Android使用SurfaceView画图

布局文件layout.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"    tools:context=".MainActivity" >    <SurfaceView        android:id="@+id/surfaceview"        android:layout_width="match_parent"        android:layout_height="match_parent"        /></RelativeLayout>

Activity 代码如下：

package com.example.surfaceview;import android.app.Activity;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.os.Bundle;import android.view.MotionEvent;import android.view.SurfaceHolder;import android.view.SurfaceHolder.Callback;import android.view.SurfaceView;import android.view.View;import android.view.View.OnTouchListener;public class MainActivity extends Activity {    // SurfaceHolder负责维护SurfaceView上绘制的内容     private SurfaceHolder holder;    private Paint paint;      @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        paint = new Paint();        // 获取SurfaceView实例         SurfaceView surface = (SurfaceView) findViewById(R.id.surfaceview);        // 初始化SurfaceHolder对象         holder = surface.getHolder();        holder.addCallback(new Callback() {            //当surface将要被销毁时回调该方法             @Override            public void surfaceDestroyed(SurfaceHolder holder) {              }            //当surface被创建时回调该方法             @Override            public void surfaceCreated(SurfaceHolder holder) {                // 锁定整个SurfaceView                 Canvas canvas = holder.lockCanvas();                // 获取背景资源                 Bitmap bitmap = BitmapFactory.decodeResource(                        MainActivity.this.getResources(),                        R.drawable.test);                // 绘制背景                 canvas.drawBitmap(bitmap, 0, 0, null);                // 绘制完成，释放画布，提交修改                 holder.unlockCanvasAndPost(canvas);                // 重新锁两次，避免下次lockCanvas遮挡                 holder.lockCanvas(new Rect(0, 0, 0, 0));                holder.unlockCanvasAndPost(canvas);                holder.lockCanvas(new Rect(0, 0, 0, 0));                holder.unlockCanvasAndPost(canvas);            }            //当一个surface的格式或大小发生改变时回调该方法             @Override            public void surfaceChanged(SurfaceHolder holder, int format,                    int width, int height) {              }        });        surface.setOnTouchListener(new OnTouchListener() {              @Override            public boolean onTouch(View v, MotionEvent event) {                // 只处理按下事件                 if (event.getAction() == MotionEvent.ACTION_DOWN) {                    int cx = (int) event.getX();                    int cy = (int) event.getY();                    System.out.println(cx+"==="+cy);                    // 锁定SurfaceView的局部区域，只更新局部内容                                         Canvas canvas = holder.lockCanvas(new Rect(cx - 60,                            cy - 60, cx + 60, cy + 60));                    // 保存canvas的当前状态                     canvas.save();                    // 旋转画布               //      canvas.rotate(30, cx, cy);                    paint.setColor(Color.RED);                    paint.setAntiAlias(true);                    canvas.drawCircle(cx, cy, 50, paint);                    // 绘制红色方块                 //    canvas.drawRect(cx - 40, cy - 40, cx, cy, paint);                    // 恢复canvas之前的保存状态 //                    canvas.restore();//                    paint.setColor(Color.GREEN);//                    // 绘制绿色方块 //                    canvas.drawRect(cx, cy, cx + 40, cy + 40, paint);                    // 绘制完成，释放画布，提交修改                     holder.unlockCanvasAndPost(canvas);                }                return false;            }        });    }  }

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