效果大概就是这样,右边是字母索引效果
做开发的时候，经常碰到产品经理设计出来的界面是参考IOS控件设计出来的 ，比如上图效果 ios有个控件是UIPickerView 就是可以上下滑动 并有些3d效果，非常炫。
但是android并没有提供这样的原生控件支持，所以需要通过其他方式实现类似效果。上图就是我开发中用到的一个效果。
话不多说 ，直接上代码：
Activity
package com.example.picscrollview; import java.util.ArrayList; import java.util.Collections; import java.util.List; import com.example.picscrollview.PickerScrollView.onSelectListener; import com.example.test.R; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Toast; public class MainActivity extends Activity implements OnClickListener { Boolean state_pressed = true; private String cities[] ={"北京版", "天津版", "上海版", "重庆版", "河北版", "山西版", "辽宁版", "吉林版", "黑龙江版", "江苏版", "浙江版", "安徽版", "福建版", "江西版", "山东版", "河南版", "湖北版", "湖南版", "广东版", "甘肃版", "四川版", "贵州版", "海南版", "云南版", "青海版", "陕西版", "广西版", "西藏版", "宁夏版", "新疆版", "内蒙古版", "澳门版", "香港版", "台湾版","全国版"}; private String[] id = { "1", "2", "3", "4", "5", "6" ,"7","8","9","10","11","12","13","14","15","16", "17", "18", "19", "20", "21", "22" ,"23","24","25","26","27","28","29","30","31","32","33","34","35"}; private PickerScrollView pickerscrlllview; // 滚动选择器 private List<Pickers> list; // 滚动选择器数据 private CharacterParser mCharacterParser; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); initData(); } public void initView() { LetterSideBar letterSideBar = (LetterSideBar) findViewById(R.id.cs_letter_sb); letterSideBar .setOnTouchingLetterChangedListener(new LetterSideBar.OnTouchingLetterChangedListener() { @Override public void onTouchingLetterChanged(String letter) { int jumpPos = getPositionForSection(letter.charAt(0)); pickerscrlllview.setSelected(jumpPos); } }); pickerscrlllview = (PickerScrollView) findViewById(R.id.pickerscrlllview); pickerscrlllview.setOnSelectListener(pickerListener); findViewById(R.id.location_confirm_btn).setOnClickListener(this); } private void initData() { mCharacterParser = CharacterParser.getInstance(); list = filledData(); PinyinComparator pinyinComparator = new PinyinComparator(); Collections.sort(list, pinyinComparator); pickerscrlllview.setData(list); pickerscrlllview.setSelected(0); } @Override protected void onResume() { super.onResume(); } public void onPause() { super.onPause(); } private List<Pickers> filledData() { List<Pickers> sortList = new ArrayList<Pickers>(); for (int i = 0, n = cities.length; i < n; i++) { Pickers picker = new Pickers(); picker.setShowConetnt(cities[i]); picker.setShowId(id[i]); String pinyin = mCharacterParser.getSelling(cities[i]); picker.setPinyin(pinyin); String sortString = pinyin.substring(0, 1).toUpperCase(); if (sortString.matches("[A-Z]")) { picker.setSortLetter(sortString.toUpperCase()); } else { picker.setSortLetter("#"); } sortList.add(picker); } return sortList; } public int getPositionForSection(int section) { for (int i = 0; i < list.size(); i++) { String sortStr = list.get(i).getSortLetter(); char firstChar = sortStr.toUpperCase().charAt(0); if (firstChar == section) { return i; } } return -1; } onSelectListener pickerListener = new onSelectListener() { @Override public void onSelect(Pickers pickers) { Toast.makeText(MainActivity.this, pickers.getShowConetnt(), Toast.LENGTH_LONG).show(); } }; @Override public void onBackPressed() { super.onBackPressed(); } @Override public void onClick(View v) { switch (v.getId()) { default: break; } } }
自定义滑动view
package com.example.picscrollview; import java.util.ArrayList; import java.util.List; import java.util.Timer; import java.util.TimerTask; import com.example.test.R; import android.annotation.SuppressLint; import android.content.Context; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Paint.Align; import android.graphics.Paint.FontMetricsInt; import android.graphics.Paint.Style; import android.os.Handler; import android.os.Message; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; /** * 自定义滚动选择器 * * @author zlw * */ @SuppressLint({ "HandlerLeak", "ClickableViewAccessibility" }) public class PickerScrollView extends View { public static final String TAG = "PickerView"; /** * text之间间距和minTextSize之比 */ public static final float MARGIN_ALPHA = 2.8f; /** * 自动回滚到中间的速度 */ public static final float SPEED = 2; private List<Pickers> mDataList; /** * 选中的位置，这个位置是mDataList的中心位置，一直不变 */ private int mCurrentSelected; private Paint mPaint; private float mMaxTextSize = 14; private float mMinTextSize = 6; private float mMaxTextAlpha = 255; private float mMinTextAlpha = 120; private int mColorText = 0x333333; private int mViewHeight; private int mViewWidth; private float mLastDownY; /** * 滑动的距离 */ private float mMoveLen = 0; private boolean isInit = false; private onSelectListener mSelectListener; private Timer timer; private MyTimerTask mTask; Handler updateHandler = new Handler() { @Override public void handleMessage(Message msg) { if (Math.abs(mMoveLen) < SPEED) { mMoveLen = 0; if (mTask != null) { mTask.cancel(); mTask = null; performSelect(); } } else // 这里mMoveLen / Math.abs(mMoveLen)是为了保有mMoveLen的正负号，以实现上滚或下滚 mMoveLen = mMoveLen - mMoveLen / Math.abs(mMoveLen) * SPEED; invalidate(); } }; public PickerScrollView(Context