Android GestureDetector: The GestureDetector App You Must Learn

Carson_Ho

Android GestureDetector: The GestureDetector App You Must Learn

2019.10.21 08:11:25

preface

• Gesture recognition inAndroidThe applications developed are very common
• todaycarsonI will explain it to you in detailAndroidGesture recognition class:GestureDetectorClass usage. (including examples)

directory

Introduction to the

Below, I will introduce the usage interface & usage class of GestureDetector in detail with examples.

Interface 1: OnGestureListener

1. The role

Detect the following user operations on the screen: press momentarily, press, long press, tap, quickly slide the screen, and drag

2. Procedure

// Step 1: Create gesture detector instance & pass in OnGestureListener interface (need to duplicate corresponding method) // there are 3 constructors, Commonly used is the second / / 1. GestureDetector GestureDetector = new GestureDetector (GestureDetector. OnGestureListener listener); // 2. GestureDetector gestureDetector=new GestureDetector(Context context,GestureDetector.OnGestureListener listener); // 3. GestureDetector gestureDetector=new GestureDetector(Context context,GestureDetector.SimpleOnGestureListener listener); GestureDetector mGestureDetector = new GestureDetector(this, new GestureDetector.OnGestureListener() { // 1. Public Boolean onDown(MotionEvent e) {log. I ("MyGesture", "onDown"); return false; } // 2. The user touches the touch screen lightly and does not release or drag // the difference with onDown() : no release/drag // that is: When the user clicks, onDown () is executed, Public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); Public void onLongPress(MotionEvent e) {log. I ("MyGesture", "onLongPress"); } public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp");} public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp"); return true; } public Boolean onScroll(MotionEvent E1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll:"); return true; } // 6. User press the touch screen, move quickly and release // parameters: // e1: first ACTION_DOWN MotionEvent // e2: last ACTION_MOVE MotionEvent // velocityX: Speed of movement on the X axis, pixels per second // velocityY: The velocity of movement on the Y axis, Public Boolean onFling(MotionEvent E1, MotionEvent e2, float velocityX, float velocityY) {log. I ("MyGesture", "onFling"); return true; }}); // Step 2-1: Make a View detect gestures - rewrite the View's onTouch function and hand the View's touch event to the GestureDetector. View.setontouchlistener (new view.onTouchListener () {@override public Boolean onTouch(View v, MotionEvent event) { mGestureDetector.onTouchEvent(event); return true; // Return true to receive touch events completely}}); // Step 2-2: Make an Activity detect gestures: Rewrite the Activity's dispatchTouchEvent function to send the touchscreen event to the GestureDetector to handle, To respond to the user gestures @ Override public Boolean dispatchTouchEvent (MotionEvent ev) {mGestureDetector. OnTouchEvent (ev); // Make GestureDetector respond to touch events super.dispatchTouchEvent(EV); // Make the Activity respond to the touch event return false; }Copy the code

3. Examples

Now perform gesture detection on a TextView activity_main.xml

<? The XML version = "1.0" encoding = "utf-8"? > <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" > <TextView android:id="@+id/textView" android:layout_width="match_parent" android:layout_height="600dp" android:text="carson_ho Test" android:textAppearance="?android:attr/textAppearanceLarge" /> </LinearLayout>Copy the code

MainActivity.java

public class MainActivity extends AppCompatActivity { TextView mTextView; GestureDetector mGestureDetector; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Step 1: MGestureDetector = new GestureDetector(this, new GestureDetector.OnGestureListener() { // 1. Public Boolean onDown(MotionEvent e) {log. I ("MyGesture", "onDown"); return false; } // 2. The user touches the touch screen lightly and does not release or drag // the difference with onDown() : no release/drag // that is: When the user clicks, onDown () is executed, Public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); Public void onLongPress(MotionEvent e) {log. I ("MyGesture", "onLongPress"); } public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp");} public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp"); return true; } public Boolean onScroll(MotionEvent E1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll:"); return true; } // 6. User press the touch screen, move quickly and release // parameters: // e1: first ACTION_DOWN MotionEvent // e2: last ACTION_MOVE MotionEvent // velocityX: Speed of movement on the X axis, pixels per second // velocityY: The velocity of movement on the Y axis, Public Boolean onFling(MotionEvent E1, MotionEvent e2, float velocityX, float velocityY) {log. I ("MyGesture", "onFling"); return true; }}); // Step 2: Let TextView detect gestures: MTextView = (TextView) findViewById(R.id.extView); mTextView = (TextView) findViewById(R.ID.extView); mTextView.setOnTouchListener(new View.OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { mGestureDetector.onTouchEvent(event); return false; }}); }}Copy the code

