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标题: 如何在OpenHarmony应用侧获取屏幕DPI [打印本页]

作者: 润开鸿_贾佳豪    时间: 2023-11-27 11:36
标题: 如何在OpenHarmony应用侧获取屏幕DPI
[md]笔者之前分享过[如何在设备侧修改屏幕 DPI](https://ost.51cto.com/posts/21367),本文则介绍在OpenHarmony应用侧获取`屏幕DPI`。


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## 1.应用侧获取屏幕DPI 实现思路

- 如图这是笔者的两台OpenHarmony设备,左边[汇思博SEEK100 sl8541e](https://gitee.com/wisbokit/resources/tree/master)的DPI为213,右边[润开鸿 DAYU200](https://gitee.com/hihope_iot/docs/tree/master/HiHope_DAYU200)的DPI为240

![af864212b74a9859f4bad5cf1aec8e7.jpg](https://dl-harmonyos.51cto.com/i ... rocess=image/resize,w_820,h_1280)

- 通过导入@ohos.display包来使用getDefaultDisplaySync()方法以获取屏幕 DPI值的方法

```
import display from '@ohos.display';

@Entry
@Component
struct Index {
  @State displayClass: display.Display | null = null

  aboutToAppear(){
    try {
      this.displayClass = display.getDefaultDisplaySync();
      console.info('Test densityDPI:' + JSON.stringify(this.displayClass.densityDPI));
    } catch (exception) {
      console.error('Failed to obtain the default display object. Code: ' + JSON.stringify(exception));
    }
  }

  build() {
    Row() {
      Column() {
        Text('屏幕DPI是'+JSON.stringify(this.displayClass.densityDPI))
          .fontSize(50)
          .fontWeight(FontWeight.Bold)
      }
      .width('100%')
    }
    .height('100%')
  }
}
```

## 2.更改开发板的屏幕DPI(以DAYU200为例)

### 2.1 方法一:更改源码编译烧录固件

- 在源码foundation/window/window_manager/resources/config/rk3568/display_manager_config.xml文件中修改dpi,编译后烧录固件。

```
<!--Window display dpi, valid range is 80~640, use 0 if no configuration is requeired-->
    <dpi>240</dpi>
```

### 2.2 方法二:发送display_manager_config.xml文件至设备etc/window/resources

- OpenHarmony固件编译烧录进入设备后,display_manager_config.xml文件会被预编译打包至设备端etc/window/resources目录下,什么,为什么只有window/resources字段,因为ohos_prebuilt_etc就是把文件放进设备的etc文件夹

```
foundation/window/window_manager/resources/config/BULID.gn文件如下,
下面代码的意思是源码foundation/window/window_manager/resources/config/rk3568/display_manager_config.xml会真正安装在设备中的etc/window/resources文件位置,

ohos_prebuilt_etc("display_manager_config") {
  if (device_name == "rk3568") {
    source = "//foundation/window/window_manager/resources/config/rk3568/display_manager_config.xml"
    install_enable = true
···
···
  relative_install_dir = "window/resources"
}
```

- 步骤如下

```
# 进入sdk\版本号\toolchain输入cmd打开命令行,重新加载系统为可读写
hdc_std shell mount -o remount,rw /

# 替换/etc/window/resources中的display_manager_config.xml文件
hdc_std file send C:\Users\jjh\display_manager_config.xml /etc/window/resources

# 然后重启开发板让设置生效
hdc reboot
```

## 3.参考资料

- https://gitee.com/openharmony/do ... /js-apis-display.md
- https://gitee.com/openharmony/do ... qs/faqs-graphics.md

[/md]




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