<typename Derived, typename Tile>
+class TiledLayerBuffer
+{
+public:
+TiledLayerBuffer()
+: mRetainedWidth(0)
+, mRetainedHeight(0)
+, mResolution(1)
+, mTileSize(gfxPrefs::LayersTileWidth(), gfxPrefs::LayersTileHeight())
+{}
+~TiledLayerBuffer() {}
+// Given a tile origin aligned to a multiple of GetScaledTileSize,
+// return the tile that describes that region.
+// NOTE: To get the valid area of that tile you must intersect
+//       (aTileOrigin.x, aTileOrigin.y,
+//        GetScaledTileSize().width, GetScaledTileSize().height)
+//       and GetValidRegion() to get the area of the tile that is valid.
+Tile GetTile(const nsIntPoint& aTileOrigin) const;
+// Given a tile x, y relative to the top left of the layer, this function
+// will return the tile for
+// (x*GetScaledTileSize().width, y*GetScaledTileSize().height,
+//  GetScaledTileSize().width, GetScaledTileSize().height)
+Tile GetTile(int x, int y) const;
+// This operates the same as GetTile(aTileOrigin), but will also replace the
+// specified tile with the placeholder tile. This does not call ReleaseTile
+// on the removed tile.
+bool RemoveTile(const nsIntPoint& aTileOrigin, Tile& aRemovedTile);
+// This operates the same as GetTile(x, y), but will also replace the
+// specified tile with the placeholder tile. This does not call ReleaseTile
+// on the removed tile.
+bool RemoveTile(int x, int y, Tile& aRemovedTile);
+const gfx::IntSize& GetTileSize() const { return mTileSize; }
+gfx::IntSize GetScaledTileSize() const { return RoundedToInt(gfx::Size(mTileSize) / mResolution); }
+unsigned int GetTileCount() const { return mRetainedTiles.Length(); }
+const nsIntRegion& GetValidRegion() const { return mValidRegion; }
+const nsIntRegion& GetPaintedRegion() const { return mPaintedRegion; }
+void ClearPaintedRegion() { mPaintedRegion.SetEmpty(); }
+// Given a position i, this function returns the position inside the current tile.
+int GetTileStart(int i, int aTileLength) const {
+return (i >= 0) ? (i % aTileLength)
+: ((aTileLength - (-i % aTileLength)) %
+aTileLength);
+}
+// Rounds the given coordinate down to the nearest tile boundary.
+int RoundDownToTileEdge(int aX, int aTileLength) const { return aX - GetTileStart(aX, aTileLength); }
+// Get and set draw scaling. mResolution affects the resolution at which the
+// contents of the buffer are drawn. mResolution has no effect on the
+// coordinate space of the valid region, but does affect the size of an
+// individual tile's rect in relation to the valid region.
+// Setting the resolution will invalidate the buffer.
+float GetResolution() const { return mResolution; }
+void SetResolution(float aResolution) {
+if (mResolution == aResolution) {
+return;
+}
+Update(nsIntRegion(), nsIntRegion());
+mResolution = aResolution;
+}
+bool IsLowPrecision() const { return mResolution < 1; }
+typedef Tile* Iterator;
+Iterator TilesBegin() { return mRetainedTiles.Elements(); }
+Iterator TilesEnd() { return mRetainedTiles.Elements() + mRetainedTiles.Length(); }
+protected:
+// The implementor should call Update() to change
+// the new valid region. This implementation will call
+// validateTile on each tile that is dirty, which is left
+// to the implementor.
+void Update(const nsIntRegion& aNewValidRegion, const nsIntRegion& aPaintRegion);
+nsIntRegion     mValidRegion;
+nsIntRegion     mPaintedRegion;
+/**
+* mRetainedTiles is a rectangular buffer of mRetainedWidth x mRetainedHeight
+* stored as column major with the same origin as mValidRegion.GetBounds().
+* Any tile that does not intersect mValidRegion is a PlaceholderTile.
+* Only the region intersecting with mValidRegion should be read from a tile,
+* another other region is assumed to be uninitialized. The contents of the
+* tiles is scaled by mResolution.
+*/
+nsTArray<Tile>  mRetainedTiles;
+int             mRetainedWidth;  // in tiles
+int             mRetainedHeight; // in tiles
+float           mResolution;
+gfx::IntSize    mTileSize;
+private:
+const Derived& AsDerived() const { return *static_cast<const Derived*>(this); }
+Derived& AsDerived() { return *static_cast<Derived*>(this); }
+bool IsPlaceholder(Tile aTile) const { return aTile == AsDerived().GetPlaceholderTile(); }
+};
+class ClientTiledLayerBuffer;
+class SurfaceDescriptorTiles;
+class ISurfaceAllocator;
+// Shadow layers may implement this interface in order to be notified when a
+// tiled layer buffer is updated.
