How to get when an ImageView is completely loaded in Android

Question

I'm developing an App which draws lines over a bunch of Images. To choose these images, I have a radio group and, whenever the user clicks in a radio button, the image is load with all its own drawings.

In my radio listenner I have the following code:

bitmap = BitmapUtils.decodeSampledBitmapFromResource(root + DefinesAndroid.CAMINHO_SHOPPINGS_SDCARD + nomeImagemAtual, size.x, size.y);
mImage.setImageBitmap(bitmap);

mImage.setDrawLines(true);
mImage.setImageBitmap(loadBitmapFromView(mImage));

the decodeSampledBitmapFromResource method I got from this link on android developers (it loads bitmaps more effitiently) http://developer.android.com/training/displaying-bitmaps/load-bitmap.html

And here's the method I call to get a Bitmap of a View

    public static Bitmap loadBitmapFromView(View v) {
        Bitmap b = Bitmap.createBitmap( v.getLayoutParams().width, v.getLayoutParams().height, Bitmap.Config.ARGB_8888);                
        Canvas c = new Canvas(b);
        v.layout(0, 0, v.getLayoutParams().width, v.getLayoutParams().height);
        v.draw(c);
        return b;
}

I'm setting the image Bitmap of mImage because I'm using ImageViewTouch library (which enables pinch zooming over an ImageView) and if I don't do it, all the canvas drawing is deleted with any interaction over the image (like zooming in/out).

The error log is the following

07-11 21:13:41.567: E/AndroidRuntime(20056): java.lang.IllegalArgumentException: width and height must be > 0
07-11 21:13:41.567: E/AndroidRuntime(20056):    at android.graphics.Bitmap.createBitmap(Bitmap.java:638)
07-11 21:13:41.567: E/AndroidRuntime(20056):    at android.graphics.Bitmap.createBitmap(Bitmap.java:620)

I'm almost sure that this error is occuring cause the image bitmap is not completely loaded when I call getBitmapFromView method.

How can I know when the view is loaded completely?

Answer 1

Call loadBitmapFromView in a such way:

mImage.post(new Runnable() {
    @Override
    public void run() {
        loadBitmapFromView(mImage);
    }
});

Runnable provided to post() method will be executed after view measuring and layouting, so getWidth() and getHeight() will return actual width and height.

What else can you do, is measuring View manually, by invoking measure, and then taking result from getMeasuredWidth() and getMeasuredHeight(). But I do not recommend this way.