安卓自定义控件--TypedArray 详解

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    我本是在阅读TvRecyclerView的源码。我没有弄明白默认的选中图标到底如何设置的。我就去看源码,看到使用了TypeArray,于是记录下来,方便以后查看。

    使用流程如下:

    在attrs.xml中定义一个属性变量

<?xml version="1.0" encoding="utf-8" ?><resources>      <declare-styleable name="TvRecyclerView">        <attr name="scrollMode"/>        <attr name="focusDrawable" format="reference" />        <attr name="isAutoProcessFocus" format="boolean" />        <attr name="focusScale" format="float" />    </declare-styleable></resources>

在layout布局中

xmlns:app="http://schemas.android.com/apk/res-auto"
此句是声明自己的命名空间

app:focusDrawable="@drawable/default_focus"
focusDrawable是自定义的属性


<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:background="#000000">    <app.com.tvrecyclerview.TvRecyclerView        android:id="@+id/tv_recycler_view"        android:layout_width="match_parent"        android:layout_height="580dp"        android:layout_centerInParent="true"        android:layout_margin="20dp"        app:focusDrawable="@drawable/default_focus"/></RelativeLayout>

在自定义控件中要用到在布局文件中定义的属性值获取方式如下

public TvRecyclerView(Context context, AttributeSet attrs, int defStyle) {    super(context, attrs, defStyle);    init();    setAttributeSet(attrs);    //省去一些代码}


private void setAttributeSet(AttributeSet attrs) {    if (attrs != null) {        TypedArray typeArray = getContext().obtainStyledAttributes(attrs, R.styleable.TvRecyclerView);        int type = typeArray.getInteger(R.styleable.TvRecyclerView_scrollMode, 0);        if (type == 1) {            mIsFollowScroll = true;        }        final Drawable drawable = typeArray.getDrawable(R.styleable.TvRecyclerView_focusDrawable);        if (drawable != null) {            setFocusDrawable(drawable);        }        mSelectedScaleValue = typeArray.getFloat(R.styleable.TvRecyclerView_focusScale, DEFAULT_SELECT_SCALE);        mIsAutoProcessFocus = typeArray.getBoolean(R.styleable.TvRecyclerView_isAutoProcessFocus, true);        if (!mIsAutoProcessFocus) {            mSelectedScaleValue = 1.0f;            setChildrenDrawingOrderEnabled(true);        }        typeArray.recycle();    }    if (mIsAutoProcessFocus) {        // set TvRecyclerView process Focus        setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);    }}
            

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