Android 自定义控件 _ 高可扩展单选按钮(再也不和产品经理吵架了)
虽然这次业务场景中,单选按钮元素的布局是:图片在上,文字在下。下次换了咋办?所以定义元素布局应该作为一个抽象函数交给
Selector
子类实现。为了实现选中的渐变效果,
Selector
需提供选项变更的时机。按钮包含一些基本的属性,比如按钮名称,按钮图标,将这些属性写成自定义属性并传递给子类解析,代码如下:
public abstract class Selector extends FrameLayout implements View.OnClickListener {
public Selector(Context context) {super(context);initView(context, null);}
public Selector(Context context, AttributeSet attrs) {super(context, attrs);initView(context, attrs);}
public Selector(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);initView(context, attrs);}
//模版方法 private void initView(Context context, AttributeSet attrs) {//读取自定义属性 if (attrs != null) {TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.Selector);int tagResId = typedArray.getResourceId(R.styleable.Selector_tag, 0);tag = context.getString(tagResId);//将自定义属性传递给子类 onObtainAttrs(typedArray);typedArray.recycle();} else {tag = “default tag”;}//构建按钮视图 View view = onCreateView();LayoutParams params = new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);this.addView(view, params);this.setOnClickListener(this);}
public void onObtainAttrs(TypedArray typedArray) {}
//子类实现该函数以定义单选按钮元素布局 protected abstract View onCreateView();
@Overridepublic void onClick(View v) {boolean isSelect = switchSelector();}
public boolean switchSelector() {boolean isSelect = this.isSelected();this.setSelected(!isSelect);//当选项变更时 onSwitchSelected(!isSelect);return !isSelect;}
//选项变更 protected abstract void onSwitchSelected(boolean isSelect);}
因为Selector
是抽象类,所以必须由子类实现它的抽象,下面的代码即是 demo 中年龄单选按钮的实现:
public class AgeSelector extends Selector {//声明按钮包含的控件 private TextView tvTitle;private ImageView ivIcon;private ImageView ivSelector;private ValueAnimator valueAnimator;
@Overridepublic void onObtainAttrs(TypedArray typedArray) {//解析自定义属性 text = typedArray.getString(R.styleable.Selector_text);iconResId = typedArray.getResourceId(R.styleable.Selector_img, 0);indicatorResId = typedArray.getResourceId(R.styleable.Selector_indicator, 0);textColor = typedArray.getColor(R.styleable.Selector_text_color, Color.parseColor("#FF222222"));textSize = typedArray.getInteger(R.styleable.Selector_text_size, 15);}
private void onBindView(String text, int iconResId, int indicatorResId, int textColor, int textSize) {//将自定义属性绑定到控件 if (tvTitle != null) {tvTitle.setText(text);tvTitle.setTextSize(TypedValue.COMPLEX_UNIT_SP, textSize);tvTitle.setTextColor(textColor);}if (ivIcon != null) {ivIcon.setImageResource(iconResId);}if (ivSelector != null) {ivSelector.setImageResource(indicatorResId);ivSelector.setAlpha(0);}}
@Overrideprotected View onCreateView() {//构建自定义按钮布局 View view = LayoutInflater.from(this.getContext()).inflate(R.layout.age_selector, null);tvTitle = view.findViewById(R.id.tv_title);ivIcon = view.findViewById(R.id.iv_icon);ivSelector = view.findViewById(R.id.iv_selector);onBindView(text, iconResId, indicatorResId, textColor, textSize);return view;}
@Overrideprotected void onSwitchSelected(boolean isSelect) {//单选按钮状态变化时做动画 if (isSelect) {playSelectedAnimation();} else {playUnselectedAnimation();}}
private void playUnselectedAnimation() {if (ivSelector == null) {return;}if (valueAnimator != null) {valueAnimator.reverse();}}
private void playSelectedAnimation() {if (ivSelector == null) {return;}valueAnimator = ValueAnimator.ofInt(0, 255);valueAnimator.setDuration(800);valueAnimator.setInterpolator(new AccelerateDecelerateInterpolator());valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator animation) {ivSelector.setAlpha((int) animation.getAnimatedValue());}});valueAnimator.start();}}
其中单选按钮的布局文件如下:
<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"android:layout_width="match_parent"android:layout_height="match_parent">
<ImageViewandroid:id="@+id/iv_selector"android:layout_width="match_parent"android:layout_height="0dp"app:layout_constraintBottom_toTopOf="@id/tv_title"app:layout_constraintTop_toTopOf="parent"app:layout_constraintVertical_chainStyle="spread"app:layout_constraintVertical_weight="122" />
<ImageViewandroid:id="@+id/iv_icon"android:layout_width="0dp"android:layout_height="0dp"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintDimensionRatio="1:1"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent"app:layout_constraintVertical_bias="0.026"app:layout_constraintWidth_percent=".81" />
<TextViewandroid:id="@+id/tv_title"android:layout_width="match_parent"android:layout_height="0dp"android:gravity="center_horizontal|bottom"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintTop_toBottomOf="@id/iv_selector"app:layout_constraintVertical_chainStyle="spread"app:layout_constraintVertical_weight="28" /></android.support.constraint.ConstraintLayout>
如何定义单选组这个抽象?
等等,好像有点不太对劲!如果运行上述代码,你会发现每个Selector
都运行良好(选中状态发生变化时有渐变动画),但多个Selector
可以同时被选中,他们并没有实现互斥选中。。。
定神一想,发现原因是Selector
这个抽象只关心自己的选中状态,它并不知道其他Selector
的状态。
所以原生控件需要RadioGroup
这个角色,它作为父亲,了解每个孩子的动向!
但我们不想要一个ViewGroup
类型的父亲,因为它管的太多,孩子不能随意布局,局限性大。
那就造一个看不见的父亲!其实父亲做的事情不就是 “在一个孩子选中的时候,通知另一个孩子取消选中”吗?
有了思路动手就干,代码如下:
public class SelectorGroup {//用于保存上次选中按钮 private HashMap<String, Selector> selectorMap = new HashMap<>();
//获取上次选中按钮 public Selector getPreSelector(String groupTag) {return selectorMap.get(groupTag);}
//取消上次选中按钮的选中状态 private void cancelPreSelector(Selector selector) {String groupTag = selector.getGroupTag();Selector preSelector = getPreSelector(groupTag);if (preSelector != null) {preSelector.setSelected(false);}}
//当单选组按钮被点击时,点击事件会通过这个方法传递给单选组 void onSelectorClick(Selector selector) {selector.setSelected(true);cancelPreSelector(selector);//将这次选中按钮保存在 map 中 selectorMap.put(selector.getGroupTag(), selector);}}
为了让`Select
orGroup`统一管理按钮点击后的选中和取消状态变更,需要将按钮的点击事件传递给它,遂修改单选按钮代码如下:
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