Add GM to test out blurmaskfilter occluders

gm/occludedrrectblur.cpp

Index: gm/occludedrrectblur.cpp
diff --git a/gm/occludedrrectblur.cpp b/gm/occludedrrectblur.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..d73867a9ecc2e312beaf097e808b7115572781af
--- /dev/null
+++ b/gm/occludedrrectblur.cpp
@@ -0,0 +1,389 @@
+/*
+ * 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 "SkBlurMaskFilter.h"
+#include "SkRRect.h"
+
+static SkRect offset_center_to(const SkIRect& src, SkScalar x, SkScalar y) {
+    SkScalar halfW = 0.5f * src.width();
+    SkScalar halfH = 0.5f * src.height();
+
+    return SkRect::MakeLTRB(x - halfW, y - halfH, x + halfW, y + halfH);
+}
+
+// compute the intersection point between the diagonal and the ellipse in the
+// lower right corner
+static SkPoint intersection(SkScalar w, SkScalar h) {
+    SkASSERT(w > 0.0f || h > 0.0f);
+
+    return SkPoint::Make(w / SK_ScalarSqrt2, h / SK_ScalarSqrt2);
+}
+
+// Use the intersection of the corners' diagonals with their ellipses to shrink
+// the bounding rect
+static SkRect compute_central_occluder(const SkRRect& rr) {
+    const SkRect r = rr.getBounds();
+
+    SkScalar newL = r.fLeft, newT = r.fTop, newR = r.fRight, newB = r.fBottom;
+
+    SkVector radii = rr.radii(SkRRect::kUpperLeft_Corner);
+    if (!radii.isZero()) {
+        SkPoint p = intersection(radii.fX, radii.fY);
+
+        newL = SkTMax(newL, r.fLeft + radii.fX - p.fX);
+        newT = SkTMax(newT, r.fTop + radii.fY - p.fY);
+    }
+
+    radii = rr.radii(SkRRect::kUpperRight_Corner);
+    if (!radii.isZero()) {
+        SkPoint p = intersection(radii.fX, radii.fY);
+
+        newR = SkTMin(newR, r.fRight + p.fX - radii.fX);
+        newT = SkTMax(newT, r.fTop + radii.fY - p.fY);
+    }
+
+    radii = rr.radii(SkRRect::kLowerRight_Corner);
+    if (!radii.isZero()) {
+        SkPoint p = intersection(radii.fX, radii.fY);
+
+        newR = SkTMin(newR, r.fRight + p.fX - radii.fX);
+        newB = SkTMin(newB, r.fBottom - radii.fY + p.fY);
+    }
+
+    radii = rr.radii(SkRRect::kLowerLeft_Corner);
+    if (!radii.isZero()) {
+        SkPoint p = intersection(radii.fX, radii.fY);
+
+        newL = SkTMax(newL, r.fLeft + radii.fX - p.fX);
+        newB = SkTMin(newB, r.fBottom - radii.fY + p.fY);
+    }
+
+    return SkRect::MakeLTRB(newL, newT, newR, newB);
+}
+
+// The widest inset rect
+static SkRect compute_widest_occluder(const SkRRect& rr) {
+    SkRect r = rr.getBounds();
+
+    const SkVector& ul = rr.radii(SkRRect::kUpperLeft_Corner);
+    const SkVector& ur = rr.radii(SkRRect::kUpperRight_Corner);
+    const SkVector& lr = rr.radii(SkRRect::kLowerRight_Corner);
+    const SkVector& ll = rr.radii(SkRRect::kLowerLeft_Corner);
+
+    SkScalar maxT = SkTMax(ul.fY, ur.fY);
+    SkScalar maxB = SkTMax(ll.fY, lr.fY);
+
+    return SkRect::MakeLTRB(r.fLeft, r.fTop + maxT, r.fRight, r.fBottom - maxB);
+
+}
+
+// The tallest inset rect
+static SkRect compute_tallest_occluder(const SkRRect& rr) {
+    SkRect r = rr.getBounds();
+
+    const SkVector& ul = rr.radii(SkRRect::kUpperLeft_Corner);
+    const SkVector& ur = rr.radii(SkRRect::kUpperRight_Corner);
+    const SkVector& lr = rr.radii(SkRRect::kLowerRight_Corner);
+    const SkVector& ll = rr.radii(SkRRect::kLowerLeft_Corner);
+
+    SkScalar maxL = SkTMax(ul.fX, ll.fX);
+    SkScalar maxR = SkTMax(ur.fX, lr.fX);
+
+    return SkRect::MakeLTRB(r.fLeft + maxL, r.fTop, r.fRight - maxR, r.fBottom);
