SkMultiPictureDraw API

gm/multipicturedraw.cpp

Index: gm/multipicturedraw.cpp
diff --git a/gm/multipicturedraw.cpp b/gm/multipicturedraw.cpp
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+/*
+ * 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 "gm.h"
+
+#include "SkColorFilter.h"
+#include "SkMultiPictureDraw.h"
+#include "SkPictureRecorder.h"
+#include "SkSurface.h"
+
+// TODO:
+//  pass around SkPicture*[2]
+//  add diff clips (path, invpath, region)
+//  research Chrome SkRegion usage
+//  break out make_hex_path mtd
+//  add rest of clip types to mpd object
+//  add static asserts
+//  fix up pub vs. protected in GM
+
+static const SkScalar kRoot3Over2 = 0.86602545f;  // sin(60)
+
+static const int kHexSide = 30;
+static const int kNumHexX = 6;
+static const int kNumHexY = 6;
+static const int kPicWidth = kNumHexX * kHexSide;
+static const int kPicHeight = SkScalarCeilToInt((kNumHexY - 0.5f) * 2 * kHexSide * kRoot3Over2);
+static const SkScalar kInset = 20.0f;
+
+// Make a picture that is a tiling of the plane with stroked hexagons where
+// each hexagon is in its own layer. The layers are to exercise Ganesh's
+// layer hoisting.
+static const SkPicture* make_picture(SkColor fillColor) {
+
+    // Create a hexagon with its center at the origin
+    SkPath hex;
+    hex.moveTo(-kHexSide, 0);
+    hex.rLineTo(SkScalarHalf(kHexSide), kRoot3Over2 * kHexSide);
+    hex.rLineTo(SkIntToScalar(kHexSide), 0);
+    hex.rLineTo(SkScalarHalf(kHexSide), -kHexSide * kRoot3Over2);
+    hex.rLineTo(-SkScalarHalf(kHexSide), -kHexSide * kRoot3Over2);
+    hex.rLineTo(-SkIntToScalar(kHexSide), 0);
+    hex.close();
+
+    SkPaint fill;
+    fill.setStyle(SkPaint::kFill_Style);
+    fill.setColor(fillColor);
+
+    SkPaint stroke;
+    stroke.setStyle(SkPaint::kStroke_Style);
+    stroke.setStrokeWidth(3);
+
+    SkPictureRecorder recorder;
+
+    SkCanvas* canvas = recorder.beginRecording(kPicWidth, kPicHeight);
+
+    SkScalar xPos, yPos = 0;
+
+    for (int y = 0; y < kNumHexY; ++y) {
+        xPos = 0;
+
+        for (int x = 0; x < kNumHexX; ++x) {
+            canvas->saveLayer(NULL, NULL);
+            canvas->translate(xPos, yPos + ((x % 2) ? kRoot3Over2 * kHexSide : 0));
+            canvas->drawPath(hex, fill);
+            canvas->drawPath(hex, stroke);
+            canvas->restore();
+
+            xPos += 1.5f * kHexSide;
+        }
+
+        yPos += 2 * kHexSide * kRoot3Over2;
+    }
+
+    return recorder.endRecording();
+}
+
+static SkSurface* compat_surface(SkCanvas* canvas, int width, int height) {
+    SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
+
+    SkSurface* surface = canvas->newSurface(info);
+    if (NULL == surface) {
+        // picture canvas returns NULL so fall back to raster
+        surface = SkSurface::NewRaster(info);
+    }
+
+    return surface;
+}
+
+// This class stores the information required to compose all the result
+// fragments potentially generated by the MultiPictureDraw object
+class ComposeStep {
+public:
+    ComposeStep() : fSurf(NULL), fX(0.0f), fY(0.0f), fPaint(NULL) { }
+    ~ComposeStep() { SkSafeUnref(fSurf);  SkDELETE(fPaint); }
+
+    SkSurface* fSurf;
+    SkScalar   fX;
+    SkScalar   fY;
+    SkPaint*   fPaint;
+};
+
+typedef void (*PFContentMtd)(SkMultiPictureDraw* mpd, 
+                             const SkPicture* pic0, const SkPicture* pic1, 
+                             SkCanvas* dest,
+                             const SkMatrix& xform);
+
