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

tools/telemetry/telemetry/core/bitmap.py

Index: tools/telemetry/telemetry/core/bitmap.py
diff --git a/tools/telemetry/telemetry/core/bitmap.py b/tools/telemetry/telemetry/core/bitmap.py
index bba779c203644c591c672749b072cee418ec66f5..471fe5f28df23d1aed4a96e46b65850f9b88c76f 100644
--- a/tools/telemetry/telemetry/core/bitmap.py
+++ b/tools/telemetry/telemetry/core/bitmap.py
@@ -51,7 +51,6 @@
     self._height = height
     self._pixels = pixels
     self._metadata = metadata or {}
-    self._crop_box = None
 
   @property
   def bpp(self):
@@ -61,36 +60,16 @@
   @property
   def width(self):
     """Width of the bitmap."""
-    if self._crop_box:
-      return self._crop_box[2]
     return self._width
 
   @property
   def height(self):
     """Height of the bitmap."""
-    if self._crop_box:
-      return self._crop_box[3]
     return self._height
-
-  @property
-  def _as_tuple(self):
-    # If we got a list of ints, we need to convert it into a byte buffer.
-    pixels = self._pixels
-    if type(pixels) is not bytearray:
-      pixels = bytearray(pixels)
-    if type(pixels) is not bytes:
-      pixels = bytes(pixels)
-    crop_box = self._crop_box or (0, 0, self._width, self._height)
-    return pixels, self._width, self._bpp, crop_box
 
   @property
   def pixels(self):
     """Flat pixel array of the bitmap."""
-    if self._crop_box:
-      from telemetry.core import bitmaptools
-      self._pixels = bitmaptools.Crop(self._as_tuple)
-      _, _, self._width, self._height = self._crop_box
-      self._crop_box = None
     if type(self._pixels) is not bytearray:
       self._pixels = bytearray(self._pixels)
     return self._pixels
@@ -104,13 +83,12 @@
 
   def GetPixelColor(self, x, y):
     """Returns a RgbaColor for the pixel at (x, y)."""
-    pixels = self.pixels
     base = self._bpp * (y * self._width + x)
     if self._bpp == 4:
-      return RgbaColor(pixels[base + 0], pixels[base + 1],
-                       pixels[base + 2], pixels[base + 3])
-    return RgbaColor(pixels[base + 0], pixels[base + 1],
-                     pixels[base + 2])
+      return RgbaColor(self._pixels[base + 0], self._pixels[base + 1],
+                       self._pixels[base + 2], self._pixels[base + 3])
+    return RgbaColor(self._pixels[base + 0], self._pixels[base + 1],
+                     self._pixels[base + 2])
 
   def WritePngFile(self, path):
     with open(path, "wb") as f:
@@ -131,11 +109,24 @@
     return Bitmap.FromPng(base64.b64decode(base64_png))
 
   def IsEqual(self, other, tolerance=0):
-    """Determines whether two Bitmaps are identical within a given tolerance.
-    Ignores alpha channel."""
-    from telemetry.core import bitmaptools
-    # pylint: disable=W0212
-    return bitmaptools.Equal(self._as_tuple, other._as_tuple, tolerance)
+    """Determines whether two Bitmaps are identical within a given tolerance."""
+
+    # Dimensions must be equal
+    if self.width != other.width or self.height != other.height:
+      return False
+
+    # Loop over each pixel and test for equality
+    if tolerance or self.bpp != other.bpp:
+      for y in range(self.height):
+        for x in range(self.width):
+          c0 = self.GetPixelColor(x, y)
+          c1 = other.GetPixelColor(x, y)
+          if not c0.IsEqual(c1, tolerance):
+            return False
+    else:
+      return self.pixels == other.pixels
+
+    return True
 
   def Diff(self, other):
     """Returns a new Bitmap that represents the difference between this image
@@ -178,28 +169,55 @@
     return diff
 
   def GetBoundingBox(self, color, tolerance=0):
-    """Finds the minimum box surrounding all occurences of |color|.
-    Returns: (top, left, width, height), match_count
-    Ignores the alpha channel."""
-    from telemetry.core import bitmaptools
-    int_color = (color.r << 16) | (color.g << 8) | color.b
-    return bitmaptools.BoundingBox(self._as_tuple, int_color, tolerance)
-
-  def Crop(self, left, top, width, height):
-    """Crops the current bitmap down to the specified box."""
-    cur_box = self._crop_box or (0, 0, self._width, self._height)
-    cur_left, cur_top, cur_width, cur_height = cur_box
-
+    """Returns a (top, left, width, height) tuple of the minimum box
+       surrounding all occurences of |color|."""
+    # TODO(szym): Implement this.
+    raise NotImplementedError("GetBoundingBox not yet implemented.")
+
+  def Crop(self, top, left, width, height):
+    """Crops the current bitmap down to the specified box.
+
+    TODO(szym): Make this O(1).
+    """
     if (left < 0 or top < 0 or
-        (left + width) > cur_width or
-        (top + height) > cur_height):
+        (left + width) > self.width or
+        (top + height) > self.height):
       raise ValueError('Invalid dimensions')
 
-    self._crop_box = cur_left + left, cur_top + top, width, height
+    img_data = [[0 for x in xrange(width * self.bpp)]
+                for y in xrange(height)]
+
+    # Copy each pixel in the sub-rect.
+    # TODO(tonyg): Make this faster by avoiding the copy and artificially
+    # restricting the dimensions.
+    for y in range(height):
+      for x in range(width):
+        c = self.GetPixelColor(x + left, y + top)
+        offset = x * self.bpp
+        img_data[y][offset] = c.r
+        img_data[y][offset + 1] = c.g
+        img_data[y][offset + 2] = c.b
+        if self.bpp == 4:
+          img_data[y][offset + 3] = c.a
+
+    # 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 Bitmap
+    crop_img = png.from_array(img_data, mode='RGBA' if self.bpp == 4 else 'RGB')
+    output = cStringIO.StringIO()
+    try:
+      crop_img.save(output)
+      width, height, pixels, meta = png.Reader(
+          bytes=output.getvalue()).read_flat()
+      self._width = width
+      self._height = height
+      self._pixels = pixels
+      self._metadata = meta
+    finally:
+      output.close()
+
     return self
 
   def ColorHistogram(self):
-    """Computes a histogram of the pixel colors in this Bitmap.
-    Returns a list of 3x256 integers."""
-    from telemetry.core import bitmaptools
-    return bitmaptools.Histogram(self._as_tuple)
+    """Returns a histogram of the pixel colors in this Bitmap."""
+    # TODO(szym): Implement this.
+    raise NotImplementedError("ColorHistogram not yet implemented.")