使用surfaceView做了一个画画板的练习，可是画出来的线断断续续，是为什么？
下面是mainactivity
package com.wxh.mywall;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.view.Menu;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity {
private SurfaceView mSurfaceView = null;
private SurfaceHolder mSurfaceHolder = null;
private Button cleanButton = null;
private Button colorButton = null;
private float oldX = 0f;
private float oldY = 0f;
private boolean canDraw = false;
private Paint mPaint = null;
//用来记录当前是哪一种颜色
private int whichColor = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mSurfaceView = (SurfaceView)this.findViewById(R.id.surfaceview);
mSurfaceHolder = mSurfaceView.getHolder();
mPaint = new Paint();
//画笔的颜色
mPaint.setColor(Color.RED);
//画笔的粗细
mPaint.setStrokeWidth(2.0f);
cleanButton = (Button)this.findViewById(R.id.flushbutton);
//按钮监听
cleanButton.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
//锁定整个SurfaceView
Canvas mCanvas = mSurfaceHolder.lockCanvas();
mCanvas.drawColor(Color.BLACK);
//绘制完成，提交修改
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
//重新锁一次
mSurfaceHolder.lockCanvas(new Rect(0, 0, 0, 0));
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
}
});
colorButton = (Button)this.findViewById(R.id.colorbutton);
//按钮监听
colorButton.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
Dialog mDialog = new AlertDialog.Builder(MainActivity.this)
.setTitle("颜色设置")
.setSingleChoiceItems(new String[]{"红色","绿色","蓝色"}, whichColor, new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
// TODO Auto-generated method stub
switch(which)
{
case 0:
{
//画笔的颜色
mPaint.setColor(Color.RED);
whichColor = 0;
break;
}
case 1:
{
//画笔的颜色
mPaint.setColor(Color.GREEN);
whichColor = 1;
break;
}
case 2:
{
//画笔的颜色106
mPaint.setColor(Color.BLUE);
whichColor = 2;
break;
}
}
}
})
.setPositiveButton("确定", new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
// TODO Auto-generated method stub
dialog.dismiss();
}
})
.create();
mDialog.show();
}
});
}
@Override
public boolean onTouchEvent(MotionEvent event)
{
//获取x坐标
float x = event.getX();
//获取y坐标（不知道为什么要减去两个偏移值才对得准屏幕）
float y = event.getY()-100;
//第一次进来先不管
if(canDraw)
{
//获取触屏事件
switch(event.getAction())
{
//如果是拖动事件
case MotionEvent.ACTION_MOVE:
{
//锁定整个SurfaceView
Canvas mCanvas = mSurfaceHolder.lockCanvas();
mCanvas.drawLine(x, y, oldX, oldY, mPaint);
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
//重新锁一次
mSurfaceHolder.lockCanvas(new Rect(0, 0, 0, 0));
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
break;
}
}
}
//保存目前的x坐标值
oldX = x;
//保存目前的y坐标值
oldY = y;
canDraw = true;
return true;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
