After our Unity runtime SpriteSheets generator, it is a good idea to optimize the generated pngs files.
pngquant is a command-line utility and a library for lossy compression of PNG images. The conversion reduces file sizes significantly (often as much as 70%) and preserves full alpha transparency. In other words this is a must have tool if you’re working with many pngs!
I used many times pngquant directly from the command line, but depending your project, you might need to run it directly inside your application! I didn’t find example for doing this, and it was way harder than I thought due to my lack of knowledge with batch and shell scripts! So here we go:
We use custom batch file (for Windows) and shell script (for Mac OS X) for launching pngquant. It will take the path to pngs to compress and overwrite them.
#!/bin/sh #!/usr/bin/env bash #$ -N $2 DIR="$( cd "$( dirname "$0" )" && pwd )" (cd "$DIR" && ./pngquant -f --ext .png "$1"/*.png)
cd %~dp0 pngquant -f --ext .png "%~1"/*.png
Now a C# example for calling thoses scripts, note it works fine with Unity too:
System.Diagnostics.Process process = new System.Diagnostics.Process(); string exec = ""; if (Application.platform == RuntimePlatform.WindowsEditor || Application.platform == RuntimePlatform.WindowsPlayer) exec = "pngquant-windows.cmd"; else if (Application.platform == RuntimePlatform.OSXEditor || Application.platform == RuntimePlatform.OSXPlayer) exec = "pngquant-osx"; else throw new Exception("Platform not supported"); process.StartInfo.FileName = Application.dataPath + "/../../" + exec; process.StartInfo.Arguments = Application.dataPath + "/../../png-to-compress"; // if your path have blank spaces use: //process.StartInfo.Arguments = "\"" + Application.dataPath + "/../../png compress\""; process.StartInfo.CreateNoWindow = true; process.StartInfo.UseShellExecute = false; process.Start();
And finally an example with AS3 for AIR:
var process:NativeProcess = new NativeProcess(); var startupInfo:NativeProcessStartupInfo = new NativeProcessStartupInfo(); var file:File = File.applicationDirectory; var exec:String = ""; if (Capabilities.os.indexOf("Windows") >= 0) exec = "pngquant-windows.cmd"; else if (Capabilities.os.indexOf("Mac") >= 0) exec = "pngquant-osx"; else throw new Error("doesn't work on " + Capabilities.os + " operating system"); file.nativePath = file.nativePath + "/../" + exec; startupInfo.executable = file; var processArgs:Vector.<String> = new Vector.<String>(); processArgs = File.applicationDirectory.nativePath + "/../png-to-compress"; startupInfo.arguments = processArgs; process.start(startupInfo);
Be sure to have a look to PngQuantNativeProcess’s git repository to be up to date!