Rewrite PictureSet with TURBO!

This changes how partial invals are done by adding a hybrid mode.

What we used to do is generate a SkPicture for the new area. This
SkPicture would possibly be larger than the actual inval, depending
on various merge rules (more SkPictures == slower to draw a tile)

The new code rewrites PictureSet entirely, preserving many of the old rules
but cleans up the code and adds the concept of a "PrerenderedInval". This is
a partial inval that WebKit has rasterized. By having WebKit produce both
a SkPicture and a SkBitmap, we avoid needing to play back the picture and
avoid overdrawing. We take this SkBitmap, and simply update the front
textures with it. This gives us full partial invals through the entire
system without hitting any driver bugs, and with minimal copies. And while
the SkPicture may be larger than the inval, the SkBitmap that is rasterized
is not - it matches the area webkit has said is dirty.

Change-Id: Ieb7ecc9db0d4f679102fda004a43399f9b319ebc

1 files changed, 309 insertions, 0 deletions

diff --git a/Source/WebKit/android/jni/PicturePile.cpp b/Source/WebKit/android/jni/PicturePile.cpp
new file mode 100644
index 0000000..9ca3588
--- /dev/null
+++ b/Source/WebKit/android/jni/PicturePile.cpp
@@ -0,0 +1,309 @@
+/*
+ * Copyright 2012, The Android Open Source Project
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#define LOG_TAG "PicturePile"
+#define LOG_NDEBUG 1
+
+#include "config.h"
+#include "PicturePile.h"
+
+#include "AndroidLog.h"
+#include "FloatRect.h"
+#include "GraphicsContext.h"
+#include "PlatformGraphicsContextSkia.h"
+#include "SkCanvas.h"
+#include "SkNWayCanvas.h"
+#include "SkPicture.h"
+#include "SkPixelRef.h"
+#include "SkRect.h"
+#include "SkRegion.h"
+
+#define ENABLE_PRERENDERED_INVALS true
+#define MAX_OVERLAP_COUNT 2
+#define MAX_OVERLAP_AREA .7
+
+namespace WebCore {
+
+static SkIRect toSkIRect(const IntRect& rect) {
+    return SkIRect::MakeXYWH(rect.x(), rect.y(), rect.width(), rect.height());
+}
+
+static IntRect extractClipBounds(SkCanvas* canvas, const IntSize& size) {
+    SkRect clip;
+    canvas->getClipBounds(&clip);
+    clip.intersect(0, 0, size.width(), size.height());
+    return enclosingIntRect(clip);
+}
+
+PicturePile::PicturePile(const PicturePile& other)
+    : m_size(other.m_size)
+    , m_pile(other.m_pile)
+    , m_webkitInvals(other.m_webkitInvals)
+{
+}
+
+PicturePile::PicturePile(SkPicture* picture)
+{
+    m_size = IntSize(picture->width(), picture->height());
+    PictureContainer pc(IntRect(0, 0, m_size.width(), m_size.height()));
+    pc.picture = picture;
+    pc.dirty = false;
+    m_pile.append(pc);
+}
+
+void PicturePile::draw(SkCanvas* canvas)
+{
+    /* Loop down recursively, subtracting the previous clip from the SkRegion,
+     * stopping when the SkRegion is empty. This will still draw back-to-front,
+     * but it will clip out anything obscured. For performance reasons we use
+     * the rect bounds of the SkRegion for the clip, so this still can't be
+     * used for translucent surfaces
+     */
+    TRACE_METHOD();
+    IntRect clipBounds = extractClipBounds(canvas, m_size);
+    SkRegion clipRegion(toSkIRect(clipBounds));
+    drawWithClipRecursive(canvas, clipRegion, m_pile.size() - 1);
+}
+
+void PicturePile::clearPrerenders()
+{
+    for (size_t i = 0; i < m_pile.size(); i++)
+        m_pile[i].prerendered.clear();
+}
+
+void PicturePile::drawWithClipRecursive(SkCanvas* canvas, SkRegion& clipRegion,
+                                        int index)
+{
+    // TODO: Add some debug visualizations of this
+    if (index < 0 || clipRegion.isEmpty())
+        return;
+    PictureContainer& pc = m_pile[index];
+    IntRect intersection = clipRegion.getBounds();
+    intersection.intersect(pc.area);
