Reorganize Layer Hoisting code

src/gpu/GrLayerHoister.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 "GrLayerCache.h"
+#include "GrLayerHoister.h"
+#include "SkPictureRangePlayback.h"
+#include "SkCanvas.h"
+#include "SkSurface.h"
+
+// Return true if any layers are suitable for hoisting
+bool GrLayerHoister::FindLayersToHoist(const GrAccelData *gpuData,
+                                       const SkPicture::OperationList* ops,
+                                       const SkRect& query,
+                                       bool pullForward[]) {
+    bool anyHoisted = false;
+    for (int i = 0; i < gpuData->numSaveLayers(); ++i) {
+        pullForward[i] = false;
+    }
+
+    // Layer hoisting pre-renders the entire layer since it will be cached and potentially
+    // reused with different clips (e.g., in different tiles). Because of this the
+    // clip will not be limiting the size of the pre-rendered layer. kSaveLayerMaxSize
+    // is used to limit which clips are pre-rendered.
+    static const int kSaveLayerMaxSize = 256;
+
+    if (NULL != ops) {
+        // In this case the picture has been generated with a BBH so we use
+        // the BBH to limit the pre-rendering to just the layers needed to cover
+        // the region being drawn
+        for (int i = 0; i < ops->numOps(); ++i) {
+            uint32_t offset = ops->offset(i);
+
+            // For now we're saving all the layers in the GrAccelData so they
+            // can be nested. Additionally, the nested layers appear before
+            // their parent in the list.
+            for (int j = 0; j < gpuData->numSaveLayers(); ++j) {
+                const GrAccelData::SaveLayerInfo& info = gpuData->saveLayerInfo(j);
+
+                if (pullForward[j]) {
+                    continue;            // already pulling forward
+                }
+
+                if (offset < info.fSaveLayerOpID || offset > info.fRestoreOpID) {
+                    continue;            // the op isn't in this range
+                }
+
+                // TODO: once this code is more stable unsuitable layers can
+                // just be omitted during the optimization stage
+                if (!info.fValid ||
+                    kSaveLayerMaxSize < info.fSize.fWidth ||
+                    kSaveLayerMaxSize < info.fSize.fHeight ||
+                    info.fIsNested) {
+                    continue;            // this layer is unsuitable
+                }
+
+                pullForward[j] = true;
+                anyHoisted = true;
+            }
+        }
+    } else {
+        // In this case there is no BBH associated with the picture. Pre-render
+        // all the layers that intersect the drawn region
+        for (int j = 0; j < gpuData->numSaveLayers(); ++j) {
+            const GrAccelData::SaveLayerInfo& info = gpuData->saveLayerInfo(j);
+
+            SkRect layerRect = SkRect::MakeXYWH(SkIntToScalar(info.fOffset.fX),
+                                                SkIntToScalar(info.fOffset.fY),
+                                                SkIntToScalar(info.fSize.fWidth),
+                                                SkIntToScalar(info.fSize.fHeight));
+
+            if (!SkRect::Intersects(query, layerRect)) {
+                continue;
+            }
+
+            // TODO: once this code is more stable unsuitable layers can
+            // just be omitted during the optimization stage
+            if (!info.fValid ||
+                kSaveLayerMaxSize < info.fSize.fWidth ||
+                kSaveLayerMaxSize < info.fSize.fHeight ||
+                info.fIsNested) {
+                continue;
+            }
+
+            pullForward[j] = true;
+            anyHoisted = true;
+        }
+    }
+
+    return anyHoisted;
+}
+
+void GrLayerHoister::DrawLayers(const SkPicture* picture,
+                                const SkTDArray<GrCachedLayer*>& atlased,
+                                const SkTDArray<GrCachedLayer*>& nonAtlased) {
+    // Render the atlased layers that require it
+    if (atlased.count() > 0) {
+        // All the atlased layers are rendered into the same GrTexture
+        SkAutoTUnref<SkSurface> surface(SkSurface::NewRenderTargetDirect(
+                                                atlased[0]->texture()->asRenderTarget(),
+                                                SkSurface::kStandard_TextRenderMode,
+                                                SkSurface::kDontClear_RenderTargetFlag));
+
+        SkCanvas* atlasCanvas = surface->getCanvas();
+
+        SkPaint paint;
+        paint.setColor(SK_ColorTRANSPARENT);
+        paint.setXfermode(SkXfermode::Create(SkXfermode::kSrc_Mode))->unref();
+
+        for (int i = 0; i < atlased.count(); ++i) {
+            GrCachedLayer* layer = atlased[i];
+
+            atlasCanvas->save();
+
+            // Add a rect clip to make sure the rendering doesn't
+            // extend beyond the boundaries of the atlased sub-rect
+            SkRect bound = SkRect::MakeXYWH(SkIntToScalar(layer->rect().fLeft),
+                                            SkIntToScalar(layer->rect().fTop),
+                                            SkIntToScalar(layer->rect().width()),
+                                            SkIntToScalar(layer->rect().height()));
+            atlasCanvas->clipRect(bound);
+
+            // Since 'clear' doesn't respect the clip we need to draw a rect
+            // TODO: ensure none of the atlased layers contain a clear call!
