Avoid creating full screen clear batches when there is already one in the queue.

src/gpu/GrDrawTarget.cpp

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDrawTarget.h"
 
 #include "GrAuditTrail.h"
@@ skipping 27 matching lines @@
 #include "instanced/InstancedRendering.h"
 
 ////////////////////////////////////////////////////////////////////////////////
 
 // Experimentally we have found that most batching occurs within the first 10 comparisons.
 static const int kDefaultMaxBatchLookback  = 10;
 static const int kDefaultMaxBatchLookahead = 10;
 
 GrDrawTarget::GrDrawTarget(GrRenderTarget* rt, GrGpu* gpu, GrResourceProvider* resourceProvider,
                            GrAuditTrail* auditTrail, const Options& options)
-    : fGpu(SkRef(gpu))
+    : fLastFullClearBatch(nullptr)
+    , fGpu(SkRef(gpu))
     , fResourceProvider(resourceProvider)
     , fAuditTrail(auditTrail)
     , fFlags(0)
     , fRenderTarget(rt) {
     // TODO: Stop extracting the context (currently needed by GrClip)
     fContext = fGpu->getContext();
 
     fClipBatchToBounds = options.fClipBatchToBounds;
     fDrawBatchBounds = options.fDrawBatchBounds;
     fMaxBatchLookback = (options.fMaxBatchLookback < 0) ? kDefaultMaxBatchLookback :
@@ skipping 221 matching lines @@
             bounds.roundOut(&iBounds);
             commandBuffer->submit(iBounds);
         }
         flushState->setCommandBuffer(nullptr);
     }
 
     fGpu->finishDrawTarget();
 }
 
 void GrDrawTarget::reset() {
+    fLastFullClearBatch = nullptr;
     fRecordedBatches.reset();
     if (fInstancedRendering) {
         fInstancedRendering->endFlush();
     }
 }
 
 static void batch_bounds(SkRect* bounds, const GrBatch* batch) {
     *bounds = batch->bounds();
     if (batch->hasZeroArea()) {
         if (batch->hasAABloat()) {
@@ skipping 151 matching lines @@
                                                 path);
     this->recordBatch(batch, appliedClip.deviceBounds());
     batch->unref();
 }
 
 void GrDrawTarget::addBatch(sk_sp<GrBatch> batch) {
     this->recordBatch(batch.get(), batch->bounds());
 }
 
 void GrDrawTarget::fullClear(GrRenderTarget* renderTarget, GrColor color) {
-    // Currently this just inserts a clear batch. However, once in MDB this can remove all the
-    // previously recorded batches and change the load op to clear with supplied color.
-    sk_sp<GrBatch> batch = GrClearBatch::Make(SkIRect::MakeWH(renderTarget->width(),
-                                                              renderTarget->height()),
-                                              color, renderTarget);
-    this->recordBatch(batch.get(), batch->bounds());
+    // Currently this just inserts or updates the last clear batch. However, once in MDB this can
+    // remove all the previously recorded batches and change the load op to clear with supplied
+    // color.
+    if (fLastFullClearBatch &&
+        fLastFullClearBatch->renderTargetUniqueID() == renderTarget->getUniqueID()) {
+        // As currently implemented, fLastFullClearBatch should be the last batch because we would
+        // have cleared it when another batch was recorded.
+        SkASSERT(fRecordedBatches.back().fBatch.get() == fLastFullClearBatch);
+        fLastFullClearBatch->setColor(color);
+        return;
+    }
+    sk_sp<GrClearBatch> batch(GrClearBatch::Make(SkIRect::MakeWH(renderTarget->width(),
+                                                                 renderTarget->height()),
+                                                 color, renderTarget));
+    if (batch.get() == this->recordBatch(batch.get(), batch->bounds())) {
+        fLastFullClearBatch = batch.get();
+    }
 }
 
