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本文實(shí)例為大家分享了Android仿iphone自定義滾動(dòng)選擇器的具體代碼，供大家參考，具體內(nèi)容如下
一、多的不說(shuō)，效果圖，先走起
二、實(shí)例源碼
（1）自定義控件
package com.pickerscrollview.views;
import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
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;
import com.pickerscrollview.bean.Pickers;
/**
* 自定義滾動(dòng)選擇器
*
* @author zengtao 2015年5月20日 下午7:36:03
*
*/
@SuppressLint({ "HandlerLeak", "ClickableViewAccessibility" })
public class PickerScrollView extends View {
public static final String TAG = "PickerView";
/**
* text之間間距和minTextSize之比
*/
public static final float MARGIN_ALPHA = 2.8f;
/**
* 自動(dòng)回滾到中間的速度
*/
public static final float SPEED = 2;
private List<Pickers> mDataList;
/**
* 選中的位置，這個(gè)位置是mDataList的中心位置，一直不變
*/
private int mCurrentSelected;
private Paint mPaint;
private float mMaxTextSize = 20;
private float mMinTextSize = 10;
private float mMaxTextAlpha = 255;
private float mMinTextAlpha = 120;
private int mColorText = 0x333333;
private int mViewHeight;
private int mViewWidth;
private float mLastDownY;
/**
* 滑動(dòng)的距離
*/
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
// 這里mMoveLen / Math.abs(mMoveLen)是為了保有mMoveLen的正負(fù)號(hào)，以實(shí)現(xiàn)上滾或下滾
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();
}
/**
* 選擇選中的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();
}
/**
* 選擇選中的內(nèi)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的高度計(jì)算字體大小
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(mColorText);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 根據(jù)index繪制view
if (isInit)
drawData(canvas);
}
private void drawData(Canvas canvas) {
// 先繪制選中的text再往上往下繪制其余的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居中繪制，注意baseline的計(jì)算才能達(dá)到居中，y值是text中心坐標(biāo)
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);
// 繪制上方data
for (int i = 1; (mCurrentSelected - i) >= 0; i++) {
drawOtherText(canvas, i, -1);
}
// 繪制下方data
for (int i = 1; (mCurrentSelected + i) < mDataList.size(); i++) {
drawOtherText(canvas, i, 1);
}
}
/**
* @param canvas
* @param position
* 距離mCurrentSelected的差值
* @param type
* 1表示向下繪制，-1表示向上繪制
*/
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);
}
/**
* 拋物線
*
* @param zero
* 零點(diǎn)坐標(biāo)
* @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) {
// 往下滑超過(guò)離開(kāi)距離
moveTailToHead();
mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize;
} else if (mMoveLen < -MARGIN_ALPHA * mMinTextSize / 2) {
// 往上滑超過(guò)離開(kāi)距離
moveHeadToTail();
mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize;
}
mLastDownY = event.getY();
invalidate();
}
private void doUp(MotionEvent event) {
// 抬起手后mCurrentSelected的位置由當(dāng)前位置move到中間選中位置
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);
}
}
（2）實(shí)體類
package com.pickerscrollview.bean;
import java.io.Serializable;
/**
*
* @author zengtao 2015年5月20日下午7:18:14
*
*/
public class Pickers implements Serializable {
private static final long serialVersionUID = 1L;
private String showConetnt;
private String showId;
public String getShowConetnt() {
return showConetnt;
}
public String getShowId() {
return showId;
}
public Pickers(String showConetnt, String showId) {
super();
this.showConetnt = showConetnt;
this.showId = showId;
}
public Pickers() {
super();
}
}
（3）主界面
package com.pickerscrollview.ui;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RelativeLayout;
import com.pickerscrollview.bean.Pickers;
import com.pickerscrollview.views.PickerScrollView;
import com.pickerscrollview.views.PickerScrollView.onSelectListener;
/**
* 主界面
*
* @author zengtao 2015年5月20日 下午7:36:03
*
*/
public class MainActivity extends Activity {
private Button bt_scrollchoose; // 滾動(dòng)選擇器按鈕
private PickerScrollView pickerscrlllview; // 滾動(dòng)選擇器
private List<Pickers> list; // 滾動(dòng)選擇器數(shù)據(jù)
private String[] id;
private String[] name;
private Button bt_yes; // 確定按鈕
private RelativeLayout picker_rel; // 選擇器布局
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
initLinstener();
initData();
}
/**
* 初始化
*/
private void initView() {
bt_scrollchoose = (Button) findViewById(R.id.bt_scrollchoose);
picker_rel = (RelativeLayout) findViewById(R.id.picker_rel);
pickerscrlllview = (PickerScrollView) findViewById(R.id.pickerscrlllview);
bt_yes = (Button) findViewById(R.id.picker_yes);
}
/**
* 設(shè)置監(jiān)聽(tīng)事件
*/
private void initLinstener() {
bt_scrollchoose.setOnClickListener(onClickListener);
pickerscrlllview.setOnSelectListener(pickerListener);
bt_yes.setOnClickListener(onClickListener);
}
/**
* 初始化數(shù)據(jù)
*/
private void initData() {
list = new ArrayList<Pickers>();
id = new String[] { "1", "2", "3", "4", "5", "6" };
name = new String[] { "中國(guó)銀行", "農(nóng)業(yè)銀行", "招商銀行", "工商銀行", "建設(shè)銀行", "民生銀行" };
for (int i = 0; i < name.length; i++) {
list.add(new Pickers(name[i], id[i]));
}
// 設(shè)置數(shù)據(jù)，默認(rèn)選擇第一條
pickerscrlllview.setData(list);
pickerscrlllview.setSelected(0);
}
// 滾動(dòng)選擇器選中事件
onSelectListener pickerListener = new onSelectListener() {
@Override
public void onSelect(Pickers pickers) {
System.out.println("選擇：" + pickers.getShowId() + "--銀行："
+ pickers.getShowConetnt());
}
};
// 點(diǎn)擊監(jiān)聽(tīng)事件
OnClickListener onClickListener = new OnClickListener() {
@Override
public void onClick(View v) {
if (v == bt_scrollchoose) {
picker_rel.setVisibility(View.VISIBLE);
} else if (v == bt_yes) {
picker_rel.setVisibility(View.GONE);
}
}
};
}
三、總結(jié)
先做一下解析，在滑動(dòng)手指的時(shí)候，有一個(gè)突出的點(diǎn)，就是有點(diǎn)像圓弧那個(gè)弧度一樣的感覺(jué)，所以我們要用parabola這個(gè)方法去計(jì)算出來(lái)，畫(huà)多大的字也是需要計(jì)算控件的高度，和寬度來(lái)繪制，首先我們先繪制中間的文體，在繪制上下兩邊的字，當(dāng)然，我們也要設(shè)置一個(gè)手勢(shì)監(jiān)聽(tīng)，用于監(jiān)聽(tīng)用戶按下，滑動(dòng)，抬起的時(shí)候，的一個(gè)操作，我們會(huì)根據(jù)手指往上移動(dòng)和向下移動(dòng)距離的多少來(lái)判斷顯示那個(gè)文字，選中了那個(gè)。
源碼下載：Android自定義滾動(dòng)選擇器
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