Question

I am currently working on a multi-line Edit Text which might have placeholders within its Text. To circumvent modifications of these placeholders I added an onClickListener to the EditText widget which checks if the cursor position is within such a placeholder. In that case the placeholder should be selected, to prevent any modifications except of completely deleting it.

This works perfectly fine on my Android 2.3 device, but on Android 4.x the selection is modified after the onClick event and the cursor shows up at the beginnning of the placeholder without the selection.

Below the source of the onClickListener.

protected void textClickListener(EditText v) { 
    Pattern p = Pattern.compile(placeholderRegex);
    Matcher matcher = p.matcher(v.getText());
    int sel_start = v.getSelectionStart();
    int sel_end = v.getSelectionEnd();
    if (sel_start == -1) {
        return;
    }
    while (matcher.find()) {
        int pattern_start = matcher.start();
        int pattern_end = pattern_start + 25;
        if (pattern_start > sel_end) {
            continue;
        }
        if (pattern_end < sel_start) {
            continue;
        }
        v.setSelection(Math.min(sel_start, pattern_start), Math.max(sel_end, pattern_end));
        return;
    }
}

This code works fine, the setSelection is called with the correct values and the selection is actually set. I set a breakpoint on the Selection.setSelection method and found out that it is called from PositionListener, which is an inner class of android.widget.editor and this sets the selection length to 0. Below is the stack trace of this setSelection call:

Selection.setSelection(Spannable, int) line: 87 
Editor$InsertionHandleView.updateSelection(int) line: 3271  
Editor$InsertionHandleView(Editor$HandleView).positionAtCursorOffset(int, boolean) line: 3045   
Editor$InsertionHandleView(Editor$HandleView).updatePosition(int, int, boolean, boolean) line: 3064 
Editor$PositionListener.onPreDraw() line: 2047  
ViewTreeObserver.dispatchOnPreDraw() line: 671  
ViewRootImpl.performTraversals() line: 1820 
ViewRootImpl.doTraversal() line: 1000   
ViewRootImpl$TraversalRunnable.run() line: 4214 
Choreographer$CallbackRecord.run(long) line: 725    
Choreographer.doCallbacks(int, long) line: 555  
Choreographer.doFrame(long, int) line: 525  
Choreographer$FrameDisplayEventReceiver.run() line: 711 
Handler.handleCallback(Message) line: 615   
Choreographer$FrameHandler(Handler).dispatchMessage(Message) line: 92   
Looper.loop() line: 137 
ActivityThread.main(String[]) line: 4745    
Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]  
Method.invoke(Object, Object...) line: 511  
ZygoteInit$MethodAndArgsCaller.run() line: 786  
ZygoteInit.main(String[]) line: 553 
NativeStart.main(String[]) line: not available [native method]

Any ideas how to prevent this or how to set the selection after this PositionListener action?

Answer 1

Migrated From Question

Finally I found out, that you have to modify the selection in an OnTouchListener. And to make it even more complicated, you have to modify the selection in both calls of that listener (ACTION_DOWN, ACTION_UP). If you just do it once (as I did for performance reasons) it won’t work either. So the finally working code is:

@TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
protected boolean textTouchListener(EditText v, MotionEvent event) {
    placeholder_selected = false;
    Pattern p = Pattern.compile(placeHolderRegex);
    Matcher matcher = p.matcher(v.getText());
    int click_position = v.getOffsetForPosition(event.getX(), event.getY());
    int sel_start = click_position;
    int sel_end = click_position;
    if (sel_start == -1) {
        return false;
    }
    while (matcher.find()) {
        int pattern_start = matcher.start();
        int pattern_end = pattern_start + 25;
        if (pattern_start > sel_end) {
            continue;
        }
        if (pattern_end < sel_start) {
            continue;
        }
        v.setSelection(Math.min(sel_start, pattern_start), Math.max(sel_end, pattern_end));
        placeholder_selected = true;
        return true;
    }
    return false;
}

The OnClickListener is still needed for compability reasons, because the method getOffsetForPosition is not available for API levels below 11 (Honeycomb). Depending on the used API, only one of both listeners has to be executed.