android– 自定义视图显示在屏幕中央

概述我写了一个自定义视图类.我在MainLayoutxml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<?xmlversion="1.0"encoding="utf-8"?><RelativeLayoutxmlns:android="http://schemas.android.com/apkes/android"android:layout_width="fill_parent&q

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

<?xml version="1.0" enCoding="utf-8"?><relativeLayout xmlns:androID="http://schemas.androID.com/apk/res/androID"    androID:layout_wIDth="fill_parent"    androID:layout_height="fill_parent"     androID:background="@drawable/cs_background"     androID:ID="@+ID/layout"     >   <com.drawings.DrawingVIEw            androID:ID="@+ID/drawingvIEw"            androID:layout_wIDth="wrap_content"            androID:layout_height="wrap_content"            androID:layout_centerInParent="true"              />  </relativeLayout>

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. ？

解决方法:

@OverrIDeprotected voID onMeasure(int wIDthMeasureSpec, int heightmeasureSpec) {    this.setMeasuredDimension(backgound.getWIDth(), backgound.getHeight());}

实现onMeasure(int,int)

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