在做时间轴或者某些类型的选择时,有时候设计师会给我们出类似下面的效果:
因此,我们就需要重新自定义scrollview,,也就是移动端常用的时间轴控件:WheelView
实现方式直接上代码:
public class WheelView extends ScrollView {
public static final String TAG = WheelView.class.getSimpleName();
public static class OnWheelViewListener {
public void onSelected(int selectedIndex, String item) {
}
}
private Context context;
// private ScrollView scrollView;
private LinearLayout views;
public WheelView(Context context) {
super(context);
init(context);
}
public WheelView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public WheelView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
// String[] items;
List items;
private List getItems() {
return items;
}
public void setItems(List list) {
if (null == items) {
items = new ArrayList();
}
items.clear();
items.addAll(list);
// 前面和后面补全
for (int i = 0; i < offset; i++) {
items.add(0, "");
items.add("");
}
initData();
}
// 每页显示的数量
public static final int OFF_SET_DEFAULT = 1;
int offset = OFF_SET_DEFAULT; // 偏移量(需要在最前面和最后面补全)
int displayItemCount;
int selectedIndex = 1; //
int itemHeight = 0;//每个条目的高度
int textSize = 20;//每个条目的字体大小
public int getOffset() {
return offset;
}
public void setOffset(int offset) {
this.offset = offset;
}
public void setTextSize(int textSize) {
this.textSize = textSize;
}
private void init(Context context) {
this.context = context;
// scrollView = ((ScrollView)this.getParent());
// Log.d(TAG, "scrollview: " + scrollView);
Log.d(TAG, "parent: " + this.getParent());
// this.setOrientation(VERTICAL);
this.setVerticalScrollBarEnabled(false);
views = new LinearLayout(context);
views.setOrientation(LinearLayout.VERTICAL);
this.addView(views);
scrollerTask = new Runnable() {
public void run() {
int newY = getScrollY();
if (initialY - newY == 0) { // stopped
final int remainder = initialY % itemHeight;
final int divided = initialY / itemHeight;
// Log.d(TAG, "initialY: " + initialY);
// Log.d(TAG, "remainder: " + remainder + ", divided: " + divided);
if (remainder == 0) {
selectedIndex = divided + offset;
onSeletedCallBack();
} else {
if (remainder > itemHeight / 2) {
WheelView.this.post(new Runnable() {
@Override
public void run() {
WheelView.this.smoothScrollTo(0, initialY - remainder + itemHeight);
selectedIndex = divided + offset + 1;
onSeletedCallBack();
}
});
} else {
WheelView.this.post(new Runnable() {
@Override
public void run() {
WheelView.this.smoothScrollTo(0, initialY - remainder);
selectedIndex = divided + offset;
onSeletedCallBack();
}
});
}
}
} else {
initialY = getScrollY();
WheelView.this.postDelayed(scrollerTask, newCheck);
}
}
};
}
int initialY;
Runnable scrollerTask;
int newCheck = 50;
public void startScrollerTask() {
initialY = getScrollY();
this.postDelayed(scrollerTask, newCheck);
}
private void initData() {
displayItemCount = offset * 2 + 1;
for (String item : items) {
views.addView(createView(item));
}
refreshItemView(0);
}
private TextView createView(String item) {
TextView tv = new TextView(context);
tv.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
tv.setSingleLine(true);
tv.setTextSize(TypedValue.COMPLEX_UNIT_SP, textSize);
tv.setText(item);
tv.setGravity(Gravity.CENTER);
int padding = dip2px(15);
tv.setPadding(padding, padding, padding, padding);
if (0 == itemHeight) {
itemHeight = getViewMeasuredHeight(tv);
Log.d(TAG, "itemHeight: " + itemHeight);
views.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, itemHeight * displayItemCount));
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) this.getLayoutParams();
this.setLayoutParams(new LinearLayout.LayoutParams(lp.width, itemHeight * displayItemCount));
}
return tv;
}
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
// Log.d(TAG, "l: " + l + ", t: " + t + ", oldl: " + oldl + ", oldt: " + oldt);
// try {
// Field field = ScrollView.class.getDeclaredField("mScroller");
// field.setAccessible(true);
// OverScroller mScroller = (OverScroller) field.get(this);
//
//
// if(mScroller.isFinished()){
// Log.d(TAG, "isFinished...");
// }
//
// } catch (Exception e) {
// e.printStackTrace();
// }
refreshItemView(t);
if (t > oldt) {
// Log.d(TAG, "向下滚动");
scrollDirection = SCROLL_DIRECTION_DOWN;
} else {
// Log.d(TAG, "向上滚动");
scrollDirection = SCROLL_DIRECTION_UP;
}
}
private void refreshItemView(int y) {
int position = y / itemHeight + offset;
int remainder = y % itemHeight;
int divided = y / itemHeight;
if (remainder == 0) {
position = divided + offset;
} else {
if (remainder > itemHeight / 2) {
position = divided + offset + 1;
}
// if(remainder > itemHeight / 2){
// if(scrollDirection == SCROLL_DIRECTION_DOWN){
// position = divided + offset;
// Log.d(TAG, ">down...position: " + position);
// }else if(scrollDirection == SCROLL_DIRECTION_UP){
// position = divided + offset + 1;
// Log.d(TAG, ">up...position: " + position);
// }
// }else{
//// position = y / itemHeight + offset;
// if(scrollDirection == SCROLL_DIRECTION_DOWN){
// position = divided + offset;
// Log.d(TAG, "> 2, View.MeasureSpec.AT_MOST);
view.measure(width, expandSpec);
return view.getMeasuredHeight();
}
}
外面设置属性和传数据的使用方式如下:
val layout_wheelview = findViewById(R.id.layout_wheelview).apply {
//设置选中的字体颜色
setCheckTextColor(Color.BLACK)
//设置条目字体大小
setTextSize(18)
//设置列表数据
setItems(listContent)
//添加滑动监听
onWheelViewListener = object : WheelView.OnWheelViewListener() {
override fun onSelected(selectedIndex: Int, item: String) {
}
}
}
外面获取当前选中的条目:
layout_wheelview.seletedIndex