【鸿蒙基于API 13实战开发】—— ArkUI基础组件之image开发

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📚鸿蒙开发往期学习笔录✒️：

✒️ 鸿蒙（OpenHarmony）南向开发保姆级知识点汇总~
✒️ 鸿蒙应用开发与鸿蒙系统开发哪个更有前景？
✒️ 嵌入式开发适不适合做鸿蒙南向开发？看完这篇你就了解了~
✒️ 对于大前端开发来说，转鸿蒙开发究竟是福还是祸？
✒️ 鸿蒙岗位需求突增！移动端、PC端、IoT到底该怎么选？
✒️ 记录一场鸿蒙开发岗位面试经历~
✒️ 持续更新中……

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image是图片组件，用来渲染展示图片。

创建image组件

在pages/index目录下的hml文件中创建一个image组件。

<!-- index.hml -->
<div class="container">
  <image style="height: 30%;" src="common/images/bg-tv.jpg"> </image>
</div>

---

/* xxx.css */
.container {
  width: 100%;
  height: 100%; 
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background-color: #F1F3F5;
}

设置image样式

通过设置width、height和object-fit属性定义图片的宽、高和缩放样式。

<!-- index.hml -->
<div class="container">
  <image src="common/images/bg-tv.jpg"> </image>
</div>

---

/* xxx.css */
.container {
  width: 100%;
  height: 100%;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background-color:#F1F3F5;
}
image{
  width: 80%;  
  height: 500px;
  border: 5px solid saddlebrown;
  border-radius: 20px;
  object-fit: contain;
  match-text-direction:true;
}

加载图片

图片成功加载时触发complete事件，返回加载的图源尺寸。加载失败则触发error事件，打印图片加载失败。

<!-- index.hml -->
<div class="container" >
  <div>
    <image src="common/images/bg-tv.jpg" oncomplete="imageComplete(1)" onerror="imageError(1)"> </image>
  </div>
  <div>
    <image src="common/images/bg-tv1.jpg" oncomplete="imageComplete(2)" onerror="imageError(2)"> </image>
  </div>
</div>

---

/* xxx.css */
.container{
  width: 100%;
  height: 100%;
  flex-direction: column;
  justify-content: center;
  align-self: center;
  background-color: #F1F3F5;
}
.container div{
  margin-left: 10%;
  width: 80%;
  height: 300px;
  margin-bottom: 40px;
}

---

// index.js
import promptAction from '@ohos.promptAction';
export default {
  imageComplete(i,e){
    promptAction.showToast({
      message: "image "+i+"'s width"+ e.width+"----image "+i+"'s height"+e.height,
      duration: 3000,
    })
  },
  imageError(i,e){
    setTimeout(()=>{
      promptAction.showToast({
        message: "Failed to load image "+i+".",
        duration: 3000,
      })
    },3000)
  }
}

场景示例

在本场景中，开发者长按图片后将慢慢隐藏图片，当完全隐藏后再重新显示原始图片。定时器setInterval每隔一段时间改变图片透明度,实现慢慢隐藏的效果，当透明度为0时清除定时器，设置透明度为1。

<!-- index.hml -->
<div class="page-container">
  <div class="content">
    <div class="image-container">
      <image class="testimage" src="{{testuri}}" style="opacity:{{imageopacity}};" onlongpress="changeopacity"> </image>
    </div>
    <div class="text-container">
      <text style="font-size: 37px;font-weight:bold;color:orange;text-align: center;width: 100%;">Touch and hold the image</text>
    </div>
  </div>
</div>

---

/* xxx.css */
.page-container {
  width: 100%;
  height: 100%;
  flex-direction:column;
  align-self: center;
  justify-content: center;
  background-color:#F1F3F5;
  background-color: #F1F3F5;
}
.content{
  flex-direction:column;
}
.image-container {
  width: 100%;
  height: 300px;
  align-items: center;
  justify-content: center;
}
.text-container {
  margin-top:50px;
  width: 100%;
  height: 60px;
  flex-direction: row;
  justify-content: space-between;
}
.testimage {
  width: 100%;  height: 400px;   
  object-fit: scale-down;  
  border-radius: 20px;
}

---

// index.js
import promptAction from '@ohos.promptAction';
export default {
  data: {
    testuri: 'common/images/bg-tv.jpg',
    imageopacity:1,
    timer: null
  },
  changeopacity: function () {
    promptAction.showToast({
      message: 'Touch and hold the image.'
    })
    var opval = this.imageopacity * 20
    clearInterval(this.timer);
    this.timer = setInterval(()=>{
      opval--;
      this.imageopacity = opval / 20
      if (opval===0) {
        clearInterval(this.timer)
        this.imageopacity = 1
      }
    },100);
  }
}