context) { super(context); init(); } public PickerScrollView(Context context, AttributeSet attrs) { super(context, attrs); init(); } public void setOnSelectListener(onSelectListener listener) { mSelectListener = listener; } private void performSelect() { if (mSelectListener != null) mSelectListener.onSelect(mDataList.get(mCurrentSelected)); } public void setData(List<Pickers> datas) { mDataList = datas; mCurrentSelected = datas.size() / 2; invalidate(); } /** * 选择选中的item的index * * @param selected */ public void setSelected(int selected) { mCurrentSelected = selected; int distance = mDataList.size() / 2 - mCurrentSelected; if (distance < 0) for (int i = 0; i < -distance; i++) { moveHeadToTail(); mCurrentSelected--; } else if (distance > 0) for (int i = 0; i < distance; i++) { moveTailToHead(); mCurrentSelected++; } invalidate(); } /** * 选择选中的内容 * * @param mSelectItem */ public void setSelected(String mSelectItem) { for (int i = 0; i < mDataList.size(); i++) if (mDataList.get(i).equals(mSelectItem)) { setSelected(i); break; } } private void moveHeadToTail() { Pickers head = mDataList.get(0); mDataList.remove(0); mDataList.add(head); } private void moveTailToHead() { Pickers tail = mDataList.get(mDataList.size() - 1); mDataList.remove(mDataList.size() - 1); mDataList.add(0, tail); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); mViewHeight = getMeasuredHeight(); mViewWidth = getMeasuredWidth(); // 按照View的高度计算字体大小 mMaxTextSize = mViewHeight / 8.0f; mMinTextSize = mMaxTextSize / 2f; isInit = true; invalidate(); } private void init() { timer = new Timer(); mDataList = new ArrayList<Pickers>(); mPaint = new Paint(Paint.ANTI_ALIAS_FLAG); mPaint.setStyle(Style.FILL); mPaint.setTextAlign(Align.CENTER); mPaint.setColor(getResources().getColor(R.color.white)); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); // 根据index绘制view if (isInit) drawData(canvas); } private void drawData(Canvas canvas) { // 先绘制选中的text再往上往下绘制其余的text float scale = parabola(mViewHeight / 4.0f, mMoveLen); float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize; mPaint.setTextSize(size); mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha)); // text居中绘制，注意baseline的计算才能达到居中，y值是text中心坐标 float x = (float) (mViewWidth / 2.0); float y = (float) (mViewHeight / 2.0 + mMoveLen); FontMetricsInt fmi = mPaint.getFontMetricsInt(); float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0)); int indexs = mCurrentSelected; String textData = mDataList.get(indexs).getShowConetnt(); canvas.drawText(textData, x, baseline, mPaint); // 绘制上方data for (int i = 1; (mCurrentSelected - i) >= 0; i++) { drawOtherText(canvas, i, -1); } // 绘制下方data for (int i = 1; (mCurrentSelected + i) < mDataList.size(); i++) { drawOtherText(canvas, i, 1); } } /** * @param canvas * @param position * 距离mCurrentSelected的差值 * @param type * 1表示向下绘制，-1表示向上绘制 */ private void drawOtherText(Canvas canvas, int position, int type) { float d = (float) (MARGIN_ALPHA * mMinTextSize * position + type * mMoveLen); float scale = parabola(mViewHeight / 4.0f, d); float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize; mPaint.setTextSize(size); mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha)); float y = (float) (mViewHeight / 2.0 + type * d); FontMetricsInt fmi = mPaint.getFontMetricsInt(); float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0)); int indexs = mCurrentSelected + type * position; String textData = mDataList.get(indexs).getShowConetnt(); canvas.drawText(textData, (float) (mViewWidth / 2.0), baseline, mPaint); } /** * 抛物线 * * @param zero * 零点坐标 * @param x * 偏移量 * @return scale */ private float parabola(float zero, float x) { float f = (float) (1 - Math.pow(x / zero, 2)); return f < 0 ? 0 : f; } @Override public boolean onTouchEvent(MotionEvent event) { switch (event.getActionMasked()) { case MotionEvent.ACTION_DOWN: doDown(event); break; case MotionEvent.ACTION_MOVE: doMove(event); break; case MotionEvent.ACTION_UP: doUp(event); break; } return true; } private void doDown(MotionEvent event) { if (mTask != null) { mTask.cancel(); mTask = null; } mLastDownY = event.getY(); } private void doMove(MotionEvent event) { mMoveLen += (event.getY() - mLastDownY); if (mMoveLen > MARGIN_ALPHA * mMinTextSize / 2) { // 往下滑超过离开距离 moveTailToHead(); mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize; } else if (mMoveLen < -MARGIN_ALPHA * mMinTextSize / 2) { // 往上滑超过离开距离 moveHeadToTail(); mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize; } mLastDownY = event.getY(); invalidate(); } private void doUp(MotionEvent event) { // 抬起手后mCurrentSelected的位置由当前位置move到中间选中位置 if (Math.abs(mMoveLen) < 0.0001) { mMoveLen = 0; return; } if (mTask != null) { mTask.cancel(); mTask = null; } mTask = new MyTimerTask(updateHandler); timer.schedule(mTask, 0, 10); } class MyTimerTask extends TimerTask { Handler handler; public MyTimerTask(Handler handler) { this.handler = handler; } @Override public void run() { handler.sendMessage(handler.obtainMessage()); } } public interface onSelectListener { void onSelect(Pickers pickers); } }
