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# 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.
"""
Bitmap is a basic wrapper for image pixels. It includes some basic processing
tools: crop, find bounding box of a color and compute histogram of color values.
"""
import array
import cStringIO
import struct
import subprocess
import warnings
from telemetry.internal.util import binary_manager
from telemetry.core import platform
from telemetry.util import color_histogram
from telemetry.util import rgba_color
import png
class _BitmapTools(object):
"""Wraps a child process of bitmaptools and allows for one command."""
CROP_PIXELS = 0
HISTOGRAM = 1
BOUNDING_BOX = 2
def __init__(self, dimensions, pixels):
binary = binary_manager.FetchPath(
'bitmaptools',
platform.GetHostPlatform().GetArchName(),
platform.GetHostPlatform().GetOSName())
assert binary, 'You must build bitmaptools first!'
self._popen = subprocess.Popen([binary],
stdin=subprocess.PIPE,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
# dimensions are: bpp, width, height, boxleft, boxtop, boxwidth, boxheight
packed_dims = struct.pack('iiiiiii', *dimensions)
self._popen.stdin.write(packed_dims)
# If we got a list of ints, we need to convert it into a byte buffer.
if type(pixels) is not bytearray:
pixels = bytearray(pixels)
self._popen.stdin.write(pixels)
def _RunCommand(self, *command):
assert not self._popen.stdin.closed, (
'Exactly one command allowed per instance of tools.')
packed_command = struct.pack('i' * len(command), *command)
self._popen.stdin.write(packed_command)
self._popen.stdin.close()
length_packed = self._popen.stdout.read(struct.calcsize('i'))
if not length_packed:
raise Exception(self._popen.stderr.read())
length = struct.unpack('i', length_packed)[0]
return self._popen.stdout.read(length)
def CropPixels(self):
return self._RunCommand(_BitmapTools.CROP_PIXELS)
def Histogram(self, ignore_color, tolerance):
ignore_color_int = -1 if ignore_color is None else int(ignore_color)
response = self._RunCommand(_BitmapTools.HISTOGRAM,
ignore_color_int, tolerance)
out = array.array('i')
out.fromstring(response)
assert len(out) == 768, (
'The ColorHistogram has the wrong number of buckets: %s' % len(out))
return color_histogram.ColorHistogram(out[:256], out[256:512], out[512:],
ignore_color)
def BoundingBox(self, color, tolerance):
response = self._RunCommand(_BitmapTools.BOUNDING_BOX, int(color),
tolerance)
unpacked = struct.unpack('iiiii', response)
box, count = unpacked[:4], unpacked[-1]
if box[2] < 0 or box[3] < 0:
box = None
return box, count
class Bitmap(object):
"""Utilities for parsing and inspecting a bitmap."""
def __init__(self, bpp, width, height, pixels, metadata=None):
assert bpp in [3, 4], 'Invalid bytes per pixel'
assert width > 0, 'Invalid width'
assert height > 0, 'Invalid height'
assert pixels, 'Must specify pixels'
assert bpp * width * height == len(pixels), 'Dimensions and pixels mismatch'
self._bpp = bpp
self._width = width
self._height = height
self._pixels = pixels
self._metadata = metadata or {}
self._crop_box = None
@property
def bpp(self):
return self._bpp
@property
def width(self):
return self._crop_box[2] if self._crop_box else self._width
@property
def height(self):
return self._crop_box[3] if self._crop_box else self._height
def _PrepareTools(self):
"""Prepares an instance of _BitmapTools which allows exactly one command.
"""
crop_box = self._crop_box or (0, 0, self._width, self._height)
return _BitmapTools((self._bpp, self._width, self._height) + crop_box,
self._pixels)
@property
def pixels(self):
if self._crop_box:
self._pixels = self._PrepareTools().CropPixels()
# pylint: disable=unpacking-non-sequence
_, _, 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
@property
def metadata(self):
self._metadata['size'] = (self.width, self.height)
self._metadata['alpha'] = self.bpp == 4
self._metadata['bitdepth'] = 8
return self._metadata
def GetPixelColor(self, x, y):
pixels = self.pixels
base = self._bpp * (y * self._width + x)
if self._bpp == 4:
return rgba_color.RgbaColor(pixels[base + 0], pixels[base + 1],
pixels[base + 2], pixels[base + 3])
return rgba_color.RgbaColor(pixels[base + 0], pixels[base + 1],
pixels[base + 2])
@staticmethod
def FromPng(png_data):
warnings.warn(
'Using pure python png decoder, which could be very slow. To speed up, '
'consider installing numpy & cv2 (OpenCV).')
width, height, pixels, meta = png.Reader(bytes=png_data).read_flat()
return Bitmap(4 if meta['alpha'] else 3, width, height, pixels, meta)
@staticmethod
def FromPngFile(path):
with open(path, "rb") as f:
return Bitmap.FromPng(f.read())
def WritePngFile(self, path):
with open(path, "wb") as f:
png.Writer(**self.metadata).write_array(f, self.pixels)
def IsEqual(self, other, tolerance=0):
# 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):
# Output dimensions will be the maximum of the two input dimensions
out_width = max(self.width, other.width)
out_height = max(self.height, other.height)
diff = [[0 for x in xrange(out_width * 3)] for x in xrange(out_height)]
# Loop over each pixel and write out the difference
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 = rgba_color.RgbaColor(0, 0, 0, 0)
if x < other.width and y < other.height:
c1 = other.GetPixelColor(x, y)
else:
c1 = rgba_color.RgbaColor(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 Bitmap
warnings.warn(
'Using pure python png decoder, which could be very slow. To speed up, '
'consider installing numpy & cv2 (OpenCV).')
diff_img = png.from_array(diff, mode='RGB')
output = cStringIO.StringIO()
try:
diff_img.save(output)
diff = Bitmap.FromPng(output.getvalue())
finally:
output.close()
return diff
def GetBoundingBox(self, color, tolerance=0):
return self._PrepareTools().BoundingBox(color, tolerance)
def Crop(self, left, top, width, height):
cur_box = self._crop_box or (0, 0, self._width, self._height)
cur_left, cur_top, cur_width, cur_height = cur_box
if (left < 0 or top < 0 or
(left + width) > cur_width or
(top + height) > cur_height):
raise ValueError('Invalid dimensions')
self._crop_box = cur_left + left, cur_top + top, width, height
return self
def ColorHistogram(self, ignore_color=None, tolerance=0):
return self._PrepareTools().Histogram(ignore_color, tolerance)
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