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 #include "SampleCode.h" 8 #include "SkView.h" 9 #include "SkCanvas.h" 10 #include "SkGradientShader.h" 11 #include "SkGraphics.h" 12 #include "SkPath.h" 13 #include "SkRegion.h" 14 #include "SkShader.h" 15 #include "SkUtils.h" 16 #include "SkColorPriv.h" 17 #include "SkColorFilter.h" 18 #include "SkTime.h" 19 #include "SkTypeface.h" 20 21 class PathClipView : public SampleView { 22 public: 23 SkRect fOval; 24 SkPoint fCenter; 25 26 PathClipView() : fOval(SkRect::MakeWH(200, 50)), fCenter(SkPoint::Make(250, 250)) {} 27 28 protected: 29 bool onQuery(SkEvent* evt) override { 30 if (SampleCode::TitleQ(*evt)) { 31 SampleCode::TitleR(evt, "PathClip"); 32 return true; 33 } 34 return this->INHERITED::onQuery(evt); 35 } 36 37 void onDrawContent(SkCanvas* canvas) override { 38 const SkRect oval = fOval.makeOffset(fCenter.fX - fOval.centerX(), 39 fCenter.fY - fOval.centerY()); 40 41 SkPaint p; 42 p.setAntiAlias(true); 43 44 p.setStyle(SkPaint::kStroke_Style); 45 canvas->drawOval(oval, p); 46 47 const SkRect r = SkRect::MakeLTRB(200, 200, 300, 300); 48 canvas->clipRect(r); 49 50 p.setStyle(SkPaint::kFill_Style); 51 p.setColor(SK_ColorRED); 52 canvas->drawRect(r, p); 53 54 p.setColor(0x800000FF); 55 canvas->drawOval(oval, p); 56 } 57 58 SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned) override { 59 return new Click(this); 60 } 61 62 bool onClick(Click* click) override { 63 fCenter.set(click->fCurr.fX, click->fCurr.fY); 64 this->inval(nullptr); 65 return false; 66 } 67 68 private: 69 typedef SampleView INHERITED; 70 }; 71 DEF_SAMPLE( return new PathClipView; ) 72 73 ////////////////////////////////////////////////////////////////////////////// 74 75 static int clip_line(const SkRect& bounds, SkPoint p0, SkPoint p1, SkPoint edges[]) { 76 SkPoint* edgesStart = edges; 77 78 if (p0.fY == p1.fY) { 79 return 0; 80 } 81 82 if (p0.fY > p1.fY) { 83 SkTSwap(p0, p1); 84 } 85 // now we're monotonic in Y: p0 <= p1 86 if (p1.fY <= bounds.top() || p0.fY >= bounds.bottom()) { 87 return 0; 88 } 89 90 double dxdy = (double)(p1.fX - p0.fX) / (p1.fY - p0.fY); 91 if (p0.fY < bounds.top()) { 92 p0.fX = SkDoubleToScalar(p0.fX + dxdy * (bounds.top() - p0.fY)); 93 p0.fY = bounds.top(); 94 } 95 if (p1.fY > bounds.bottom()) { 96 p1.fX = SkDoubleToScalar(p1.fX + dxdy * (bounds.bottom() - p1.fY)); 97 p1.fY = bounds.bottom(); 98 } 99 100 // Now p0...p1 is strictly inside bounds vertically, so we just need to clip horizontally 101 102 if (p0.fX > p1.fX) { 103 SkTSwap(p0, p1); 104 } 105 // now we're left-to-right: p0 .. p1 106 107 if (p1.fX <= bounds.left()) { // entirely to the left 108 p0.fX = p1.fX = bounds.left(); 109 *edges++ = p0; 110 *edges++ = p1; 111 return 2; 112 } 113 if (p0.fX >= bounds.right()) { // entirely to the right 114 p0.fX = p1.fX = bounds.right(); 115 *edges++ = p0; 116 *edges++ = p1; 117 return 2; 118 } 119 120 if (p0.fX < bounds.left()) { 121 float y = SkDoubleToScalar(p0.fY + (bounds.left() - p0.fX) / dxdy); 122 *edges++ = SkPoint::Make(bounds.left(), p0.fY); 123 *edges++ = SkPoint::Make(bounds.left(), y); 124 p0.set(bounds.left(), y); 125 } 126 if (p1.fX > bounds.right()) { 127 float y = SkDoubleToScalar(p0.fY + (bounds.right() - p0.fX) / dxdy); 128 *edges++ = p0; 129 *edges++ = SkPoint::Make(bounds.right(), y); 130 *edges++ = SkPoint::Make(bounds.right(), p1.fY); 131 } else { 132 *edges++ = p0; 133 *edges++ = p1; 134 } 135 return SkToInt(edges - edgesStart); 136 } 137 138 static void draw_clipped_line(SkCanvas* canvas, const SkRect& bounds, 139 SkPoint p0, SkPoint p1, const SkPaint& paint) { 140 SkPoint verts[6]; 141 int count = clip_line(bounds, p0, p1, verts); 142 143 SkPath path; 144 path.addPoly(verts, count, false); 145 canvas->drawPath(path, paint); 146 } 147 148 // Demonstrate edge-clipping that is used in the scan converter 149 // 150 class EdgeClipView : public SampleView { 151 enum { 152 N = 3 153 }; 154 public: 155 SkPoint fPoly[N]; 156 SkRect fClip; 157 SkColor fEdgeColor[N]; 158 159 EdgeClipView() : fClip(SkRect::MakeLTRB(150, 150, 550, 450)) { 160 fPoly[0].set(300, 40); 161 fPoly[1].set(550, 250); 162 fPoly[2].set(40, 450); 163 164 fEdgeColor[0] = 0xFFFF0000; 165 fEdgeColor[1] = 0xFF00FF00; 166 