+}
+
+static void draw_rrect(SkCanvas* canvas, const SkRRect& rr, const SkRRect& occRR) {
+    const SkScalar kBlurSigma = 5.0f;
+
+    SkRect occRect;
+    SkColor strokeColor;
+
+    {
+        SkRect occRect1 = compute_central_occluder(occRR);
+        SkRect occRect2 = compute_widest_occluder(occRR);
+        SkRect occRect3 = compute_tallest_occluder(occRR);
+
+        SkScalar area1 = occRect1.width() * occRect1.height();
+        SkScalar area2 = occRect2.width() * occRect2.height();
+        SkScalar area3 = occRect3.width() * occRect3.height();
+
+        if (area1 >= area2 && area1 >= area3) {
+            strokeColor = SK_ColorRED;
+            occRect = occRect1;
+        } else if (area2 > area3) {
+            strokeColor = SK_ColorYELLOW;
+            occRect = occRect2;
+        } else {
+            strokeColor = SK_ColorCYAN;
+            occRect = occRect3;
+        }
+    }
+
+    // draw the blur
+    SkPaint paint;
+    paint.setMaskFilter(SkBlurMaskFilter::Make(kNormal_SkBlurStyle, kBlurSigma, occRect));
+    canvas->drawRRect(rr, paint);
+
+    // draw the stroked geometry of the full occluder
+    SkPaint stroke;
+    stroke.setStyle(SkPaint::kStroke_Style);
+    stroke.setColor(SK_ColorBLUE);
+    canvas->drawRRect(occRR, stroke);
+
+    // draw the geometry of the occluding rect
+    stroke.setColor(strokeColor);
+    canvas->drawRect(occRect, stroke);
+}
+
+static void draw_45(SkCanvas* canvas, SkRRect::Corner corner,
+                    SkScalar dist, const SkPoint& center) {
+    SkRRect::Corner left, right;
+    SkVector dir;
+
+    static const SkScalar kSize = 64.0f / SK_ScalarSqrt2;
+
+    switch (corner) {
+    case SkRRect::kUpperLeft_Corner:
+        left = SkRRect::kUpperRight_Corner;
+        right = SkRRect::kLowerLeft_Corner;
+
+        dir.set(-SK_ScalarRoot2Over2, -SK_ScalarRoot2Over2);
+        break;
+    case SkRRect::kUpperRight_Corner:
+        left = SkRRect::kUpperLeft_Corner;
+        right = SkRRect::kLowerRight_Corner;
+        dir.set(SK_ScalarRoot2Over2, -SK_ScalarRoot2Over2);
+        break;
+    case SkRRect::kLowerRight_Corner:
+        left = SkRRect::kLowerLeft_Corner;
+        right = SkRRect::kUpperRight_Corner;
+        dir.set(SK_ScalarRoot2Over2, SK_ScalarRoot2Over2);
+        break;
+    case SkRRect::kLowerLeft_Corner:
+        left = SkRRect::kLowerRight_Corner;
+        right = SkRRect::kUpperLeft_Corner;
+        dir.set(-SK_ScalarRoot2Over2, SK_ScalarRoot2Over2);
+        break;    
+    }
+    
+    SkRect r = SkRect::MakeWH(kSize, kSize);
+    // UL, UR, LR, LL
+    SkVector radii[4] = { { 0.0f, 0.0f }, { 0.0f, 0.0f }, { 0.0f, 0.0f }, { 0.0f, 0.0f } };
+    radii[left] = SkVector::Make(kSize, kSize);
+    radii[right] = SkVector::Make(kSize, kSize);
+    SkRRect rr;
+    rr.setRectRadii(
+            offset_center_to(r.roundOut(), center.fX + dist*dir.fX, center.fY + dist*dir.fY),
+            radii);
+
+    SkRRect occRR;
+    dist -= 10.0f;
+    occRR.setRectRadii(
+            offset_center_to(r.roundOut(), center.fX + dist*dir.fX, center.fY + dist*dir.fY),
+            radii);
+
+    draw_rrect(canvas, rr, occRR);
+}    
+
+static void draw_45_simple(SkCanvas* canvas, const SkVector& v, 
+                           SkScalar dist, const SkPoint& center) {
+    SkIRect r = SkIRect::MakeWH(64, 64);
+    SkRRect rr = SkRRect::MakeRectXY(
