Hawaiʻi's Technology Community
Support Bounce Property for Scrollview in Android
In IPhone, scrollView.bounce is used to control the nice bouncing behavior for scrolling.
Let's create the similar support in Android :)
First, create a custom view
public class BouncingHorizentalScrollView extends HorizontalScrollView {
public static final int GAP = 100;
public BouncingHorizentalScrollView(Context context) {
super(context);
init();
}
public BouncingHorizentalScrollView( Context context, AttributeSet attrs){
super(context, attrs);
init();
}
public BouncingHorizentalScrollView( Context context,
AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
LayoutInflater inflater = (LayoutInflater) getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
inflater.inflate(R.layout.mygallery, this);
}
@override
public void fling(int velocityX) {
super.fling(velocityX);
int duration = calculate(velocityX, 0);
checkingFling( duration );
}
private void checkingFling(final int duration ){
postDelayed( new Runnable() {
@Override
public void run() {
int left = getScrollX();
boolean checked = false;
if ( left < GAP ){
smoothScrollBy( GAP - left, 0 );
checked = true;
}else{
View child = getChildAt(0);
int gap = left + getWidth() - ( child.getWidth() - GAP );
if ( gap > 0 ){
smoothScrollBy( -gap, 0 );
checked = true;
}
}
if ( checked ){
return;
}
int newDuration = duration - 200;
if ( newDuration > 0 ){
checkingFling( newDuration );
}
}
}, 200 );
}
private int calculate(int velocityX, int velocityY){
float ppi = getContext().getResources().getDisplayMetrics().density * 160.0f;
float mDeceleration = 9.8f // g (m/s^2)
* 39.37f // inch/meter
* ppi // pixels per inch
* ViewConfiguration.getScrollFriction();
float velocity = (float)Math.hypot(velocityX, velocityY);
return (int) (1000 * velocity / mDeceleration); // Duration is in
// milliseconds
}
public void scrollBy(int x, final int y) {
super.scrollBy(x, y);
postDelayed( new Runnable() {
@Override
public void run() {
int left = getScrollX();
if ( left < GAP ){
scrollTo( GAP, 0 );
} else {
View child = ETGallery.this.getChildAt(0);
int gap = left + getWidth() - ( child.getWidth() - GAP );
if ( gap > 0 ){
//scrollTo( child.getWidth() - GAP, 0 );
scrollBy( -gap , y);
}
}
}
}, 200);
}
public void adjustLeft(){
checkingFling(400);
}
public void animateToLeft(){
postDelayed( new Runnable() {
@Override
public void run() {
View child = getChildAt(0);
scrollTo( child.getWidth(), 0 );
postDelayed( new Runnable() {
@Override
public void run() {
fullScroll(View.FOCUS_LEFT);
adjustLeft();
}
}, 200);
}
}, 200);
}
}
in the layout file we specify the left-most and right-most padding area for bouncing.
<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/TableLayout01" android:layout_width="wrap_content"
android:layout_height="wrap_content">
<TableRow android:id="@+id/TableRow01" android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView android:id="@+id/leftPadding"
android:layout_width="100px"
android:layout_height="wrap_content" />
<!-- more items go here. -->
<TextView android:id="@+id/rightPadding"
android:layout_width="100px"
android:layout_height="wrap_content" />
</TableRow>
</TableLayout>
That's it.
Views: 8092
Replies to This Discussion
-
Permalink Reply by Daniel Leuck on
-
Thank you for sharing this code Hanning! I hope all is well with you.
-
-
Permalink Reply by WatchSound on
-
Thank you, Dan.
Daniel Leuck said:Thank you for sharing this code Hanning! I hope all is well with you. -
-
Permalink Reply by Windu Nurfebtiaman on
-
Hai..... I try your code but I got an error when I make this...the error in this line:
View child = ETGallery.this.getChildAt(0);
thanks for your help, I'm newbie in android programming..
btw sorry my english is not good.
-
-
-
HI, I have the same problem, what is ETGallery?
If i want use this code for vertical scroll (ScrollView), how i can modify it? Please help me!
Sorry for my bad english..
Windu Nurfebtiaman said:Hai..... I try your code but I got an error when I make this...the error in this line:
View child = ETGallery.this.getChildAt(0);
thanks for your help, I'm newbie in android programming..
btw sorry my english is not good.
-
© 2024 Created by Daniel Leuck.
Powered by
