Resize iOS images

resize_ios_images.py

'''
requires imagemagick to be installed. http://www.imagemagick.org/script/index.php
requires pngquant to be installed if using compression on pngs. http://pngquant.org/
'''
import os
import sys
import subprocess
import argparse
import shutil
import mimetypes

def copyImage(imageIn, imageOut):
    shutil.copy(imageIn, imageOut)

def resizeImage(imageIn, imageOut, percentage):
	command = ["convert", imageIn, "-resize", percentage, imageOut]
	subprocess.call(command)


def compressPNG(imagePath, numberOfColors):
	command = ["pngquant", numberOfColors, "--force", "--ext", ".png", imagePath]
	subprocess.call(command)

def compressJPG(imagePath, quality):
	command = ["convert", "-quality", quality, imagePath]
	subprocess.call(command)
	print command

def process2xImages(args):
	inputDir = args.input
	if(inputDir[-1:] != "/"):
		inputDir = inputDir + "/"
	imagesToProcess = []
	fileList = os.listdir(inputDir)

	for fileName in fileList:
		inputFile = inputDir + fileName
		if(validFile(inputFile)):
			imagesToProcess.append(inputFile)

	outDir = args.output
	if(outDir == None):
		outDir = inputDir

	if(outDir[-1:] != "/"):
		outDir = outDir + "/"

	totalFiles = len(imagesToProcess)
	processed = 0

	for image in imagesToProcess:
		outImagePath = image.replace(inputDir, outDir)
		if(inputDir != outDir):
			copyImage(image, outImagePath)
		resizedImagePath = outImagePath.replace("@2x", "")
		resizeImage(image, resizedImagePath, "50%")

		mimetype = mimetypes.guess_type(outImagePath)[0]
		
		if(args.compresspngs == True and mimetype == "image/png"):
			compressPNG(outImagePath, args.pngcolors)
			compressPNG(resizedImagePath, args.pngcolors)

		if(args.compressjpgs == True and mimetype == "image/jpeg"):
			compressJPG(outImagePath, args.jpegcompression)
			compressJPG(resizedImagePath, args.jpegcompression)

		processed += 1
		complete = float(processed)/float(totalFiles)
 		percentageComplete = str(int(complete * 100.0))
 		outputText = percentageComplete + "% : " + str(processed) + " of " + str(totalFiles)
 		sys.stdout.write('\r' + outputText)
 		sys.stdout.flush()

 	print "\nDone: processed " + str(totalFiles) + " files"


def validFile(filePath):
	extension = os.path.splitext(filePath)[1].lower()
	valid = False
	if(extension == ".png" or extension == ".jpeg" or extension == ".jpg"):
		valid = True

	if "@2x" not in filePath and valid == True:
		valid = False
	return valid

def checkArgsAndGetDir(args):
	if(args.input == None):
		print "Not enough arguments. You need to supply an input directory"
		exit(1)

	elif os.path.isdir(args.input) == False:
		print args.input + " is not a directory"
		exit(1)
	checkInstalledTools(args)

def checkInstalledTools(args):
	# check for image magic
	try:
		subprocess.check_call(["convert"], stdout=open(os.devnull, "wb"))
	except subprocess.CalledProcessError:
		print "something went wrong with imagemagick"
		exit(1)
	except OSError:
		print "imagemagick needs to be installed. You can find it at: http://www.imagemagick.org/script/command-line-tools.php"
		exit(1)
	#check for pngquant if needed
	if(args.compresspngs == True):
		try:
			subprocess.check_call(["pngquant", "-h"], stdout=open(os.devnull, "wb"))
		except subprocess.CalledProcessError:
			print "something went wrong with pngquant"
			exit(1)
		except OSError:
			print "pngquant needs to be installed. You can find it at: http://pngquant.org/"
			exit(1)

def start():
	parser = argparse.ArgumentParser(description="A utility to resize retina images for iOS.")
	parser.add_argument("-i", "--input", metavar="", required=True, help="The image directory to use for sampling.")
	parser.add_argument("-o", "--output", metavar="", required=False, type=str, help="The directory to save the images. If left blank will use the input directory.")
	parser.add_argument("-c", "--compresspngs", help="Will compress PNGs if set", action="store_true")
	parser.add_argument("-d", "--pngcolors", metavar="", required=False, type=str, default="256", help="Number of colors to use when compressing pngs if compress pngs is on.  Default 256.")
	parser.add_argument("-j", "--compressjpgs", help="Will compress JPEGs if set", action="store_true")
	parser.add_argument("-g", "--jpegcompression", metavar="", required=False, type=str, default="10", help="Compression to use for jpegs.  Default 90.")
	args = parser.parse_args()

	checkArgsAndGetDir(args)
	process2xImages(args)

start()