android 中 getWidth() 和getMeasureWidth()的区别，移动app快速开发框架

最新推荐文章于 2025-01-16 01:30:03 发布

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最新推荐文章于 2025-01-16 01:30:03 发布

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本文详细介绍了Android中视图测量的相关概念，包括`getMeasuredWidth()`与`getWidth()`的区别。`getMeasuredWidth()`返回的是视图的原始测量宽度，而`getWidth()`提供的是实际布局中的宽度，可能受到加减因素的影响。文章还探讨了测量流程，如`onMeasure()`、`setMeasuredDimension()`和`setMeasuredDimensionRaw()`的作用，以及`MEASURED_SIZE_MASK`在测量过程中的意义。

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{@hide}
同理
*/
protected int mRight;
所以，这只是一个通过加减得到的一个相对值，并不是真正测量得到的尺寸；

getMeasuredWidth

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. 原始宽度

*/
public final int getMeasuredWidth() {
return mMeasuredWidth & MEASURED_SIZE_MASK;
}

这里有两个变量，一个是 mMeasuredWidth，一个是 MEASURED_SIZE_MASK

/**

Bits of {@link #getMeasuredWidthAndState()} and
{@link #getMeasuredWidthAndState()} that provide the actual（真实的） measured size.
*/
public static final int MEASURED_SIZE_MASK = 0x00ffffff;

MEASURED_SIZE_MASK 是一个16进制的树，这里需要说明一下，view 的测量结果，它封装在：MeasureSpec类中，主要包含测量结果和测量模式，有三种，分别是：MeasureSpec.UNSPECIFIED，MeasureSpec.AT_MOST，MeasureSpec.EXACTLY，MeasureSpec通过makeMeasureSpec() 方法将模式和大小，封装在了一起，一个int值，高2位是测量模式，低30位是view的尺寸；

mMeasuredWidth 的值是怎么设置上的；

流程子view 的 onMeasure()---->setMeasuredDimension()----->setMeasuredDimensionRaw()
第一步：setMeasuredDimension();

/**

This method must be called by {@link #onMeasure(int, int)} to store the
measured width and measured height. Failing to do so will trigger an
exception at measurement time.
这个方法必须在onMeasure(int, int)中调用
@param measuredWidth The measured width of this view. May be a complex
bit mask as defined by {@link #MEASURED_SIZE_MASK} and
{@link #MEASURED_STATE_TOO_SMALL}.
@param measuredHeight The measured height of this view. May be a complex
bit mask as defined by {@link #MEASURED_SIZE_MASK} and
{@link #MEASURED_STATE_TOO_SMALL}.
*/
protected final void setMeasuredDimension(int measuredWidth, int measuredHeight) {
boolean optical = isLayoutModeOptical(this)

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;
if (optical != isLayoutModeOptical(mParent)) {
Insets insets = getOpticalInsets();
int opticalWidth = insets.left + insets.right;
int opticalHeight = insets.top + insets.bottom;

measuredWidth += optical ? opticalWidth : -opticalWidth;
measuredHeight += optical ? opticalHeight : -opticalHeight;
}
// 设置view的原始尺寸
setMeasuredDimensionRaw(measuredWidth, measuredHeight);
}

第二步：setMeasuredDimensionRaw();

/**
*

Sets the measured dimension without extra processing for things like optical bounds.
Useful for reapplying consistent values that have already been cooked with adjustments
for optical bounds, etc. such as those from the measurement cache.
@param measuredWidth The measured width of this view. May be a complex
bit mask as defined by {@link #MEASURED_SIZE_MASK} and
{@link #MEASURED_STATE_TOO_SMALL}.
@param measuredHeight The measured height of this view. May be a complex
bit mask as defined by {@link #MEASURED_SIZE_MASK} and
{@link #MEASURED_STATE_TOO_SMALL}.
*/
private void setMeasuredDimensionRaw(int measuredWidth, int measuredHeight) {
mMeasuredWidth = measuredWidth;
mMeasuredHeight = measuredHeight;
mPrivateFlags |= PFLAG_MEASURED_DIMENSION_SET;