+            atlasCanvas->drawRect(bound, paint);
+
+            // info.fCTM maps the layer's top/left to the origin.
+            // Since this layer is atlased, the top/left corner needs
+            // to be offset to the correct location in the backing texture.
+            atlasCanvas->translate(bound.fLeft, bound.fTop);
+            atlasCanvas->concat(layer->ctm());
+
+            SkPictureRangePlayback rangePlayback(picture,
+                                                 layer->start(),
+                                                 layer->stop());
+            rangePlayback.draw(atlasCanvas, NULL);
+
+            atlasCanvas->restore();
+        }
+
+        atlasCanvas->flush();
+    }
+
+    // Render the non-atlased layers that require it
+    for (int i = 0; i < nonAtlased.count(); ++i) {
+        GrCachedLayer* layer = nonAtlased[i];
+
+        // Each non-atlased layer has its own GrTexture
+        SkAutoTUnref<SkSurface> surface(SkSurface::NewRenderTargetDirect(
+            layer->texture()->asRenderTarget(),
+            SkSurface::kStandard_TextRenderMode,
+            SkSurface::kDontClear_RenderTargetFlag));
+
+        SkCanvas* layerCanvas = surface->getCanvas();
+
+        // Add a rect clip to make sure the rendering doesn't
+        // extend beyond the boundaries of the atlased sub-rect
+        SkRect bound = SkRect::MakeXYWH(SkIntToScalar(layer->rect().fLeft),
+                                        SkIntToScalar(layer->rect().fTop),
+                                        SkIntToScalar(layer->rect().width()),
+                                        SkIntToScalar(layer->rect().height()));
+
+        layerCanvas->clipRect(bound); // TODO: still useful?
+
+        layerCanvas->clear(SK_ColorTRANSPARENT);
+
+        layerCanvas->concat(layer->ctm());
+
+        SkPictureRangePlayback rangePlayback(picture,
+                                             layer->start(),
+                                             layer->stop());
+        rangePlayback.draw(layerCanvas, NULL);
+
+        layerCanvas->flush();
+    }
+}
+
+void GrLayerHoister::UnlockLayers(GrLayerCache* layerCache, const SkPicture* picture) {
+    SkPicture::AccelData::Key key = GrAccelData::ComputeAccelDataKey();
+
+    const SkPicture::AccelData* data = picture->EXPERIMENTAL_getAccelData(key);
+    SkASSERT(NULL != data);
+
+    const GrAccelData *gpuData = static_cast<const GrAccelData*>(data);
+    SkASSERT(0 != gpuData->numSaveLayers());
+
+    // unlock the layers
+    for (int i = 0; i < gpuData->numSaveLayers(); ++i) {
+        const GrAccelData::SaveLayerInfo& info = gpuData->saveLayerInfo(i);
+
+        GrCachedLayer* layer = layerCache->findLayer(picture->uniqueID(),
+                                                     info.fSaveLayerOpID,
+                                                     info.fRestoreOpID,
+                                                     info.fOriginXform);
+        layerCache->unlock(layer);
+    }
+
+#if DISABLE_CACHING
+    // This code completely clears out the atlas. It is required when
+    // caching is disabled so the atlas doesn't fill up and force more
+    // free floating layers
+    layerCache->purge(picture->uniqueID());
+
+    layerCache->purgeAll();
+#endif
+}
+