Android 自定义底部上拉控件的实现方法
作者：却把清梅嗅
下面小编就为大家分享一篇Android 自定义底部上拉控件的实现方法，具有很好的参考价值，希望对大家有所帮助。一起跟随小编过来看看吧
前言
又到了新的一月，今天提供一个Android自定义底部上拉布局的实现，起因是自己在项目中需要实现这样一个控件，干脆自己写一个练练手。
写完了觉得能想到的需求都基本有了（可能会有其它需求，不过基本上改吧改吧就行了），又花了一点时间直接放到了Github上托管，希望能给您一些参考价值：
SlideBottomLayout-Android 简单易上手的Android底部上拉控件
先看一下实现效果：
分析一下这种控件的基本需求有以下几种：
1.有一个部分是能够作为把手（就是图中的handle，）进行拖拽的，这部分高度是暴露在界面中的 -> 需要实现：Handle按钮
* 特殊需求特殊分析，比如让这个Handle透明实现无Handle的效果
2.底部上啦布局是有一定高度限制的，不一定覆盖设备的整个屏幕 -> 需要自定义最大高度
3.当从底部上拉一点点时抬手，布局缩回，若超过一定高度，自动弹到最高，隐藏同理 -> 需要自定义自动到达顶部/隐藏的阈值
直接使用
直接使用也很简单，笔者进行了简单的封装，以供参考：
1. 在Project的build.gradle文件中添加：
allprojects {
repositories {
...
maven { url 'https://jitpack.io' }
}
}
2.在Module的build.gradle文件中添加：
dependencies {
compile 'com.github.qingmei2:SlideBottomLayout-Android:1.2.3'
}
3.Add view in your layout:
需要注意的是：为了简单实现，笔者偷了个懒，设定为该布局下只能有一个直接的子View(类似ScrollView)
因此如果您添加需要一个布局，请在外面嵌套一个ViewGroup：
<com.qingmei2.library.SlideBottomLayout
android:id="@+id/slideLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_marginTop="200dp"
app:handler_height="50dp">
<!--app:handler_height:该属性就是您要暴露出来Handle的高度，详见下方的TextView(id=handle)-->
<!--Just one child-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/handle"
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#d95858"
android:gravity="center"
android:text="handle"
android:textColor="@android:color/white"
android:textSize="16sp" />
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</android.support.v7.widget.RecyclerView>
</LinearLayout>
</com.qingmei2.library.SlideBottomLayout>
实现步骤
具体代码如下，其中上述需求的设置方式都已经在代码中声明：
先看下属性声明：
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="SlideBottomLayout">
<attr name="handler_height" format="dimension"></attr>
</declare-styleable>
</resources>
public class SlideBottomLayout extends LinearLayout {
public void setShortSlideListener(ShortSlideListener listener) {
this.shortSlideListener = listener;
}
private ShortSlideListener shortSlideListener;
/**
* The {@link MotionEvent#ACTION_DOWN} gesture location.
*/
private int downY;
/**
* The {@link MotionEvent#ACTION_MOVE} gesture location.
*/
private int moveY;
/**
* the value of moved distance by the gesture. When the value was modified and not exceed
* the {@link #movedMaxDis}, then make this ViewGroup move.
*/
private int movedDis;
/**
* The max distance that the {@link SlideBottomLayout} can scroll to, it used to compare with the
* {@link #downY}, determine whether it can slide by the gesture.
*/
private int movedMaxDis;
/**
* ChildView of the {@link SlideBottomLayout}, you can set a Layout such as the {@link LinearLayout}、
* {@link android.widget.RelativeLayout} ect.
* We set the rules that {@link SlideBottomLayout} just can have one child-view, or else get a
* {@link RuntimeException} at {@link #onFinishInflate()}
*/
private View childView;
/**
* The control {@link SlideBottomLayout} automatically switches the threshold of the state. if
* this ViewGroup moved distance more than {@link #movedMaxDis} * it, switch the state of
* {@link #arriveTop} right now.
* </p>
* See the {@link #touchActionUp(float)}.
*/
private float hideWeight = 0.25f;
//3.注意，这个接口用来设置「需要自定义自动到达顶部/隐藏的阈值」
public void setHideWeight(float hideWeight) {
if (hideWeight <= 0 || hideWeight > 1)
throw new IllegalArgumentException("hideWeight should belong (0f,1f]");
this.hideWeight = hideWeight;
}
private Scroller mScroller;
/**
* It means the {@link #childView} is arriving the top of parent or else.
*/
private boolean arriveTop = false;
/**
* the {@link #childView} Initially visible height
*/
private float visibilityHeight;
//1.初始化Handle显示高度，建议您在xml中设置对应属性来实现该效果
public void setVisibilityHeight(float visibilityHeight) {
this.visibilityHeight = visibilityHeight;
}
public SlideBottomLayout(@NonNull Context context) {
super(context);
}
public SlideBottomLayout(@NonNull Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
initAttrs(context, attrs);
}
public SlideBottomLayout(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initAttrs(context, attrs);
}
/**
* Get the config from {@link R.styleable}, then init other configrations{@link #initConfig(Context)}.
*
* @param context the {@link Context}
* @param attrs the configs in layout attrs.