 void GrDrawTarget::discard(GrRenderTarget* renderTarget) {
     // Currently this just inserts a discard batch. However, once in MDB this can remove all the
     // previously recorded batches and change the load op to discard.
     if (this->caps()->discardRenderTargetSupport()) {
         GrBatch* batch = new GrDiscardBatch(renderTarget);
         this->recordBatch(batch, batch->bounds());
         batch->unref();
     }
@@ skipping 25 matching lines @@
 
 static void join(SkRect* out, const SkRect& a, const SkRect& b) {
     SkASSERT(a.fLeft <= a.fRight && a.fTop <= a.fBottom);
     SkASSERT(b.fLeft <= b.fRight && b.fTop <= b.fBottom);
     out->fLeft   = SkTMin(a.fLeft,   b.fLeft);
     out->fTop    = SkTMin(a.fTop,    b.fTop);
     out->fRight  = SkTMax(a.fRight,  b.fRight);
     out->fBottom = SkTMax(a.fBottom, b.fBottom);
 }
 
-void GrDrawTarget::recordBatch(GrBatch* batch, const SkRect& clippedBounds) {
+GrBatch* GrDrawTarget::recordBatch(GrBatch* batch, const SkRect& clippedBounds) {
     // A closed drawTarget should never receive new/more batches
     SkASSERT(!this->isClosed());
 
     // Check if there is a Batch Draw we can batch with by linearly searching back until we either
     // 1) check every draw
     // 2) intersect with something
     // 3) find a 'blocker'
     GR_AUDIT_TRAIL_ADDBATCH(fAuditTrail, batch);
     GrBATCH_INFO("Re-Recording (%s, B%u)\n"
         "\tBounds LRTB (%f, %f, %f, %f)\n",
@@ skipping 16 matching lines @@
                 GrBATCH_INFO("\t\tBreaking because of (%s, B%u) Rendertarget\n",
                     candidate->name(), candidate->uniqueID());
                 break;
             }
             if (candidate->combineIfPossible(batch, *this->caps())) {
                 GrBATCH_INFO("\t\tCombining with (%s, B%u)\n", candidate->name(),
                     candidate->uniqueID());
                 GR_AUDIT_TRAIL_BATCHING_RESULT_COMBINED(fAuditTrail, candidate, batch);
                 join(&fRecordedBatches.fromBack(i).fClippedBounds,
                      fRecordedBatches.fromBack(i).fClippedBounds, clippedBounds);
-                return;
+                return candidate;
             }
             // Stop going backwards if we would cause a painter's order violation.
             const SkRect& candidateBounds = fRecordedBatches.fromBack(i).fClippedBounds;
             if (!can_reorder(candidateBounds, clippedBounds)) {
                 GrBATCH_INFO("\t\tIntersects with (%s, B%u)\n", candidate->name(),
                     candidate->uniqueID());
                 break;
             }
             ++i;
             if (i == maxCandidates) {
                 GrBATCH_INFO("\t\tReached max lookback or beginning of batch array %d\n", i);
                 break;
             }
         }
     } else {
         GrBATCH_INFO("\t\tFirstBatch\n");
     }
     GR_AUDIT_TRAIL_BATCHING_RESULT_NEW(fAuditTrail, batch);
     fRecordedBatches.emplace_back(RecordedBatch{sk_ref_sp(batch), clippedBounds});
+    fLastFullClearBatch = nullptr;
+    return batch;
 }
 
 void GrDrawTarget::forwardCombine() {
     for (int i = 0; i < fRecordedBatches.count() - 2; ++i) {
         GrBatch* batch = fRecordedBatches[i].fBatch.get();
         const SkRect& batchBounds = fRecordedBatches[i].fClippedBounds;
         int maxCandidateIdx = SkTMin(i + fMaxBatchLookahead, fRecordedBatches.count() - 1);
         int j = i + 1;
         while (true) {
             GrBatch* candidate = fRecordedBatches[j].fBatch.get();
@@ skipping 32 matching lines @@
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 void GrDrawTarget::clearStencilClip(const SkIRect& rect, bool insideClip, GrRenderTarget* rt) {
     GrBatch* batch = new GrClearStencilClipBatch(rect, insideClip, rt);
     this->recordBatch(batch, batch->bounds());
     batch->unref();
 }