Simple Image Cropping with Flex

Here is a simple, pure as3, image cropper I wrote for Flex. I’ll try do a post later in the week describing how to use it in Flash cs3 and cs4.

[kml_flashembed publishmethod=”static” fversion=”9.0.0″ useexpressinstall=”true” replaceId=”flex_image_crop” movie=”” width=”640″ height=”458″ targetclass=”flashmovie”]

screenshot for people without flash



  • Very Simple
  • Allows you to set min and max values for height and width
  • Holding shift key keeps aspect ratio

You currently have to do the cropping on your own, either in flash or server side. I will followup later with examples of how to do that.

To embed this into you application, all you have to do is:

import com.wirelust.imagecrop.ImageCrop;
import com.wirelust.imagecrop.CropBox;
private var imageCrop:ImageCrop = new ImageCrop();
private function onCreationComplete():void {
	// imageBox is an mx:HBox in my mxml
	var crop:CropBox = imageCrop.cropBox;
	// Set up the initial crop
	crop.cropX = 178;
	crop.cropY = 187;
	crop.cropWidth = 249;
	crop.cropHeight = 219;

You can then listen for CropBox.EVENT_CHANGED to get the dimensions of the box as it changes:

private function onCreationComplete():void {
	// snipped ...
	crop.addEventListener(CropBox.EVENT_CHANGED, onCropChanged);
private function onCropChanged(event:Event):void {
	if (imageCrop.cropBox != null) {
		xValue.text = imageCrop.cropBox.cropX.toString();
		yValue.text = imageCrop.cropBox.cropY.toString();
		widthValue.text = imageCrop.cropBox.cropWidth.toString();
		heightValue.text = imageCrop.cropBox.cropHeight.toString();


 Download source code

  • Trinu

    How to capture the selected image

  • Samarth

    their is an error in the above code..

    error is shown in the image…
    help required urgent…

  • Parthiya Dharamsoth

        I am not getting in the above code what is the cropBox and how can i do this using flex 4.5.
       Can any one help me.

  • You can just comment out the call to ExternalInterface. this is just used to send the values back to the web browser so it can be easily displayed for debugging. it isn’t needed for the application to work.

  • Samarth

    crop boz is the area which you want to crop in an image..

  • Samarth

    okay..thank you..

  • Oleg

    There is an error in resizeCrop function. There is missing the check for cropMaxHeight. Also the check does not look where the starting points of the crop are. You will get a bigger cropbox than allowed, if the crop point x,y are not 0.

    Here my quick-fix line 296 in the

    private function resizeCrop(newX:Number, newY:Number, newWidth:Number, newHeight:Number):void {
    if (newWidth >= cropMinWidth &&
    newHeight >= cropMinHeight &&
    newX >= 0 &&
    newX = 0 &&
    newY <= height &&
    /* (cropMaxWidth == 0 || newWidth <= cropMaxWidth) && */ OLD

    (cropMaxWidth == 0 || (newWidth+newX) <= cropMaxWidth) && //NEW
    (cropMaxHeight == 0 || (newHeight+newY) <= cropMaxHeight) //NEW
    ) {