如何在安卓中清除SurfaceView？
我有一个如下的类 -
我有一个如下的类 -
class DrawingPanel extends SurfaceView implements SurfaceHolder.Callback {
请问我应该调用哪个方法来清除我的自定义绘图面板？
这是我的类 -
package com.applenty.LearnToCount;
import java.util.ArrayList;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.Toast;
public class WhiteBoard extends Activity {
private ArrayList<Path> _graphics = new ArrayList<Path>();
private Paint mPaint;
Button button_clear;
FrameLayout layout;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.shake);
layout = new FrameLayout(this);
final LinearLayout l1 = new LinearLayout(this);
final LinearLayout l2 = new LinearLayout(this);
final DrawingPanel drawingPanel = new DrawingPanel(this);
// drawingPanel.setBackgroundColor(Color.WHITE);
LayoutParams params = new LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
button_clear = new Button(this);
button_clear.setText("Clear Screen");
button_clear.setGravity(Gravity.TOP | Gravity.LEFT);
button_clear.setVisibility(View.VISIBLE);
button_clear.setId(1);
button_clear.setLayoutParams(params);
//layout.addView(button_clear);
drawingPanel.setLayoutParams(params);
drawingPanel.setId(2);
l1.addView(button_clear);
l2.addView(drawingPanel);
layout.addView(l2);
layout.addView(l1);
setContentView(layout);
mPaint = new Paint();
mPaint.setDither(true);
mPaint.setColor(Color.RED);
mPaint.setColorFilter(new ColorFilter());
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(5);
button_clear = (Button)findViewById(1);
button_clear.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Toast t = Toast.makeText(WhiteBoard.this, "ISNIDE", 3);
t.show();
Log.d("DEBUG","CLEARING***************************");
//Canvas canvas = new Canvas();
//canvas.drawColor(0);
//Canvas canvas = new Canvas();
//canvas.drawColor(Color.WHITE);
drawingPanel.setBackgroundColor(Color.WHITE);
Canvas c = new Canvas();
drawingPanel._thread.getSurfaceHolder().unlockCanvasAndPost(c);
//drawingPanel.getHolder().unlockCanvasAndPost(canvas);
//canvas = drawingPanel.getHolder().lockCanvas(null);
}
});
}
class DrawingPanel extends SurfaceView implements SurfaceHolder.Callback {
private DrawingThread _thread;
private Path path;
public DrawingPanel(Context context) {
super(context);
getHolder().addCallback(this);
_thread = new DrawingThread(getHolder(), this);
}
public boolean onTouchEvent(MotionEvent event) {
synchronized (_thread.getSurfaceHolder()) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
path = new Path();
path.moveTo(event.getX(), event.getY());
path.lineTo(event.getX(), event.getY());
} else if (event.getAction() == MotionEvent.ACTION_MOVE) {
path.lineTo(event.getX(), event.getY());
} else if (event.getAction() == MotionEvent.ACTION_UP) {
path.lineTo(event.getX(), event.getY());
_graphics.add(path);
}
return true;
}
}
@Override
public void onDraw(Canvas canvas) {
for (Path path : _graphics) {
// canvas.drawPoint(graphic.x, graphic.y, mPaint);
canvas.drawPath(path, mPaint);
}
}
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
_thread.setRunning(true);
_thread.start();
}
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
boolean retry = true;
_thread.setRunning(false);
while (retry) {
try {
_thread.join();
retry = false;
} catch (InterruptedException e) {
// we will try it again and again...
}
}
}
}
class DrawingThread extends Thread {
private SurfaceHolder _surfaceHolder;
private DrawingPanel _panel;
private boolean _run = false;
public DrawingThread(SurfaceHolder surfaceHolder, DrawingPanel panel) {
_surfaceHolder = surfaceHolder;
_panel = panel;
}
public void setRunning(boolean run) {
_run = run;
}
public SurfaceHolder getSurfaceHolder() {
return _surfaceHolder;
}
@Override
public void run() {
Canvas c;
while (_run) {
c = null;
try {
c = _surfaceHolder.lockCanvas(null);
synchronized (_surfaceHolder) {
_panel.onDraw(c);
}
} finally {
// do this in a finally so that if an exception is thrown
// during the above, we don't leave the Surface in an
// inconsistent state
if (c != null) {
_surfaceHolder.unlockCanvasAndPost(c);
}
}
}
}
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
startActivity(new Intent(WhiteBoard.this, HomeActivity.class));
finish();
return true;
}
return true;
}
}
我希望您能够在OnClickListner上清除屏幕。有什么想法请提出...