移动开发例题4_5

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:orientation="vertical"
        >

    <com.example.ex4_5.HandWrite
        android:id="@+id/hand"
        android:layout_height="280dp"
        android:layout_width="match_parent"
        />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:gravity="center_horizontal"
        >
        <Button
            android:id="@+id/clear"
            android:layout_width="200dp"
            android:layout_height="wrap_content"
            android:text="清屏"
            />
    </LinearLayout>


</LinearLayout>

package com.example.ex4_5;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;


public class MainActivity extends Activity {
    private HandWrite handWrite=null;
    private Button clear =null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        handWrite=(HandWrite)findViewById(R.id.hand);
        clear=(Button)findViewById(R.id.clear);
        clear.setOnClickListener(new mClick());
    }

    public class mClick implements OnClickListener{
        public void onClick(View v){
            handWrite.clear();
        }

    }
}

package com.example.ex4_5;
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.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class HandWrite extends View {
   Paint paint=null;
   Bitmap originalBitmap=null;
   Bitmap new1_Bitmap=null;
   Bitmap new2_Bitmap=null;
   float startX=0,startY=0;
   float clickX=0,clickY=0;
   boolean isMove=true;
   boolean isClear=false;
   int color= Color.GREEN;
   float strokeWidth=2.0f;

   public HandWrite(Context context, AttributeSet attrs){
       super(context,attrs);
       originalBitmap= BitmapFactory.decodeResource(getResources(),R.drawable.icon2).copy(Bitmap.Config.ARGB_8888,true);
       new1_Bitmap=Bitmap.createBitmap(originalBitmap);
   }
   public void clear(){
       isClear=true;
       new2_Bitmap=Bitmap.createBitmap(originalBitmap);
       invalidate();
   }
   public void setstyle(float strokeWidth){
       this.strokeWidth=strokeWidth;
   }
   @Override
    protected void onDraw(Canvas canvas){
       super.onDraw(canvas);
       canvas.drawBitmap(HandWriting(new1_Bitmap),0,0,null);
   }
   public Bitmap HandWriting(Bitmap o_Bitmap){
       Canvas canvas=null;
       if(isClear){
           canvas=new Canvas(new2_Bitmap);
       }else {
           canvas=new Canvas(o_Bitmap);
       }
       paint=new Paint();
       paint.setStyle(Paint.Style.STROKE);
       paint.setAntiAlias(true);
       paint.setColor(color);
       paint.setStrokeWidth(strokeWidth);
       if(isMove){
           canvas.drawLine(startX,startY,clickX,clickY,paint);
       }
       startX=clickX;
       startY=clickY;
       if(isClear){
           return new2_Bitmap;
       }
       return o_Bitmap;
   }
   @Override
    public boolean onTouchEvent(MotionEvent event){
      clickX=event.getX();
      clickY=event.getY();
      if(event.getAction()==MotionEvent.ACTION_DOWN){
          isMove=false;
          invalidate();
          return true;
      }else if(event.getAction()==MotionEvent.ACTION_MOVE){
          isMove=true;
          invalidate();
          return true;

      }
      return  super.onTouchEvent(event);

   }
}