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      1 /*
      2  * Copyright 2011 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #include "Sample.h"
      9 #include "SkAnimTimer.h"
     10 #include "SkCanvas.h"
     11 #include "SkFont.h"
     12 #include "SkGradientShader.h"
     13 #include "SkString.h"
     14 
     15 static void draw_gradient2(SkCanvas* canvas, const SkRect& rect, SkScalar delta) {
     16     SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorMAGENTA };
     17     SkScalar pos[] = { 0, 0.25f, 0.75f, SK_Scalar1 };
     18 
     19     SkScalar l = rect.fLeft;
     20     SkScalar t = rect.fTop;
     21     SkScalar w = rect.width();
     22     SkScalar h = rect.height();
     23 
     24     SkASSERT(0 == SkScalarMod(w, SK_Scalar1 * 5));
     25 
     26     SkPoint c0 = { l + 2 * w / 5 + delta, t + h / 2 };
     27     SkPoint c1 = { l + 3 * w / 5, t + h / 2 };
     28     SkScalar r0 = w / 5;
     29     SkScalar r1 = 2 * w / 5;
     30     SkPaint paint;
     31     paint.setShader(SkGradientShader::MakeTwoPointConical(c0, r0, c1, r1, colors,
     32                                                           pos, SK_ARRAY_COUNT(pos),
     33                                                           SkShader::kClamp_TileMode));
     34     canvas->drawRect(rect, paint);
     35 }
     36 
     37 
     38 class DegenerateTwoPtRadialsView : public Sample {
     39 public:
     40     DegenerateTwoPtRadialsView() {
     41         fTime = 0;
     42         this->setBGColor(0xFFDDDDDD);
     43     }
     44 
     45 protected:
     46     bool onQuery(Sample::Event* evt) override {
     47         if (Sample::TitleQ(*evt)) {
     48             Sample::TitleR(evt, "DegenerateTwoPtRadials");
     49             return true;
     50         }
     51         return this->INHERITED::onQuery(evt);
     52     }
     53 
     54     void onDrawContent(SkCanvas* canvas) override {
     55         SkScalar delta = fTime / 15.f;
     56         int intPart = SkScalarFloorToInt(delta);
     57         delta = delta - SK_Scalar1 * intPart;
     58         if (intPart % 2) {
     59             delta = SK_Scalar1 - delta;
     60         }
     61         delta -= SK_ScalarHalf;
     62         static const int DELTA_SCALE = 500;
     63         delta /= DELTA_SCALE;
     64 
     65         SkScalar w = SK_Scalar1 * 500;
     66         SkScalar h = SK_Scalar1 * 500;
     67         SkScalar l = SK_Scalar1 * 100;
     68         SkScalar t = SK_Scalar1 * 100;
     69         draw_gradient2(canvas, SkRect::MakeXYWH(l, t, w, h), delta);
     70         SkString txt;
     71         txt.appendf("gap at \"tangent\" pt = %f", SkScalarToFloat(delta));
     72         canvas->drawString(txt, l + w / 2 + w * DELTA_SCALE * delta, t + h + SK_Scalar1 * 10,
     73                            SkFont(), SkPaint());
     74     }
     75 
     76     bool onAnimate(const SkAnimTimer& timer) override {
     77         fTime = SkDoubleToScalar(timer.secs() / 15);
     78         return true;
     79     }
     80 
     81 private:
     82     SkScalar           fTime;
     83     typedef Sample INHERITED;
     84 };
     85 
     86 //////////////////////////////////////////////////////////////////////////////
     87 
     88 DEF_SAMPLE( return new DegenerateTwoPtRadialsView(); )
     89