*/
private void initAttrs(Context context, AttributeSet attrs) {
final TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.SlideBottomLayout);
visibilityHeight = ta.getDimension(R.styleable.SlideBottomLayout_handler_height, 0);
ta.recycle();
initConfig(context);
}
private void initConfig(Context context) {
if (mScroller == null)
mScroller = new Scroller(context);
this.setBackgroundColor(Color.TRANSPARENT);
}
/**
* It start a judgement for ensure the child-view be unique in this method，then assgin it
* to {{@link #childView}.
* this method will be called before the {@link #onMeasure(int, int)}
*/
@Override
protected void onFinishInflate() {
super.onFinishInflate();
if (getChildCount() == 0 || getChildAt(0) == null) {
throw new RuntimeException("there have no child-View in the SlideBottomLayout！");
}
if (getChildCount() > 1) {
throw new RuntimeException("there just alow one child-View in the SlideBottomLayout!");
}
childView = getChildAt(0);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
movedMaxDis = (int) (childView.getMeasuredHeight() - visibilityHeight);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
childView.layout(0, movedMaxDis, childView.getMeasuredWidth(), childView.getMeasuredHeight() + movedMaxDis);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
final float dy = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (touchActionDown(dy))
return true;
break;
case MotionEvent.ACTION_MOVE:
if (touchActionMove(dy))
return true;
break;
case MotionEvent.ACTION_UP:
if (touchActionUp(dy))
return true;
break;
}
return super.onTouchEvent(event);
}
@Override
public void computeScroll() {
super.computeScroll();
if (mScroller == null)
mScroller = new Scroller(getContext());
if (mScroller.computeScrollOffset()) {
scrollTo(0, mScroller.getCurrY());
postInvalidate();
}
}
/**
* When the touch event is {@link MotionEvent#ACTION_UP},
* then judge the state of view group and control the {@link Scroller} to scroll.
* <p>
* In this ViewGroup, we set the rules that is if this scroll gesture's move distance
* more than {@link #movedMaxDis} * {@link #hideWeight}(default hideWeight value is 1/4 heights
* of this ViewGroup), then call {@link #hide()} or {@link #show()} right now. which method will
* be call depends on {@link #arriveTop}.
* <p
* if the scroll gesture's move distance don't reach the goal value, then call the
* {@link ShortSlideListener#onShortSlide(float)} if you call {@link #setShortSlideListener(ShortSlideListener)}
* init this ViewGroup. else will call {@link #hide()}.
*
* @param eventY The location of trigger
* @return Be used to determine consume this event or else.
*/
public boolean touchActionUp(float eventY) {
if (movedDis > movedMaxDis * hideWeight) {
switchVisible();
} else {
if (shortSlideListener != null) {
shortSlideListener.onShortSlide(eventY);
} else {
hide();
}
}
return true;
}
/**
* When the touch event is {@link MotionEvent#ACTION_MOVE},
* then judge the state of view group and control the {@link Scroller} to scroll.
* <p>
* In this ViewGroup, we set the rules that is if this scroll gesture's move distance
* more than {@link #movedMaxDis} * {@link #hideWeight}(default hideWeight value is 1/4 heights of this ViewGroup),
* then call {@link #hide()} or {@link #show()} right now.
* <p>
*
* @param eventY The location of trigger
* @return Be used to determine consume this event or else.
*/
public boolean touchActionMove(float eventY) {
moveY = (int) eventY;
//the dy is sum of the move distance, the value > 0 means scroll up, the value < 0 means scroll down.
final int dy = downY - moveY;
if (dy > 0) { //scroll up
movedDis += dy;
if (movedDis > movedMaxDis)
movedDis = movedMaxDis;
if (movedDis < movedMaxDis) {
scrollBy(0, dy);
downY = moveY;
return true;
}
} else { //scroll down
movedDis += dy;
if (movedDis < 0) movedDis = 0;
if (movedDis > 0) {
scrollBy(0, dy);
}
downY = moveY;
return true;
}
return false;
}
/**
* When the touch event is {@link MotionEvent#ACTION_DOWN},
* Record the location of this action.
*
* @param eventY The location of trigger
* @return Be used to determine consume this event or else.
*/
public boolean touchActionDown(float eventY) {
downY = (int) eventY;
//Whether custom this gesture.
if (!arriveTop && downY < movedMaxDis) {
return false;
} else
return true;
}
/**
* the extand method for showing {@link SlideBottomLayout}
*/
public void show() {
scroll2TopImmediate();
}
/**
* the extand method for hiding {@link SlideBottomLayout}
*/
public void hide() {
scroll2BottomImmediate();
}
/**
* @return The ViewGroup is arrive top or else.
*/
public boolean switchVisible() {
if (arriveTop())
hide();
else
show();
return arriveTop();
}
public boolean arriveTop() {
return this.arriveTop;
}
public void scroll2TopImmediate() {
mScroller.startScroll(0, getScrollY(), 0, (movedMaxDis - getScrollY()));
invalidate();
movedDis = movedMaxDis;
arriveTop = true;
}
public void scroll2BottomImmediate() {
mScroller.startScroll(0, getScrollY(), 0, -getScrollY());
postInvalidate();
movedDis = 0;
arriveTop = false;
}
}
注释也比较明了，如果有疑问，详细请参照SlideBottomLayout-Android 简单易上手的Android底部上拉控件
里面有相对详细的使用说明，此外，如果还有一些需求，您可以在issue中提出，提前感谢！
以上这篇Android 自定义底部上拉控件的实现方法就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持脚本之家。