Question

I’ve got a small ImageView inside of a fullscreen FrameLayout, and I’d like to set it such that when I touch the FrameLayout, the imageview moves to that position.

I’ve read all the other SO questions I can find about moving ImageView but I haven’t seen why my solution is not working yet.

In a custom view which extends FrameLayout:

@Override
public boolean onInterceptTouchEvent(MotionEvent event){

    if(event.getActionMasked() == MotionEvent.ACTION_DOWN){
        ImageView iv = (ImageView) this.findViewById(R.id.draggedImage);
        FrameLayout.LayoutParams params = (LayoutParams) iv.getLayoutParams();
        params.leftMargin = (int) event.getX();
        params.bottomMargin = (int) event.getY();
        iv.setLayoutParams(params);
        iv.invalidate();
        invalidate();           
    }
    return true;
}

I’ve changed the layoutparams margin to reflect the new touch position, and invalidated the imageview and framelayout (not sure which of these I should be doing), but the imageView doesn’t budge (just sits always in the top left corner of the frame).

I’ve also verified that this method is being called when I touch the screen and the params is getting set with sane X and Y values.

My layout:

<CustomFrameLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <!-- some other unrelated views -->

    <ImageView
        android:id="@+id/draggedImage"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:src="@drawable/pause" />    

</CustomFrameLayout>

Edit:
Should have mentioned that I’m trying to target API level 10, so I can’t use any of the Honeycomb view orientation goodness 🙁

Answer 1

Through trial and error and searching found that I was missing this call:

params.gravity = Gravity.LEFT | Gravity.BOTTOM;

Initially the gravity was just -1, so the margins had no effect, because it didn’t know which side it was supposed to be basing the margins from. Adding a gravity gives it a side to anchor to so that it can be moved out by the amount in the margin.

Works perfectly now.