add explicit clamping after chopping w/ t to ensure we're in the clip

git-svn-id: http://skia.googlecode.com/svn/trunk@430 2bbb7eff-a529-9590-31e7-b0007b416f81

diff --git a/samplecode/SampleLineClipper.cpp b/samplecode/SampleLineClipper.cpp
index ccf4281..9573810 100644 (file)
--- a/samplecode/SampleLineClipper.cpp
+++ b/samplecode/SampleLineClipper.cpp
@@ -34,6 +34,23 @@ static void check_clipper(int count, const SkPoint pts[], const SkRect& clip) {
         SkASSERT(pts[i].fY >= clip.fTop);
         SkASSERT(pts[i].fY <= clip.fBottom);
     }
+
+    if (count > 1) {
+        // now check that we're monotonic in Y
+        if (pts[0].fY > pts[count - 1].fY) {
+            for (int i = 1; i < count; i++) {
+                SkASSERT(pts[i - 1].fY >= pts[i].fY);
+            }
+        } else if (pts[0].fY < pts[count - 1].fY) {
+            for (int i = 1; i < count; i++) {
+                SkASSERT(pts[i - 1].fY <= pts[i].fY);
+            }
+        } else {
+            for (int i = 1; i < count; i++) {
+                SkASSERT(pts[i - 1].fY == pts[i].fY);
+            }
+        }
+    }
 }
 
 static void line_clipper(const SkPoint src[], const SkRect& clip,
@@ -59,9 +76,11 @@ static void quad_clipper(const SkPoint src[], const SkRect& clip,
         while ((verb = clipper.next(pts)) != SkPath::kDone_Verb) {
             switch (verb) {
                 case SkPath::kLine_Verb:
+                    check_clipper(2, pts, clip);
                     canvas->drawPoints(SkCanvas::kLines_PointMode, 2, pts, p0);
                     break;
                 case SkPath::kQuad_Verb:
+                    check_clipper(3, pts, clip);
                     drawQuad(canvas, pts, p0);
                     break;
                 default:
@@ -84,6 +103,7 @@ enum {
 };
 
 class LineClipperView : public SkView {
+    int         fCounter;
     int         fProcIndex;
     SkRect      fClip;
     SkRandom    fRand;
@@ -94,16 +114,18 @@ class LineClipperView : public SkView {
             fPts[i].set(fRand.nextUScalar1() * 640,
                         fRand.nextUScalar1() * 480);
         }
+        fCounter += 1;
     }
 
 public:
        LineClipperView() {
+        fProcIndex = 1;
+        fCounter = 0;
+
         int x = (640 - W)/2;
         int y = (480 - H)/2;
         fClip.set(x, y, x + W, y + H);
         this->randPts();
-        
-        fProcIndex = 1;
     }
     
 protected:

diff --git a/src/core/SkQuadClipper.cpp b/src/core/SkQuadClipper.cpp
index 9d76298..5abbe8e 100644 (file)
--- a/src/core/SkQuadClipper.cpp
+++ b/src/core/SkQuadClipper.cpp
@@ -17,6 +17,22 @@
 #include "SkQuadClipper.h"
 #include "SkGeometry.h"
 
