Android 画图类View与SurfaceView之学习

最新推荐文章于 2025-08-22 17:02:47 发布

转载最新推荐文章于 2025-08-22 17:02:47 发布 · 61 阅读

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原文链接：http://www.cnblogs.com/leihupqrst/p/3730429.html

文章标签：

#移动开发 #java

本文介绍了一个使用Android SurfaceView进行Canvas绘图的例子。通过一个自定义的SurfaceView组件，实现了循环绘图的功能，并展示了如何锁定画布、绘制位图及基本图形。文章还提供了MainActivity的实现代码，用于初始化视图并响应按键事件来改变绘图位置。

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Canvas 的使用：

lockCanvas 锁定画布，绘图之前必须锁定画布才能得到当前画布对象

unlockCanvasAndPost 开始绘制时锁定画布，绘制完成之后解锁画布

TestSurfaceView.java 代码：

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class TestSurfaceView extends SurfaceView implements  SurfaceHolder.Callback {
	//控制循环
	private boolean mbLoop = false;
	
	//定义SurfaceHolder对象
	private SurfaceHolder mSurfaceHolder = null;
	private int miCount = 0;
	public int x = 50, y = 50;
	private int mWidth = 1280, mHeight = 720;
	private Bitmap mBitmap = null;

	public TestSurfaceView(Context context) {
		super(context);
		
		//实例化SurfaceHolder
		mSurfaceHolder = this.getHolder();
		
		//添加回调
		mSurfaceHolder.addCallback(this);
		this.setFocusable(true);
	}
	
	  public void setDisplayWH(int w, int h) {  
	        mWidth = w;  
	        mHeight = h;  
	    }
	  
	   public void setBitmap(Bitmap bitmap) {  
	        this.mBitmap = bitmap;  
	    }  

	@Override
	public void surfaceCreated(SurfaceHolder holder) {
		mbLoop = true;
		
		Thread th = new Thread(new Runnable(){

			@Override
			public void run() {
				while(mbLoop){
					try {
						Thread.sleep(200);
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
					synchronized(mSurfaceHolder){
						drawBitmap();
						DrawData();
					}
				}

			}
			
		});
		th.start();
		
	}

	@Override
	public void surfaceChanged(SurfaceHolder holder, int format, int width,
			int height) {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void surfaceDestroyed(SurfaceHolder holder) {
		// TODO Auto-generated method stub
		
	}  
	
    private void drawBitmap() {  
        // 锁定画布，得到canvas  
        if (mSurfaceHolder == null || this.mBitmap == null)  
            return;  
  
        Canvas canvas = mSurfaceHolder.lockCanvas();  
        if (canvas == null) {  
            return;  
        }  
  
        // 绘图  
        Paint paint = new Paint();  
        paint.setAntiAlias(true);  
        paint.setColor(Color.BLUE);  
  
        canvas.drawBitmap(this.mBitmap, 200, 0, paint);  
  
        // 绘制后解锁，绘制后必须解锁才能显示  
        mSurfaceHolder.unlockCanvasAndPost(canvas);  
    } 
    
    // 绘图方法  
    private void DrawData() {  
        if (mSurfaceHolder == null)  
            return;  
  
        // 锁定画布，得到canvas  
        Canvas canvas = mSurfaceHolder.lockCanvas();  
        if (canvas == null) {  
            return;  
        }  
  
        if (miCount < 100) {  
            miCount++;  
        } else {  
            miCount = 0;  
        }  
  
        // 绘图  
        Paint mPaint = new Paint();  
        mPaint.setAntiAlias(true);  
        mPaint.setColor(Color.BLACK);  
  
        // 绘制矩形--清屏作用  
        canvas.drawRect(0, 0, mWidth, mHeight, mPaint);  
          
        switch (miCount % 4) {  
        case 0:  
            mPaint.setColor(Color.BLUE);  
            break;  
        case 1:  
            mPaint.setColor(Color.GREEN);  
            break;  
        case 2:  
            mPaint.setColor(Color.RED);  
            break;  
        case 3:  
            mPaint.setColor(Color.YELLOW);  
            break;  
        default:  
            mPaint.setColor(Color.WHITE);  
            break;  
        }  
  
        // 绘制矩形--  
        canvas.drawCircle(x, y, 50, mPaint);  
          
        // 绘制后解锁，绘制后必须解锁才能显示  
        mSurfaceHolder.unlockCanvasAndPost(canvas);  
    }  
	
}

MainActivity代码：

import android.app.Activity;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;


public class MainActivity extends Activity {  
	    static final String TAG = "MainActivity";  
	    private TestSurfaceView mTestSurfaceView = null;  
	    private int mWidth = 0, mHeight = 0;  
	  
	    @Override  
	    public void onCreate(Bundle savedInstanceState) {  
	        super.onCreate(savedInstanceState);  
	  
	        initView();  
	  
	        startTestSurfaceView();  
	          
	        // setContentView(R.layout.main);  
	    }  
	  
	    void initView() {  
	        // 使用自定义的View  
	        mTestSurfaceView = new TestSurfaceView(this);  
	        setContentView(mTestSurfaceView);         
	        //获取手机分辨率
	        DisplayMetrics dm = new DisplayMetrics();  
	        getWindowManager().getDefaultDisplay().getMetrics(dm);  
	        mWidth = dm.widthPixels;  
	        mHeight = dm.heightPixels;  
	        Log.i(TAG, "Display Metrics width:" + mWidth + " mHeight:" + mHeight);  
	    }  
	  
	    @Override  
	    public boolean onCreateOptionsMenu(Menu menu) {  
	        getMenuInflater().inflate(R.menu.main, menu);  
	        return true;  
	    }  
	  
	    public boolean onKeyDown(int keyCode, android.view.KeyEvent event) {  
	        switch (keyCode) {  
	        case KeyEvent.KEYCODE_DPAD_DOWN:  
	            if (mTestSurfaceView.y >= mHeight)  
	                mTestSurfaceView.y = 0;  
	            mTestSurfaceView.y += 10;  
	            break;  
	        case KeyEvent.KEYCODE_DPAD_UP:  
	            if (mTestSurfaceView.y <= 0)  
	                mTestSurfaceView.y = mHeight;  
	            mTestSurfaceView.y -= 10;  
	            break;  
	        case KeyEvent.KEYCODE_DPAD_LEFT:  
	            if (mTestSurfaceView.x <= 0)  
	                mTestSurfaceView.x = mWidth;  
	            mTestSurfaceView.x -= 10;  
	            break;  
	        case KeyEvent.KEYCODE_DPAD_RIGHT:  
	            if (mTestSurfaceView.x >= mWidth)  
	                mTestSurfaceView.x = 0;  
	            mTestSurfaceView.x += 10;  
	            break;  
	        case KeyEvent.KEYCODE_BACK:  
	            this.finish();  
	            break;  
	        }  
	        return false;  
	    };  
	  
	    void startTestSurfaceView() {  
	        mTestSurfaceView.setDisplayWH(mWidth, mHeight);  
	        mTestSurfaceView.setBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher));
	    }  

}

转载于:https://www.cnblogs.com/leihupqrst/p/3730429.html