4. The schematic

I tested it by making a series of gestures on the screen

Interface 2: OnDoubleTapListener

1. The role

Detect that the user clicks or double-clicks the screen

2. Procedure

// Step 1: Create gesture detector instance If the OnDoubleTapListener interface is used, the GestureDetector interface needs to be used. If the OnDoubleTapListener interface is used, the GestureDetector interface must be passed to the OnGestureListener interface. You must also implement the OnGestureListener interface // there are three constructors, Commonly used is the second / / 1. GestureDetector GestureDetector = new GestureDetector (GestureDetector. OnGestureListener listener); // 2. GestureDetector gestureDetector=new GestureDetector(Context context,GestureDetector.OnGestureListener listener); // 3. GestureDetector gestureDetector=new GestureDetector(Context context,GestureDetector.SimpleOnGestureListener listener); GestureDetector mGestureDetector = new GestureDetector(this, new GestureDetector.OnGestureListener() { // 1. Public Boolean onDown(MotionEvent e) {log. I ("MyGesture", "onDown"); return false; } // 2. The user touches the touch screen lightly and does not release or drag // the difference with onDown() : no release/drag // that is: When the user clicks, onDown () is executed, Public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); Public void onLongPress(MotionEvent e) {log. I ("MyGesture", "onLongPress"); } public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp");} public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp"); return true; } public Boolean onScroll(MotionEvent E1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll:"); return true; } // 6. User press the touch screen, move quickly and release // parameters: // e1: first ACTION_DOWN MotionEvent // e2: last ACTION_MOVE MotionEvent // velocityX: Speed of movement on the X axis, pixels per second // velocityY: The velocity of movement on the Y axis, Public Boolean onFling(MotionEvent E1, MotionEvent e2, float velocityX, float velocityY) {log. I ("MyGesture", "onFling"); return true; }}); // Step 2: Create & set OnDoubleTapListener interface implementation class mGestureDetector. SetOnDoubleTapListener (new GestureDetector. OnDoubleTapListener () {/ / 1. Click event / / about OnDoubleTapListener onSingleTapConfirmed () and OnGestureListener onSingleTapUp () / / onSingleTapConfirmed: the difference between // onSingleTapUp: // onSingleTapUp: Public Boolean onSingleTapConfirmed(MotionEvent e) {log. I ("MyGesture", "onSingleTapConfirmed"); return false; Public Boolean onDoubleTap(MotionEvent e) {log. I ("MyGesture", "onDoubleTap"); return false; } // other actions that occur between double clicks after the onDoubleTap is triggered, including down, up, and Move events; public boolean onDoubleTapEvent(MotionEvent e) { Log.i("MyGesture", "onDoubleTapEvent"); return false; }}); // Step 3-1: Make a View detect gestures - rewrite the View's onTouch function and hand the View's touch event to the GestureDetector. View.setontouchlistener (new view.onTouchListener () {@override public Boolean onTouch(View v, MotionEvent event) { mGestureDetector.onTouchEvent(event); return true; // Return true to receive touch events completely}}); // Step 3-2: Make an Activity detect gestures: Rewrite the Activity's dispatchTouchEvent function to send the touchscreen event to the GestureDetector to handle, To respond to the user gestures @ Override public Boolean dispatchTouchEvent (MotionEvent ev) {mGestureDetector. OnTouchEvent (ev); // Make GestureDetector respond to touch events super.dispatchTouchEvent(EV); // Make the Activity respond to the touch event return false; }Copy the code

3. Examples

Now perform gesture detection on a TextView activity_main.xml

<? The XML version = "1.0" encoding = "utf-8"? > <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" > <TextView android:id="@+id/textView" android:layout_width="match_parent" android:layout_height="600dp" android:text="carson_ho Test" android:textAppearance="?android:attr/textAppearanceLarge" /> </LinearLayout>Copy the code