+class TiledLayerComposer
+{
+public:
+/**
+* Update the current retained layer with the updated layer data.
+* It is expected that the tiles described by aTiledDescriptor are all in the
+* ReadLock state, so that the locks can be adopted when recreating a
+* ClientTiledLayerBuffer locally. This lock will be retained until the buffer
+* has completed uploading.
+*/
+virtual void UseTiledLayerBuffer(ISurfaceAllocator* aAllocator,
+const SurfaceDescriptorTiles& aTiledDescriptor) = 0;
+/**
+* If some part of the buffer is being rendered at a lower precision, this
+* returns that region. If it is not, an empty region will be returned.
+*/
+virtual const nsIntRegion& GetValidLowPrecisionRegion() const = 0;
+#if defined(MOZ_WIDGET_GONK) && ANDROID_VERSION >= 17
+/**
+* Store a fence that will signal when the current buffer is no longer being read.
+* Similar to android's GLConsumer::setReleaseFence()
+*/
+virtual void SetReleaseFence(const android::sp<android::Fence>& aReleaseFence) = 0;
+#endif
+};
+// Normal integer division truncates towards zero,
+// we instead want to floor to hangle negative numbers.
+static inline int floor_div(int a, int b)
+{
+int rem = a % b;
+int div = a/b;
+if (rem == 0) {
+return div;
+} else {
+// If the signs are different substract 1.
+int sub;
+sub = a ^ b;
+// The results of this shift is either 0 or -1.
+sub >>= 8*sizeof(int)-1;
+return div+sub;
+}
+}
+template<typename Derived, typename Tile> Tile
+TiledLayerBuffer<Derived, Tile>::GetTile(const nsIntPoint& aTileOrigin) const
+{
+// TODO Cache firstTileOriginX/firstTileOriginY
+// Find the tile x/y of the first tile and the target tile relative to the (0, 0)
+// origin, the difference is the tile x/y relative to the start of the tile buffer.
+gfx::IntSize scaledTileSize = GetScaledTileSize();
+int firstTileX = floor_div(mValidRegion.GetBounds().x, scaledTileSize.width);
+int firstTileY = floor_div(mValidRegion.GetBounds().y, scaledTileSize.height);
+return GetTile(floor_div(aTileOrigin.x, scaledTileSize.width) - firstTileX,
+floor_div(aTileOrigin.y, scaledTileSize.height) - firstTileY);
+}
+template<typename Derived, typename Tile> Tile
+TiledLayerBuffer<Derived, Tile>::GetTile(int x, int y) const
+{
+int index = x * mRetainedHeight + y;
+return mRetainedTiles.SafeElementAt(index, AsDerived().GetPlaceholderTile());
+}
+template<typename Derived, typename Tile> bool
+TiledLayerBuffer<Derived, Tile>::RemoveTile(const nsIntPoint& aTileOrigin,
+Tile& aRemovedTile)
+{
+gfx::IntSize scaledTileSize = GetScaledTileSize();
+int firstTileX = floor_div(mValidRegion.GetBounds().x, scaledTileSize.width);
+int firstTileY = floor_div(mValidRegion.GetBounds().y, scaledTileSize.height);
+return RemoveTile(floor_div(aTileOrigin.x, scaledTileSize.width) - firstTileX,
+floor_div(aTileOrigin.y, scaledTileSize.height) - firstTileY,
+aRemovedTile);
+}
+template<typename Derived, typename Tile> bool
+TiledLayerBuffer<Derived, Tile>::RemoveTile(int x, int y, Tile& aRemovedTile)
+{
+int index = x * mRetainedHeight + y;
+const Tile& tileToRemove = mRetainedTiles.SafeElementAt(index, AsDerived().GetPlaceholderTile());
+if (!IsPlaceholder(tileToRemove)) {
+aRemovedTile = tileToRemove;
+mRetainedTiles[index] = AsDerived().GetPlaceholderTile();
+return true;
+}
+return false;
+}
+template<typename Derived, typename Tile> void
+TiledLayerBuffer<Derived, Tile>::Update(const nsIntRegion& aNewValidRegion,
+const nsIntRegion& aPaintRegion)
+{
+gfx::IntSize scaledTileSize = GetScaledTileSize();
+nsTArray<Tile>  newRetainedTiles;
+nsTArray<Tile>& oldRetainedTiles = mRetainedTiles;
+const nsIntRect oldBound = mValidRegion.GetBounds();
+const nsIntRect newBound = aNewValidRegion.GetBounds();
+const nsIntPoint oldBufferOrigin(RoundDownToTileEdge(oldBound.x, scaledTileSize.width),
+RoundDownToTileEdge(oldBound.y, scaledTileSize.height));
+const nsIntPoint newBufferOrigin(RoundDownToTileEdge(newBound.x, scaledTileSize.width),
+RoundDownToTileEdge(newBound.y, scaledTileSize.height));
+const nsIntRegion& oldValidRegion = mValidRegion;
+const nsIntRegion& newValidRegion = aNewValidRegion;
+const int oldRetainedHeight = mRetainedHeight;
+// Pass 1: Recycle valid content from the old buffer
+// Recycle tiles from the old buffer that contain valid regions.
