[telemetry] Implement per-pixel algorithms in Bitmap as a C++ extension.

tools/telemetry/telemetry/core/bitmap_unittest.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import tempfile
 import os
 import unittest
 
 from telemetry.core import bitmap
 from telemetry.core import util
@@ skipping 43 matching lines @@
     orig = bitmap.Bitmap.FromPngFile(test_png_path)
     temp_file = tempfile.NamedTemporaryFile().name
     orig.WritePngFile(temp_file)
     new_file = bitmap.Bitmap.FromPngFile(temp_file)
     self.assertTrue(orig.IsEqual(new_file))
 
   def testWriteCroppedBmpToPngFile(self):
     pixels = [255,0,0, 255,255,0, 0,0,0,
               255,255,0, 0,255,0, 0,0,0]
     orig = bitmap.Bitmap(3, 3, 2, pixels)
-    orig.Crop(0, 0, 2, 2)
+    orig.Crop((0, 0, 2, 2))
     temp_file = tempfile.NamedTemporaryFile().name
     orig.WritePngFile(temp_file)
     new_file = bitmap.Bitmap.FromPngFile(temp_file)
     self.assertTrue(orig.IsEqual(new_file))
 
   def testIsEqual(self):
     bmp = bitmap.Bitmap.FromBase64Png(test_png)
     file_bmp = bitmap.Bitmap.FromPngFile(test_png_path)
     self.assertTrue(bmp.IsEqual(file_bmp))
+    self.assertTrue(bmp.IsEqual(file_bmp), 1)

[tonyg, 2013/12/12 22:17:48]

I don't understand, why the second test? Maybe a msg other than 1 would explain.

[szym, 2013/12/12 22:54:12]

Leftover from when Equal had two distinct codepaths.
Removed.

 
   def testDiff(self):
     file_bmp = bitmap.Bitmap.FromPngFile(test_png_path)
     file_bmp_2 = bitmap.Bitmap.FromPngFile(test_png_2_path)
 
     diff_bmp = file_bmp.Diff(file_bmp)
 
     self.assertEquals(2, diff_bmp.width)
     self.assertEquals(2, diff_bmp.height)
 
@@ skipping 11 matching lines @@
     diff_bmp.GetPixelColor(1, 1).AssertIsRGB(255, 0, 255)
     diff_bmp.GetPixelColor(0, 1).AssertIsRGB(255, 255, 0)
     diff_bmp.GetPixelColor(1, 0).AssertIsRGB(0, 0, 255)
 
     diff_bmp.GetPixelColor(0, 2).AssertIsRGB(255, 255, 255)
     diff_bmp.GetPixelColor(1, 2).AssertIsRGB(255, 255, 255)
     diff_bmp.GetPixelColor(2, 0).AssertIsRGB(255, 255, 255)
     diff_bmp.GetPixelColor(2, 1).AssertIsRGB(255, 255, 255)
     diff_bmp.GetPixelColor(2, 2).AssertIsRGB(255, 255, 255)
 
+  def testGetBoundingBox(self):
+    pixels = [0,0,0, 0,0,0, 0,0,0, 0,0,0,
+              0,0,0, 1,0,0, 1,0,0, 0,0,0,
+              0,0,0, 0,0,0, 0,0,0, 0,0,0]
+    bmp = bitmap.Bitmap(3, 4, 3, pixels)
+    box, count = bmp.GetBoundingBox(bitmap.RgbaColor(1, 0, 0))

[tonyg, 2013/12/12 22:17:48]

Should this really return count? I don't understand why.

[szym, 2013/12/12 22:54:12]

See Tab.StopVideoCapture. Checking pixel count is more robust than checking
bounding box size. I would even consider using relative pixel count to account
for different capture resolution.

+    self.assertEquals(box, (1, 1, 2, 1))
+    self.assertEquals(count, 2)
+
+    box, count = bmp.GetBoundingBox(bitmap.RgbaColor(0, 1, 0))
+    self.assertEquals(box, None)
+    self.assertEquals(count, 0)
+
   def testCrop(self):
     pixels = [0,0,0, 0,0,0, 0,0,0, 0,0,0,
               0,0,0, 1,0,0, 1,0,0, 0,0,0,
               0,0,0, 0,0,0, 0,0,0, 0,0,0]
     bmp = bitmap.Bitmap(3, 4, 3, pixels)
-    bmp.Crop(1, 1, 2, 1)
+    bmp.Crop((1, 1, 2, 1))
 
     self.assertEquals(bmp.width, 2)
     self.assertEquals(bmp.height, 1)
     bmp.GetPixelColor(0, 0).AssertIsRGB(1, 0, 0)
     bmp.GetPixelColor(1, 0).AssertIsRGB(1, 0, 0)
     self.assertEquals(bmp.pixels, bytearray([1,0,0, 1,0,0]))
+
+  def testHistogram(self):
+    pixels = [1,2,3, 1,2,3, 1,2,3, 1,2,3,
+              1,2,3, 8,7,6, 5,4,6, 1,2,3,
+              1,2,3, 8,7,6, 5,4,6, 1,2,3]
+    bmp = bitmap.Bitmap(3, 4, 3, pixels)
+    bmp.Crop((1, 1, 2, 2))
+
+    histogram = bmp.ColorHistogram()
+    self.assertEquals(sum(histogram), bmp.width * bmp.height * 3)
+    self.assertEquals(histogram[5], 2)
+    self.assertEquals(histogram[8], 2)
+    self.assertEquals(histogram[4 + 256], 2)
+    self.assertEquals(histogram[7 + 256], 2)
+    self.assertEquals(histogram[6 + 512], 4)