MainActivity.java

public class MainActivity extends AppCompatActivity { TextView mTextView; GestureDetector mGestureDetector; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Step 1: MGestureDetector = new GestureDetector(this, new GestureDetector.OnGestureListener() { // 1. Public Boolean onDown(MotionEvent e) {log. I ("MyGesture1", "onDown"); return false; } // 2. The user touches the touch screen lightly and does not release or drag // the difference with onDown() : no release/drag // that is: When the user clicks, onDown () is executed, Public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); Public void onLongPress(MotionEvent e) {log. I ("MyGesture", "onLongPress"); } public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp");} public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp"); return true; } public Boolean onScroll(MotionEvent E1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll:"); return true; } // 6. User press the touch screen, move quickly and release // parameters: // e1: first ACTION_DOWN MotionEvent // e2: last ACTION_MOVE MotionEvent // velocityX: Speed of movement on the X axis, pixels per second // velocityY: The velocity of movement on the Y axis, Public Boolean onFling(MotionEvent E1, MotionEvent e2, float velocityX, float velocityY) {log. I ("MyGesture", "onFling"); return true; }}); // Step 2: Create & set OnDoubleTapListener interface implementation class mGestureDetector. SetOnDoubleTapListener (new GestureDetector. OnDoubleTapListener () {/ / 1. Click event / / about OnDoubleTapListener onSingleTapConfirmed () and OnGestureListener onSingleTapUp () / / onSingleTapConfirmed: the difference between // onSingleTapUp: // onSingleTapUp: Public Boolean onSingleTapConfirmed(MotionEvent e) {log. I ("MyGesture", "onSingleTapConfirmed"); return false; Public Boolean onDoubleTap(MotionEvent e) {log. I ("MyGesture", "onDoubleTap"); return false; } // other actions that occur between double clicks after the onDoubleTap is triggered, including down, up, and Move events; public boolean onDoubleTapEvent(MotionEvent e) { Log.i("MyGesture", "onDoubleTapEvent"); return false; }}); MTextView = (TextView) findViewById(R.id.extView); mTextView = (TextView) findViewById(R.id.extView); mTextView.setOnTouchListener(new View.OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { mGestureDetector.onTouchEvent(event); return true; }}); }}Copy the code

4. Test the effect

The log effect is as follows

Use the class: SimpleOnGestureListener

1. The role

The gesture detection function of the two interfaces is integrated

2. Differences between the two interfaces

• Functions in the OnGestureListener and OnDoubleTapListener interfaces are mandatory overridden
• The SimpleOnGestureListener class, on the other hand, can be optionally overwritten, because the SimpleOnGestureListener class already implements all of the interface functions, except that they are empty

3. Procedure

// Step 1: Create gesture detector instance // there are three constructors, Here is the third / / 1. GestureDetector GestureDetector = new GestureDetector (GestureDetector. OnGestureListener listener); // 2. GestureDetector gestureDetector=new GestureDetector(Context context,GestureDetector.OnGestureListener listener); // 3. GestureDetector gestureDetector=new GestureDetector(Context context,GestureDetector.SimpleOnGestureListener listener); GestureDetector mGestureDetector = new GestureDetector(this, New GestureDetector. SimpleOnGestureListener () {/ / / 1 / OnGestureListener interface function. Public Boolean onDown(MotionEvent e) {log. I ("MyGesture1", "onDown"); return false; } // 2. The user touches the touch screen lightly and does not release or drag // the difference with onDown() : no release/drag // that is: When the user clicks, onDown () is executed, Public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); Public void onLongPress(MotionEvent e) {log. I ("MyGesture", "onLongPress"); } public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp");} public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp"); return true; } public Boolean onScroll(MotionEvent E1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll:"); return true; } // 6. User press the touch screen, move quickly and release // parameters: // e1: first ACTION_DOWN MotionEvent // e2: last ACTION_MOVE MotionEvent // velocityX: Speed of movement on the X axis, pixels per second // velocityY: The velocity of movement on the Y axis, Public Boolean onFling(MotionEvent E1, MotionEvent e2, float velocityX, float velocityY) {log. I ("MyGesture", "onFling"); return true; } // OnDoubleTapListener function // 1. Click event / / about OnDoubleTapListener onSingleTapConfirmed () and OnGestureListener onSingleTapUp () / / onSingleTapConfirmed: the difference between // onSingleTapUp: // onSingleTapUp: Public Boolean onSingleTapConfirmed(MotionEvent e) {log. I ("MyGesture", "onSingleTapConfirmed"); return false; Public Boolean onDoubleTap(MotionEvent e) {log. I ("MyGesture", "onDoubleTap"); return false; } // other actions that occur between double clicks after the onDoubleTap is triggered, including down, up, and Move events; public boolean onDoubleTapEvent(MotionEvent e) { Log.i("MyGesture", "onDoubleTapEvent"); return false; }}); // Step 2-1: Make a View detect gestures - rewrite the View's onTouch function and hand the View's touch event to the GestureDetector. View.setontouchlistener (new view.onTouchListener () {@override public Boolean onTouch(View v, MotionEvent event) { mGestureDetector.onTouchEvent(event); return true; // Return true to receive touch events completely}}); // Step 2-2: Make an Activity detect gestures: Rewrite the Activity's dispatchTouchEvent function to send the touchscreen event to the GestureDetector to handle, To respond to the user gestures @ Override public Boolean dispatchTouchEvent (MotionEvent ev) {mGestureDetector. OnTouchEvent (ev); // Make GestureDetector respond to touch events super.dispatchTouchEvent(EV); // Make the Activity respond to the touch event return false; }Copy the code

