Use Offscreen Surface for Split Screen

tools/viewer/Viewer.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "Viewer.h"
 
 #include "GMSlide.h"
 #include "ImageSlide.h"
 #include "SKPSlide.h"
+#include "sk_app/WindowContext.h"
 
+#include "GrRenderTarget.h"
 #include "SkCanvas.h"
 #include "SkCommonFlags.h"
+#include "SkDashPathEffect.h"
 #include "SkMetaData.h"
 #include "SkOSFile.h"
 #include "SkRandom.h"
 #include "SkStream.h"
+#include "SkSurface.h"
 
 using namespace sk_app;
 
 Application* Application::Create(int argc, char** argv, void* platformData) {
     return new Viewer(argc, argv, platformData);
 }
 
 static void on_paint_handler(SkCanvas* canvas, void* userData) {
     Viewer* vv = reinterpret_cast<Viewer*>(userData);
 
@@ skipping 323 matching lines @@
         contentRect.fLeft +=
                 inSplitScreen ? (contentRect.fRight - contentRect.fLeft) * 0.5f : 0.0f;
         canvas->clipRect(contentRect);
         canvas->translate(contentRect.fLeft, contentRect.fTop);
     }
 
     canvas->clear(SK_ColorWHITE);
     canvas->concat(fDefaultMatrix);
     canvas->concat(computeMatrix());
 
-    canvas->getMetaData().setBool(kImageColorXformMetaData, inSplitScreen);
-    fSlides[fCurrentSlide]->draw(canvas);
+    if (inSplitScreen) {
+        sk_sp<SkSurface> offscreenSurface =
+                fWindow->getContext()->createRenderSurface(nullptr, 0, true, true);
+        fSlides[fCurrentSlide]->draw(offscreenSurface->getCanvas());
+        sk_sp<SkImage> snapshot = offscreenSurface->makeImageSnapshot();
+        canvas->drawImage(snapshot, 0, 0);
+    } else {
+        fSlides[fCurrentSlide]->draw(canvas);
+    }
+
     canvas->restoreToCount(count);
+
+    if (inSplitScreen) {
+        // Draw split line
+        SkPaint paint;
+        SkScalar intervals[] = {10.0f, 5.0f};
+        paint.setPathEffect(SkDashPathEffect::Make(intervals, 2, 0.0f));
+        SkRect contentRect = fWindow->getContentRect();
+        SkScalar middleX = (contentRect.fLeft + contentRect.fRight) * 0.5f;
+        canvas->drawLine(middleX, contentRect.fTop, middleX, contentRect.fBottom, paint);
+    }
 }
 
 void Viewer::onPaint(SkCanvas* canvas) {
     drawSlide(canvas, false);
     if (fSplitScreen && fWindow->supportsContentRect()) {
         drawSlide(canvas, true);
     }
 
     if (fDisplayStats) {
         drawStats(canvas);
@@ skipping 183 matching lines @@
         bool newSplitScreen = stateValue.equals(kON);
         if (newSplitScreen != fSplitScreen) {
             fSplitScreen = newSplitScreen;
             fWindow->inval();
             updateUIState();
         }
     } else {
         SkDebugf("Unknown stateName: %s", stateName.c_str());
     }
 }