This article helps to making Scrollable TextView using TextView with dispatchKeyEvent
we can make a scrollable textview while implement the setMovementMethod and dispatchKeyEvent.
1. private TextView mTextView;
2. Set the Required data in the TextView
mTextView = (TextView) findViewById(R.id.textView1);
mTextView.setText("this is for testing \nthis is for testing \nthis is for testing
\nthis is for testing \nthis is for testing \nthis is for testing \n");
3. mTextView.setMovementMethod(new ScrollingMovementMethod(){.....})
4. Override the methods in ScrollingMovementMethod
new ScrollingMovementMethod() {
public void onTakeFocus(TextView widget, Spannable text, int dir) {}
@Override
public boolean onKeyDown(TextView widget, Spannable buffer,
int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_DOWN:
for (int i = 0, scrollAmount = getScrollAmount(widget); i < scrollAmount; i++) {
down(widget, buffer);
}
return true;
case KeyEvent.KEYCODE_DPAD_UP:
for (int i = 0, scrollAmount = getScrollAmount(widget); i < scrollAmount; i++) {
up(widget, buffer);
}
return true;
default:
return super.onKeyDown(widget, buffer, keyCode, event);
}
}
private int getScrollAmount(TextView widget) {
final int visibleLineCount = (int) ((1f * widget.getHeight()) / widget
.getLineHeight());
int scrollAmount = visibleLineCount - 1;
if (scrollAmount < 1) {
scrollAmount = 1;
}
return scrollAmount;
}
}
5. Call the dispatch method in your code
mTextView.dispatchKeyEvent(event);
SAMPLE
public class MainActivity extends Activity {
/** Called when the activity is first created. */
private TextView mTextView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mTextView = (TextView) findViewById(R.id.textView1);
mTextView
.setText("this is for testing \nthis is for testing \nthis is for testing \nthis is for testing \nthis is for testing \nthis is for testing \n");
mTextView.setMovementMethod(new ScrollingMovementMethod() {
public void onTakeFocus(TextView widget, Spannable text, int dir) {
}
@Override
public boolean onKeyDown(TextView widget, Spannable buffer,
int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_DOWN:
for (int i = 0, scrollAmount = getScrollAmount(widget); i < scrollAmount; i++) {
down(widget, buffer);
}
return true;
case KeyEvent.KEYCODE_DPAD_UP:
for (int i = 0, scrollAmount = getScrollAmount(widget); i < scrollAmount; i++) {
up(widget, buffer);
}
return true;
default:
return super.onKeyDown(widget, buffer, keyCode, event);
}
}
private int getScrollAmount(TextView widget) {
final int visibleLineCount = (int) ((1f * widget.getHeight()) / widget
.getLineHeight());
int scrollAmount = visibleLineCount - 1;
if (scrollAmount < 1) {
scrollAmount = 1;
}
return scrollAmount;
}
});
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_DOWN:
return true;
case KeyEvent.KEYCODE_DPAD_UP:
mTextView.dispatchKeyEvent(event);
return true;
default:
return super.onKeyDown(keyCode, event);
}
}
}
