add check/hack to avoid drawing outside of the clip for hairlines

git-svn-id: http://skia.googlecode.com/svn/trunk@134 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 157 insertions, 0 deletions

diff --git a/samplecode/SampleHairline.cpp b/samplecode/SampleHairline.cpp
new file mode 100644
index 0000000000..9763d0f1dd
--- /dev/null
+++ b/samplecode/SampleHairline.cpp
@@ -0,0 +1,157 @@
+#include "SampleCode.h"
+#include "SkView.h"
+#include "SkCanvas.h"
+#include "Sk64.h"
+#include "SkCornerPathEffect.h"
+#include "SkGradientShader.h"
+#include "SkGraphics.h"
+#include "SkImageDecoder.h"
+#include "SkKernel33MaskFilter.h"
+#include "SkPath.h"
+#include "SkRandom.h"
+#include "SkRegion.h"
+#include "SkShader.h"
+#include "SkUtils.h"
+#include "SkColorPriv.h"
+#include "SkColorFilter.h"
+#include "SkTime.h"
+#include "SkTypeface.h"
+#include "SkXfermode.h"
+
+#include "SkStream.h"
+#include "SkXMLParser.h"
+#include "SkColorPriv.h"
+#include "SkImageDecoder.h"
+
+static SkRandom gRand;
+
+static void test_chromium_9005() {
+    SkBitmap bm;
+    bm.setConfig(SkBitmap::kARGB_8888_Config, 800, 600);
+    bm.allocPixels();
+
+    SkCanvas canvas(bm);
+
+    SkPoint pt0 = { SkFloatToScalar(799.33374f), SkFloatToScalar(1.2360189f) };
+    SkPoint pt1 = { SkFloatToScalar(808.49969f), SkFloatToScalar(-7.4338055f) };
+    
+    SkPaint paint;
+    paint.setAntiAlias(true);
+    canvas.drawLine(pt0.fX, pt0.fY, pt1.fX, pt1.fY, paint);
+}
+
+static void generate_pts(SkPoint pts[], int count, int w, int h) {
+    for (int i = 0; i < count; i++) {
+        pts[i].set(gRand.nextUScalar1() * 3 * w - SkIntToScalar(w),
+                   gRand.nextUScalar1() * 3 * h - SkIntToScalar(h));
+    }
+}
+
+static bool check_zeros(const SkPMColor pixels[], int count, int skip) {
+    for (int i = 0; i < count; i++) {
+        if (*pixels) {
+            return false;
+        }
+        pixels += skip;
+    }
+    return true;
+}
+
+static bool check_bitmap_margin(const SkBitmap& bm, int margin) {
+    size_t rb = bm.rowBytes();
+    for (int i = 0; i < margin; i++) {
+        if (!check_zeros(bm.getAddr32(0, i), bm.width(), 1)) {
+            return false;
+        }
+        int bottom = bm.height() - i - 1;
+        if (!check_zeros(bm.getAddr32(0, bottom), bm.width(), 1)) {
+            return false;
+        }
+        // left column
+        if (!check_zeros(bm.getAddr32(i, 0), bm.height(), rb >> 2)) {
+            return false;
+        }
+        int right = bm.width() - margin + i;
+        if (!check_zeros(bm.getAddr32(right, 0), bm.height(), rb >> 2)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+#define WIDTH   80
+#define HEIGHT  60
+#define MARGIN  4
+
+class HairlineView : public SkView {
+public:
+	HairlineView() {}
+    
+protected:
+    // overrides from SkEventSink
+    virtual bool onQuery(SkEvent* evt) {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "Hairines");
+            return true;
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+    
+    void show_bitmaps(SkCanvas* canvas, const SkBitmap& b0, const SkBitmap& b1,
+                      const SkIRect& inset) {
+        canvas->drawBitmap(b0, 0, 0, NULL);
+        canvas->drawBitmap(b1, SkIntToScalar(b0.width()), 0, NULL);
+    }
+
+    void drawBG(SkCanvas* canvas) {
+//        canvas->drawColor(0xFFDDDDDD);
+        canvas->drawColor(SK_ColorWHITE);
+   //     canvas->drawColor(SK_ColorBLACK);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) {
+        this->drawBG(canvas);
+        
+        if (true) {
+            test_chromium_9005();
+        }
+        
+        SkBitmap bm, bm2;
+        bm.setConfig(SkBitmap::kARGB_8888_Config,
+                     WIDTH + MARGIN*2,
+                     HEIGHT + MARGIN*2);
+        bm.allocPixels();
+        // this will erase our margin, which we want to always stay 0
+        bm.eraseColor(0);
+
+        bm2.setConfig(SkBitmap::kARGB_8888_Config, WIDTH, HEIGHT,
+                      bm.rowBytes());
+        bm2.setPixels(bm.getAddr32(MARGIN, MARGIN));
+        
+        SkCanvas c2(bm2);
+        SkPaint paint;
+        paint.setAntiAlias(true);
+        for (int i = 0; i < 10000; i++) {
+            SkPoint pts[2];
+            generate_pts(pts, 2, WIDTH, HEIGHT);
+            bm2.eraseColor(0);
+            c2.drawLine(pts[0].fX, pts[0].fY, pts[1].fX, pts[1].fY, paint);
+            if (!check_bitmap_margin(bm, MARGIN)) {
+                SkDebugf("---- hairline failure (%g %g) (%g %g)\n",
+                         pts[0].fX, pts[0].fY, pts[1].fX, pts[1].fY);
+                break;
+            }
+        }
+        
+        this->inval(NULL);
+    }
+
+private:
+    typedef SkView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static SkView* MyFactory() { return new HairlineView; }
+static SkViewRegister reg(MyFactory);
+