Android(安卓)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" };@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mainBt = (Button) findViewById(R.id.main_bt);mainBt.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// 构建弹出框ViewView 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() {@Overridepublic 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();}});}}

展示最终效果：

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<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;    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();    }}

若是你发现了代码中的bug，请不吝赐教 ~_~

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！

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