HarmonyOS 通过RawFileEntry读取PNG图片PixelMap，经ImagePacker编码，为JPEG格式。

HarmonyOS 通过RawFileEntry读取PNG图片PixelMap，经ImagePacker编码，为JPEG格式。本来PNG图片是透明图片，转成JPEG格式后成黑色背景。代码如下:如何不产生黑色背景。

RawFileEntry rawFileEntry = getContext().getResourceManager().getRawFileEntry("resources/rawfile/ccdraw/assets/symbol_PLA/commandorgan/6.png");
Resource resource = rawFileEntry.openRawFile();
ImageSource.SourceOptions sourceOptions = new ImageSource.SourceOptions();
sourceOptions.formatHint = "image/png";
ImageSource imageSource = ImageSource.create(resource, sourceOptions);
pixelMap = imageSource.createPixelmap(null);

ImagePacker imagePacker = ImagePacker.create();
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ImagePacker.PackingOptions packingOptions = new ImagePacker.PackingOptions();
imagePacker.initializePacking(byteArrayOutputStream, packingOptions);
imagePacker.addImage(pixelMap);
imagePacker.finalizePacking();
byte[] bytes = byteArrayOutputStream.toByteArray();
base64String = Base64.getEncoder().encodeToString(bytes);

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图像编码就是将PixelMap图像编码成不同存档格式图片，用于后续其他处理，比如保存、传输等。当前仅支持JPEG格式。

public static class PackingOptions {
    public String format = "image/jpeg";
    public int numberHint = 1;
    public int quality = 100;

    public PackingOptions() {
        throw new RuntimeException("Stub!");
    }
}