SkRecordDraw: incorporate clip into BBH

src/core/SkRecordDraw.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkRecordDraw.h"
 #include "SkTSort.h"
 
 void SkRecordDraw(const SkRecord& record,
                   SkCanvas* canvas,
                   const SkBBoxHierarchy* bbh,
                   SkDrawPictureCallback* callback) {
     SkAutoCanvasRestore saveRestore(canvas, true /*save now, restore at exit*/);
 
     if (NULL != bbh) {
         // Draw only ops that affect pixels in the canvas's current clip.
-        SkIRect devBounds;
-        canvas->getClipDeviceBounds(&devBounds);
+        SkIRect query;
+#if 1   // TODO: Why is this the right way to make the query?  I'd think it'd be the else branch.

[Stephen White, 2014/08/14 17:40:04]

I'm not super-familiar with the BBH code, but it looks like
SkPicturePlayback::getActiveOps() does the same thing.
I'm guessing that SkBBH::search() takes a rect in object-space coords, 
not device-space coords, despite the fact that takes an SkIRect.

Maybe Justin knows.

[mtklein, 2014/08/14 17:54:03]

Yeah, stole this from there.

As far as I can tell, all the BBHs ought to work entirely in device coordinates,
and yet... many GMs draw wrong if we query the device coordinates directly.  A
little bit of debugging made it look like we maybe get back a different bounds
that I'd hope from getClipDeviceBounds().  The top-left tile looks right, and
everything's the right size, but the other tiles all start from (0,0).  No
translation offset.

+        SkRect clipBounds;
+        canvas->getClipBounds(&clipBounds);
+        clipBounds.roundOut(&query);
+#else
+        canvas->getClipDeviceBounds(&query);
+#endif
         SkTDArray<void*> ops;
-        bbh->search(devBounds, &ops);
+        bbh->search(query, &ops);
 
         // FIXME: QuadTree doesn't send these back in the order we inserted them.  :(
         // Also remove the sort in SkPictureData::getActiveOps()?
         if (ops.count() > 0) {
             SkTQSort(ops.begin(), ops.end() - 1, SkTCompareLT<void*>());
         }
 
         SkRecords::Draw draw(canvas);
         for (int i = 0; i < ops.count(); i++) {
             if (NULL != callback && callback->abortDrawing()) {
@@ skipping 77 matching lines @@
 // To implement this, we keep a stack of active Save blocks.  As we consume ops
 // inside the Save/Restore block, drawing ops are unioned with the bounds of
 // the block, and control ops are stashed away for later.  When we finish the
 // block with a Restore, our bounds are complete, and we go back and fill them
 // in for all the control ops we stashed away.
 class FillBounds : SkNoncopyable {
 public:
     FillBounds(const SkRecord& record, SkBBoxHierarchy* bbh) : fBounds(record.count()) {
         // Calculate bounds for all ops.  This won't go quite in order, so we'll need
         // to store the bounds separately then feed them in to the BBH later in order.
+        const SkIRect largest = SkIRect::MakeLargest();
         fCTM.setIdentity();
+        fClipBounds = largest;
         for (fCurrentOp = 0; fCurrentOp < record.count(); fCurrentOp++) {
             record.visit<void>(fCurrentOp, *this);
         }
 
         // If we have any lingering unpaired Saves, simulate restores to make
         // sure all ops in those Save blocks have their bounds calculated.
         while (!fSaveStack.isEmpty()) {
             this->popSaveBlock();
         }
 
         // Any control ops not part of any Save/Restore block draw everywhere.
         while (!fControlIndices.isEmpty()) {
-            this->popControl(SkIRect::MakeLargest());
+            this->popControl(largest);
         }
 
         // Finally feed all stored bounds into the BBH.  They'll be returned in this order.
         SkASSERT(NULL != bbh);
         for (uintptr_t i = 0; i < record.count(); i++) {
             if (!fBounds[i].isEmpty()) {
                 bbh->insert((void*)i, fBounds[i], true/*ok to defer*/);
             }
         }
         bbh->flushDeferredInserts();
     }
 
-    template <typename T> void operator()(const T& r) {
-        this->updateCTM(r);
-        this->trackBounds(r);
+    template <typename T> void operator()(const T& op) {
+        this->updateCTM(op);
+        this->updateClipBounds(op);
+        this->trackBounds(op);
     }
 
 private:
     struct SaveBounds {
-        int controlOps;  // Number of control ops in this Save block, including the Save.
-        SkIRect bounds;  // Bounds of everything in the block.
+        int controlOps;        // Number of control ops in this Save block, including the Save.
+        SkIRect bounds;        // Bounds of everything in the block.
+        const SkPaint* paint;  // Unowned.  If set, adjusts the bounds of all ops in this block.
     };
 
     template <typename T> void updateCTM(const T&) { /* most ops don't change the CTM */ }
-    void updateCTM(const Restore& r)   { fCTM = r.matrix; }
-    void updateCTM(const SetMatrix& r) { fCTM = r.matrix; }
-    void updateCTM(const Concat& r)    { fCTM.preConcat(r.matrix); }
+    void updateCTM(const Restore& op)   { fCTM = op.matrix; }
+    void updateCTM(const SetMatrix& op) { fCTM = op.matrix; }
+    void updateCTM(const Concat& op)    { fCTM.preConcat(op.matrix); }
+
+    template <typename T> void updateClipBounds(const T&) { /* most ops don't change the clip */ }
+    void updateClipBounds(const Restore& op)    { fClipBounds = op.devBounds; }
+    void updateClipBounds(const ClipPath& op)   { fClipBounds = op.devBounds; }
+    void updateClipBounds(const ClipRRect& op)  { fClipBounds = op.devBounds; }
+    void updateClipBounds(const ClipRect& op)   { fClipBounds = op.devBounds; }
+    void updateClipBounds(const ClipRegion& op) { fClipBounds = op.devBounds; }
+    void updateClipBounds(const SaveLayer& op)  {
+        if (op.bounds) {
+            fClipBounds.intersect(this->adjustAndMap(*op.bounds, op.paint));
+        }
+    }
 
