Android的onMeasure方法

  mode共有三种情况，取值分别为

  MeasureSpec.UNSPECIFIED,MeasureSpec.EXACTLY,MeasureSpec.AT_MOST。

  以下是框架中View的onMeasure的典型实现：

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

	int measuredHeight = measureHeight(heightMeasureSpec);

	int measuredWidth = measureWidth(widthMeasureSpec);

	setMeasuredDimension(measuredHeight, measuredWidth);

}

private int measureHeight(int measureSpec) {

	int specMode = MeasureSpec.getMode(measureSpec);
	int specSize = MeasureSpec.getSize(measureSpec);

	// Default size if no limits are specified.

	int result = 500;
	if (specMode == MeasureSpec.AT_MOST) {

		// Calculate the ideal size of your
		// control within this maximum size.
		// If your control fills the available
		// space return the outer bound.

		result = specSize;
	} else if (specMode == MeasureSpec.EXACTLY) {

		// If your control can fit within these bounds return that
		// value.
		result = specSize;
	}

	return result;
}

private int measureWidth(int measureSpec) {
	int specMode = MeasureSpec.getMode(measureSpec);
	int specSize = MeasureSpec.getSize(measureSpec);

	// Default size if no limits are specified.
	int result = 500;
	if (specMode == MeasureSpec.AT_MOST) {
		// Calculate the ideal size of your control
		// within this maximum size.
		// If your control fills the available space
		// return the outer bound.
		result = specSize;
	}

	else if (specMode == MeasureSpec.EXACTLY) {
		// If your control can fit within these bounds return that
		// value.

		result = specSize;
	}

	return result;
}

Android的onMeasure方法

原文：http://blog.csdn.net/pocoyoshamoo/article/details/18862121