add asScalars() to document when we want to treat SkPoint or SkRect as an array

of SkScalars.
Review URL: https://codereview.chromium.org/12530010

git-svn-id: http://skia.googlecode.com/svn/trunk@8041 2bbb7eff-a529-9590-31e7-b0007b416f81

include/core/SkPoint.h

@@ -504,6 +504,11 @@ struct SK_API SkPoint {
             fY = -tmp;
         }
     }
+
+    /**
+     *  cast-safe way to treat the point as an array of (2) SkScalars.
+     */
+    const SkScalar* asScalars() const { return &fX; }
 };
 
 typedef SkPoint SkVector;

include/core/SkRect.h

@@ -769,6 +769,11 @@ struct SK_API SkRect {
      *  other. When this returns, left <= right && top <= bottom
      */
     void sort();
+    
+    /**
+     *  cast-safe way to treat the rect as an array of (4) SkScalars.
+     */
+    const SkScalar* asScalars() const { return &fLeft; }
 };
 
 #endif

tests/PointTest.cpp

@@ -8,8 +8,20 @@
 // Unit tests for src/core/SkPoint.cpp and its header
 
 #include "SkPoint.h"
+#include "SkRect.h"
 #include "Test.h"
 
+static void test_casts(skiatest::Reporter* reporter) {
+    SkPoint p = { 0, 0 };
+    SkRect  r = { 0, 0, 0, 0 };
+
+    const SkScalar* pPtr = SkTCast<const SkScalar*>(&p);
+    const SkScalar* rPtr = SkTCast<const SkScalar*>(&r);
+
+    REPORTER_ASSERT(reporter, p.asScalars() == pPtr);
+    REPORTER_ASSERT(reporter, r.asScalars() == rPtr);
+}
+
 // Tests that SkPoint::length() and SkPoint::Length() both return
 // approximately expectedLength for this (x,y).
 static void test_length(skiatest::Reporter* reporter, SkScalar x, SkScalar y,
@@ -37,6 +49,8 @@ static void test_Normalize(skiatest::Reporter* reporter,
 }
 
 static void PointTest(skiatest::Reporter* reporter) {
+    test_casts(reporter);
+
     test_length(reporter, SkIntToScalar(3), SkIntToScalar(4), SkIntToScalar(5));
     test_length(reporter, SkFloatToScalar(0.6f), SkFloatToScalar(0.8f),
                 SK_Scalar1);