+    if (pc.picture && !intersection.isEmpty()) {
+        clipRegion.op(intersection, SkRegion::kDifference_Op);
+        drawWithClipRecursive(canvas, clipRegion, index - 1);
+        int saved = canvas->save();
+        canvas->clipRect(intersection);
+        canvas->translate(pc.area.x(), pc.area.y());
+        canvas->drawPicture(*pc.picture);
+        canvas->restoreToCount(saved);
+    } else
+        drawWithClipRecursive(canvas, clipRegion, index - 1);
+}
+
+// Used by WebViewCore
+void PicturePile::invalidate(const IntRect& dirtyRect)
+{
+    // This will typically happen if the document has been resized but we haven't
+    // drawn yet. As the first draw after a size change will do a full inval anyway,
+    // don't bother tracking individual rects
+    // TODO: Instead of clipping here, we should take the invals as given
+    // and when the size changes just inval the deltas. This prevents a full
+    // redraw for a page that grows
+    IntRect inval = dirtyRect;
+    inval.intersect(IntRect(0, 0, m_size.width(), m_size.height()));
+    if (inval.isEmpty()) {
+        ALOGV("Rejecting inval " INT_RECT_FORMAT, INT_RECT_ARGS(dirtyRect));
+        return;
+    }
+    // TODO: Support multiple non-intersecting webkit invals
+    if (m_webkitInvals.size())
+        m_webkitInvals[0].unite(inval);
+    else
+        m_webkitInvals.append(inval);
+}
+
+void PicturePile::setSize(const IntSize& size)
+{
+    if (m_size == size)
+        return;
+    m_size = size;
+    // TODO: See above about just adding invals for new content
+    m_pile.clear();
+    m_webkitInvals.clear();
+    IntRect area(0, 0, size.width(), size.height());
+    m_webkitInvals.append(area);
+    m_pile.append(area);
+}
+
+void PicturePile::updatePicturesIfNeeded(PicturePainter* painter)
+{
+    applyWebkitInvals();
+    for (size_t i = 0; i < m_pile.size(); i++) {
+        PictureContainer& pc = m_pile[i];
+        if (pc.dirty)
+            updatePicture(painter, pc);
+    }
+}
+
+void PicturePile::updatePicture(PicturePainter* painter, PictureContainer& pc)
+{
+    /* The ref counting here is a bit unusual. What happens is begin/end recording
+     * will ref/unref the recording canvas. However, 'canvas' might be pointing
+     * at an SkNWayCanvas instead of the recording canvas, which needs to be
+     * unref'd. Thus what we do is ref the recording canvas so that we can
+     * always unref whatever canvas we have at the end.
+     */
+    TRACE_METHOD();
+    SkPicture* picture = new SkPicture();
+    SkCanvas* canvas = picture->beginRecording(pc.area.width(), pc.area.height(),
+            SkPicture::kUsePathBoundsForClip_RecordingFlag);
+    SkSafeRef(canvas);
+    canvas->translate(-pc.area.x(), -pc.area.y());
+    IntRect drawArea = pc.area;
+    if (pc.prerendered.get()) {
+        SkCanvas* prerender = painter->createPrerenderCanvas(pc.prerendered.get());
+        if (!prerender) {
+            ALOGV("Failed to create prerendered for " INT_RECT_FORMAT,
+                    INT_RECT_ARGS(pc.prerendered->area));
+            pc.prerendered.clear();
+        } else {
+            drawArea.unite(pc.prerendered->area);
+            SkNWayCanvas* nwayCanvas = new SkNWayCanvas(drawArea.width(), drawArea.height());
+            nwayCanvas->addCanvas(canvas);
+            nwayCanvas->addCanvas(prerender);
+            SkSafeUnref(canvas);
+            SkSafeUnref(prerender);
+            canvas = nwayCanvas;
+        }
+    }
+    WebCore::PlatformGraphicsContextSkia pgc(canvas);
+    WebCore::GraphicsContext gc(&pgc);
+    ALOGV("painting picture: " INT_RECT_FORMAT, INT_RECT_ARGS(drawArea));
+    painter->paintContents(&gc, drawArea);
+    SkSafeUnref(canvas);
+    picture->endRecording();
+
+    SkSafeUnref(pc.picture);
+    pc.picture = picture;
