Android 自定义控件WheelView
一、定义WheelView
融合网友的杰作，实现滑动选择效果。
二、WheelView的使用
public class MainActivity extends Activity {
private Button mainBt;
private static final String TAG = MainActivity.class.getSimpleName();
private static final String[] PLANETS = new String[] { "赵云", "关羽", "张飞",
"吕布", "典韦", "马超", "黄忠", "诸葛亮" };
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mainBt = (Button) findViewById(R.id.main_bt);
mainBt.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// 构建弹出框View
View outerView = LayoutInflater.from(MainActivity.this)
.inflate(R.layout.wheel_view, null);
WheelView wv = (WheelView) outerView
.findViewById(R.id.wheel_view_wv);
// wv.setOffset(0);// 偏移量
wv.setOffset(2);
wv.setItems(Arrays.asList(PLANETS));// 实际内容
wv.setSeletion(0);// 设置默认被选中的项目
// wv.setSeletion(3);
wv.setOnWheelViewListener(new WheelView.OnWheelViewListener() {
@Override
public void onSelected(int selectedIndex, String item) {
// 选中后的处理事件
Log.d(TAG, "[Dialog]selectedIndex: " + selectedIndex
+ ", item: " + item);
}
});
// 展示弹出框
new AlertDialog.Builder(MainActivity.this)
.setTitle("WheelView in Dialog").setView(outerView)
.setPositiveButton("OK", null).show();
}
});
}
}
三、自定义控件源码【复制可直接使用】
是的，自定义控件源码才是最宝贝的。重走Android路，希望以后的自己，能够构造出来更多炫酷的控件。
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);
}
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();
}
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;
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, 20);
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);
refreshItemView(t);
if (t > oldt) {
scrollDirection = SCROLL_DIRECTION_DOWN;
} else {
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();
}
} 这里是源码Demo
经历 + 总结 = 人生
没有最好的选择，只有最适合的选择！