+// Just a single picture with no clip
+static void no_clip(SkMultiPictureDraw* mpd, 
+                    const SkPicture* pic0, const SkPicture* pic1, 
+                    SkCanvas* dest, const SkMatrix& xform) {
+    mpd->add(pic0, dest, &xform);
+}
+
+// Two pictures with a rect clip on the second one
+static void rect_clip(SkMultiPictureDraw* mpd, 
+                      const SkPicture* pic0, const SkPicture* pic1, 
+                      SkCanvas* dest, const SkMatrix& xform) {
+    mpd->add(pic0, dest, &xform);
+
+    SkRect rect = SkRect::MakeWH(SkIntToScalar(kPicWidth), SkIntToScalar(kPicHeight));
+    rect.inset(kInset, kInset);
+    xform.mapRect(&rect);
+
+    mpd->add(pic1, dest, rect, &xform);
+}
+
+// Two pictures with a round rect clip on the second one
+static void rrect_clip(SkMultiPictureDraw* mpd,
+                       const SkPicture* pic0, const SkPicture* pic1, 
+                       SkCanvas* dest, const SkMatrix& xform) {
+    mpd->add(pic0, dest, &xform);
+
+    SkRect rect = SkRect::MakeWH(SkIntToScalar(kPicWidth), SkIntToScalar(kPicHeight));
+    rect.inset(kInset, kInset);
+    xform.mapRect(&rect);
+
+    SkRRect rrect;
+    rrect.setRectXY(rect, kInset, kInset);
+
+    mpd->add(pic1, dest, rrect, &xform);
+}
+
+static const PFContentMtd gContentMtds[] = {
+    no_clip,
+    rect_clip,
+    rrect_clip
+};
+// TODO: static asserts
+
+typedef void(*PFLayoutMtd)(SkCanvas*, SkMultiPictureDraw*, PFContentMtd,
+                           const SkPicture*, const SkPicture*,
+                           SkTArray<ComposeStep>*);
+
+// Draw the content into a single canvas
+static void simple(SkCanvas* finalCanvas, SkMultiPictureDraw* mpd, 
+                   PFContentMtd pfGen, 
+                   const SkPicture* pic0, const SkPicture* pic1,
+                   SkTArray<ComposeStep> *composeSteps) {
+
+    ComposeStep& step = composeSteps->push_back();
+
+    step.fSurf = SkSafeRef(compat_surface(finalCanvas, kPicWidth, kPicHeight));
+
+    SkCanvas* subCanvas = step.fSurf->getCanvas();
+
+    (*pfGen)(mpd, pic0, pic1, subCanvas, SkMatrix::I());
+}
+
+// Draw the content into multiple canvases/tiles
+static void tiled(SkCanvas* finalCanvas, SkMultiPictureDraw* mpd,
+                  PFContentMtd pfGen, 
+                  const SkPicture* pic0, const SkPicture* pic1,
+                  SkTArray<ComposeStep> *composeSteps) {
+    static const int kNumTilesX = 2;
+    static const int kNumTilesY = 2;
+    static const int kTileWidth = kPicWidth / kNumTilesX;
+    static const int kTileHeight = kPicHeight / kNumTilesY;
+
+    SkASSERT(kPicWidth == kNumTilesX * kTileWidth);
+    SkASSERT(kPicHeight == kNumTilesY * kTileHeight);
+
+    static const SkColor colors[kNumTilesX][kNumTilesY] = {
+        SK_ColorCYAN, SK_ColorMAGENTA, SK_ColorYELLOW, SK_ColorGREEN
+    };
+
+    for (int y = 0; y < kNumTilesY; ++y) {
+        for (int x = 0; x < kNumTilesX; ++x) {
+            ComposeStep& step = composeSteps->push_back();
+
+            step.fX = SkIntToScalar(x*kTileWidth);
+            step.fY = SkIntToScalar(y*kTileHeight);
+            step.fPaint = SkNEW(SkPaint);
+            step.fPaint->setColorFilter(
+                SkColorFilter::CreateModeFilter(colors[x][y], SkXfermode::kModulate_Mode))->unref();
+
+            step.fSurf = SkSafeRef(compat_surface(finalCanvas, kTileWidth, kTileHeight));
+
+            SkCanvas* subCanvas = step.fSurf->getCanvas();
+
+            SkMatrix trans;
