js实现左右滑动分页

﹏ヽ暗。殇╰゛Y 2022-06-08 12:47 306阅读 0赞

/**
     * 以下为项目的左右滑动分页
     */
    var startx, starty;
    //获得角度
    function getAngle(angx, angy) {
      return Math.atan2(angy, angx) * 180 / Math.PI;
    };
    
    //根据起点终点返回方向 1向上 2向下 3向左 4向右 0未滑动
    function getDirection(startx, starty, endx, endy) {
      var angx = endx - startx;
      var angy = endy - starty;
      var result = 0;
    
      //如果滑动距离太短
      if (Math.abs(angx) < 2 && Math.abs(angy) < 2) {
        return result;
      }
    
      var angle = getAngle(angx, angy);
      if(angle >= -135 && angle <= -45) {
        result = 1;
      }else if (angle > 45 && angle < 135) {
        result = 2;
      }else if ((angle >= 135 && angle <= 180) || (angle >= -180 && angle < -135)) {
        result = 3;
      }else if (angle >= -45 && angle <= 45) {
        result = 4;
      }
      return result;
    }
    
    //手指接触屏幕
    document.getElementById("item").addEventListener("touchstart", function(e) {
      startx = e.touches[0].pageX;
      starty = e.touches[0].pageY;
    }, false);
    //手指离开屏幕
    document.getElementById("item").addEventListener("touchend", function(e) {
      var endx, endy;
      endx = e.changedTouches[0].pageX;
      endy = e.changedTouches[0].pageY;
      var direction = getDirection(startx, starty, endx, endy);
      switch (direction) {
        case 0:
          //alert("未滑动！");
          break;
        case 1:
          //alert("向上！")
          break;
        case 2:
          //alert("向下！")
          break;
        case 3:
          //alert("向左！")  下一页
          if(gotoPage < totalPage){
            getItemListByBarId(barId,gotoPage + 1,openid,0);
          }
          break;
        case 4:
          //alert("向右！")   上一页
          if(gotoPage != 1){
            getItemListByBarId(barId,gotoPage - 1,openid,0);
          }
          break;
          default:
        }
    }, false);