获取Android控件的宽和高

一

/**
* view 初始化完毕，宽高已经确定。<br/>
* 当 Activity 的窗口得到和失去焦点的时候，这个方法均会被调用。<br/>
* 频繁调用 onResume 和 onPause 这个方法也会被频繁调用。
* @param hasFocus
*/
@Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
if (hasFocus) {
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();
}
}

二

@Override
protected void onStart() {
super.onStart();

/* 通过 post 可以将一个 Runnable 投递到消息队列的尾部。等到用的时候 view 也初始化好了。 */
view.post(new Runnable() {
@Override
public void run() {
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();
}
});
}

三

@Override
protected void onStart() {
super.onStart();
/* 当 view树 的状态发生改变或者 View 树内部的 View 可见性发生改变时， onGlobalLayout 会被回调。*/
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
ViewTreeObserver viewTreeObserver = view.getViewTreeObserver();
viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
view.getViewTreeObserver().removeOnGlobalLayoutListener(this);
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();
}
});
}
}

四, measure

具体数值

/* 比如宽高是100px */
int widthMeasureSpec = View.MeasureSpec.makeMeasureSpec(100, View.MeasureSpec.EXACTLY);
int heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(100, View.MeasureSpec.EXACTLY);
view.measure(widthMeasureSpec, heightMeasureSpec);
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();

wrap_content

/* view 的尺寸是使用20位二进制表示（最大是30个1，即 2的30次方-1 ，也就是 (1 << 30) - 1 */
int widthMeasureSpec = View.MeasureSpec.makeMeasureSpec((1 << 30) - 1, View.MeasureSpec.AT_MOST);
int heightMeasureSpec = View.MeasureSpec.makeMeasureSpec((1 << 30) - 1, View.MeasureSpec.AT_MOST);
view.measure(widthMeasureSpec, heightMeasureSpec);
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();

match_parent不可用