+                            offset_center_to(r, center.fX + dist*v.fX, center.fY + dist*v.fY),
+                            8, 8);
+
+    dist -= 10.0f;
+    SkRRect occRR = SkRRect::MakeRectXY(
+                            offset_center_to(r, center.fX + dist*v.fX, center.fY + dist*v.fY), 
+                            8, 8);
+
+    draw_rrect(canvas, rr, occRR);
+}
+
+static void draw_90(SkCanvas* canvas, const SkVector& v, SkScalar dist, const SkPoint& center) {
+    static const int kWidth = 25;
+
+    SkIRect r;
+    if (fabs(v.fX) < fabs(v.fY)) {
+        r = SkIRect::MakeWH(kWidth, 64);
+    } else {
+        r = SkIRect::MakeWH(64, kWidth);
+    }
+    SkRRect rr = SkRRect::MakeOval(
+                            offset_center_to(r, center.fX + dist*v.fX, center.fY + dist*v.fY));
+
+    dist -= 10.0f;
+    SkRRect occRR = SkRRect::MakeOval(
+                            offset_center_to(r, center.fX + dist*v.fX, center.fY + dist*v.fY));
+
+    draw_rrect(canvas, rr, occRR);
+}
+
+static void draw_90_simple(SkCanvas* canvas, const SkVector& v,
+                           SkScalar dist, const SkPoint& center) {
+    static const int kLength = 128;
+    static const int kWidth = 32;
+
+    SkIRect r;
+    if (fabs(v.fX) < fabs(v.fY)) {
+        r = SkIRect::MakeWH(kLength, kWidth);
+    } else {
+        r = SkIRect::MakeWH(kWidth, kLength);
+    }
+    SkRRect rr = SkRRect::MakeRectXY(
+                            offset_center_to(r, center.fX + dist*v.fX, center.fY + dist*v.fY),
+                            8, 8);
+
+    dist -= 10.0f;
+    SkRRect occRR = SkRRect::MakeRectXY(
+                            offset_center_to(r, center.fX + dist*v.fX, center.fY + dist*v.fY),
+                            8, 8);
+
+    draw_rrect(canvas, rr, occRR);
+}
+
+
+static void draw_30_60(SkCanvas* canvas, int foo, const SkVector& v,
+                       SkScalar dist, const SkPoint& center) {
+    SkRRect::Corner left, right;
+
+    static const int kLength = 64;
+    static const int kWidth = 30;
+
+    switch (foo) {
+    case 0:
+        left = SkRRect::kUpperRight_Corner;
+        right = SkRRect::kLowerLeft_Corner;
+        break;
+    case 1:
+        left = SkRRect::kUpperLeft_Corner;
+        right = SkRRect::kLowerRight_Corner;
+        break;
+    case 2:
+        left = SkRRect::kLowerLeft_Corner;
+        right = SkRRect::kUpperRight_Corner;
+        break;
+    case 3:
+        left = SkRRect::kLowerRight_Corner;
+        right = SkRRect::kUpperLeft_Corner;
+        break;    
+    }
+
+    SkIRect r;
+    if (fabs(v.fX) < fabs(v.fY)) {
+        r = SkIRect::MakeWH(kLength, kWidth);
+    } else {
+        r = SkIRect::MakeWH(kWidth, kLength);
+    }
+    // UL, UR, LR, LL
+    SkVector radii[4] = { { 0.0f, 0.0f }, { 0.0f, 0.0f }, { 0.0f, 0.0f }, { 0.0f, 0.0f } };
+    radii[left] = SkVector::Make(SkIntToScalar(kWidth), SkIntToScalar(kWidth));
+    radii[right] = SkVector::Make(SkIntToScalar(kWidth), SkIntToScalar(kWidth));
+    SkRRect rr;
+    rr.setRectRadii(offset_center_to(r, center.fX + dist*v.fX, center.fY + dist*v.fY), radii);
+
+    dist -= 10.0f;
+    SkRRect occRR;
+    occRR.setRectRadii(offset_center_to(r, center.fX + dist*v.fX, center.fY + dist*v.fY), radii);
+    draw_rrect(canvas, rr, occRR);        
+}
+
+namespace skiagm {
+
+class OccludedRRectBlurGM : public GM {
+public:
+    OccludedRRectBlurGM() {
+        this->setBGColor(sk_tool_utils::color_to_565(0xFFCCCCCC));
