Question

I have a Horizontal Scroll view in my layout. It contains a a linear layout(orientation vertical) which in turn contains buttons. in this area I can horizontally scroll (The buttons don’t fit together in one screen at a time in most phones). Android provides me this comfort. Now below this horizontal scroll view, there is a Relative layout.
Now what I want is, when I swipe horizontally in the Relative Layout, I want the buttons in the horizontal scroll view to scroll.
I have tried to implement this by overriding the onTouchEvent(). The problem with this is that, the buttons scroll infinitely(they go out of the screen). I am not able to put a limit. I tried to put a limit. But some how it exceeds the limit by 1 and stops. Then I am not able to scroll.

This is my layout :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:focusableInTouchMode="true" >

    <HorizontalScrollView xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="wrap_content" android:layout_height="wrap_content">
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"  
        android:id="@+id/llt"
        >

        <Button
        android:id="@+id/login"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:background="@drawable/button1"
        style="@style/ButtonText"
       android:text="Groups" />

        <Button 
            android:id="@+id/login1"
            android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:background="@drawable/button1"
        style="@style/ButtonText"
            android:text="QandA"/>
                <Button 
            android:id="@+id/login2"
            android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:background="@drawable/button1"
            style="@style/ButtonText" 
            android:text="Pending Requests"/>
            <Button
            android:id="@+id/login3"
            android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:background="@drawable/button1"
            style="@style/ButtonText"
            android:text="Settings"
            ></Button>
                        <Button 
            android:id="@+id/login4"
            android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:background="@drawable/button1"
        style="@style/ButtonText" 
            android:text="Help"/>
    </LinearLayout>        
        </HorizontalScrollView>

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/rl1"
     android:layout_width="fill_parent"
    android:layout_height="fill_parent" 
   >
    .
    .
    .

This is what I have tried :

@Override 
 public boolean onTouchEvent(MotionEvent event) {
   switch (event.getAction()) {
       case MotionEvent.ACTION_DOWN: {
           currentX = (int) event.getRawX();
           currentY = (int) event.getRawY();
           break;
       }

       case MotionEvent.ACTION_MOVE: {
           int x2 = (int) event.getRawX();
           int y2 = (int) event.getRawY();
           if(location1[0]<=leftconst&&(location2[0]+rightmost.getWidth())>=rightconst)
           {
           llt.scrollBy(currentX - x2 ,0);
           }
           currentX = x2;
           currentY = y2;
           break;
       }   
       case MotionEvent.ACTION_UP: {
           break;
       }
   }
     return true; 
 }

leftconst and rightconst are equal to 3 and screenwidth, respectively. But when scrolling it it stops a both ends. Then after that scrolling is not possible. leftmost is the button with id login and rightmost is the button with id login4

Answer 1

After analyzing my own code more deeply, I found that the limits made the scrolling stop forever(it should not stop if the user is scrolling the other way). So I have added another check in the if statement to the check the direction of scrolling (by storing the previous position).

case MotionEvent.ACTION_MOVE: {
           int x2 = (int) event.getRawX();
           int y2 = (int) event.getRawY();
           int location1[] = new int[2];
           int location2[]=new int[2];
           leftmost.getLocationOnScreen(location1);
           rightmost.getLocationOnScreen(location2);
          Toast.LENGTH_SHORT).show();
           if((x2-currentX<0||location1[0]+1<leftconst)&&((location2[0]+rightmost.getWidth())+1>rightconst||x2-currentX>0))
           {
           llt.scrollBy(currentX - x2 ,0);
           }
           currentX = x2;
           currentY = y2;
           break;
       }

Edit
A more better and simpler solution without the if statement itself. Instead of scrolling the LinearLayout(llt), just scroll the **HorizontalScrollView** itself! There is no need to specify any limit as the HorizontalScrollView takes care of that.

case MotionEvent.ACTION_MOVE: {
           int x2 = (int) event.getRawX();
           int y2 = (int) event.getRawY();
           hscrv.scrollBy(currentX - x2 ,0);
           currentX = x2;
           currentY = y2;
           break;
       }

hscrv is the horizontal scroll view containing the linear layout and the buttons.