path ops : add support for inverse fill

gm/pathopsinverse.cpp

Index: gm/pathopsinverse.cpp
===================================================================
--- gm/pathopsinverse.cpp	(revision 0)
+++ gm/pathopsinverse.cpp	(revision 0)
@@ -0,0 +1,116 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+#include "SkBitmap.h"
+#include "SkPath.h"
+#include "SkPathOps.h"
+#include "SkRect.h"
+
+namespace skiagm {
+
+class PathOpsInverseGM : public GM {
+public:
+    PathOpsInverseGM() {
+        this->makePaints();

[bsalomon, 2013/04/22 13:13:57]

There's a virtual on GM called "onOnceBeforeDraw". For some reason that I can't
recall we sometimes create the GMs without running them (maybe to get their
names?). onOnceBeforeDraw() is called once per GM but only when the draw will be
called.

+    }
+
+protected:
+    void makePaints() {
+        const unsigned oneColor = 0xFF8080FF;
+        const unsigned twoColor = 0x807F1f1f;
+        SkColor blendColor = blend(oneColor, twoColor);
+        makePaint(&onePaint, oneColor);
+        makePaint(&twoPaint, twoColor);
+        makePaint(&opPaint[kDifference_PathOp], oneColor);
+        makePaint(&opPaint[kIntersect_PathOp], blendColor);
+        makePaint(&opPaint[kUnion_PathOp], 0xFFc0FFc0);
+        makePaint(&opPaint[kReverseDifference_PathOp], twoColor);
+        makePaint(&opPaint[kXOR_PathOp], 0xFFa0FFe0);
+        makePaint(&outlinePaint, 0xFF000000);
+        outlinePaint.setStyle(SkPaint::kStroke_Style);
+    }
+
+    SkColor blend(SkColor one, SkColor two) {
+        SkBitmap temp;
+        temp.setConfig(SkBitmap::kARGB_8888_Config, 1, 1);
+        temp.allocPixels();
+        SkCanvas canvas(temp);
+        canvas.drawColor(one);
+        canvas.drawColor(two);
+        void* pixels = temp.getPixels();
+        return *(SkColor*) pixels;
+    }
+
+    void makePaint(SkPaint* paint, SkColor color) {
+        paint->setAntiAlias(true);
+        paint->setStyle(SkPaint::kFill_Style);
+        paint->setColor(color);
+    }
+
+    virtual SkString onShortName() SK_OVERRIDE {
+        return SkString("pathopsinverse");
+    }
+
+    virtual SkISize onISize() SK_OVERRIDE {
+        return make_isize(1200, 900);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        SkPath one, two;
+        int yPos = 0;
+        for (int oneFill = 0; oneFill <= 1; ++oneFill) {
+            SkPath::FillType oneF = oneFill ? SkPath::kInverseEvenOdd_FillType
+                    : SkPath::kEvenOdd_FillType;
+            for (int twoFill = 0; twoFill <= 1; ++twoFill) {
+                SkPath::FillType twoF = twoFill ? SkPath::kInverseEvenOdd_FillType
+                        : SkPath::kEvenOdd_FillType;
+                one.reset();
+                one.setFillType(oneF);
+                one.addRect(10, 10, 70, 70);
+                two.reset();
+                two.setFillType(twoF);
+                two.addRect(40, 40, 100, 100);
+                canvas->save();
+                canvas->translate(0, SkIntToScalar(yPos));
+                canvas->clipRect(SkRect::MakeWH(110, 110), SkRegion::kIntersect_Op, true);
+                canvas->drawPath(one, onePaint);
+                canvas->drawPath(one, outlinePaint);
+                canvas->drawPath(two, twoPaint);
+                canvas->drawPath(two, outlinePaint);
+                canvas->restore();
+                int xPos = 150;
+                for (int op = kDifference_PathOp; op <= kReverseDifference_PathOp; ++op) {
+                    SkPath result;
+                    Op(one, two, (SkPathOp) op, &result);
+                    canvas->save();
+                    canvas->translate(SkIntToScalar(xPos), SkIntToScalar(yPos));
+                    canvas->clipRect(SkRect::MakeWH(110, 110), SkRegion::kIntersect_Op, true);
+                    canvas->drawPath(result, opPaint[op]);
+                    canvas->drawPath(result, outlinePaint);
+                    canvas->restore();
+                    xPos += 150;
+                }
+                yPos += 150;
+            }
+        }
+    }
+
+private:
+    SkPaint onePaint;

[bsalomon, 2013/04/22 13:13:57]

fOnePaint, etc?

+    SkPaint twoPaint;
+    SkPaint outlinePaint;
+    SkPaint opPaint[kReverseDifference_PathOp - kDifference_PathOp + 1];
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static GM* MyFactory(void*) { return new PathOpsInverseGM; }
+static GMRegistry reg(MyFactory);
+
+}