+    }
+
+protected:
+
+    SkString onShortName() override {
+        return SkString("occludedrrectblur");
+    }
+
+    SkISize onISize() override {
+        return SkISize::Make(kWidth, kHeight);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        const SkPoint center = SkPoint::Make(kWidth/2, kHeight/2);
+
+        // outer-most big RR
+        {
+            SkIRect r = SkIRect::MakeWH(420, 420);
+            SkRRect rr = SkRRect::MakeRectXY(offset_center_to(r, center.fX, center.fY), 64, 64);
+            draw_rrect(canvas, rr, rr);
+
+#if 1
+            // TODO: remove this. Until we actually start skipping the middle draw we need this
+            // to provide contrast
+            SkPaint temp;
+            temp.setColor(sk_tool_utils::color_to_565(0xFFCCCCCC));
+            r.inset(32, 32);
+            canvas->drawRect(offset_center_to(r, center.fX, center.fY), temp);
+#endif
+        }
+
+        // center circle
+        {
+            SkIRect r = SkIRect::MakeWH(32, 32);
+            SkRRect rr = SkRRect::MakeOval(offset_center_to(r, center.fX, center.fY));
+            draw_rrect(canvas, rr, rr);
+        }
+
+        draw_45(canvas, SkRRect::kUpperLeft_Corner, 64, center);
+        draw_45(canvas, SkRRect::kUpperRight_Corner, 64, center);
+        draw_45(canvas, SkRRect::kLowerRight_Corner, 64, center);
+        draw_45(canvas, SkRRect::kLowerLeft_Corner, 64, center);
+
+        draw_90(canvas, SkVector::Make(-1.0f, 0.0f), 64, center);
+        draw_90(canvas, SkVector::Make(0.0f, -1.0f), 64, center);
+        draw_90(canvas, SkVector::Make(1.0f, 0.0f), 64, center);
+        draw_90(canvas, SkVector::Make(0.0f, 1.0f), 64, center);
+
+        static const SkScalar kRoot3Over2 = 0.8660254037844386f;
+
+        draw_30_60(canvas, 3, SkVector::Make(0.5f, kRoot3Over2), 120, center);
+        draw_30_60(canvas, 1, SkVector::Make(kRoot3Over2, 0.5f), 120, center);
+
+        draw_30_60(canvas, 0, SkVector::Make(-0.5f, kRoot3Over2), 120, center);
+        draw_30_60(canvas, 2, SkVector::Make(-kRoot3Over2, 0.5f), 120, center);
+
+        draw_30_60(canvas, 3, SkVector::Make(-0.5f, -kRoot3Over2), 120, center);
+        draw_30_60(canvas, 1, SkVector::Make(-kRoot3Over2, -0.5f), 120, center);
+
+        draw_30_60(canvas, 0, SkVector::Make(0.5f, -kRoot3Over2), 120, center);
+        draw_30_60(canvas, 2, SkVector::Make(kRoot3Over2, -0.5f), 120, center);
+
+        draw_45_simple(canvas, SkVector::Make(-SK_ScalarRoot2Over2, -SK_ScalarRoot2Over2),
+                       190, center);
+        draw_45_simple(canvas, SkVector::Make(SK_ScalarRoot2Over2, -SK_ScalarRoot2Over2),
+                       190, center);
+        draw_45_simple(canvas, SkVector::Make(SK_ScalarRoot2Over2, SK_ScalarRoot2Over2),
+                       190, center);
+        draw_45_simple(canvas, SkVector::Make(-SK_ScalarRoot2Over2, SK_ScalarRoot2Over2),
+                       190, center);
+
+        draw_90_simple(canvas, SkVector::Make(-1.0f, 0.0f), 150, center);
+        draw_90_simple(canvas, SkVector::Make(0.0f, -1.0f), 150, center);
+        draw_90_simple(canvas, SkVector::Make(1.0f, 0.0f), 150, center);
+        draw_90_simple(canvas, SkVector::Make(0.0f, 1.0f), 150, center);
+    }
+
+private:
+    static const int kWidth = 440;
+    static const int kHeight = 440;
+
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM(return new OccludedRRectBlurGM;)
+}