Android自定义滚动选择器实例代码

android自定义滚动选择器

实现图片的效果

代码如下

package com.linzihui.widget;

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 java.util.arraylist;
import java.util.list;
import java.util.timer;
import java.util.timertask;

/**
 * 自定义滚动选择器
 * 
 * @author cuiran
 *
 */
@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 = 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(mcolortext);
  }

  @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);
  }
}

package com.linzihui.widget;

import java.io.serializable;

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();
  }

}

使用的时候 新建一个activity 里面对vieｗ进行处理

 pickerscrlllview=(pickerscrollview)findviewbyid(r.id.pickerscrlllview);
    pickerscrlllview.setonselectlistener(pickerlistener);

 pickerscrollview.onselectlistener pickerlistener0 = new pickerscrollview.onselectlistener() {

    @override
    public void onselect(pickers pickers) {
      s1=pickers.getshowconetnt();
    }
  };

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