harmony 鸿蒙<image> Development

2022-08-09
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<image> Development

The <image> component is used to render and display images. For details, see image.

Creating an <image> Component

Create an <image> component in the .hml file under pages/index.

<!-- 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;
}

en-us_image_0000001223127736

Setting the Image Style

Set the width, height, and object-fit attributes to define the width, height, and scale type of the image.

<!-- 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;
}

en-us_image_0000001222807796

Loading the Image

When the image is successfully loaded, the complete event is triggered, and the loaded image is returned. If an exception occurs during image loading, the error event is triggered, and the image loading failure log is printed.

<!-- 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)
  }
}

en-us_image_images

Example Scenario

In this example you touch and hold an image to gradually hide it. After the image is completely hidden, it will show in its original setting. Set a setInterval timer to change the image opacity at a specified interval so that it is hidden gradually. When the opacity changes to 0, the timer is cleared and the opacity is set to 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);
  }
}

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