+            trans.setTranslate(-SkIntToScalar(x*kTileWidth), -SkIntToScalar(y*kTileHeight));
+
+            (*pfGen)(mpd, pic0, pic1, subCanvas, trans);
+        }
+    }
+}
+
+static const PFLayoutMtd gLayoutMthds[] = { simple, tiled };
+// TODO: static asserts
+
+namespace skiagm {
+    /**
+     * This GM exercises the SkMultiPictureDraw object. It tests the
+     * cross product of:
+     *      tiled vs. all-at-once rendering (e.g., into many or just 1 canvas)
+     *      different clips (e.g., none, rect, rrect)
+     *      single vs. multiple pictures (e.g., normal vs. picture-pile-style content)
+     */
+    class MultiPictureDraw : public GM {
+    public:
+        enum Content {
+            NoClipSingle_Content,
+            RectClipMulti_Content,
+            RRectClipMulti_Content,
+        };
+
+        enum Layout {
+            Simple_Layout,
+            Tiled_Layout
+        };
+
+        MultiPictureDraw(Content content, Layout layout) : fContent(content), fLayout(layout) { }
+
+        virtual SkString onShortName() SK_OVERRIDE { 
+            static const char* gContentNames[] = { "noclip", "rectclip", "rrectclip" };
+            static const char* gLayoutNames[] = { "simple", "tiled" };
+            // TODO: static asserts
+
+            SkString name("multipicturedraw_"); 
+
+            name.append(gContentNames[fContent]);
+            name.append("_");
+            name.append(gLayoutNames[fLayout]);
+            return name;
+        }
+
+        virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+            SkMultiPictureDraw mpd;
+            SkTArray<ComposeStep> composeSteps;
+
+            // Fill up the MultiPictureDraw
+            (*gLayoutMthds[fLayout])(canvas, &mpd, gContentMtds[fContent], fPictures[0], fPictures[1], &composeSteps);
+
+            mpd.draw();
+
+            // Compose all the drawn canvases into the final canvas
+            for (int i = 0; i < composeSteps.count(); ++i) {
+                const ComposeStep& step = composeSteps[i];
+
+                SkAutoTUnref<SkImage> image(step.fSurf->newImageSnapshot());
+
+                image->draw(canvas, step.fX, step.fY, step.fPaint);
+            }
+        }
+
+    protected:
+        Content      fContent;
+        Layout       fLayout;
+        SkAutoTUnref<const SkPicture> fPictures[2];
+
+        virtual SkISize onISize() SK_OVERRIDE { return SkISize::Make(kPicWidth, kPicHeight); }
+
+        virtual void onOnceBeforeDraw() SK_OVERRIDE {
+            fPictures[0].reset(make_picture(SK_ColorWHITE));
+            fPictures[1].reset(make_picture(SK_ColorLTGRAY));
+        }
+
+        virtual uint32_t onGetFlags() const SK_OVERRIDE { return kAsBench_Flag | kSkipTiled_Flag; }
+
+    private:
+        typedef GM INHERITED;
+    };
+
+    DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::NoClipSingle_Content, MultiPictureDraw::Simple_Layout));)
+    DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::RectClipMulti_Content, MultiPictureDraw::Simple_Layout));)
+    DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::RRectClipMulti_Content, MultiPictureDraw::Simple_Layout));)
+
+    DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::NoClipSingle_Content, MultiPictureDraw::Tiled_Layout));)
+    DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::RectClipMulti_Content, MultiPictureDraw::Tiled_Layout));)
+    DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::RRectClipMulti_Content, MultiPictureDraw::Tiled_Layout));)
+}