+static bool quick_reject(const SkRect& bounds, const SkRect& clip) {
+    return bounds.fTop >= clip.fBottom || bounds.fBottom <= clip.fTop;
+}
+
+static inline void clamp_le(SkScalar& value, SkScalar max) {
+    if (value > max) {
+        value = max;
+    }
+}
+
+static inline void clamp_ge(SkScalar& value, SkScalar min) {
+    if (value < min) {
+        value = min;
+    }
+}
+
 static bool chopMonoQuadAt(SkScalar c0, SkScalar c1, SkScalar c2,
                            SkScalar target, SkScalar* t) {
     /* Solve F(t) = y where F(t) := [0](1-t)^2 + 2[1]t(1-t) + [2]t^2
@@ -132,6 +148,8 @@ static void chop_quad_in_Y(SkPoint pts[3], const SkRect& clip) {
         if (chopMonoQuadAtY(pts, clip.fTop, &t)) {
             // take the 2nd chopped quad
             SkChopQuadAt(pts, tmp, t);
+            clamp_ge(tmp[2].fY, clip.fTop);
+            clamp_ge(tmp[3].fY, clip.fTop);
             pts[0] = tmp[2];
             pts[1] = tmp[3];
         } else {
@@ -149,6 +167,8 @@ static void chop_quad_in_Y(SkPoint pts[3], const SkRect& clip) {
     if (pts[2].fY > clip.fBottom) {
         if (chopMonoQuadAtY(pts, clip.fBottom, &t)) {
             SkChopQuadAt(pts, tmp, t);
+            clamp_le(tmp[1].fY, clip.fBottom);
+            clamp_le(tmp[2].fY, clip.fBottom);
             pts[1] = tmp[1];
             pts[2] = tmp[2];
         } else {
@@ -223,6 +243,8 @@ void SkQuadClipper2::clipMonoQuad(const SkPoint srcPts[3], const SkRect& clip) {
         if (chopMonoQuadAtX(pts, clip.fLeft, &t)) {
             SkChopQuadAt(pts, tmp, t);
             this->appendVLine(clip.fLeft, tmp[0].fY, tmp[2].fY, reverse);
+            clamp_ge(tmp[2].fX, clip.fLeft);
+            clamp_ge(tmp[3].fX, clip.fLeft);
             pts[0] = tmp[2];
             pts[1] = tmp[3];
         } else {
@@ -236,6 +258,8 @@ void SkQuadClipper2::clipMonoQuad(const SkPoint srcPts[3], const SkRect& clip) {
     if (pts[2].fX > clip.fRight) {
         if (chopMonoQuadAtX(pts, clip.fRight, &t)) {
             SkChopQuadAt(pts, tmp, t);
+            clamp_le(tmp[1].fX, clip.fRight);
+            clamp_le(tmp[2].fX, clip.fRight);
             this->appendQuad(tmp, reverse);
             this->appendVLine(clip.fRight, tmp[2].fY, tmp[4].fY, reverse);
         } else {
@@ -248,21 +272,14 @@ void SkQuadClipper2::clipMonoQuad(const SkPoint srcPts[3], const SkRect& clip) {
     }
 }
 
-static bool quick_reject_quad(const SkPoint srcPts[3], const SkRect& clip) {
-    return (srcPts[0].fY <= clip.fTop &&
-            srcPts[1].fY <= clip.fTop &&
-            srcPts[2].fY <= clip.fTop)
-            ||
-           (srcPts[0].fY >= clip.fBottom &&
-            srcPts[1].fY >= clip.fBottom &&
-            srcPts[2].fY >= clip.fBottom);
-}
-
 bool SkQuadClipper2::clipQuad(const SkPoint srcPts[3], const SkRect& clip) {
     fCurrPoint = fPoints;
     fCurrVerb = fVerbs;
 
-    if (!quick_reject_quad(srcPts, clip)) {
+    SkRect  bounds;
+    bounds.set(srcPts, 3);
+    
+    if (!quick_reject(bounds, clip)) {
         SkPoint monoY[5];
         int countY = SkChopQuadAtYExtrema(srcPts, monoY);
         for (int y = 0; y <= countY; y++) {
@@ -283,6 +300,38 @@ bool SkQuadClipper2::clipQuad(const SkPoint srcPts[3], const SkRect& clip) {
     return SkPath::kDone_Verb != fVerbs[0];
 }
 
