The Android custom control implements the small ball _android that moves with the finger

A small demo about a custom control that moves with the fingers of the ball.
First look at the effect of the picture:

The implementation code is as follows:

1. Custom Control class

Package Com.dc.customview.view;
Import Android.content.Context;
Import Android.graphics.Canvas;
Import Android.graphics.Color;
Import Android.graphics.Paint;
Import Android.util.AttributeSet;
Import android.view.MotionEvent;
Import Android.view.View;

Import Android.view.WindowManager;
  public class Drawcircle extends View {//The initial position of the circle private int x = 100;
  private int y = 100;
  
  Context context; /** * has a style resource file called * @param context * @param attrs * @param defstyle/Public drawcircle (context Contex
    T, AttributeSet attrs, int defstyle) {Super (context, attrs, Defstyle);
  This.context = context;  /** * XML Creation Call * @param context * @param attrs/Public drawcircle (context, AttributeSet attrs)
    {Super (context, attrs);
  This.context = context;
    /** * Java code creation Call * @param context/Public drawcircle (context) {super (context);
  This.context = context; } @Override protected void OnDraw (Canvas Canvas) {Super.ondraw (Canvas);
    Brush Paint Paint = new Paint ();

    Paint.setcolor (color.red);
  Draw the Circle//CX: The x coordinate of the center: the y-coordinate of the center//cy//radius: The radius of the circle//paint: The Brush canvas.drawcircle (x, y, paint); @Override public boolean ontouchevent (Motionevent event) {switch (event.getaction ()) {case Motionevent.
          
          Action_down:case MotionEvent.ACTION_MOVE:case motionevent.action_up://Get the x,y coordinates of the current touch point
          x = (int) event.getx ();
        

        y = (int) event.gety ();
    Break
    //Get screen width high windowmanager manager = (WindowManager) context.getsystemservice (Context.window_service);
    int width = Manager.getdefaultdisplay (). GetWidth ();
    
    int heigh = Manager.getdefaultdisplay (). GetHeight (); Redraw the circle, control the ball will not be moved out of the screen if (x>=20 && y>=20 && x<=width-20 && y<=heigh-90) {inval
    Idate ();
    //Handle the touch event yourself return true;

 }
  
}

2. Referencing custom controls

First: References in XML

<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:id= "@+id/rl" >
  
  <!--the full class name of the custom control-->
  <com.dc.customview.view.drawcircle
    Android : id= "@+id/circle"
    android:layout_width= "wrap_content"
    android:layout_height= "wrap_content" >
  </com.dc.customview.view.DrawCircle>

</RelativeLayout>

Second: References in code

Package Com.dc.customview;

Import com.dc.customview.view.DrawCircle;

Import Android.os.Bundle;
Import android.app.Activity;
Import Android.view.Menu;
Import Android.view.View;
Import Android.widget.RelativeLayout;

public class Mainactivity extends activity {

  @Override
  protected void onCreate (Bundle savedinstancestate) {
    super.oncreate (savedinstancestate);
    Setcontentview (r.layout.activity_main);
    
    Get the container
    relativelayout container = (relativelayout) Findviewbyid (R.ID.RL);
    
    Create a custom control
    drawcircle circle = new Drawcircle (this);
    
    Add to Container
    Container.addview (circle);
  }

Above, the demo will run to the simulator or mobile phone, you can achieve a red circle, with the finger touch move and move the effect.

The above is the entire content of this article, I hope to help you learn, but also hope that we support the cloud habitat community.