+    pc.dirty = false;
+}
+
+void PicturePile::reset()
+{
+    m_size = IntSize(0,0);
+    m_pile.clear();
+    m_webkitInvals.clear();
+}
+
+void PicturePile::applyWebkitInvals()
+{
+    m_dirtyRegion.setEmpty();
+    if (!m_webkitInvals.size())
+        return;
+    // Build the invals (TODO: Support multiple inval regions)
+    IntRect inval = m_webkitInvals[0];
+    m_dirtyRegion.setRect(toSkIRect(inval));
+    for (size_t i = 1; i < m_webkitInvals.size(); i++) {
+        inval.unite(m_webkitInvals[i]);
+        m_dirtyRegion.op(toSkIRect(m_webkitInvals[i]), SkRegion::kUnion_Op);
+    }
+    m_webkitInvals.clear();
+    ALOGV("Webkit inval: " INT_RECT_FORMAT, INT_RECT_ARGS(inval));
+    if (inval.isEmpty())
+        return;
+
+    // Find the overlaps
+    Vector<int> overlaps;
+    for (size_t i = 0; i < m_pile.size(); i++) {
+        PictureContainer& pc = m_pile[i];
+        if (pc.area.contains(inval)) {
+            if (pc.dirty) {
+                ALOGV("Found already dirty intersection");
+                return;
+            }
+            if (pc.area == inval) {
+                appendToPile(inval);
+                return;
+            }
+            // Don't count the base surface as an overlap
+            if (pc.area.size() != m_size)
+                overlaps.append(i);
+        } else if (pc.area.intersects(inval))
+            overlaps.append(i);
+    }
+
+    if (overlaps.size() >= MAX_OVERLAP_COUNT) {
+        ALOGV("Exceeds overlap count");
+        IntRect overlap = inval;
+        for (int i = (int) overlaps.size() - 1; i >= 0; i--) {
+            overlap.unite(m_pile[overlaps[i]].area);
+            m_pile.remove(overlaps[i]);
+        }
+        float overlapArea = overlap.width() * overlap.height();
+        float totalArea = m_size.width() * m_size.height();
+        if (overlapArea / totalArea > MAX_OVERLAP_AREA)
+            overlap = IntRect(0, 0, m_size.width(), m_size.height());
+        appendToPile(overlap, inval);
+        return;
+    }
+
+    // Append!
+    appendToPile(inval);
+}
+
+void PicturePile::appendToPile(const IntRect& inval, const IntRect& originalInval)
+{
+    ALOGV("Adding inval " INT_RECT_FORMAT " for original inval " INT_RECT_FORMAT,
+            INT_RECT_ARGS(inval), INT_RECT_ARGS(originalInval));
+    // Remove any entries this obscures
+    for (int i = (int) m_pile.size() - 1; i >= 0; i--) {
+        if (inval.contains(m_pile[i].area))
+            m_pile.remove(i);
+    }
+    PictureContainer container(inval);
+    if (ENABLE_PRERENDERED_INVALS) {
+        container.prerendered = PrerenderedInval::create(originalInval.isEmpty()
+                                                         ? inval : originalInval);
+    }
+    m_pile.append(container);
+}
+
+PrerenderedInval* PicturePile::prerenderedInvalForArea(const IntRect& area)
+{
+    ALOGV("Checking for prerendered inval for area " INT_RECT_FORMAT,
+            INT_RECT_ARGS(area));
+    for (int i = (int) m_pile.size() - 1; i >= 0; i--) {
+        if (m_pile[i].area.intersects(area)) {
+            RefPtr<PrerenderedInval> inval = m_pile[i].prerendered;
+            if (inval.get() && inval->area.contains(area)) {
+                ALOGV("Returning prerendered %p for area " INT_RECT_FORMAT,
+                        m_pile[i].prerendered.get(), INT_RECT_ARGS(area));
+                return inval.get();
+            }
+            if (inval.get()) {
+                ALOGV("Prerendered area doesn't contain requested area; prerendered="
+                        INT_RECT_FORMAT, INT_RECT_ARGS(inval->area));
+            } else
+                ALOGV("No prerendered in intersection");
+            return 0;
+        }
+    }
+    ALOGV("No containers found");
+    return 0;
+}
+
+} // namespace WebCore