【快应用】任意拖动图标实现案例

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问题背景：

快应用页面开发阶段，ui布局时总是会遇到要在页面上实现一个可以任意拖动的导航栏，且在拖动时不能超出屏幕和导航栏不能在到边界时被压缩。一些开发者就会被困住了，这里就介绍一个实现导航栏的一个简易方式。

 

方案：

1、通过block实现组件堆叠效果，使得image图标位于list组件上方，并将image的样式设置为“position: fixed”。

2、通过监听image组件的touchmove触摸事件实现动态设置其位置，具体可参见“通用事件”中的“touchmove事件”和“TouchEvent类型说明”。

3、device.getInfoSync获取页面的宽高来设置边界，保证导航栏不会滑到屏幕外。

 

实现代码：

<template>

  <div class="item-container">

    <block>

      <!-- <stack> -->

      <div class="container">

        <list class="list" style="height: 100px" for="{{this.dataList}}">

          <list-item class="list-item" type="content">

            <text>{{ $item.name }}</text>

          </list-item>

        </list>

      </div>

      <image id="img" style="position: fixed;left: {{this.clientX}};top:{{this.clientY}}" class="image" src="/Common/logo.png" ontouchmove="touchmove"></image>

      <!-- </stack> -->

    </block>

  </div>

</template>

<style>

  .item-container {

    margin-bottom: 50px;

    flex-direction: column;

  }

  .container {

    flex-direction: column;

  }

  .list {

    flex-direction: column;

  }

  .image {

    border-radius: 100px;

    height: 150px;

  }

  .list-item {

    border: 1px solid #c21f1f;

  }

</style>

<script>

  import device from '@system.device';

  export default {

    data: {

      clientX: "",

      clientY: "",

      width: 0,

      height: 0,

      dataList: [

        { name: "Language" },

        { name: "Maths" },

        { name: "English" },

        { name: "PE" },

        { name: "History" },

        { name: "Geography" },

        { name: "Science" },

        { name: "Physics" },

        { name: "Chemical" },

        { name: "Biology" },

        { name: "Music" },

        { name: "Art" },

        { name: "Language1" },

        { name: "Maths1" },

      ]

    },

    onInit: function () {

      this.$page.setTitleBar({ text: "Long press to drag the icon" });

      console.info("Application onInit");

    },

    onShow(options) {

      console.info("Application onShow");

      const res = device.getInfoSync();

      this.width = res.windowLogicWidth

      this.height = res.windowLogicHeight

      console.info("hjj", typeof this.width);

    },

    onHide(options) {

      console.info("Application onHide");

    },

    touchmove: function (TouchEvent) {

      console.log(JSON.stringify(TouchEvent.changedTouches));

      this.clientX = (TouchEvent.changedTouches[0].clientX - 75) + "px"

      this.clientY = (TouchEvent.changedTouches[0].clientY - 75) + "px"

      console.log("clientX = " + TouchEvent.changedTouches[0].clientX);

      console.log("clientY = " + TouchEvent.changedTouches[0].clientY);

      if ((TouchEvent.changedTouches[0].clientX - 75) <= 0) {

        this.clientX = 0 + "px"

      }

      if ((TouchEvent.changedTouches[0].clientY - 75) <= 0) {

        this.clientY = 0 + "px"

      }

      if ((TouchEvent.changedTouches[0].clientX) >= this.width - 75) {

        this.clientX = 600 + "px"

      }

      if ((TouchEvent.changedTouches[0].clientY) >= this.height - 75) {

        this.clientY = 1230 + "px"

      }

 

    }

  };

</script>

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