仿IOS滚轮效果(安卓中的竖直滑动选择器)

仿IOS滚轮效果(安卓中的竖直滑动选择器)

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 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<String> items;

private List<String> getItems() {
return items;
}

public void setItems(List<String> list) {
if (null == items) {
items = new ArrayList<String>();
}
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();

}

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）

public int getOffset() {
return offset;
}

public void setOffset(int offset) {
this.offset = offset;
}

int displayItemCount; // 每页显示的数量

int selectedIndex = 1;

private void init(Context context) {
this.context = context;
Log.d(TAG, "parent: " + this.getParent());
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;
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);
}

int itemHeight = 0;
/**
* 这里可以设置字体的属性 大小啦,边距啦,什么东西都可以在这里设置;
*/
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);
// 设置字体大小为20sp
tv.setTextSize(TypedValue.COMPLEX_UNIT_SP, 20);
// 设置文字内容
tv.setText(item);
// 设置文字居中
tv.setGravity(Gravity.CENTER);
// 设置内边距
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);

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;
}

}

int childSize = views.getChildCount();
for (int i = 0; i < childSize; i++) {
TextView itemView = (TextView) views.getChildAt(i);
if (null == itemView) {
return;
}
if (position == i) {
itemView.setTextColor(Color.parseColor("#0288ce"));
} else {
itemView.setTextColor(Color.parseColor("#bbbbbb"));
}
}
}

/**
* 获取选中区域的边界
*/
int[] selectedAreaBorder;

private int[] obtainSelectedAreaBorder() {
if (null == selectedAreaBorder) {
selectedAreaBorder = new int[2];
selectedAreaBorder[0] = itemHeight * offset;
selectedAreaBorder[1] = itemHeight * (offset + 1);
}
return selectedAreaBorder;
}

private int scrollDirection = -1;
private static final int SCROLL_DIRECTION_UP = 0;
private static final int SCROLL_DIRECTION_DOWN = 1;

Paint paint;
int viewWidth;

@Override
public void setBackgroundDrawable(Drawable background) {

if (viewWidth == 0) {
viewWidth = ((Activity) context).getWindowManager().getDefaultDisplay().getWidth();
Log.d(TAG, "viewWidth: " + viewWidth);
}

if (null == paint) {
paint = new Paint();
paint.setColor(Color.parseColor("#83cde6"));
paint.setStrokeWidth(dip2px(1f));
}

background = new Drawable() {
@Override
public void draw(Canvas canvas) {
canvas.drawLine(viewWidth * 1 / 6, obtainSelectedAreaBorder()[0], viewWidth * 5 / 6, obtainSelectedAreaBorder()[0], paint);
canvas.drawLine(viewWidth * 1 / 6, obtainSelectedAreaBorder()[1], viewWidth * 5 / 6, obtainSelectedAreaBorder()[1], paint);
}

@Override
public void setAlpha(int alpha) {

}

@Override
public void setColorFilter(ColorFilter cf) {

}

@Override
public int getOpacity() {
return 0;
}
};

super.setBackgroundDrawable(background);

}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
Log.d(TAG, "w: " + w + ", h: " + h + ", oldw: " + oldw + ", oldh: " + oldh);
viewWidth = w;
setBackgroundDrawable(null);
}

/**
* 选中回调
*/
private void onSeletedCallBack() {
if (null != onWheelViewListener) {
onWheelViewListener.onSelected(selectedIndex, items.get(selectedIndex));
}

}

public void setSeletion(int position) {
final int p = position;
selectedIndex = p + offset;
this.post(new Runnable() {
@Override
public void run() {
WheelView.this.smoothScrollTo(0, p * itemHeight);
}
});

}

public String getSeletedItem() {
return items.get(selectedIndex);
}

public int getSeletedIndex() {
return selectedIndex - offset;
}

@Override
public void fling(int velocityY) {
super.fling(velocityY / 3);
}

@Override
public boolean onTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_UP) {

startScrollerTask();
}
return super.onTouchEvent(ev);
}

private OnWheelViewListener onWheelViewListener;

public OnWheelViewListener getOnWheelViewListener() {
return onWheelViewListener;
}

public void setOnWheelViewListener(OnWheelViewListener onWheelViewListener) {
this.onWheelViewListener = onWheelViewListener;
}

private int dip2px(float dpValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}

private int getViewMeasuredHeight(View view) {
int width = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
int expandSpec = View.MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2, View.MeasureSpec.AT_MOST);
view.measure(width, expandSpec);
return view.getMeasuredHeight();
}
}

<你的包名+WheelView
android:id="@+id/wv"
android:layout_width="match_parent"
android:layout_height="wrap_content" />

// 初始化仿IOS滚轮效果的数据
// 在这里可以设置滚轮的偏移量
mWheelView.setOffset(2);
//设置每一个Item中的数据 mArrayList中装着的是一堆String字符串
mWheelView.setItems(mArrayList);
mWheelView.setOnWheelViewListener(new WheelView.OnWheelViewListener() {
@Override
public void onSelected(int selectedIndex, String item) {
//selectedIndex当前高亮的位置
//item当前高亮的位置的内容
}
});