Prevent parent from getting touch events only for certain views?

Question

I have a ScrollView and linear layout inside it. Inside the linear layout i have multiple views. One of the multiple views (DrawView lets say)is used to draw stuff so i have to override onTouchEvent of that method and draw things. Currently when i drag or move on the DrawView, the ScrollView also handles the touch leading the entire view moving. What i want is that when i touch the DrawView , the scroll view should not move . I went through some of these answers here

How to vary between child and parent view group touch events

but i did not find anything that i can add in DrawView which will prevent the ScrollView from moving up and down. Note that DrawView does not extend ViewGroup so i don't have access to requestDisallowInterceptTouchEvent

score 4 · Accepted Answer · answered Jun 28 '18 at 06:16

4

You can get the ScrollView from your DrawView's onTouchEvent:

ScrollView scrollView = (ScrollView) getParent();

then you can call requestDisallowInterceptTouchEvent on scrollView to prevent it from scrolling when you touch the DrawView.

scrollView.requestDisallowInterceptTouchEvent(true);

answered Jun 28 '18 at 06:16

Hong Duan

4,234
2
27
50

Thanks , i did something similar. – Dishonered Jun 28 '18 at 06:56

score 2 · Answer 2 · answered Jun 28 '18 at 06:03

You can prevent scroll of ScrollView whenever your DrawView gets touch event. To do That you need to create a custom ScrollView calls like below ^{[Original Code Snippet]}

public class MyScrollView extends ScrollView {
    private boolean enableScrolling = true;
    public MyScrollView(Context context) {
        super(context);
    }

    public MyScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {

        if (scrollingEnabled()) {
            return super.onInterceptTouchEvent(ev);
        } else {
            return false;
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        if (scrollingEnabled()) {
            return super.onTouchEvent(ev);
        } else {
            return false;
        }
    }

    private boolean scrollingEnabled(){
        return enableScrolling;
    }

    public void setScrolling(boolean enableScrolling) {
        this.enableScrolling = enableScrolling;
    }
}

And you can call scrollView.setScrolling(true/false) as per your requirement.

Thanks this is a valid solution but a simpler solution would be the one suggested by @Hong Duan. — Dishonered, Jun 28 '18 at 07:06

score 1 · Answer 3 · answered Jun 28 '18 at 07:01

1

So i ended up doing this in my DrawView in the onTouchEvent method

getParent().requestDisallowInterceptTouchEvent(true); , it worked!

answered Jun 28 '18 at 07:01

Dishonered

8,449
9
37
50

Prevent parent from getting touch events only for certain views?

3 Answers3

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