自定义view onMeasure方法的重写

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="vertical">    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="自定义view  onMeasure用法 (MeasureDemoActivity)"/>    <phoebe.frame.view.CustomView        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:background="@android:color/holo_red_light"/></LinearLayout>

@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {String widthSpec = MeasureSpec.toString(widthMeasureSpec);String heightSpec = MeasureSpec.toString(heightMeasureSpec);Log.d("measure_spec", widthSpec + "  --- " + heightSpec);super.onMeasure(widthMeasureSpec, heightMeasureSpec);Log.d("measure_spec", getMeasuredWidth() + " " + getMeasuredHeight());}

02-21 19:07:23.740: D/measure_spec(19713): MeasureSpec: EXACTLY 720 MeasureSpec: AT_MOST 114302-21 19:07:23.740: D/measure_spec(19713): 720 1143

如果自定义view的宽高设置为wrap_content 可以看到 measureSpec的值为了 AT_MOST (match_parent   对应的measureSpec为EXACTLY)

view是充满整个layout页面。很显然这并不是我们想要的效果

如果要实现设置wrap_content以后view的宽高刚好是view content的宽高，则需要重写onMeasure

(至于怎么重写，先不讨论、、可以参考 TextView的源码)

另外摘一段网上的代码

http://stackoverflow.com/questions/12266899/onmeasure-custom-view-explanation

@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    int desiredWidth = 100;    int desiredHeight = 100;    int widthMode = MeasureSpec.getMode(widthMeasureSpec);    int widthSize = MeasureSpec.getSize(widthMeasureSpec);    int heightMode = MeasureSpec.getMode(heightMeasureSpec);    int heightSize = MeasureSpec.getSize(heightMeasureSpec);    int width;    int height;    //Measure Width    if (widthMode == MeasureSpec.EXACTLY) {        //Must be this size        width = widthSize;    } else if (widthMode == MeasureSpec.AT_MOST) {        //Can't be bigger than...        width = Math.min(desiredWidth, widthSize);    } else {        //Be whatever you want        width = desiredWidth;    }    //Measure Height    if (heightMode == MeasureSpec.EXACTLY) {        //Must be this size        height = heightSize;    } else if (heightMode == MeasureSpec.AT_MOST) {        //Can't be bigger than...        height = Math.min(desiredHeight, heightSize);    } else {        //Be whatever you want        height = desiredHeight;    }    //MUST CALL THIS    setMeasuredDimension(width, height);}