+// Insert placeholders tiles if we have no valid area for that tile
+// which we will allocate in pass 2.
+// TODO: Add a tile pool to reduce new allocation
+int tileX = 0;
+int tileY = 0;
+int tilesMissing = 0;
+// Iterate over the new drawing bounds in steps of tiles.
+for (int32_t x = newBound.x; x < newBound.XMost(); tileX++) {
+// Compute tileRect(x,y,width,height) in layer space coordinate
+// giving us the rect of the tile that hits the newBounds.
+int width = scaledTileSize.width - GetTileStart(x, scaledTileSize.width);
+if (x + width > newBound.XMost()) {
+width = newBound.x + newBound.width - x;
+}
+tileY = 0;
+for (int32_t y = newBound.y; y < newBound.YMost(); tileY++) {
+int height = scaledTileSize.height - GetTileStart(y, scaledTileSize.height);
+if (y + height > newBound.y + newBound.height) {
+height = newBound.y + newBound.height - y;
+}
+const nsIntRect tileRect(x,y,width,height);
+if (oldValidRegion.Intersects(tileRect) && newValidRegion.Intersects(tileRect)) {
+// This old tiles contains some valid area so move it to the new tile
+// buffer. Replace the tile in the old buffer with a placeholder
+// to leave the old buffer index unaffected.
+int tileX = floor_div(x - oldBufferOrigin.x, scaledTileSize.width);
+int tileY = floor_div(y - oldBufferOrigin.y, scaledTileSize.height);
+int index = tileX * oldRetainedHeight + tileY;
+// The tile may have been removed, skip over it in this case.
+if (IsPlaceholder(oldRetainedTiles.
+SafeElementAt(index, AsDerived().GetPlaceholderTile()))) {
+newRetainedTiles.AppendElement(AsDerived().GetPlaceholderTile());
+} else {
+Tile tileWithPartialValidContent = oldRetainedTiles[index];
+newRetainedTiles.AppendElement(tileWithPartialValidContent);
+oldRetainedTiles[index] = AsDerived().GetPlaceholderTile();
+}
+} else {
+// This tile is either:
+// 1) Outside the new valid region and will simply be an empty
+// placeholder forever.
+// 2) The old buffer didn't have any data for this tile. We postpone
+// the allocation of this tile after we've reused any tile with
+// valid content because then we know we can safely recycle
+// with taking from a tile that has recyclable content.
+newRetainedTiles.AppendElement(AsDerived().GetPlaceholderTile());
+if (aPaintRegion.Intersects(tileRect)) {
+tilesMissing++;
+}
+}
+y += height;
+}
+x += width;
+}
+// Keep track of the number of horizontal/vertical tiles
+// in the buffer so that we can easily look up a tile.
+mRetainedWidth = tileX;
+mRetainedHeight = tileY;
+// Pass 1.5: Release excess tiles in oldRetainedTiles
+// Tiles in oldRetainedTiles that aren't in newRetainedTiles will be recycled
+// before creating new ones, but there could still be excess unnecessary
+// tiles. As tiles may not have a fixed memory cost (for example, due to
+// double-buffering), we should release these excess tiles first.
+int oldTileCount = 0;
+for (size_t i = 0; i < oldRetainedTiles.Length(); i++) {
+Tile oldTile = oldRetainedTiles[i];
+if (IsPlaceholder(oldTile)) {
+continue;
+}
+if (oldTileCount >= tilesMissing) {
+oldRetainedTiles[i] = AsDerived().GetPlaceholderTile();
+AsDerived().ReleaseTile(oldTile);
+} else {
+oldTileCount ++;
+}
+}
+NS_ABORT_IF_FALSE(aNewValidRegion.Contains(aPaintRegion), "Painting a region outside the visible region");
+#ifdef DEBUG
+nsIntRegion oldAndPainted(oldValidRegion);
+oldAndPainted.Or(oldAndPainted, aPaintRegion);
+#endif
+NS_ABORT_IF_FALSE(oldAndPainted.Contains(newValidRegion), "newValidRegion has not been fully painted");
+nsIntRegion regionToPaint(aPaintRegion);
+// Pass 2: Validate
+// We know at this point that any tile in the new buffer that had valid content
+// from the previous buffer is placed correctly in the new buffer.