fEdgeColor[2] = 0xFF0000FF; 167 } 168 169 protected: 170 bool onQuery(SkEvent* evt) override { 171 if (SampleCode::TitleQ(*evt)) { 172 SampleCode::TitleR(evt, "EdgeClip"); 173 return true; 174 } 175 return this->INHERITED::onQuery(evt); 176 } 177 178 static SkScalar snap(SkScalar x) { 179 return SkScalarRoundToScalar(x * 0.5f) * 2; 180 } 181 static SkPoint snap(const SkPoint& pt) { 182 return SkPoint::Make(snap(pt.x()), snap(pt.y())); 183 } 184 static void snap(SkPoint dst[], const SkPoint src[], int count) { 185 for (int i = 0; i < count; ++i) { 186 dst[i] = snap(src[i]); 187 } 188 } 189 190 void onDrawContent(SkCanvas* canvas) override { 191 SkPath path; 192 path.addPoly(fPoly, N, true); 193 194 // Draw the full triangle, stroked and filled 195 SkPaint p; 196 p.setAntiAlias(true); 197 p.setColor(0xFFE0E0E0); 198 canvas->drawPath(path, p); 199 p.setStyle(SkPaint::kStroke_Style); 200 p.setStrokeWidth(2); 201 for (int i = 0; i < N; ++i) { 202 const int j = (i + 1) % N; 203 p.setColor(fEdgeColor[i]); 204 p.setAlpha(0x88); 205 canvas->drawLine(fPoly[i], fPoly[j], p); 206 } 207 p.setStyle(SkPaint::kFill_Style); 208 209 // Draw the clip itself 210 p.setColor(0xFF8888CC); 211 canvas->drawRect(fClip, p); 212 213 // Draw the filled triangle through the clip 214 p.setColor(0xFF88CC88); 215 canvas->save(); 216 canvas->clipRect(fClip); 217 canvas->drawPath(path, p); 218 canvas->restore(); 219 220 p.setStyle(SkPaint::kStroke_Style); 221 p.setStrokeWidth(6); 222 223 // Draw each of the "Edges" that survived the clipping 224 // We use a layer, so we can PLUS the different edge-colors, showing where two edges 225 // canceled each other out. 226 canvas->saveLayer(nullptr, nullptr); 227 p.setBlendMode(SkBlendMode::kPlus); 228 for (int i = 0; i < N; ++i) { 229 const int j = (i + 1) % N; 230 p.setColor(fEdgeColor[i]); 231 draw_clipped_line(canvas, fClip, fPoly[i], fPoly[j], p); 232 } 233 canvas->restore(); 234 } 235 236 class MyClick : public Click { 237 public: 238 MyClick(SkView* view) : Click(view) {} 239 virtual void handleMove() = 0; 240 }; 241 242 class VertClick : public MyClick { 243 SkPoint* fPt; 244 public: 245 VertClick(SkView* view, SkPoint* pt) : MyClick(view), fPt(pt) {} 246 void handleMove() override { *fPt = snap(fCurr); } 247 }; 248 249 class DragRectClick : public MyClick { 250 SkRect* fRect; 251 public: 252 DragRectClick(SkView* view, SkRect* rect) : MyClick(view), fRect(rect) {} 253 void handleMove() override { fRect->offset(fCurr.x() - fPrev.x(), fCurr.y() - fPrev.y()); } 254 }; 255 256 class DragPolyClick : public MyClick { 257 SkPoint fSrc[100]; 258 SkPoint* fPoly; 259 int fCount; 260 public: 261 DragPolyClick(SkView* view, SkPoint poly[], int count) 262 : MyClick(view), fPoly(poly), fCount(count) 263 { 264 SkASSERT((size_t)count <= SK_ARRAY_COUNT(fSrc)); 265 memcpy(fSrc, poly, count * sizeof(SkPoint)); 266 } 267 void handleMove() override { 268 const SkScalar dx = fCurr.x() - fOrig.x(); 269 const SkScalar dy = fCurr.y() - fOrig.y(); 270 for (int i = 0; i < fCount; ++i) { 271 fPoly[i].set(snap(fSrc[i].x() + dx), snap(fSrc[i].y() + dy)); 272 } 273 } 274 }; 275 276 class DoNothingClick : public MyClick { 277 public: 278 DoNothingClick(SkView* view) : MyClick(view) {} 279 void handleMove() override {} 280 }; 281 282 static bool hit_test(const SkPoint& pt, SkScalar x, SkScalar y) { 283 const SkScalar rad = 8; 284 const SkScalar dx = pt.x() - x; 285 const SkScalar dy = pt.y() - y; 286 return dx*dx + dy*dy <= rad*rad; 287 } 288 289 SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned) override { 290 for (int i = 0; i < N; ++i) { 291 if (hit_test(fPoly[i], x, y)) { 292 return new VertClick(this, &fPoly[i]); 293 } 294 } 295 296 SkPath path; 297 path.addPoly(fPoly, N, true); 298 if (path.contains(x, y)) { 299 return new DragPolyClick(this, fPoly, N); 300 } 301 302 if (fClip.intersects(SkRect::MakeLTRB(x - 1, y - 1, x + 1, y + 1))) { 303 return new DragRectClick(this, &fClip); 304 } 305 return new DoNothingClick(this); 306 } 307 308 bool onClick(Click* click) override { 309 ((MyClick*)click)->handleMove(); 310 this->inval(nullptr); 311 return false; 312 } 313 314 private: 315 typedef SampleView INHERITED; 316 }; 317 DEF_SAMPLE( return new EdgeClipView; ) 318