Manage OLE

Info

OLE (Object Linking & Embedding) is a Microsoft technology that allows data and objects created in one application to be placed in another application through linking or embedding.

Consider a chart created in MS Excel. The chart is then placed inside a PowerPoint slide. That Excel chart is considered an OLE object.

An OLE object may appear as an icon. In this case, when you double-click the icon, the chart gets opened in its associated application (Excel), or you are asked to select an application for object opening or editing.
An OLE object may display actual contents—for example, the contents of a chart. In this case, the chart is activated in PowerPoint, the chart interface loads, and you get to modify the chart’s data within the PowerPoint app.

Aspose.Slides for .NET allows you to insert OLE Objects into slides as OLE Object Frames (OleObjectFrame).

Adding OLE Object Frames to Slides

Assuming you already created a chart in Microsoft Excel and want to embed that chart in a slide as an OLE Object Frame using Aspose.Slides for .NET, you can do it this way:

Create an instance of the Presentation class.
Get a slide’s reference through its index.
Open the Excel file containing the Excel chart object and save it to MemoryStream.
Add the OleObjectFrame to the slide containing the array of bytes and other information about the OLE object.
Write the modified presentation as a PPTX file.

In the example below, we added a chart from an Excel file to a slide as an OleObjectFrame using Aspose.Slides for .NET.
Note that the IOleEmbeddedDataInfo constructor takes an embeddable object extension as a second parameter. This extension allows PowerPoint to correctly interpret the file type and choose the right application to open this OLE object.

// Instantiates the Presentation class that represents the PPTX file
using (Presentation pres = new Presentation())
{
    // Accesses the first slide
    ISlide sld = pres.Slides[0];

    // Loads an excel file to stream
    MemoryStream mstream = new MemoryStream();
    using (FileStream fs = new FileStream("book1.xlsx", FileMode.Open, FileAccess.Read))
    {
        byte[] buf = new byte[4096];

        while (true)
        {
            int bytesRead = fs.Read(buf, 0, buf.Length);
            if (bytesRead <= 0)
                break;
            mstream.Write(buf, 0, bytesRead);
        }
    }

    // Creates a data object for embedding
    IOleEmbeddedDataInfo dataInfo = new OleEmbeddedDataInfo(mstream.ToArray(), "xlsx");

    // Adds an Ole Object Frame shape
    IOleObjectFrame oleObjectFrame = sld.Shapes.AddOleObjectFrame(0, 0, pres.SlideSize.Size.Width,
        pres.SlideSize.Size.Height, dataInfo);

    //Writes the PPTX file to disk
    pres.Save("OleEmbed_out.pptx", SaveFormat.Pptx);
}

Adding Linked OLE Object frames

Aspose.Slides for .NET allows you to add an OleObjectFrame without embedding data but only with a link to the file.

This C# code shows you how to add an OleObjectFrame with a linked Excel file to a slide:

using (Presentation pres = new Presentation())
{
	// Accesses the first slide
	ISlide slide = pres.Slides[0];

	// Adds an Ole Object Frame with a linked Excel file
    IOleObjectFrame oleObjectFrame = slide.Shapes.AddOleObjectFrame(20, 20, 200, 150, "Excel.Sheet.12", "book1.xlsx");

	// Writes the PPTX file to disk
	pres.Save("OleLinked_out.pptx", SaveFormat.Pptx);
}

Accessing OLE Object Frames

If an OLE object is already embedded in a slide, you can find or access that object easily this way:

Create an instance of the Presentation class.
Obtain the reference of the slide by using its index.
Access the OleObjectFrame shape. In our example, we used the previously created PPTX that has only one shape on the first slide. We then cast that object as an OleObjectFrame. This was the desired OLE Object Frame to be accessed.
Once the OLE Object Frame is accessed, you can perform any operation on it. In the example below, an OLE Object Frame (an Excel chart object embedded in a slide) is accessed—and then its file data gets written to an Excel file:

// Loads the PPTX to a presentation object
using (Presentation pres = new Presentation("AccessingOLEObjectFrame.pptx"))
{
    // Accesses the first slide
    ISlide sld = pres.Slides[0];

    // Casts the shape to OleObjectFrame
    OleObjectFrame oleObjectFrame = sld.Shapes[0] as OleObjectFrame;

    // Reads the OLE Object and writes it to disk
    if (oleObjectFrame != null)
    {
        // Gets embedded file data
        byte[] data = oleObjectFrame.EmbeddedData.EmbeddedFileData;

        // Gets embedded file extention
        string fileExtention = oleObjectFrame.EmbeddedData.EmbeddedFileExtension;

        // Creates a path to save the extracted file
        string extractedPath = "excelFromOLE_out" + fileExtention;

        // Saves extracted data
        using (FileStream fstr = new FileStream(extractedPath, FileMode.Create, FileAccess.Write))
        {
            fstr.Write(data, 0, data.Length);
        }
    }
}

Accessing Linked OLE Object Frames Properties

Aspose.Slides allows you to access linked OLE Object Frame properties.

