android - 在Android中的画布上拖动形状

Question

我想在android中制作拖放游戏

在初始阶段，图像被绘制在画布上，在触摸事件中，它将从该位置移动并放置在特定点

我能为此做些什么？谁能给我一些建议

Answer 1

第 1 步您将需要覆盖onTouchEvent

关注 Snippet 将对您有所帮助。

拖动图像.java

import android.app.Activity;  
import android.os.Bundle;  
import android.widget.LinearLayout;  
import android.widget.TextView;  

public class dragimage extends Activity {  

 sample mView;  
 sample1 mView1;  

    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  

        setContentView(R.layout.main);  

    }  
}  

主要的.xml

  <!--?xml version="1.0" encoding="utf-8"?-->  

<
linearlayout xmlns: android = "http://schemas.android.com/apk/res/android"
android: orientation = "vertical"
android: layout_width = "fill_parent"
android: layout_height = "fill_parent" >

< com.mani.dragimage.sample
android: id = "@+id/view"
android: layout_width = "fill_parent"
android: layout_height = "fill_parent" / >


< /linearlayout >

示例.java

package com.mani.dragimage;  


import android.content.Context;  
import android.graphics.Bitmap;  
import android.graphics.BitmapFactory;  
import android.graphics.Canvas;  
import android.graphics.Color;  
import android.graphics.Paint;  
import android.graphics.Rect;  
import android.graphics.RectF;  
import android.graphics.Region;  
import android.util.AttributeSet;  
import android.view.Display;  
import android.view.MotionEvent;  
import android.view.View;  
import android.view.ViewConfiguration;  
import android.view.WindowManager;  
public final class sample extends View{  
    Paint mPaint;  
    Rect mRect;  
    Bitmap bitmap;  
    private int mTouchSlop;  
    private int mTouchMode;  
    int mScreenHeight;  
    int mScreenWidth;  
    int prevX;  
    int prevY;  
    static final int TOUCH_MODE_TAP = 1;  
    static final int TOUCH_MODE_DOWN = 2;  
    final int mImageWidth = 100;  
    final int mImageHeight = 100;  
    Rect mImagePosition;  
    Region mImageRegion;  
    boolean canImageMove;  

 public sample(Context context,AttributeSet attrs)  
 {  
     super(context,attrs);  
     bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.chrome);  
     mPaint = new Paint();  
     mPaint.setTextSize(25);  
     mPaint.setColor(0xFF0000FF);  
     //Size for image  
     mImagePosition = new Rect(10,10,mImageWidth,mImageHeight);  
     mImageRegion = new Region();  
     mImageRegion.set(mImagePosition);  
     final ViewConfiguration configuration = ViewConfiguration.get(context);  
     mTouchSlop = configuration.getScaledTouchSlop();  
     Display display = (WindowManager)context.getSystemService(context.WINDOW_SERVICE)).getDefaultDisplay();    
     mScreenHeight = display.getHeight();   
     mScreenWidth = display.getWidth();  
     canImageMove = false;  
 }  


 public boolean onTouchEvent(MotionEvent event)  
 {  
  int positionX = (int)event.getRawX();  
  int positionY = (int)event.getRawY();  

  switch(event.getAction())  
        {  
       case MotionEvent.ACTION_DOWN: {  
          mTouchMode = TOUCH_MODE_DOWN;  

         if(mImageRegion.contains(positionX, positionY))  
      {  
       prevX = positionX;  
       prevY = positionY;  
      canImageMove = true;  
      }  
       }  
       break;  

       case MotionEvent.ACTION_MOVE:   
       {  
       if(canImageMove == true)  
        {  
   // Check if we have moved far enough that it looks more like a  
   // scroll than a tap  
       final int distY = Math.abs(positionY - prevY);  
       final int distX = Math.abs(positionX - prevX);  

          if (distX > mTouchSlop || distY > mTouchSlop)  
          {  
      int deltaX =  positionX-prevX ;  
    int deltaY =  positionY-prevY;  
    // Check if delta is added, is the rectangle is within the visible screen  
    if((mImagePosition.left+ deltaX) > 0 && ((mImagePosition.right +deltaX) < mScreenWidth )  && (mImagePosition.top +deltaY) >0 && ((mImagePosition.bottom+deltaY)))  
     {  
    // invalidate current position as we are moving...  
     mImagePosition.left = mImagePosition.left + deltaX;  
     mImagePosition.top = mImagePosition.top + deltaY;  
     mImagePosition.right = mImagePosition.left + mImageWidth;  
     mImagePosition.bottom = mImagePosition.top + mImageHeight;  
     mImageRegion.set(mImagePosition);  
     prevX = positionX;  
     prevY = positionY;  

     invalidate();  
     }  
           }  
         }   
        }     
 break;  
       case MotionEvent.ACTION_UP:   
        canImageMove = false;  
        break;   
       }  
  return true;  
 }  

 @Override  
 public void onDraw(Canvas canvas)  
 {  
  Paint paint = new Paint();  
  paint.setStyle(Paint.Style.FILL);  

  // make the entire canvas white  
  paint.setColor(Color.CYAN);  
  Rect rect = new Rect(0,0,this.getWidth(),this.getHeight());  
  canvas.drawRect(mImagePosition, paint);   
  //canvas.drawBitmap(bitmap, null,mImagePosition, null);  
 }  


}