RVG RVG - 6 months ago 25
Android Question

Custom View show on center of the screen

i write a custom view class.

i've implement the custom view on Main Layout xml. and set parameter for center of the screen using below code

<?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>


In graphics layout , it show correctly on center postion. But when i execute on simulator, it shows on left top corner.

i've tried to change to implement the layout programmatically, using below code.

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);


But still its show on left top corener.

My drawingview class is,

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;

}

}


what is the problem? and how to show the custom view on center of the screen. ?

Answer
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

    this.setMeasuredDimension(backgound.getWidth(), backgound.getHeight());
}

implement the onMeasure(int,int)