+// We know that any tile in the old buffer that isn't a place holder is
+// of no use and can be recycled.
+// We also know that any place holder tile in the new buffer must be
+// allocated.
+tileX = 0;
+#ifdef GFX_TILEDLAYER_PREF_WARNINGS
+printf_stderr("Update %i, %i, %i, %i\n", newBound.x, newBound.y, newBound.width, newBound.height);
+#endif
+for (int x = newBound.x; x < newBound.x + newBound.width; tileX++) {
+// Compute tileRect(x,y,width,height) in layer space coordinate
+// giving us the rect of the tile that hits the newBounds.
+int tileStartX = RoundDownToTileEdge(x, scaledTileSize.width);
+int width = scaledTileSize.width - GetTileStart(x, scaledTileSize.width);
+if (x + width > newBound.XMost())
+width = newBound.XMost() - x;
+tileY = 0;
+for (int y = newBound.y; y < newBound.y + newBound.height; tileY++) {
+int tileStartY = RoundDownToTileEdge(y, scaledTileSize.height);
+int height = scaledTileSize.height - GetTileStart(y, scaledTileSize.height);
+if (y + height > newBound.YMost()) {
+height = newBound.YMost() - y;
+}
+const nsIntRect tileRect(x, y, width, height);
+nsIntRegion tileDrawRegion;
+tileDrawRegion.And(tileRect, regionToPaint);
+if (tileDrawRegion.IsEmpty()) {
+// We have a tile but it doesn't hit the draw region
+// because we can reuse all of the content from the
+// previous buffer.
+#ifdef DEBUG
+int currTileX = floor_div(x - newBufferOrigin.x, scaledTileSize.width);
+int currTileY = floor_div(y - newBufferOrigin.y, scaledTileSize.height);
+int index = currTileX * mRetainedHeight + currTileY;
+NS_ABORT_IF_FALSE(!newValidRegion.Intersects(tileRect) ||
+!IsPlaceholder(newRetainedTiles.
+SafeElementAt(index, AsDerived().GetPlaceholderTile())),
+"If we don't draw a tile we shouldn't have a placeholder there.");
+#endif
+y += height;
+continue;
+}
+int tileX = floor_div(x - newBufferOrigin.x, scaledTileSize.width);
+int tileY = floor_div(y - newBufferOrigin.y, scaledTileSize.height);
+int index = tileX * mRetainedHeight + tileY;
+NS_ABORT_IF_FALSE(index >= 0 &&
+static_cast<unsigned>(index) < newRetainedTiles.Length(),
+"index out of range");
+Tile newTile = newRetainedTiles[index];
+// Try to reuse a tile from the old retained tiles that had no partially
+// valid content.
+while (IsPlaceholder(newTile) && oldRetainedTiles.Length() > 0) {
+AsDerived().SwapTiles(newTile, oldRetainedTiles[oldRetainedTiles.Length()-1]);
+oldRetainedTiles.RemoveElementAt(oldRetainedTiles.Length()-1);
+if (!IsPlaceholder(newTile)) {
+oldTileCount--;
+}
+}
+// We've done our best effort to recycle a tile but it can be null
+// in which case it's up to the derived class's ValidateTile()
+// implementation to allocate a new tile before drawing
+nsIntPoint tileOrigin(tileStartX, tileStartY);
+newTile = AsDerived().ValidateTile(newTile, nsIntPoint(tileStartX, tileStartY),
+tileDrawRegion);
+NS_ABORT_IF_FALSE(!IsPlaceholder(newTile), "index out of range");
+#ifdef GFX_TILEDLAYER_PREF_WARNINGS
+printf_stderr("Store Validate tile %i, %i -> %i\n", tileStartX, tileStartY, index);
+#endif
+newRetainedTiles[index] = newTile;
+y += height;
+}
+x += width;
+}
+// At this point, oldTileCount should be zero
+NS_ABORT_IF_FALSE(oldTileCount == 0, "Failed to release old tiles");
+mRetainedTiles = newRetainedTiles;
+mValidRegion = aNewValidRegion;
+mPaintedRegion.Or(mPaintedRegion, aPaintRegion);
+}
+} // layers
+} // mozilla
+#endif // GFX_TILEDLAYERBUFFER_H

The Tor Browser / file comparison

comparison: gfx/layers/TiledLayerBuffer.h

gfx/layers/TiledLayerBuffer.h