DIY 一个用于生成桌面墙纸的“网络相机”

Ben 写了一个 python 脚本——WebCam，区区百十行代码，实现了从网络或本地目录抓取多幅图片并随机拼合到一起，所生成的图片可以作为漂亮的桌面墙纸。这个脚本程序虽然不是非常智能，但是它可以作为一个 python 编程示例供初学者借鉴。您也可以尝试做一个 Lua 或 Ruby 版本这个脚本的全部代码如下

#！ /usr/bin/env python

# Copyright 2009 by Benjamin Fogle
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# （at your option） any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

import sys
import os
import os.path
import urllib2
import tempfile
import math

# Constants. Change these to customize the script
# In ksh: CONFIG_FILE=$HOME/lectures/examples/LEC-05/webcam_config
CONFIG_FILE=os.getenv（"HOME"） + "/.webcam_config"
TARGET=os.getenv（"HOME"） + "/Pictures/Wallpapers/webcam.jpg"
SCREEN_X = 1024
SCREEN_Y = 768

def GetTiles（num_images）:
"""Returns a tuple （N,M） representing the tile grid"""
# This algorithm could be much improved
tile = math.ceil（math.sqrt（N））
return （tile, tile）

def GetImageSize（N, M）:
"""Returns a the max size of each image based on the screen size
and the tile grid"""
global SCREEN_X
global SCREEN_Y
ImgX = SCREEN_X / N
ImgY = SCREEN_Y / M
return （ImgX, ImgY）

def CopyFile（src_fp, dest_fp）:
"""Copy a file intelligently"""
data = src_fp.read（49152） # Copy 48k at a time
while data:
dest_fp.write（data）
data = src_fp.read（49152）
# Note: shutils.copyfileobj does this too.

if len（sys.argv）！= 1:
print "Usage: %s" % （sys.argv[0]）
print
print "Config file is located in %s" % CONFIG_FILE
sys.exit（1）

# Make sure the config file is readable and that it is a regular file
# There is a better way to do this that we will learn later.
if not os.access（CONFIG_FILE, os.R_OK） or not os.path.isfile（CONFIG_FILE）:
print "Error: %s could not be opened！" % CONFIG_FILE
sys.exit（2）

urls = [] # Url to download from. Read from config file
captions = [] # Captions for each image. Read from config file
filenames = [] # Temporary file names

config_fp = open（CONFIG_FILE, "r"）
line = config_fp.readline（）
N=0
while line:
params = line.split（":::"）
urls.append（params[0].strip（））
captions.append（params[1].strip（））
line = config_fp.readline（）
N+=1
config_fp.close（）

# Download each url. This is how to iterate over mutliple lists at once
for url, caption in zip（urls, captions）:
url_fp = urllib2.urlopen（url）
# The following two lines are the preffered way to open a temporary
# file.
fd, name = tempfile.mkstemp（）
img_fp = os.fdopen（fd, "w"）
filenames.append（name）
CopyFile（url_fp, img_fp）
url_fp.close（）
img_fp.close（） # The data won"t appear in img_fp until it"s closed
# Use the ImageMagick suite from the shell to add a caption
os.system（"convert "%s" -set comment "%s" "%s"" %
（name, caption, name））

# Figure out the parameters
tilex, tiley = GetTiles（N）
imgx, imgy = GetImageSize（tilex, tiley）

# Use ImageMagick again to assemble the wallpaper
cmd = "montage -geometry %dx%d
-tile %dx%d
-set caption "%%c"
-pointsize 32
-size %dx%d
-texture plasma:
+polaroid
-background black " % （imgx, imgy, tilex, tiley,
SCREEN_X, SCREEN_Y）

# Add each image file to the command string
for filename in filenames:
cmd += ""%s" " % filename

# Add the output file to the command string and execute
cmd += TARGET
os.system（cmd）

# Cleanup
for filename in filenames:
os.unlink（filename） # In ksh: rm $filename