Android TV自定义处理焦点控件
尹超
Android stuido有android tv项目模板，有一套规则，如果想开发TV版项目可以按照那个模板来，不过那个模板定制性太强。tv版app和其他app有一点不同，就是用遥控器进行操作，所以要想按照自己需求来开发，就要处理好焦点事件。
其实也不复杂，只要继承现有的控件，在onFocusChanged事件中，对自己的需求进行定制就可以了。提供几个例子：
1.显示图片的控件，默认加载默认图片，当获得焦点以后，切换选中图片，失去焦点，切换默认图片
public class FocusImageView extends ImageButton
{
private int defaultImageResources = -1;
private int focusImageResources = -1;
public FocusImageView(Context context)
{
super(context);
}
public FocusImageView(Context context, AttributeSet attrs)
{
this(context, attrs, 0);
}
public FocusImageView(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
setAttributeSet(attrs);
}
@Override
protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect)
{
super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
if (gainFocus)
{
if (focusImageResources != -1)
{
setBackgroundResource(focusImageResources);
}
}
else
{
if (defaultImageResources != -1)
{
setBackgroundResource(defaultImageResources);
}
}
}
private void setAttributeSet(AttributeSet attrs)
{
if (attrs != null)
{
TypedArray typeArray = getContext().obtainStyledAttributes(attrs, R.styleable.FocusImageView);
defaultImageResources = typeArray.getResourceId(R.styleable.FocusImageView_defaultImageResources, -1);
focusImageResources = typeArray.getResourceId(R.styleable.FocusImageView_focusImageResources, -1);
if (defaultImageResources != -1)
{
setBackgroundResource(defaultImageResources);
}
}
}
}attrs.xml
<resources>
<declare-styleable name="FocusImageView">
<attr name="defaultImageResources" format="integer" />
<attr name="focusImageResources" format="integer" />
</declare-styleable>
</resources>布局文件引用：
<项目的包名.widget.focusview.FocusImageView
android:id="@+id/iv_wulianwang"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:defaultImageResources="@mipmap/wulianwangdefault"
app:focusImageResources="@mipmap/wulianwangselected">
</项目的包名.widget.focusview.FocusImageView>当然，如果只是在获取焦点和失去焦点，切换图片，可以定义selector，在drawable下，定义一个selector
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@mipmap/bingliselected" android:state_focused="true" />
<item android:drawable="@mipmap/binglidefault" />
</selector>然后在布局中调用
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:focusable="true"
android:background="@drawable/focus_selector">2.一个布局，内部控件获得焦点，可以放大，失去焦点，内部控件可以缩小：
public class FocusRelativeLayout extends RelativeLayout {
private Animation scaleSmallAnimation;
private Animation scaleBigAnimation;
public FocusRelativeLayout(Context context) {
super(context);
}
public FocusRelativeLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public FocusRelativeLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) {
super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
if (gainFocus) {
zoomOut();
} else {
zoomIn();
}
}
private void zoomIn() {
if (scaleSmallAnimation == null) {
scaleSmallAnimation = AnimationUtils.loadAnimation(getContext(), R.anim.anim_scale_small);
}
startAnimation(scaleSmallAnimation);
}
private void zoomOut() {
if (scaleBigAnimation == null) {
scaleBigAnimation = AnimationUtils.loadAnimation(getContext(), R.anim.anim_scale_big);
}
startAnimation(scaleBigAnimation);
}
}anim_scale_big.xml
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
android:fillAfter="true"
android:shareInterpolator="false">
<scale
android:duration="350"
android:fromXScale="1.0"
android:fromYScale="1.0"
android:interpolator="@android:anim/accelerate_decelerate_interpolator"
android:pivotX="50.0%"
android:pivotY="50.0%"
android:repeatCount="0"
android:toXScale="1.08"
android:toYScale="1.08" />
</set>anim_scale_small.xml
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
android:fillAfter="true"
android:shareInterpolator="false">
<scale
android:duration="350"
android:fromXScale="1.08"
android:fromYScale="1.08"
android:interpolator="@android:anim/accelerate_decelerate_interpolator"
android:pivotX="50.0%"
android:pivotY="50.0%"
android:repeatCount="0"
android:toXScale="1.0"
android:toYScale="1.0" />
</set>布局文件引用：
<包名.view.FocusRelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#424242"
android:clipChildren="true"
android:focusable="true">
<ImageView
android:layout_width="100dp"
android:layout_height="100dp"
android:scaleType="fitXY"
android:src="@drawable/pic2"
android:layout_margin="5dp"/>
</包名.view.FocusRelativeLayout>3.进入界面，让某个控件获取焦点
根据需求，可能对进入界面，首先选中哪个控件有需求，可以在布局文件里边，使用<requestFocus/>属性
<包名.widget.focusview.FocusImageView
android:id="@+id/iv_bingli"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:defaultImageResources="@mipmap/binglidefault"
app:focusImageResources="@mipmap/bingliselected"
>
<requestFocus></requestFocus>
</包名.widget.focusview.FocusImageView>
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