SurfaceView实现示波器

package com.example.administrator.surfaceviewtest; import android.content.DialogInterface; 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.support.v7.app.AppCompatActivity; import android.util.Log; import android.view.MotionEvent; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.widget.Button; import java.util.Timer; import java.util.TimerTask; public class MainActivity extends AppCompatActivity { private static final String TAG = "MainActivity"; Paint paint; SurfaceHolder holder; SurfaceView view1; final int WIDTH = 500, HEIGHT = 500, X_OFFSET = 150; int cx = X_OFFSET; int centerY= HEIGHT/2; Timer timer = new Timer(); TimerTask timertask; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main1); view1 = (SurfaceView)findViewById(R.id.surfaceview1); holder = view1.getHolder(); paint = new Paint(); paint.setColor(Color.GREEN); paint.setStrokeWidth(3); Button btn1 = (Button)findViewById(R.id.btn1); Button btn2 = (Button)findViewById(R.id.btn2); View.OnClickListener listener = new View.OnClickListener() { @Override public void onClick(final View v) { drawBack(holder); cx = X_OFFSET; if (timertask != null) timertask.cancel(); timertask = new TimerTask() { @Override public void run() { int cy = v.getId() == R.id.btn1?centerY-(int)(100*Math.sin((cx-5)*2*Math.PI/150)): centerY-(int)(100*Math.cos((cx - 5) * 2 * Math.PI / 150)); Canvas canvas = holder.lockCanvas(new Rect(cx,cy-2,cx+2,cy+2)); canvas.drawPoint(cx,cy,paint); Log.i(TAG, "x,y:" + cx + "," + cy); cx++; if (cx>WIDTH) { timertask.cancel(); timertask = null; } holder.unlockCanvasAndPost(canvas); } }; timer.schedule(timertask,0,20); } }; btn1.setOnClickListener(listener); btn2.setOnClickListener(listener); holder.addCallback(new SurfaceHolder.Callback() { @Override public void surfaceCreated(SurfaceHolder holder) { Log.i(TAG, "surfaceCreated~~~"); drawBack(holder); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { } @Override public void surfaceDestroyed(SurfaceHolder holder) { timertask.cancel(); } }); } private void drawBack(SurfaceHolder holder) { Canvas canvas = holder.lockCanvas(); canvas.drawColor(Color.WHITE); Paint paint = new Paint(); paint.setColor(Color.BLACK); paint.setStrokeWidth(3); canvas.drawLine(X_OFFSET, centerY, WIDTH, centerY, paint); canvas.drawLine(X_OFFSET, 140, X_OFFSET, HEIGHT, paint); holder.unlockCanvasAndPost(canvas); holder.lockCanvas(new Rect(0,0,0,0)); holder.unlockCanvasAndPost(canvas); } }