Android : Locating the item at center position of the screen after selecting it ,In the horizontalscrollview

10,964

Solution 1

After long try , I have got it with this

for (int i = 0; i < 20; i++) {
    final Button b = new Button(this);
    b.setText("t" + i);
    b.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
       int scrollX = (b.getLeft() - (screenWidth / 2)) + (b.getWidth() / 2);
       hsl.smoothScrollTo(scrollX, 0);
    }
});

ll.addView(b);
}

Solution 2

This is how your onCreate should look like:

hsl = (HorizontalScrollView) findViewById(R.id.scrollView);
LinearLayout ll = (LinearLayout) findViewById(R.id.horizontalbar);

Display display = getWindowManager().getDefaultDisplay();
Point size = new Point();
display.getSize(size);
final int width = size.x;

for (int i = 0; i < 20; i++) {
    final Button b = new Button(this);
    b.setText("t" + i);
    b.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            int center = (width - b.getWidth())/2;
            hsl.scrollTo(b.getLeft() - center, b.getTop());
        }
    });

    ll.addView(b);
}

The only thing i didn't discover is why i need to substract additional 200px (in my case). Probably some padding or something else. Instead of 200, you could discover how many dips is it and call function:

public static int convertDipToPixels(Context c, float dips) {
    return (int) (dips * c.getResources().getDisplayMetrics().density + 0.5f);
}
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Mayur Raval
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Mayur Raval

Native Android,Flutter,React Native Developer

Updated on July 06, 2022

Comments

  • Mayur Raval
    Mayur Raval almost 2 years

    I am trying to scroll item to the middle position of the screen after selecting it.I have used Horizontalscrollview and LinearLayout inside it to add item. I show in the XML

    XML

    <RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context=".MainActivity" >
    
      <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_above="@+id/bottom"
            android:orientation="vertical" >
    
           <HorizontalScrollView
                    android:id="@+id/scrollView"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_below="@+id/updown"
                    android:layout_weight="0.8"
                    android:fadingEdgeLength="0dp" >
    
                    <LinearLayout
                        android:id="@+id/horizontalbar"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:background="@color/tlbackground"
                        android:baselineAligned="true"
                        android:orientation="horizontal" >
                    </LinearLayout>
           </HorizontalScrollView>
      </LinearLayout>
    </RelativeLayout>
    

    Class

    public class MainActivity extends FragmentActivity implements ActionBar.TabListener
    {
    
        @Override
        protected void onCreate(Bundle savedInstanceState) 
        {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          hsl = (HorizontalScrollView) findViewById(R.id.scrollView);
          LinearLayout l1 = (LinearLayout)findViewById(R.id.horizontalbar);
    
            for(int i = 0; i < 20; i++)
            {
                Button b = new Button(this);
                b.setText("t"+i);
                ll.addView(b);
            }
         }
    }
    

    I want something like in figure

    before click

    enter image description here

    after click

    enter image description here

    How can I Scroll that selected item to the middle in HorizontalScrollview?