android - Synchronizing Toolbar Height with ViewPager -

i have activity toolbar , viewpager, in viewpager there 3 fragments, every fragment should set different height toolbar means when 1st fragment selected fragment toolbar's height should x , when 2nd fragment selected toolbar height should y , so.

now want changing of toolbar height synchronized viewpager scrolling, advice that?

here output ..

for sample code https://github.com/msquare097/mflex-toolbar ,....

first of nice question , interesting... , implement it.
have used toolbar minimum height changing on viewpager scroll.

first of declare toolbar height respect fragments in activity viewpager implemented.

i have take directly integer. load dimen dp , convert px. in viewpager have taken 4 fragment. declaring 4 toolbar's height.

int heightforpage0 = 150; int heightforpage1 = 400; int heightforpage2 = 300; int heightforpage3 = 600; 

after setting adapter add listener

mviewpager.addonpagechangelistener(this);

and override 3 method , write below code..

@override     public void onpagescrolled(int position, float positionoffset, int positionoffsetpixels) {         log.d(tag,positionoffset+"");          int currentheight;         int nextheight;          switch (position) {             case 0:                 currentheight = heightforpage0;                 nextheight = heightforpage1;                 calculateheightandapply(currentheight, nextheight, positionoffset);                 break;             case 1:                 currentheight = heightforpage1;                 nextheight = heightforpage2;                 calculateheightandapply(currentheight, nextheight, positionoffset);                 break;             case 2:                 currentheight = heightforpage2;                 nextheight = heightforpage3;                 calculateheightandapply(currentheight, nextheight, positionoffset);                 break;             case 3:                 // last page don't have worry it.                 // bcoz there no next page available;                 break;         }     }      @override     public void onpageselected(int position) {}      @override     public void onpagescrollstatechanged(int state) {} 

and here magical method have called in onpagescrolled..

private void calculateheightandapply(int currentheight, int nextheight, float positionoffset) {     if (positionoffset==0) {         return;     }     int diff = nextheight - currentheight;         int newheight = (int) ((positionoffset*diff));         mtoolbar.setminimumheight(currentheight+newheight); }