CODEWITHSUNDEEP
androidscrollscreen-size
Adam Katz
Adam Katz

Reputation: 6962

android horizontal scroll button to middle of screen

I have a horizontal scroll bar that holds 12 buttons, I want to scroll to a specific button to be the middle of the screen,

Currently I am using

monthScrollView.smoothScrollBy((int) buttons.get(arrayNumber).getX(),0);

Which scrolls the button just off the screen, so how to I find the value of half the screen to subtract?

Upvotes: 0

Views: 1639

Answers (1)

Neo
Neo

Reputation: 3584

Try

int[] loc = new int[2];
buttons.get(arrayNumber).getLocationInWindow(loc);
horizontalScrollView.scrollTo(loc[0], 0);

Example Code - activity_scroll.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/black">

    <HorizontalScrollView
        android:id="@+id/horizon"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <Button
                android:id="@+id/button_1"
                android:layout_width="100dp"
                android:layout_height="100dp"
                android:text="1"
                android:layout_margin="5dp" />

            <Button
                android:id="@+id/button_2"
                android:layout_width="100dp"
                android:text="2"
                android:layout_height="100dp"
                android:layout_margin="5dp" />

            <Button
                android:id="@+id/button_3"
                android:layout_width="100dp"
                android:text="3"
                android:layout_height="100dp"
                android:layout_margin="5dp" />

            <Button
                android:id="@+id/button_4"
                android:layout_width="100dp"
                android:text="4"
                android:layout_height="100dp"
                android:layout_margin="5dp" />

            <Button
                android:id="@+id/button_5"
                android:layout_width="100dp"
                android:text="5"
                android:layout_height="100dp"
                android:layout_margin="5dp" />

            <Button
                android:id="@+id/button_6"
                android:text="6"
                android:layout_width="100dp"
                android:layout_height="100dp"
                android:layout_margin="5dp" />

            <Button
                android:id="@+id/button_7"
                android:layout_width="100dp"
                android:text="7"
                android:layout_height="100dp"
                android:layout_margin="5dp" />
        </LinearLayout>
    </HorizontalScrollView>
</RelativeLayout>

TestActivity.java

public class TestActivity extends AppCompatActivity implements View.OnClickListener {
    View[] views = new View[7];
    int res[] = {R.id.button_1, R.id.button_2, R.id.button_3, R.id.button_4, R.id.button_5, R.id.button_6, R.id.button_7};
    HorizontalScrollView horizontalScrollView;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_scroll);
        for (int i = 0; i < res.length; i++) {
            views[i] = findViewById(res[i]);
            views[i].setOnClickListener(this);
        }
        horizontalScrollView = (HorizontalScrollView) findViewById(R.id.horizon);
    }

    @Override
    public void onClick(View v) {
        int[] loc = new int[2];
        views[3].getLocationInWindow(loc);
        horizontalScrollView.scrollTo(loc[0], 0);

    }
}

My working example.

Upvotes: 1

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