Add blurcircles2 GM

In GM mode this draws an array of circles with different radii and different blur radii. Below each circle an almost-circle path is drawn with the same blur filter for comparison.

In Sample mode this draws a single circle and almost-circle with animating radius and blur radius.

BUG=skia:5224
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1974353003

Review-Url: https://codereview.chromium.org/1974353003

2 files changed, 158 insertions, 0 deletions

diff --git a/gm/SkAnimTimer.h b/gm/SkAnimTimer.h
index 2c8a723e5b..060de00c2e 100644
--- a/gm/SkAnimTimer.h
+++ b/gm/SkAnimTimer.h
@@ -104,6 +104,23 @@ public:
         return SkDoubleToScalar(value);
     }
 
+    /**
+     * Transitions from ends->mid->ends linearly over period seconds. The phase specifies a phase
+     * shift in seconds.
+     */
+    SkScalar pingPong(SkScalar period, SkScalar phase, SkScalar ends, SkScalar mid) const {
+        return PingPong(this->secs(), period, phase, ends, mid);
+    }
+
+    /** Helper for computing a ping-pong value without a SkAnimTimer object. */
+    static SkScalar PingPong(double t, SkScalar period, SkScalar phase, SkScalar ends,
+                             SkScalar mid) {
+        double value = ::fmod(t + phase, period);
+        double half = period / 2.0;
+        double diff = ::fabs(value - half);
+        return SkDoubleToScalar(ends + (1.0 - diff / half) * (mid - ends));
+    }
+
 private:
     double  fBaseTimeNanos;
     double  fCurrTimeNanos;
diff --git a/gm/blurcircles2.cpp b/gm/blurcircles2.cpp
new file mode 100644
index 0000000000..284c1ab24e
--- /dev/null
+++ b/gm/blurcircles2.cpp
@@ -0,0 +1,141 @@
+/*
+* 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 "gm.h"
+#include "SkAnimTimer.h"
+#include "SkBlurMask.h"
+#include "SkBlurMaskFilter.h"
+#include "SkCanvas.h"
+#include "SkPaint.h"
+#include "SkPath.h"
+#include "SkString.h"
+
+/**
+ * In GM mode this draws an array of circles with different radii and different blur radii. Below
+ * each circle an almost-circle path is drawn with the same blur filter for comparison.
+ *
+ * In Sample mode this draws a single circle and almost-circle with animating radius and blur
+ * radius.
+ */
+class BlurCircles2GM : public skiagm::GM {
+public:
+    BlurCircles2GM() {
+        fAnimRadius = SkAnimTimer::PingPong(0, kRadiusPingPoingPeriod, kRadiusPingPoingShift,
+                                            kMinRadius, kMaxRadius);
+        fAnimBlurRadius = SkAnimTimer::PingPong(0, kBlurRadiusPingPoingPeriod,
+                                                kBlurRadiusPingPoingShift, kMinBlurRadius,
+                                                kMaxBlurRadius);
+    }
+
+protected:
+    SkString onShortName() override { return SkString("blurcircles2"); }
+
+    SkISize onISize() override {
+        return SkISize::Make(730, 1350);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        static constexpr SkScalar kMaxR = kMaxRadius + kMaxBlurRadius;
+
+        auto almostCircleMaker = [] (SkScalar radius, SkPath* dst) {
+            dst->reset();
+            dst->addArc(SkRect::MakeXYWH(-radius, -radius, 2 * radius, 2 * radius), 0, 355);
+            dst->setIsVolatile(true);
+            dst->close();
+        };
+
+        auto blurMaker = [] (SkScalar radius) ->sk_sp<SkMaskFilter> {
+            return SkBlurMaskFilter::Make(kNormal_SkBlurStyle,
+                                          SkBlurMask::ConvertRadiusToSigma(radius),
+                                          SkBlurMaskFilter::kHighQuality_BlurFlag);
+        };
+
+        SkPaint paint;
+        paint.setColor(SK_ColorBLACK);
+
+        if (this->getMode() == kSample_Mode) {
+            paint.setMaskFilter(blurMaker(fAnimBlurRadius));
