繼承自view的自定義控制元件的wrap_content和padding兩個屬性不會生效，解決方法

/**
 * 自定義一個圓形
 * @author luoshen
 * 2016年11月29日下午1:28:04
 */
public class CircleView extends View{

	
	private int mColor = Color.RED;
	
	private Paint mPaint  = new Paint(Paint.ANTI_ALIAS_FLAG);
	
	public CircleView(Context context, AttributeSet attrs, int defStyleAttr) {
		super(context, attrs, defStyleAttr);
		
		init();
	}

	public CircleView(Context context, AttributeSet attrs) {
		super(context, attrs);
		init();
	}

	public CircleView(Context context) {
		super(context);
		init();
	}
	
	
	private void init(){
		
		mPaint.setColor(mColor);
	}
	
	/**
	 * 此方法中的程式碼是為了讓wrap_content屬性生效，並給此屬性設定寬高
	 */
	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		//取出寬度的測量模式
		int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
		//取出寬度的確切數值
		int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);
		//取出高度的測量模式
		int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
		//取出高度的確切數值
		int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);
		
		if (widthSpecMode == MeasureSpec.AT_MOST && heightMeasureSpec == MeasureSpec.AT_MOST) {
			//設定wrap_content屬性的寬高
			setMeasuredDimension(200, 200);
			
		}else if (widthSpecMode == MeasureSpec.AT_MOST) {
			
			setMeasuredDimension(200, heightSpecSize);
			
		}else if (heightSpecMode == MeasureSpec.AT_MOST) {
			
			setMeasuredDimension(widthSpecSize, 200);
			
		}
	}
	
	
	/**
	 * 此方法內部的程式碼是為了讓padding屬性生效
	 * 
	 * 並且畫了一個圓
	 */
	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		
		int paddingLeft = getPaddingLeft();
		
		int paddingRight = getPaddingRight();
		
		int paddingTop = getPaddingTop();
		
		int paddingBottom = getPaddingBottom();
		//減去padding值
		int width = getWidth() - paddingLeft - paddingRight;
		int height = getHeight() - paddingBottom - paddingTop;
		
		int radius = Math.min(width,height)/2;
		
		canvas.drawCircle(paddingLeft+width/2, paddingTop+height/2, radius, mPaint);
	}
	

}