我如何知道是否已绘制视图

Question

I want to know if its possible to know if a view has been drawn on the screen.

I am not interested in setting a listener and waiting for it, as I already know how to do that. I am looking for a call, to get a true/false on if the view is currently on the screen.

I dont believe I can simply check the visibility as that is a preset variable, regardless of its state, though I could be wrong.

If the view is not draw, I will set a ViewTreeObserver and wait for it, but that is only neccessary if the view has not yet been drawn.

Answer 1

since getVisibility() returns a predefined property and u don't want to set a listener; i think the only option is View.isShown(). i hope this helps.

Answer 2

if you just want to observe one view, try to create a custom view and override the draw() and set a flag in it like:

public DemoView extends TextView {
    private boolean mHasDrawn;
    // ...
    @override
    public void draw(Canvas canvas) {
        super.draw(canvas);
        mHasDrawn = true;
    }
}

then you can check the mHasDrawn to ensure the view has been drawn. However, I think setting a listener is better than this.