code_21-22_gestures.txt

[source code] Android Development Tutorials 21 and 22 - Gestures

***** Tutorial Notes

** 21 – Gestures
Touch Gestures include: Scroll, Fling, Double-Tap, and Swipe.

//Layout//
1. Start with a EmptyActivity and delete Hello World. Add a Large Text with the id buckysMessage. TextView text will change to reflect the state the gesture you perform.

//Java//
1. Get your imports including android.support.v4.view.GestureDetectorCompat
2. Activity implements GestureDetector.OnGestureListener, GestureDetector.OnDoubleTapListener
NOTE: Don't change the Activity to ActionBarActivity like Bucky. You will get rendering problems

3. Add variables  for TextView and gestureDetector
4. Use Alt-Ins to implement all the required methods (below on Create()
5. In onCreate(), get a ref to TextView and create the gesture object and implement the listener.
6. Set the actions for the call back methods e.g. buckysMessage.setText("onSingleTapConfirmed"); 
NOTE: Be sure to return true in event overrides to consume the touch event.

** 22 - Running the Gesture App
NOTE: V7. ActionBarActivity is a child of support.v4.FragmentActivity, which is a child of Activity

We need one last statement to check touch events for gesture events.
1. Override Activity onTouchEvent (after Gestures)
2. Add a line to check for gestures i.e. this.gestureDetector.onTouchEvent(event);
Run and test the app.


***** manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.thenewboston.swiperdiaper">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

***** MainActivity.java
package com.thenewboston.swiperdiaper;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import android.view.MotionEvent;
import android.view.GestureDetector;
import android.support.v4.view.GestureDetectorCompat;

public class MainActivity extends AppCompatActivity implements GestureDetector.OnGestureListener,
        GestureDetector.OnDoubleTapListener{

    private TextView buckysMessage;
    private GestureDetectorCompat gestureDetector;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        buckysMessage = (TextView)findViewById(R.id.buckysMessage);
        this.gestureDetector = new GestureDetectorCompat(this,this);
        gestureDetector.setOnDoubleTapListener(this);
    }

    //////////////// Begin Gestures ////////////////

    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        buckysMessage.setText("onSingleTapConfirmed");
        return true;
    }

    @Override
    public boolean onDoubleTap(MotionEvent e) {
        buckysMessage.setText("onDoubleTap");
        return true;
    }

    @Override
    public boolean onDoubleTapEvent(MotionEvent e) {
        buckysMessage.setText("onDoubleTapEvent");
        return true;
    }

    @Override
    public boolean onDown(MotionEvent e) {
        buckysMessage.setText("onDown");
        return true;
    }

    @Override
    public void onShowPress(MotionEvent e) {
        buckysMessage.setText("onShowPress");
    }

    @Override
    public boolean onSingleTapUp(MotionEvent e) {
        buckysMessage.setText("onSingleTapUp");
        return true;
    }

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
        buckysMessage.setText("onScroll");
        return true;
    }

    @Override
    public void onLongPress(MotionEvent e) {
        buckysMessage.setText("onLongPress");
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        buckysMessage.setText("onFling");
        return true;
    }

    //////////////// End Gestures ////////////////

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

***** activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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: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.thenewboston.swiperdiaper.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="@string/buckys_text"
        android:id="@+id/buckysMessage"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

***** strings.xml
<resources>
    <string name="app_name">SwiperDiaper</string>
    <string name="buckys_text">Gestures</string>
</resources>