【软通动力】HarmonyOS三方件开发指南(7)

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2021-06-02

发表自话题:HarmonyOS 2

1. 组件compress功能介绍
1.1.  组件介绍:
        compress是一个轻量级图像压缩库。compress允许将大照片压缩成小尺寸的照片,图像质量损失非常小或可以忽略不计。

1.2.  手机模拟器上运行效果:
   

2. 组件compress使用方法
2.1.  添加依赖
        将compress-debug.har复制到应用的entry\libs目录下即可(由于build.gradle中已经依赖的libs目录下的*.har,因此不需要再做修改)。

2.2.  设置布局

2.3.  图像压缩
核心类:Compressor

核心方法:

(1)自定义压缩:

public static File customCompress(Context context, File file, int width, int height, int ) throws IOException

参数:

context - 应用程序上下文

file - 待压缩图片抽象路径名

width - 压缩后宽度

height - 压缩后高度

- 图片压缩质量,范围0~100

结果:

返回压缩后图片抽象路径名。

异常:

发生I/O异常

(2)默认压缩:

public static File defaultCompress(Context context, File file) throws IOException

参数:

context - 应用程序上下文

file - 待压缩图片抽象路径名

结果:

返回压缩后图片抽象路径名。

异常:

发生I/O异常

简单示例:

运行示例前需要在模拟器保存一张截图或使用相机功能照一张照片

public void onStart(Intent intent) { super.onStart(intent); super.setUIContent(ResourceTable.Layout_ability_main); // 请求文件的读取权限 String[] permissions = {"ohos.permission.READ_USER_STORAGE"}; reser(permissions, 0); // 获取压缩按钮并绑定事件 Button button = (Button) findComponentById(ResourceTable.Id_button); if (button != null) { // 为按钮设置点击回调 button.setClickedListener(new Component.ClickedListener() { @Override public void onClick(Component component) { try { File file = new File(System.getProperty("java.io.tmpdir") + File.separator + tmpName); HiLog.error(LOG_LABEL, "old size..." + file.length() + " ...b"); // 默认压缩 // File newFile = Compressor.defaultCompress(file); // 自定义压缩 File newFile = Compressor.customCompress(getContext(), file, 500, 1000, 60); Text text = (Text) findComponentById(ResourceTable.Id_text); text.setText("size: " + newFile.length() + " b"); HiLog.error(LOG_LABEL, "new size..." + newFile.length() + " ...b"); PixelMap newPixelMap = Compressor.decode(newFile); Image image = (Image) findComponentById(ResourceTable.Id_image1); image.setPixelMap(newPixelMap); } catch (IOException e) { e.printStackTrace(); } } }); } // 获取选择图片按钮并绑定事件 Button chooseButton = (Button) findComponentById(ResourceTable.Id_choose_button); if (chooseButton != null) { // 为按钮设置点击回调 chooseButton.setClickedListener(new Component.ClickedListener() { @Override public void onClick(Component component) { DataAbilityHelper helper = DataAbilityHelper.creator(getContext()); try { ResultSet resultSet = helper.query(AVStorage.Images.Media.EXTERNAL_DATA_ABILITY_URI, null, null); while (resultSet != null && resultSet.goToNextRow()) { // 互殴媒体库的图片 int id = resultSet.getInt(resultSet.getColumnIndexForName(AVStorage.Images.Media.ID)); HiLog.error(LOG_LABEL, "id:..." + id + " ..."); Uri uri = Uri.appendEncodedPathToUri(AVStorage.Images.Media.EXTERNAL_DATA_ABILITY_URI, "" + id); // 根据图片的uri打开文件并保存到临时目录中 FileDescriptor fileDescriptor = helper.openFile(uri, "r"); ImageSource.DecodingOptions decodingOpts = new ImageSource.DecodingOptions(); decodingOpts.sampleSize = ImageSource.DecodingOptions.DEFAULT_SAMPLE_SIZE; ImageSource imageSource = ImageSource.create(fileDescriptor, null); PixelMap pixelMap = imageSource.createThumbnailPixelmap(decodingOpts, true); ImagePacker imagePacker = ImagePacker.create(); tmpName = UUID.randomUUID().toString(); File file = new File(System.getProperty("java.io.tmpdir") + File.separator + tmpName); FileOutputStream outputStream = new FileOutputStream(file); ImagePacker.PackingOptions packingOptions = new ImagePacker.PackingOptions(); packingOptions. = 100; boolean result = imagePacker.initializePacking(outputStream, packingOptions); result = imagePacker.addImage(pixelMap); long dataSize = imagePacker.finalizePacking(); // 显示图片和图片大小 Text text = (Text) findComponentById(ResourceTable.Id_text); text.setText("size: " + file.length() + " b"); Image image = (Image) findComponentById(ResourceTable.Id_image1); image.setPixelMap(pixelMap); } } catch (DataAbilityRemoteException | FileNotFoundException e) { e.printStackTrace(); } } }); } }

3. 组件compress开发实现
3.1.  拷贝图片制临时目录
传入的图片路径拷贝临时文件到应用的临时目录。

private static File copyToCache(Context context, File imageFile) throws IOException { PixelMap pixelMap = decode(imageFile); String cachePath = context.getCacheDir() + File.separator + imageFile.getName(); File cacheFile = new File(cachePath); int = 100; // 压缩质量 refreshTmpFile(pixelMap, cacheFile, ); return cacheFile; }

 3.2.  图片解码
对临时目录里的图片进行解码

private static PixelMap decode(File file, int width, int height) { ImageSource imageSource = ImageSource.create(file, null); mageSource.DecodingOptions decodingOpts = new ImageSource.DecodingOptions(); decodingOpts.desiredSize = new Size(width, height); return imageSource.createPixelmap(decodingOpts); }

 3.3.  图片编码
按照开发人员设定的规则进行编码,生成新图片

private static void refreshTmpFile(PixelMap pixelMap, File file, int ) throws IOException { ImagePacker imagePacker = ImagePacker.create(); ImagePacker.PackingOptions options = new ImagePacker.PackingOptions(); options. = ; imagePacker.initializePacking(new FileOutputStream(file), options); imagePacker.addImage(pixelMap); imagePacker.finalizePacking(); }

 

项目源代码地址:https://github.com/isoftstone-dev/Compressor_Harmony

欢迎交流:

 

 

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