Need to change alpha of imageView in colapsinglayout

Question

I have toolbar, tab layout and imageview inside Collapsing layout. I need to change alpha of that image to be equal of collapse state of that imageview. It means ->

image completely hide : alpha = 0%

image 50% scrolled : alpha = 50%

image completely shown : alpha = 100%

Unfurtunatelly, i haven't found any xml parameter which could affect this. Is there any simple solution for this?

score 3 · Answer 1 · answered Jun 21 '18 at 15:21

Also if you have some layouts you could use scroll listener like this:

appBarLayout.addOnOffsetChangedListener((appBarLayout, verticalOffset) -> {
            float offsetAlpha = (appBarLayout.getY() / appBarLayout.getTotalScrollRange());
            int value = 255 - (int)(255 * offsetAlpha * -1);
            toolbarTotalContainer.getBackground().setAlpha(value);
        });

Where toolbarTotalContainer is some container of some Views.

score 2 · Accepted Answer · edited May 23 '17 at 12:08

2

You can try a couple of things depending on your needs.

If you're looking for a simple solution you may be able to use the app:contentScrim XML attribute on CollapsingToolbarLayout to achieve the effect you're looking for. See: Coordinator Behavior ImageView

If that isn't sufficient, a more "correct" solution would involve adding an OnOffsetChangedListener and using that to calculate and apply the alpha change for your ImageView. See: android setAlpha on imageView into CollapsingToolbarLayout does not work

edited May 23 '17 at 12:08

Community

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answered Aug 10 '16 at 21:25

Bryan Dunlap

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Thank you. The second solution was exactly what I need. It works great. – Tom Wayne Aug 10 '16 at 22:28

Need to change alpha of imageView in colapsinglayout

2 Answers2