Android Developers Maximum: Cannot detect MotionEvent.ACTION_MOVE and ACTION

Refer to former exercises, "Detect single touch on custom View to draw icon on canvas" and "Detect multi touch on custom View to draw icons on canvas"; true is return from onTouchEvent() method of the custom view, indicate that the event was handled.

If false is returned from onTouchEvent() method, indicate that your code will not handle the events, and the system will not pass you the subsequent events such as MotionEvent.ACTION_MOVE and MotionEvent.ACTION_UP.

This example show two custome View, MyView on left side and MyView2 on right side. MyView handle user touch and display icon in onTouchEvent() method and return true. MyView2 do the same job by extending MyView, but return false in onTouchEvent() method. It can be noticed that MyView2 on right side can detect MotionEvent.ACTION_DOWN only, not MotionEvent.ACTION_MOVE and MotionEvent.ACTION_UP.

Modify from last the exercise "Detect multi touch on custom View to draw icons on canvas", create MyView2.java extends MyView, override onTouchEvent() to return false.

package com.example.androiddrawinview;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;

public class MyView2 extends MyView {

 public MyView2(Context context) {
  super(context);
  // TODO Auto-generated constructor stub
 }

 public MyView2(Context context, AttributeSet attrs) {
  super(context, attrs);
  // TODO Auto-generated constructor stub
 }

 public MyView2(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  // TODO Auto-generated constructor stub
 }

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  super.onTouchEvent(event);
  return false;
 }

}

Modify /res/layout/fragment_main.xml to replace the MyView on right hand side to MyView2.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.androiddrawinview.MainActivity$PlaceholderFragment" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://arteluzevida.blogspot.com/"
        android:textStyle="bold" />

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

        <com.example.androiddrawinview.MyView
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:layout_margin="10dp" />
        <com.example.androiddrawinview.MyView2
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:layout_margin="10dp" />
    </LinearLayout>

</LinearLayout>

Download the files.

Cannot detect MotionEvent.ACTION_MOVE and ACTION_UP