android自定义屏幕,android – 自定义视图显示在屏幕中央

我写了一个自定义视图类.

我在Main Layout xml上实现了自定义视图.并使用以下代码设置屏幕中心的参数

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:background="@drawable/cs_background"

android:id="@+id/layout"

>

android:id="@+id/drawingview"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerInParent="true"

/>

在图形布局中,它在中心位置正确显示.但是当我在模拟器上执行时,它显示在左上角.

我试图改变以编程方式实现布局,使用下面的代码.

RelativeLayout layout = new RelativeLayout(this);

DrawingView myView = new DrawingView(this);

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);

params.addRule(RelativeLayout.CENTER_IN_PARENT, RelativeLayout.TRUE);

layout.addView(myView,params);

setContentView(linearLayout);

但它仍然是左顶级核心的表现.

我的绘图视图是,

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Paint;

import android.graphics.Path;

import android.util.AttributeSet;

import android.view.MotionEvent;

import android.view.View;

public class DrawingView extends View

{

Context context;

private Path mPath;

private Bitmap backgound;

private Paint mPaint;

private float mX,mY;

private static final float TOUCH_TOLERANCE =4;

public DrawingView(Context c)

{

super(c);

context = c;

init();

}

public DrawingView (Context c, AttributeSet as)

{

super(c,as);

context = c;

init();

}

private void init()

{

mPath = new Path();

mPaint = new Paint();

mPaint.setAntiAlias(true);

mPaint.setDither(true);

mPaint.setColor(0xFFFF0000);

mPaint.setStyle(Paint.Style.STROKE);

mPaint.setStrokeJoin(Paint.Join.ROUND);

mPaint.setStrokeCap(Paint.Cap.ROUND);

mPaint.setStrokeWidth(12);

backgound = BitmapFactory.decodeResource(context.getResources(), R.drawable.cs_one);

}

@Override

protected void onDraw(Canvas canvas)

{

canvas.drawBitmap(backgound, 0, 0, null);

if(!mPath.isEmpty())

canvas.drawPath(mPath, mPaint);

invalidate();

}

private void touch_start(float x, float y)

{

mPath.moveTo(x, y);

}

private void touch_move(float x, float y)

{

float dx = Math.abs(x - mX);

float dy = Math.abs(y - mY);

if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE)

{

mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);

}

}

@Override

public boolean onTouchEvent(MotionEvent event)

{

float x = event.getX();

float y = event.getY();

switch (event.getAction()) {

case MotionEvent.ACTION_DOWN:

touch_start(x, y);

break;

case MotionEvent.ACTION_MOVE:

touch_move(x, y);

break;

case MotionEvent.ACTION_UP:

// touch_up();

break;

}

invalidate();

return true;

}

}

问题是什么？以及如何在屏幕中心显示自定义视图. ？