Read a PNG image using Haxe - haxe

Question

Using the Haxe programming language, is there any cross-platform way to read a PNG image, and get the pixel data from the image?
I have a file called stuff.png, and I want to obtain an array of RGB values from the image (as an integer array).

Answer 1

Here's an example usage of the Haxe format library to read a PNG file. You need -lib format in your compiler args / build.hxml:
function readPixels(file:String):{data:Bytes, width:Int, height:Int} {
var handle = sys.io.File.read(file, true);
var d = new format.png.Reader(handle).read();
var hdr = format.png.Tools.getHeader(d);
var ret = {
data:format.png.Tools.extract32(d),
width:hdr.width,
height:hdr.height
};
handle.close();
return ret;
}
Here's an example of how to get ARGB pixel data from the above:
public static function main() {
if (Sys.args().length == 0) {
trace('usage: PNGReader <filename>');
Sys.exit(1);
}
var filename = Sys.args()[0];
var pixels = readPixels(filename);
for (y in 0...pixels.height) {
for (x in 0...pixels.width) {
var p = pixels.data.getInt32(4*(x+y*pixels.width));
// ARGB, each 0-255
var a:Int = p>>>24;
var r:Int = (p>>>16)&0xff;
var g:Int = (p>>>8)&0xff;
var b:Int = (p)&0xff;
// Or, AARRGGBB in hex:
var hex:String = StringTools.hex(p,8);
trace('${ x },${ y }: ${ a },${ r },${ g },${ b } - ${ StringTools.hex(p,8) }');
}
}

Answer 2

You can always access the pixel data with BitmapData.getPixels/BitmapData.setPixels.
If you are using haXe NME, you can use Assets.getBitmapData() to load an asset image file.
If you want to load images from network, then you can use Loader class, it can asynchronous loading remote images, but in flash please mind the cross-domain issue.
For more generic ByteArray -> BitmapData conversion, use following code:
var ldr = new Loader();
ldr.loadBytes(cast(byteArray)); // bytearray contains raw image data
var dp: DisplayObject = ldr.content; // actually ontent should be of Bitmap class
var bitmapData = new BitmapData(Std.int(dp.width), Std.int(dp.height), true, 0);
bitmapData.draw(dp);