Question

I am developing a custom ViewGroup that contains a number of views. In the constructor, I create a number of FrameLayouts that will each contain two ImageViews. Each Framelayout and the child views are created using the following code.

FrameLayout frame = new FrameLayout(context);

ImageView digitView = new ImageView(context);
digitView.setScaleType(ScaleType.CENTER_CROP);
frame.addView(digitView,
        new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT));

ImageView bezelView = new ImageView(context);
bezelView.setScaleType(ScaleType.CENTER_CROP);
bezelView.setImageResource(R.drawable.bezel);
frame.addView(bezelView);


this.addView(frame, params); 

In the onMeasure callback I set the dimensions of the custom ViewGroup

        this.setMeasuredDimension(254, 43);

and in the onLayout callback, I calculate the dimensions of each of the FrameLayouts and call the layout method for each

@Override
protected void onLayout (boolean changed, int left, int top, int right, int bottom)
{
    if (changed)
    {
        float width = (float)(right - left) / (float)this.digits;

        if ((int)(width/ASPECT_RATIO) > bottom- top)
            width = (float)(bottom - top) * ASPECT_RATIO;
        this.digitWidth = (int)width;
        this.digitHeight = (int)(width/ASPECT_RATIO);

        this.xOffset = ((right - left) - (this.digits * this.digitWidth))/2;
        this.yOffset = ((bottom - top) - this.digitHeight)/2;

        for (int i = this.digits-1; i >=0; i--)
        {
            int x = xOffset + i * this.digitWidth;
            this.placeFrames.get(i).layout(x, this.yOffset, x + this.digitWidth, yOffset + this.digitHeight); 

        }
    }
}

The issue I am having is that the FrameLayouts are being correctly sized and positioned within the custom GroupView, but the ImageViews are not being resized by the FrameLayouts – they have zero width and height. I validated this using the HierarchyViewer.

I think I’ve missed something – I assumed that the layout method on the FrameLayout would take care of resizing the child ImageViews based on the layout parameters passed in when they were added to the FrameLayout as children, but it seems not.

A pointer in the right direction would be very much appreciated.

Thanks

Andrew

Answer 1

I assumed that the layout method on the FrameLayout would take care of resizing the child ImageViews based on the layout parameters passed in when they were added to the FrameLayout as children, but it seems not.

You are not layout() these ImageView objects yourself nor calling super.onLayout()..