cachedImageView.js

cachedImageView = function(basedir, uri, obj, attr, cacheage) {
    /**
    Appcelerator Titanium ImageView /w cache
    
    This function attempts to cache a remote image and then returns it again
    when it's requested.
    
    The file is stored in a directory "basedir," this is to try and help
    you keep files unique. It's not special or magical, but not dirty either.

    basedir + filename are used to determine if the file exists locally,
    if not it's then fetched from uri, stores and sets the "image" property
    of obj.
    
    Usage:
    
        var imgv = Ti.UI.createImageView({
            width: 90,
            height: 90,
            image: 'default.png'
        });
        cachedImageView('bucket_name', 'http://127.0.0.1:8000/1.png', imgv, "image", 1000); // 1 second, cache expiry.
        cachedImageView('bucket_name', 'http://127.0.0.1:8000/1@2x.png', imgv, "hires", 1000);
    */
    var filename = uri.split('/');
    filename = filename[filename.length - 1];
    
    var storedTime = Ti.App.Properties.getDouble("CACHE_TIME_"+filename, -1);
    var now = new Date().getTime();
     
    var f = Ti.Filesystem.getFile(Ti.Filesystem.applicationDataDirectory, basedir, filename);
    
    if (f.exists() && ((now - storedTime) < cacheage && storedTime != -1)) { // image was stored within the cacheage time.
        obj[attr] = f.nativePath;
    } else {
    	if (f.exists()) {
    		// It exists, now we need to delete it.
    		f.deleteFile();
    		var f = Ti.Filesystem.getFile(Ti.Filesystem.applicationDataDirectory, basedir, filename); // Now recreate it.
    	}
    
        // create basedir if it doesn't exist.
        var d = Ti.Filesystem.getFile(Ti.Filesystem.applicationDataDirectory, basedir);
        if (!d.exists()) {
            d.createDirectory();
        }
         
        // retrieve remote image.
        var req = Ti.Network.createHTTPClient();
        req.open('GET', uri);
        req.onload = function() {
            if (req.status == 200) {
                f.write(req.responseData);
                Ti.App.Properties.setDouble("CACHE_TIME_"+filename, now);
                obj[attr] = f.nativePath;
            }
        }
        req.send();
    }
}