尝试获取 PowerPoint 2010 幻灯片中的所有图片，但出现错误

Question

我正在编写一个使用 Open XML SDK 2.0 的小型控制台程序。我基本上只是想在 PowerPoint 幻灯片上获取所有图片。但是，当我运行该程序时，出现以下错误：

Cannot access part because parent package was closed.

我的 ppt 只有一张幻灯片和一张图片。这只是一个原型程序。我不熟悉 Open XML SDK 2.0，所以我不确定这个错误告诉我什么以及如何修复它。我希望有人能指出我正确的方向。这是我的代码：

using System;
using System.Collections.Generic;
using DocumentFormat.OpenXml.Presentation;
using A = DocumentFormat.OpenXml.Drawing;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml;
using System.Text;
using System.Data;
using System.Linq;
namespace OpenXmlDemo
{
    public class Program
    {
        static void Main(string[] args)
        {
            var file = @"C:\Users\kjennings\Desktop\Test PPTs\This is the Title - Copy.pptx";
            var index = 0;
            var slidePart = GetSlidePart(file, index);
            var images = slidePart.Slide.Descendants<Picture>().Select(p => p); // error occurs here

            foreach (var image in images)
            {
                // Just placeholder code below.  It never makes it here.
                var pic = image;
            }
        }

        public static SlidePart GetSlidePart(string docName, int slideIndex)
        {
            using (var ppt = PresentationDocument.Open(docName, false))
            {
                // Get the relationship ID of the first slide.
                var presentationPart = ppt.PresentationPart;

                // Verify that the presenation part and the presenation exist,
                if (presentationPart != null && presentationPart.Presentation != null)
                {
                    var presentation = presentationPart.Presentation;

                    if (presentation.SlideIdList != null)
                    {
                        var slideIds = presentation.SlideIdList.ChildElements;

                        if (slideIndex < slideIds.Count)
                        {
                            // Get the relationship ID of the slide.
                            var slidePartRelationship = (slideIds[slideIndex] as SlideId).RelationshipId;

                            // Get the specified slide part from the relationship ID.
                            var slidePart = (SlidePart)presentationPart.GetPartById(slidePartRelationship);

                            return slidePart;
                        }
                    }
                }

                // No slide found.
                return null;
            }
        }
    }
}

Answer 1

GetSlidePart 中的 using 语句正在关闭文档。来自documentation 为PresentationDocument.Dispose：

刷新并保存内容，关闭文档，释放所有资源。

如果您将文档的打开重构到 GetSlidePart 之外，您的代码应该可以按预期工作：

static void Main(string[] args)
{
    var file = @"C:\Users\kjennings\Desktop\Test PPTs\This is the Title - Copy.pptx";
    var index = 0;

    //open the document here for use throughout the application
    using (var ppt = PresentationDocument.Open(file, false))
    {
        var slidePart = GetSlidePart(ppt, index);
        var images = slidePart.Slide.Descendants<Picture>().Select(p => p);

        foreach (var image in images)
        {
            // Just placeholder code below.  It now gets here...
            var pic = image;
        }
    }
}

//pass the open document in here...
public static SlidePart GetSlidePart(PresentationDocument ppt, int slideIndex)
{
    // Get the relationship ID of the first slide.
    var presentationPart = ppt.PresentationPart;

    // Verify that the presenation part and the presenation exist,
    if (presentationPart != null && presentationPart.Presentation != null)
    {
        var presentation = presentationPart.Presentation;

        if (presentation.SlideIdList != null)
        {
            var slideIds = presentation.SlideIdList.ChildElements;

            if (slideIndex < slideIds.Count)
            {
                // Get the relationship ID of the slide.
                var slidePartRelationship = (slideIds[slideIndex] as SlideId).RelationshipId;

                // Get the specified slide part from the relationship ID.
                var slidePart = (SlidePart)presentationPart.GetPartById(slidePartRelationship);

                return slidePart;
            }
        }
    }

    // No slide found.
    return null;
}