4. Examples

Now perform gesture detection on a TextView activity_main.xml

<? The XML version = "1.0" encoding = "utf-8"? > <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" > <TextView android:id="@+id/textView" android:layout_width="match_parent" android:layout_height="600dp" android:text="carson_ho Test" android:textAppearance="?android:attr/textAppearanceLarge" /> </LinearLayout>Copy the code

MainActivity.java

public class MainActivity extends AppCompatActivity { TextView mTextView; GestureDetector mGestureDetector; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Step 1: MGestureDetector = new GestureDetector(this, New GestureDetector. SimpleOnGestureListener () {/ / / 1 / OnGestureListener interface function. Public Boolean onDown(MotionEvent e) {log. I ("MyGesture1", "onDown"); return false; } // 2. The user touches the touch screen lightly and does not release or drag // the difference with onDown() : no release/drag // that is: When the user clicks, onDown () is executed, Public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); public void onShowPress(MotionEvent e) {log. I ("MyGesture", "onShowPress"); Public void onLongPress(MotionEvent e) {log. I ("MyGesture", "onLongPress"); } public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp");} public Boolean onSingleTapUp(MotionEvent e) {log. I ("MyGesture", "onSingleTapUp"); return true; } public Boolean onScroll(MotionEvent E1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll:"); return true; } // 6. User press the touch screen, move quickly and release // parameters: // e1: first ACTION_DOWN MotionEvent // e2: last ACTION_MOVE MotionEvent // velocityX: Speed of movement on the X axis, pixels per second // velocityY: The velocity of movement on the Y axis, Public Boolean onFling(MotionEvent E1, MotionEvent e2, float velocityX, float velocityY) {log. I ("MyGesture", "onFling"); return true; } // OnDoubleTapListener function // 1. Click event / / about OnDoubleTapListener onSingleTapConfirmed () and OnGestureListener onSingleTapUp () / / onSingleTapConfirmed: the difference between // onSingleTapUp: // onSingleTapUp: Public Boolean onSingleTapConfirmed(MotionEvent e) {log. I ("MyGesture", "onSingleTapConfirmed"); return false; Public Boolean onDoubleTap(MotionEvent e) {log. I ("MyGesture", "onDoubleTap"); return false; } // other actions that occur between double clicks after the onDoubleTap is triggered, including down, up, and Move events; public boolean onDoubleTapEvent(MotionEvent e) { Log.i("MyGesture", "onDoubleTapEvent"); return false; }}); MTextView = (TextView) findViewById(R.id.extView); mTextView = (TextView) findViewById(R.id.extView); mTextView.setOnTouchListener(new View.OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { mGestureDetector.onTouchEvent(event); return true; }}); }}Copy the code

5. Test the effect

The log effect is as follows

At this point, the usage of the Android gesture recognition class GestureDetector class is explained.

conclusion

• This paper mainly focuses onAndroidGesture recognition class:GestureDetectorThe use of classes is fully explained
• And I’m going to continue with thatAndroidDevelopment of relevant knowledge, interested students can continue to pay attention to my blogDevelopment notes for Carson_Ho

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