Android使用SurfaceView实现签名板

Posted 2023-03-23 kiba518

SurfaceView使用

首先创建一个SurfaceViewSign类，继承SurfaceView类，继承 SurfaceHolder.Callback和Runnable接口，代码如下：

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
​
public class SurfaceViewSign extends SurfaceView implements SurfaceHolder.Callback,Runnable 
​
    //SurfaceHolder
    private SurfaceHolder holder;
    //用于绘图的Canvas
    private Canvas canvas;
    //子线程标志位
    private boolean isDrawing;
    //画笔
    private Paint paint;
    //路径
    private Path path;
​
    private Bitmap bitmap;
    private Canvas getCanvas;
    /**
     * 获取mCanvas里的bitmap
     * */
    public Bitmap getBitmap() 
        getCanvas.drawColor(Color.WHITE);//画布背景色
        getCanvas.drawPath(path, paint);
        getCanvas.save();
        getCanvas.restore();
        return bitmap;
        //region bitmap压缩到文件
//        File file = new File(Environment.getExternalStorageDirectory().getPath() + "/share_pic.png");// 保存到sdcard根目录下，文件名为share_pic.png
//        FileOutputStream fos = null;
//        try 
//            fos = new FileOutputStream(file);
//            bitmap.compress(Bitmap.CompressFormat.PNG, 50, fos);
//
//         catch (FileNotFoundException e) 
//            // TODO Auto-generated catch block
//            e.printStackTrace();
//        
//        try 
//            fos.close();
//         catch (IOException e) 
//            // TODO Auto-generated catch block
//            e.printStackTrace();
//        
        //endregion
    
​
    public SurfaceViewSign(Context context) 
        super(context);
        initView();
    
​
​
    public SurfaceViewSign(Context context, AttributeSet attrs) 
        super(context, attrs);
        initView();
    
​
    public SurfaceViewSign(Context context, AttributeSet attrs, int defStyleAttr) 
        super(context, attrs, defStyleAttr);
        initView();
    
​
    private void initView() 
        bitmap = Bitmap.createBitmap(1000,1000, Bitmap.Config.ARGB_8888);
        getCanvas = new Canvas(bitmap);
        holder = getHolder();
        //添加回调
        holder.addCallback(this);
        path =new Path();
        //初始化画笔
        paint =new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(6);
        paint.setAntiAlias(true);
        paint.setColor(Color.RED);//画笔颜色
        setFocusable(true);
        setFocusableInTouchMode(true);
        this.setKeepScreenOn(true);
​
​
    
    //Surface的生命周期
    @Override
    public void surfaceCreated(SurfaceHolder holder) 
        isDrawing =true;
        new Thread(this).start();
    
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) 
​
    
​
    @Override
    public void surfaceDestroyed(SurfaceHolder holder) 
        isDrawing =false;
​
    
​
    @Override
    public void run() 
        long start =System.currentTimeMillis();
        while(isDrawing)
            draw();
            long end = System.currentTimeMillis();
            if(end-start<100)
                try
                    Thread.sleep(100-end+start);
                 catch (InterruptedException e) 
                    e.printStackTrace();
                
            
        
    
​
    private void draw() 
        try
            //锁定画布并返回画布对象
            canvas = holder.lockCanvas();
            canvas.drawColor(Color.WHITE);//设置画布背景色
            canvas.drawPath(path, paint);  //画线
​
        catch (Exception e)
        finally 
            if(canvas !=null)
                holder.unlockCanvasAndPost(canvas);//解锁
        
    
​
    /**
     * 绘制触摸滑动路径
     * @param event MotionEvent
     * @return true
     */
    @Override
    public boolean onTouchEvent(MotionEvent event) 
        int x=(int) event.getX();
        int y= (int) event.getY();
        switch (event.getAction())
            case MotionEvent.ACTION_DOWN:
                path.moveTo(x,y);
                break;
            case MotionEvent.ACTION_MOVE:
                path.lineTo(x,y);
                break;
            case MotionEvent.ACTION_UP:
                break;
        
        return true;
    
​
    /**
     * 清屏
     * @return true
     */
    public boolean reDraw()
        path.reset();
        return true;
    
​
​

​

然后创建一个测试Activity，然后编写他的页面代码如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:focusable="true"
    android:focusableInTouchMode="true"
    android:orientation="vertical"
    android:background="@color/white"
    tools:ignore="MissingClass">
    <com.kiba.test.control.surfaceview.SurfaceViewSign
        android:id="@+id/sv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        />
    <View
          android:layout_width="match_parent"
          android:layout_height="1dp"
          android:background="@color/red"></View>
    <ImageView
       android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        ></ImageView>
 
     
</LinearLayout>

然后在activity里编写点击事件如下：

@SingleClick
    @OnClick(R.id.imageView)
    public void ImageClick()
    
        Bitmap bitmap =sv.getBitmap();
        imageView.setImageBitmap(bitmap);
        imageView2.setImageBitmap(bitmap);
    

这样就实现了简单的签名，并且获取到了签名的图片，类型是bitmap。

效果图如下：

 

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