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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 "SampleCode.h"
      9 #include "SkView.h"
     10 #include "SkCanvas.h"
     11 #include "SkGradientShader.h"
     12 #include "SkString.h"
     13 
     14 static void draw_gradient2(SkCanvas* canvas, const SkRect& rect, SkScalar delta) {
     15     SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorMAGENTA };
     16     SkScalar pos[] = { 0, 0.25f, 0.75f, SK_Scalar1 };
     17 
     18     SkScalar l = rect.fLeft;
     19     SkScalar t = rect.fTop;
     20     SkScalar w = rect.width();
     21     SkScalar h = rect.height();
     22 
     23     SkASSERT(0 == SkScalarMod(w, SK_Scalar1 * 5));
     24 
     25     SkPoint c0 = { l + 2 * w / 5 + delta, t + h / 2 };
     26     SkPoint c1 = { l + 3 * w / 5, t + h / 2 };
     27     SkScalar r0 = w / 5;
     28     SkScalar r1 = 2 * w / 5;
     29     SkShader* s = SkGradientShader::CreateTwoPointConical(c0, r0, c1, r1, colors,
     30                                                          pos, SK_ARRAY_COUNT(pos),
     31                                                          SkShader::kClamp_TileMode);
     32     SkPaint paint;
     33     paint.setShader(s)->unref();
     34 
     35     canvas->drawRect(rect, paint);
     36 }
     37 
     38 
     39 class DegenerateTwoPtRadialsView : public SampleView {
     40 
     41 public:
     42     DegenerateTwoPtRadialsView() {
     43         fTime = 0;
     44         this->setBGColor(0xFFDDDDDD);
     45     }
     46 
     47 protected:
     48     // overrides from SkEventSink
     49     virtual bool onQuery(SkEvent* evt) {
     50         if (SampleCode::TitleQ(*evt)) {
     51             SampleCode::TitleR(evt, "DegenerateTwoPtRadials");
     52             return true;
     53         }
     54         return this->INHERITED::onQuery(evt);
     55     }
     56 
     57     virtual void onDrawContent(SkCanvas* canvas) {
     58         fTime += SampleCode::GetAnimSecondsDelta();
     59         SkScalar delta = fTime / 15.f;
     60         int intPart = SkScalarFloorToInt(delta);
     61         delta = delta - SK_Scalar1 * intPart;
     62         if (intPart % 2) {
     63             delta = SK_Scalar1 - delta;
     64         }
     65         delta -= SK_ScalarHalf;
     66         static const int DELTA_SCALE = 500;
     67         delta /= DELTA_SCALE;
     68 
     69         SkScalar w = SK_Scalar1 * 500;
     70         SkScalar h = SK_Scalar1 * 500;
     71         SkScalar l = SK_Scalar1 * 100;
     72         SkScalar t = SK_Scalar1 * 100;
     73         draw_gradient2(canvas, SkRect::MakeXYWH(l, t, w, h), delta);
     74         SkString txt;
     75         txt.appendf("gap at \"tangent\" pt = %f", SkScalarToFloat(delta));
     76         SkPaint paint;
     77         paint.setAntiAlias(true);
     78         paint.setColor(SK_ColorBLACK);
     79         canvas->drawText(txt.c_str(), txt.size(), l + w/2 + w*DELTA_SCALE*delta, t + h + SK_Scalar1 * 10, paint);
     80         this->inval(NULL);
     81     }
     82 
     83 private:
     84     SkScalar           fTime;
     85     typedef SampleView INHERITED;
     86 };
     87 
     88 //////////////////////////////////////////////////////////////////////////////
     89 
     90 static SkView* MyFactory() { return new DegenerateTwoPtRadialsView; }
     91 static SkViewRegister reg(MyFactory);
     92