如何使用OpenXmlSdk将图像插入PowerPoint中的幻灯片并将其设置为背景？

Question

我需要在演示文稿中插入一张新幻灯片并将图像设置为背景。我找到了method to insert a new slide into a presentation，并且有效。

基于this method，我试图将图像插入幻灯片并设置为背景，但是失败了。

这是我不完整的代码。

    // Declare and instantiate a new slide.
    Slide slide = new Slide(new CommonSlideData(new Background()));

    // Specify background properties
    BackgroundProperties bgPr = new BackgroundProperties();

    BlipFill blipFill = new BlipFill() { Dpi = 0, RotateWithShape = true };

    string embedId = "rId2"; // specify embed id
    Drawing.Blip blip = new Drawing.Blip(new Drawing.Luminance()) { Embed = embedId };
    Drawing.SourceRectangle srcRect = new Drawing.SourceRectangle();
    Drawing.Stretch stretch = new Drawing.Stretch(new Drawing.FillRectangle());

    blipFill.AppendChild(blip);
    blipFill.AppendChild(srcRect);
    blipFill.AppendChild(stretch);

    Drawing.EffectList effectList = new Drawing.EffectList();

    bgPr.AppendChild(blipFill);
    bgPr.AppendChild(effectList);
    slide.CommonSlideData.Background.AppendChild(bgPr);

    // Create the slide part for the new slide.
    SlidePart slidePart = presentationPart.AddNewPart<SlidePart>();

    // Add imagePart to slidePart
    ImagePart imagePart = slidePart.AddImagePart(ImagePartType.Bmp, embedId);
    using (FileStream fileStream = new FileStream(imagePath, FileMode.Open))
    {
        imagePart.FeedData(fileStream);
    }

    // Save the new slide part.
    slide.Save(slidePart);