Add text animation sample; tweak DrawShip sample

samplecode/SampleAnimatedText.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SampleCode.h"
+#include "SkView.h"
+#include "SkCanvas.h"
+#include "SkUtils.h"
+#include "SkColorPriv.h"
+#include "SkColorFilter.h"
+#if SK_SUPPORT_GPU
+#include "SkGpuDevice.h"
+#endif
+#include "SkRandom.h"
+#include "SkSystemEventTypes.h"
+#include "SkTime.h"
+#include "SkTypeface.h"
+#include "SkXfermode.h"
+#include "Timer.h"
+
+#include "GrContext.h"
+
+SkRandom gRand;
+
+static void DrawTheText(SkCanvas* canvas, const char text[], size_t length, SkScalar x, SkScalar y,
+                        const SkPaint& paint) {
+    SkPaint p(paint);
+
+    p.setSubpixelText(true);
+    canvas->drawText(text, length, x, y, p);
+}
+
+// This sample demonstrates the cache behavior of bitmap vs. distance field text
+// It renders variously sized text with an animated scale and rotation.
+// Specifically one should:
+//   use 'D' to toggle between bitmap and distance field fonts
+//   use '2' to toggle between scaling the image by 2x
+//            -- this feature boosts the rendering out of the small point-size
+//               SDF-text special case (which falls back to bitmap fonts for small points)
+
+class AnimatedTextView : public SampleView {
+public:
+    AnimatedTextView() : fScale(1.0f), fScaleInc(0.1f), fRotation(0.0f), fSizeScale(1) {
+        fCurrentTime = 0;
+        fTimer.start();
+        memset(fTimes, 0, sizeof(fTimes));
+    }
+
+protected:
+    // overrides from SkEventSink
+    bool onQuery(SkEvent* evt) override {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "AnimatedText");
+            return true;
+        }
+
+        SkUnichar uni;
+        if (SampleCode::CharQ(*evt, &uni)) {
+            if ('2' == uni) {
+                if (fSizeScale == 2) {
+                    fSizeScale = 1;
+                } else {
+                    fSizeScale = 2;
+                }
+                return true;
+            }
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+
+    void onDrawContent(SkCanvas* canvas) override {
+        SkPaint paint;
+        SkSafeUnref(paint.setTypeface(SkTypeface::CreateFromFile("/skimages/samplefont.ttf")));
+        paint.setAntiAlias(true);
+        paint.setFilterQuality(kMedium_SkFilterQuality);
+
+        SkString outString("fps: ");
+        fTimer.end();
+
+        // TODO: generalize this timing code in utils
+        fTimes[fCurrentTime] = (float)(fTimer.fWall);
+        fCurrentTime = (fCurrentTime + 1) & 0x1f;
+
+        float meanTime = 0.0f;
+        for (int i = 0; i < 32; ++i) {
+            meanTime += fTimes[i];
+        }
+        meanTime /= 32.f;
+        SkScalar fps = 1000.f / meanTime;
+        outString.appendScalar(fps);
+        outString.append(" ms: ");
+        outString.appendScalar(meanTime);
+
+        SkString modeString("Text scale: ");
+        modeString.appendU32(fSizeScale);
+        modeString.append("x");
+
+        fTimer.start();
+
+        canvas->save();
+
+#if SK_SUPPORT_GPU
+        SkBaseDevice* device = canvas->getDevice_just_for_deprecated_compatibility_testing();
+        GrContext* grContext = canvas->getGrContext();
+        if (grContext) {
+            grContext->drawFontCache(SkRect::MakeXYWH(512, 10, 512, 512), kA8_GrMaskFormat, paint,
+                                     reinterpret_cast<SkGpuDevice*>(device)->accessRenderTarget());
+        }
+#endif
+        canvas->translate(180, 180);
+        canvas->rotate(fRotation);
+        canvas->scale(fScale, fScale);
+        canvas->translate(-180, -180);
+
+        const char* text = "Hamburgefons";
+        size_t length = strlen(text);
+
+        SkScalar y = SkIntToScalar(0);
+        for (int i = 12; i <= 26; i++) {
+            paint.setTextSize(SkIntToScalar(i*fSizeScale));
+            y += paint.getFontSpacing();
+            DrawTheText(canvas, text, length, SkIntToScalar(110), y, paint);
+        }
+        canvas->restore();
+
+        paint.setTextSize(16);
+        canvas->drawText(outString.c_str(), outString.size(), 512.f, 540.f, paint);
+        canvas->drawText(modeString.c_str(), modeString.size(), 768.f, 540.f, paint);
+    }
+
+    bool onAnimate(const SkAnimTimer& timer) override {
+        // We add noise to the scale and rotation animations to 
+        // keep the font atlas from falling into a steady state
+        fRotation += (1.0f + gRand.nextRangeF(-0.1f, 0.1f));
+        fScale += (fScaleInc + gRand.nextRangeF(-0.025f, 0.025f));
+        if (fScale >= 2.0f) {
+            fScaleInc = -0.1f;
+        } else if (fScale <= 1.0f) {
+            fScaleInc = 0.1f;
+        }
+        return true;
+    }
+
+private:
+    float fScale;
+    float fScaleInc;
+    float fRotation;
+    int   fSizeScale;
+
+    WallTimer   fTimer;
+    float       fTimes[32];
+    int         fCurrentTime;
+
+
+    typedef SampleView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static SkView* MyFactory() { return new AnimatedTextView; }
+static SkViewRegister reg(MyFactory);