+///////////////////////////////////////////////////////////////////////////////
+
+bool SkQuadClipper2::clipCubic(const SkPoint srcPts[4], const SkRect& clip) {
+    fCurrPoint = fPoints;
+    fCurrVerb = fVerbs;
+    
+    SkRect  bounds;
+    bounds.set(srcPts, 4);
+    
+    if (!quick_reject(bounds, clip)) {
+        SkPoint monoY[5];
+        int countY = SkChopQuadAtYExtrema(srcPts, monoY);
+        for (int y = 0; y <= countY; y++) {
+            SkPoint monoX[5];
+            int countX = SkChopQuadAtXExtrema(&monoY[y * 2], monoX);
+            SkASSERT(countY + countX <= 3);
+            for (int x = 0; x <= countX; x++) {
+                this->clipMonoQuad(&monoX[x * 2], clip);
+                SkASSERT(fCurrVerb - fVerbs < kMaxVerbs);
+                SkASSERT(fCurrPoint - fPoints <= kMaxPoints);
+            }
+        }
+    }
+    
+    *fCurrVerb = SkPath::kDone_Verb;
+    fCurrPoint = fPoints;
+    fCurrVerb = fVerbs;
+    return SkPath::kDone_Verb != fVerbs[0];
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 void SkQuadClipper2::appendVLine(SkScalar x, SkScalar y0, SkScalar y1,
                                  bool reverse) {
     *fCurrVerb++ = SkPath::kLine_Verb;
@@ -297,7 +346,7 @@ void SkQuadClipper2::appendVLine(SkScalar x, SkScalar y0, SkScalar y1,
 
 void SkQuadClipper2::appendQuad(const SkPoint pts[3], bool reverse) {
     *fCurrVerb++ = SkPath::kQuad_Verb;
-
+    
     if (reverse) {
         fCurrPoint[0] = pts[2];
         fCurrPoint[2] = pts[0];
@@ -309,6 +358,19 @@ void SkQuadClipper2::appendQuad(const SkPoint pts[3], bool reverse) {
     fCurrPoint += 3;
 }
 
+void SkQuadClipper2::appendCubic(const SkPoint pts[4], bool reverse) {
+    *fCurrVerb++ = SkPath::kCubic_Verb;
+    
+    if (reverse) {
+        for (int i = 0; i < 4; i++) {
+            fCurrPoint[i] = pts[3 - i];
+        }
+    } else {
+        memcpy(fCurrPoint, pts, 4 * sizeof(SkPoint));
+    }
+    fCurrPoint += 4;
+}
+
 SkPath::Verb SkQuadClipper2::next(SkPoint pts[]) {
     SkPath::Verb verb = *fCurrVerb;
 
@@ -323,6 +385,11 @@ SkPath::Verb SkQuadClipper2::next(SkPoint pts[]) {
             fCurrPoint += 3;
             fCurrVerb += 1;
             break;
+        case SkPath::kCubic_Verb:
+            memcpy(pts, fCurrPoint, 4 * sizeof(SkPoint));
+            fCurrPoint += 4;
+            fCurrVerb += 1;
+            break;
         case SkPath::kDone_Verb:
             break;
         default:

diff --git a/src/core/SkQuadClipper.h b/src/core/SkQuadClipper.h
index 9f9a6d5..4f38b5d 100644 (file)
--- a/src/core/SkQuadClipper.h
+++ b/src/core/SkQuadClipper.h
@@ -44,6 +44,7 @@ private:
 class SkQuadClipper2 {
 public:
     bool clipQuad(const SkPoint pts[3], const SkRect& clip);
+    bool clipCubic(const SkPoint pts[4], const SkRect& clip);
 
     SkPath::Verb next(SkPoint pts[]);
     
@@ -61,6 +62,7 @@ private:
     void clipMonoQuad(const SkPoint srcPts[3], const SkRect& clip);
     void appendVLine(SkScalar x, SkScalar y0, SkScalar y1, bool reverse);
     void appendQuad(const SkPoint pts[3], bool reverse);
+    void appendCubic(const SkPoint pts[4], bool reverse);
 };
 
 #endif