[telemetry] Move telemetry/core/chrome/ to telemetry/core/backends/chrome/

tools/telemetry/telemetry/core/chrome/png_bitmap.py

-# Copyright (c) 2012 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 base64
-import cStringIO
-
-from telemetry.core import util
-
-util.AddDirToPythonPath(util.GetTelemetryDir(), 'third_party', 'png')
-import png  # pylint: disable=F0401
-
-
-class PngColor(object):
-  """Encapsulates an RGB color retreived from a PngBitmap"""
-
-  def __init__(self, r, g, b, a=255):
-    self.r = r
-    self.g = g
-    self.b = b
-    self.a = a
-
-  def IsEqual(self, expected_color, tolerance=0):
-    """Verifies that the color is within a given tolerance of
-    the expected color"""
-    r_diff = abs(self.r - expected_color.r)
-    g_diff = abs(self.g - expected_color.g)
-    b_diff = abs(self.b - expected_color.b)
-    a_diff = abs(self.a - expected_color.a)
-    return (r_diff <= tolerance and g_diff <= tolerance
-        and b_diff <= tolerance and a_diff <= tolerance)
-
-  def AssertIsRGB(self, r, g, b, tolerance=0):
-    assert self.IsEqual(PngColor(r, g, b), tolerance)
-
-  def AssertIsRGBA(self, r, g, b, a, tolerance=0):
-    assert self.IsEqual(PngColor(r, g, b, a), tolerance)
-
-
-class PngBitmap(object):
-  """Utilities for parsing and inspecting a PNG"""
-
-  def __init__(self, png_data):
-    self._png_data = png_data
-    self._png = png.Reader(bytes=self._png_data)
-    rgba8_data = self._png.asRGBA8()
-    self._width = rgba8_data[0]
-    self._height = rgba8_data[1]
-    self._pixels = list(rgba8_data[2])
-    self._metadata = rgba8_data[3]
-
-  @property
-  def width(self):
-    """Width of the snapshot"""
-    return self._width
-
-  @property
-  def height(self):
-    """Height of the snapshot"""
-    return self._height
-
-  def GetPixelColor(self, x, y):
-    """Returns a PngColor for the pixel at (x, y)"""
-    row = self._pixels[y]
-    offset = x * 4
-    return PngColor(row[offset], row[offset+1], row[offset+2], row[offset+3])
-
-  def WriteFile(self, path):
-    with open(path, "wb") as f:
-      f.write(self._png_data)
-
-  @staticmethod
-  def FromFile(path):
-    with open(path, "rb") as f:
-      return PngBitmap(f.read())
-
-  @staticmethod
-  def FromBase64(base64_png):
-    return PngBitmap(base64.b64decode(base64_png))
-
-  def IsEqual(self, expected_png, tolerance=0):
-    """Verifies that two PngBitmaps are identical within a given tolerance"""
-
-    # Dimensions must be equal
-    if self.width != expected_png.width or self.height != expected_png.height:
-      return False
-
-    # Loop over each pixel and test for equality
-    for y in range(self.height):
-      for x in range(self.width):
-        c0 = self.GetPixelColor(x, y)
-        c1 = expected_png.GetPixelColor(x, y)
-        if not c0.IsEqual(c1, tolerance):
-          return False
-
-    return True
-
-  def Diff(self, other_png):
-    """Returns a new PngBitmap that represents the difference between this image
-    and another PngBitmap"""
-
-    # Output dimensions will be the maximum of the two input dimensions
-    out_width = max(self.width, other_png.width)
-    out_height = max(self.height, other_png.height)
-
-    diff = [[0 for x in xrange(out_width * 3)] for x in xrange(out_height)]
-
-    # Loop over each pixel and test for equality
-    for y in range(out_height):
-      for x in range(out_width):
-        if x < self.width and y < self.height:
-          c0 = self.GetPixelColor(x, y)
-        else:
-          c0 = PngColor(0, 0, 0, 0)
-
-        if x < other_png.width and y < other_png.height:
-          c1 = other_png.GetPixelColor(x, y)
-        else:
-          c1 = PngColor(0, 0, 0, 0)
-
-        offset = x * 3
-        diff[y][offset] = abs(c0.r - c1.r)
-        diff[y][offset+1] = abs(c0.g - c1.g)
-        diff[y][offset+2] = abs(c0.b - c1.b)
-
-    # This particular method can only save to a file, so the result will be
-    # written into an in-memory buffer and read back into a PngBitmap
-    diff_img = png.from_array(diff, mode='RGB')
-    output = cStringIO.StringIO()
-    try:
-      diff_img.save(output)
-      diff_png = PngBitmap(output.getvalue())
-    finally:
-      output.close()
-
-    return diff_png
-