【Android】getwidth和getmeasuredwidth的区别以及两者的使用场景

首先，看getWidth()的官方说明：

public final int getWidth ()

Added in API level 1

Return the width of the your view.

Returns

The width of your view, in pixels.

返回view的宽度，说的不详细，再看getWidth源码：

[java] view
plaincopy

<span style="font-size:18px;"> /**

* Return the width of the your view.

*

* @return The width of your view, in pixels.

*/

@ViewDebug.ExportedProperty(category = "layout")

public final int getWidth() {

return mRight - mLeft;

}</span>

从源码可以看出，getwidth返回的是右边坐标减轻坐标减去左边坐标，这要在布局之后才能确定它们的坐标，也就是说在布局后才能调用getwidth来获取。所以getWidth()获得的宽度是View在设定好布局后整个View的宽度。

而对于getmeasuredwidth,

public final int getMeasuredWidthAndState ()

Added in API level 11

Return the full width measurement information for this view as computed by the most recent call to

measure(int,
int)

. This result is a bit mask as defined by

MEASURED_SIZE_MASK

and

MEASURED_STATE_TOO_SMALL

.
This should be used during measurement and layout calculations only. Use

getWidth()

to
see how wide a view is after layout.

Returns

The measured width of this view as a bit mask.

得到的是最近一次调用measure()方法测量后得到的是View的宽度，它应该仅仅用在测量和Layout的计算中。再看源码：

[java] view
plaincopy

/**

* Like {@link #getMeasuredWidthAndState()}, but only returns the

* raw width component (that is the result is masked by

* {@link #MEASURED_SIZE_MASK}).

*

* @return The raw measured width of this view.

*/

public final int getMeasuredWidth() {

return mMeasuredWidth & MEASURED_SIZE_MASK;

}

return The raw measured width of this view 获得的是原始的测量宽度。所以说getMeasuredWidth()是对View上的内容进行测量后得到的View内容占据的宽度。前提是你必须在父布局的onLayout()方法或者此View的onDraw()方法里调用measure(0,0);(measure中的参数的值你自己可以定义)，否则你得到的结果和getWidth()得到的结果是一样的。

两者的使用场合：

getMeasuredWidth:在自定义view重写onLayout时、在我们用layoutinflater动态加载view后想获得view的原始宽度时。

getWidth:一般在view已经布局后呈现出来了，想获取宽度时