     // The bounds of these ops must be calculated when we hit the Restore
     // from the bounds of the ops in the same Save block.
-    void trackBounds(const Save&)       { this->pushSaveBlock(); }
+    void trackBounds(const Save&)          { this->pushSaveBlock(NULL); }
     // TODO: bounds of SaveLayer may be more complicated?
-    void trackBounds(const SaveLayer&)  { this->pushSaveBlock(); }
-    void trackBounds(const Restore&)    { fBounds[fCurrentOp] = this->popSaveBlock(); }
+    void trackBounds(const SaveLayer& op)  { this->pushSaveBlock(op.paint); }
+    void trackBounds(const Restore&) { fBounds[fCurrentOp] = this->popSaveBlock(); }
 
     void trackBounds(const Concat&)     { this->pushControl(); }
     void trackBounds(const SetMatrix&)  { this->pushControl(); }
     void trackBounds(const ClipRect&)   { this->pushControl(); }
     void trackBounds(const ClipRRect&)  { this->pushControl(); }
     void trackBounds(const ClipPath&)   { this->pushControl(); }
     void trackBounds(const ClipRegion&) { this->pushControl(); }
 
     // For all other ops, we can calculate and store the bounds directly now.
     template <typename T> void trackBounds(const T& op) {
         fBounds[fCurrentOp] = this->bounds(op);
         this->updateSaveBounds(fBounds[fCurrentOp]);
     }
 
-    // TODO: remove this trivially-safe default when done bounding all ops
-    template <typename T> SkIRect bounds(const T&) { return SkIRect::MakeLargest(); }
-
-    void pushSaveBlock() {
+    void pushSaveBlock(const SkPaint* paint) {
         // Starting a new Save block.  Push a new entry to represent that.
-        SaveBounds sb = { 0, SkIRect::MakeEmpty() };
+        SaveBounds sb = { 0, SkIRect::MakeEmpty(), paint };
         fSaveStack.push(sb);
         this->pushControl();
     }
 
     SkIRect popSaveBlock() {
         // We're done the Save block.  Apply the block's bounds to all control ops inside it.
         SaveBounds sb;
         fSaveStack.pop(&sb);
         while (sb.controlOps --> 0) {
             this->popControl(sb.bounds);
@@ skipping 18 matching lines @@
         fControlIndices.pop();
     }
 
     void updateSaveBounds(const SkIRect& bounds) {
         // If we're in a Save block, expand its bounds to cover these bounds too.
         if (!fSaveStack.isEmpty()) {
             fSaveStack.top().bounds.join(bounds);
         }
     }
 
-    SkIRect bounds(const NoOp&) { return SkIRect::MakeEmpty(); }  // NoOps don't draw anywhere.
+    // TODO: Remove this default when done bounding all ops.
+    template <typename T> SkIRect bounds(const T&) { return fClipBounds; }
+    SkIRect bounds(const Clear&) { return SkIRect::MakeLargest(); }  // Ignores the clip
+    SkIRect bounds(const NoOp&)  { return SkIRect::MakeEmpty(); }    // NoOps don't draw anywhere.
+
+    // Adjust rect for all paints that may affect its geometry, then map it to device space.
+    SkIRect adjustAndMap(SkRect rect, const SkPaint* paint) {
+        // Adjust rect for its own paint.
+        if (paint && paint->canComputeFastBounds()) {
+            rect = paint->computeFastBounds(rect, &rect);

[Stephen White, 2014/08/14 17:23:07]

If you have a paint that can't computeFastBounds(), you'll have to 
assume the bounds are the entire clip rect(at least, that's how the
old code in SkBBoxRecord worked).

[mtklein, 2014/08/14 17:54:03]

Thanks, good catch.  All the bounds are the clip right now, so it never came up.
:)

We don't do this check today for the SaveLayer paints.  Seem right to do fail to
the clip bounds if those paints can't compute bounds too?

+        }
+        // Adjust rect for all the paints from the SaveLayers we're inside.
+        // For SaveLayers, only image filters will affect the bounds.
+        for (int i = fSaveStack.count() - 1; i >= 0; i--) {
+            if (fSaveStack[i].paint &&
+                fSaveStack[i].paint->getImageFilter() &&
+                fSaveStack[i].paint->canComputeFastBounds()) {
+                rect = fSaveStack[i].paint->computeFastBounds(rect, &rect);
+            }
+        }
+        // Map the rect back to device space.
+        fCTM.mapRect(&rect);
+        SkIRect devRect;
+        rect.roundOut(&devRect);
+        return devRect;
+    }
 
     SkAutoTMalloc<SkIRect> fBounds;  // One for each op in the record.
     SkMatrix fCTM;
+    SkIRect fClipBounds;
     unsigned fCurrentOp;
     SkTDArray<SaveBounds> fSaveStack;
     SkTDArray<unsigned>   fControlIndices;
 };
 
 }  // namespace SkRecords
 
 void SkRecordFillBounds(const SkRecord& record, SkBBoxHierarchy* bbh) {
     SkRecords::FillBounds(record, bbh);
 }