Adding my Bitmap2Path sample for 1on1 meeting.

tests/PathUtilsTest.cpp

Index: tests/PathUtilsTest.cpp
diff --git a/tests/PathUtilsTest.cpp b/tests/PathUtilsTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..0d3e236fc1301f65553a9ddea078dc13b0f2e11e
--- /dev/null
+++ b/tests/PathUtilsTest.cpp
@@ -0,0 +1,137 @@
+
+/*
+ * 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 "Test.h"
+
+#include "SkBitmap.h"
+#include "SkCanvas.h"
+#include "SkPathUtils.h"
+#include "SkRandom.h"
+#include "SkTime.h"
+
+#define NUM_IT 100000
+#define ON  0xFF000000 // black pixel
+#define OFF 0x00000000 // transparent pixel    
+
+class SkBitmap;
+
+//this function is redefined for sample, test, and bench. is there anywhere
+// I can put it to avoid code duplcation?           
+static void fillRandomBits( int chars, char* bits ){
+    SkTime time;
+    SkMWCRandom rand = SkMWCRandom( time.GetMSecs() );
+
+    for (int i = 0; i < chars; ++i){
+        bits[i] = rand.nextU();
+    }
+}
+
+//also defined within PathUtils.cpp, but not in scope here. Anyway to call it
+// without re-defining it?
+static int getBit( const char* buffer, int x ) {
+    int byte = x >> 3;
+    int bit = x & 7;
+
+    return buffer[byte] & (1 << bit);
+}
+
+static void bin2SkBitmap(const char* bin_bmp, SkBitmap* sk_bmp,
+                               int h, int w, int stride){
+    //init the SkBitmap
+    sk_bmp->setConfig(SkBitmap::kARGB_8888_Config, w, h);
+    sk_bmp->allocPixels();
+
+    for (int y = 0; y < h; ++y) { // for every row
+
+        const char* curLine = &bin_bmp[y * stride];
+        for (int x = 0; x < w; ++x) {// for every pixel
+            if (getBit(curLine, x)) {
+                *sk_bmp->getAddr32(x,y) = ON;
+            }
+            else {
+                *sk_bmp->getAddr32(x,y) = OFF;
+            }
+        }
+    }
+}
+
+static bool test_bmp(skiatest::Reporter* reporter,
+                      const SkBitmap* bmp1, const SkBitmap* bmp2,
+                      int h, int w) {
+    for (int y = 0; y < h; ++y) { // loop through all pixels
+        for (int x = 0; x < w; ++x) {
+            REPORTER_ASSERT( reporter, *bmp1->getAddr32(x,y) == *bmp1->getAddr32(x,y) );
+        }
+    }
+    return true;
+}
+
+static void test_path_eq(skiatest::Reporter* reporter, const SkPath* path,
+                      const SkBitmap* truth, int h, int w){
+    // make paint
+    SkPaint bmpPaint;
+    bmpPaint.setAntiAlias(true);  // Black paint for bitmap
+    bmpPaint.setStyle(SkPaint::kFill_Style);
+    bmpPaint.setColor(SK_ColorBLACK);
+    
+    // make bmp
+    SkBitmap bmp;
+    bmp.setConfig(SkBitmap::kARGB_8888_Config, w, h);
+    bmp.allocPixels();
+    SkCanvas(bmp).drawPath(*path, bmpPaint);
+
+    // test bmp
+    test_bmp(reporter, &bmp, truth, h, w);
+}
+
+static void test_path(skiatest::Reporter* reporter, const SkBitmap* truth,
+                            const char* bin_bmp, int h, int w, int stride){
+    // make path
+    SkPath path;
+    SkPathUtils::BitsToPath_Path(&path, bin_bmp, h, w, stride);
+    
+    //test for correctness
+    test_path_eq(reporter, &path, truth, h, w);
+}
+
+static void test_region(skiatest::Reporter* reporter, const SkBitmap* truth,
+                            const char* bin_bmp, int h, int w, int stride){
+    //generate bitmap
+    SkPath path;
+    SkPathUtils::BitsToPath_Region(&path, bin_bmp, h, w, stride);
+    
+    //test for correctness
+    test_path_eq(reporter, &path, truth, h, w);
+}
+
+static void TestPathUtils(skiatest::Reporter* reporter) {
+    const int w[4] = {4, 8, 12, 16};
+    int h = 8, stride = 4;
+    char bits[ h * stride ];
+    static char* bin_bmp = &bits[0];
+
+    //loop to run randomized test lots of times
+    for (int it = 0; it < NUM_IT; ++it)
+    {
+        // generate a random binary bitmap
+        fillRandomBits( h * stride, bin_bmp); // generate random bitmap    
+    
+        // for each bitmap width, use subset of binary bitmap
+        for (int i = 0; i < 4; ++i) {
+            // generate truth bitmap
+            SkBitmap bmpTruth;
+            bin2SkBitmap(bin_bmp, &bmpTruth, h, w[i], stride);
+
+            test_path(reporter, &bmpTruth, bin_bmp, h, w[i], stride);
+            test_region(reporter, &bmpTruth, bin_bmp, h, w[i], stride);
+        }
+    }
+}
+
+#include "TestClassDef.h"
+DEFINE_TESTCLASS("PathUtils", PathUtils, TestPathUtils)