+            SkISize size = canvas->getBaseLayerSize();
+            SkPath almostCircle;
+            almostCircleMaker(fAnimRadius, &almostCircle);
+            canvas->save();
+                canvas->translate(size.fWidth / 2.f, size.fHeight / 4.f);
+                canvas->drawCircle(0, 0, fAnimRadius, paint);
+                canvas->translate(0, 2 * kMaxR);
+                canvas->drawPath(almostCircle, paint);
+            canvas->restore();
+        } else {
+            canvas->save();
+            static constexpr SkScalar kPad = 5;
+            static constexpr SkScalar kRadiusSteps = 5;
+            static constexpr SkScalar kBlurRadiusSteps = 5;
+            canvas->translate(kPad + kMinRadius + kMaxBlurRadius,
+                              kPad + kMinRadius + kMaxBlurRadius);
+            SkScalar lineWidth = 0;
+            for (int r = 0; r < kRadiusSteps - 1; ++r) {
+                const SkScalar radius = r * (kMaxRadius - kMinRadius) / kBlurRadiusSteps +
+                                        kMinRadius;
+                lineWidth += 2 * (radius + kMaxBlurRadius) + kPad;
+            }
+            for (int br = 0; br < kBlurRadiusSteps; ++br) {
+                const SkScalar blurRadius = br * (kMaxBlurRadius - kMinBlurRadius) /
+                                            kBlurRadiusSteps + kMinBlurRadius;
+                const SkScalar maxRowR = blurRadius + kMaxRadius;
+                paint.setMaskFilter(blurMaker(blurRadius));
+                canvas->save();
+                for (int r = 0; r < kRadiusSteps; ++r) {
+                    const SkScalar radius = r * (kMaxRadius - kMinRadius) / kBlurRadiusSteps +
+                                            kMinRadius;
+                    SkPath almostCircle;
+                    almostCircleMaker(radius, &almostCircle);
+                    canvas->save();
+                        canvas->drawCircle(0, 0, radius, paint);
+                        canvas->translate(0, 2 * maxRowR + kPad);
+                        canvas->drawPath(almostCircle, paint);
+                    canvas->restore();
+                    const SkScalar maxColR = radius + kMaxBlurRadius;
+                    canvas->translate(maxColR * 2 + kPad, 0);
+                }
+                canvas->restore();
+                SkPaint blackPaint;
+                blackPaint.setColor(SK_ColorBLACK);
+                const SkScalar lineY = 3 * maxRowR + 1.5f * kPad;
+                if (br != kBlurRadiusSteps - 1) {
+                    canvas->drawLine(0, lineY, lineWidth, lineY, blackPaint);
+                }
+                canvas->translate(0, maxRowR * 4 + 2 * kPad);
+            }
+            canvas->restore();
+        }
+    }
+
+    bool onAnimate(const SkAnimTimer& timer) override {
+        fAnimRadius = timer.pingPong(kRadiusPingPoingPeriod, kRadiusPingPoingShift, kMinRadius,
+                                     kMaxRadius);
+        fAnimBlurRadius = timer.pingPong(kBlurRadiusPingPoingPeriod, kBlurRadiusPingPoingShift,
+                                         kMinBlurRadius, kMaxBlurRadius);
+        return true;
+    }
+
+private:
+    static constexpr SkScalar kMinRadius = 15;
+    static constexpr SkScalar kMaxRadius = 45;
+    static constexpr SkScalar kRadiusPingPoingPeriod = 8;
+    static constexpr SkScalar kRadiusPingPoingShift = 3;
+
+    static constexpr SkScalar kMinBlurRadius = 5;
+    static constexpr SkScalar kMaxBlurRadius = 45;
+    static constexpr SkScalar kBlurRadiusPingPoingPeriod = 3;
+    static constexpr SkScalar kBlurRadiusPingPoingShift = 1.5;
+
+    SkScalar    fAnimRadius;
+    SkScalar    fAnimBlurRadius;
+
+    typedef skiagm::GM INHERITED;
+};
+
+DEF_GM(return new BlurCircles2GM();)