This C# code shows you how to check if an OLE Object is linked and then obtain the path to the linked file:

using (Presentation pres = new Presentation("OleLinked.ppt"))
{
	// Accesses the first slide
	ISlide slide = pres.Slides[0];

	// Gets the first shape as Ole Object Frame
	OleObjectFrame oleObjectFrame = slide.Shapes[0] as OleObjectFrame;

	// Check if the Ole Object is linked.
	if (oleObjectFrame != null && oleObjectFrame.IsObjectLink)
	{
		// Prints the full path to a linked file
		Console.WriteLine("Ole Object Frame is linked to: " + oleObjectFrame.LinkPathLong);

		// Prints the relative path to a linked file if present.
		// Only the PPT presentations can contain the relative path.
		string relativePath = oleObjectFrame.LinkPathRelative;
		if (!string.IsNullOrEmpty(relativePath))
		{
			Console.WriteLine("Ole Object Frame relative path: " + oleObjectFrame.LinkPathRelative);
		}
	}
}

Changing OLE Object Data

If an OLE object is already embedded in a slide, you can easily access that object and modify its data this way:

Open the desired presentation with the embedded OLE Object by creating an instance of the Presentation class.
Get the slide’s reference through its index.
Access the OLEObjectFrame shape. In our example, we used the previously created PPTX that has one shape on the first slide. We then cast that object as an OleObjectFrame. This was the desired OLE Object Frame to be accessed.
Once the OLE Object Frame is accessed, you can perform any operation on it.
Create the Workbook object and access the OLE Data.
Access the desired Worksheet and amend the data.
Save the updated Workbook in streams.
Change the OLE object data from stream data. In the example below, an OLE Object Frame (an Excel chart object embedded in a slide) is accessed—and then its file data is modified to change the chart data:

using (Presentation pres = new Presentation("ChangeOLEObjectData.pptx"))
{
    ISlide slide = pres.Slides[0];

    OleObjectFrame ole = null;

    // Traverses all shapes for Ole frame
    foreach (IShape shape in slide.Shapes)
    {
        if (shape is OleObjectFrame)
        {
            ole = (OleObjectFrame)shape;
        }
    }

    if (ole != null)
    {
        using (MemoryStream msln = new MemoryStream(ole.EmbeddedData.EmbeddedFileData))
        {
            // Reads object data in Workbook
            Workbook Wb = new Workbook(msln);

            using (MemoryStream msout = new MemoryStream())
            {
                // Modifies the workbook data
                Wb.Worksheets[0].Cells[0, 4].PutValue("E");
                Wb.Worksheets[0].Cells[1, 4].PutValue(12);
                Wb.Worksheets[0].Cells[2, 4].PutValue(14);
                Wb.Worksheets[0].Cells[3, 4].PutValue(15);

                OoxmlSaveOptions so1 = new OoxmlSaveOptions(Aspose.Cells.SaveFormat.Xlsx);
                Wb.Save(msout, so1);

                // Changes Ole frame object data
                IOleEmbeddedDataInfo newData = new OleEmbeddedDataInfo(msout.ToArray(), ole.EmbeddedData.EmbeddedFileExtension);
                ole.SetEmbeddedData(newData);
            }
        }
    }

    pres.Save("OleEdit_out.pptx", SaveFormat.Pptx);
}

Embedding Other File Types in Slides

Besides Excel charts, Aspose.Slides for .NET allows you to embed other types of files in slides. For example, you can insert HTML, PDF, and ZIP files as objects into a slide. When a user double-clicks the inserted object, the object automatically gets launched in the relevant program, or the user gets directed to select an appropriate program to open the object.

This C# code shows you how to embed HTML and ZIP in a slide:

using (Presentation pres = new Presentation())
{
  ISlide slide = pres.Slides[0];
  
  byte[] htmlBytes = File.ReadAllBytes("embedOle.html");
  IOleEmbeddedDataInfo dataInfoHtml = new OleEmbeddedDataInfo(htmlBytes, "html");
  IOleObjectFrame oleFrameHtml = slide.Shapes.AddOleObjectFrame(150, 120, 50, 50, dataInfoHtml);
  oleFrameHtml.IsObjectIcon = true;

  byte[] zipBytes = File.ReadAllBytes("embedOle.zip");
  IOleEmbeddedDataInfo dataInfoZip = new OleEmbeddedDataInfo(zipBytes, "zip");
  IOleObjectFrame oleFrameZip = slide.Shapes.AddOleObjectFrame(150, 220, 50, 50, dataInfoZip);
  oleFrameZip.IsObjectIcon = true;

  pres.Save("embeddedOle.pptx", SaveFormat.Pptx);
}

Setting File Types for Embedded Objects

When working on presentations, you may need to replace old OLE objects with new ones. Or you may need to replace an unsupported OLE object with a supported one.

Aspose.Slides for .NET allows you to set the file type for an embedded object. This way, you get to change the OLE frame data or its extension.

This C# code shows you how to set the file type for an embedded OLE object:

using (Presentation pres = new Presentation("embeddedOle.pptx"))
{
    ISlide slide = pres.Slides[0];
    IOleObjectFrame oleObjectFrame = (IOleObjectFrame)slide.Shapes[0];
    Console.WriteLine($"Current embedded data extension is: {oleObjectFrame.EmbeddedData.EmbeddedFileExtension}");
   
    oleObjectFrame.SetEmbeddedData(new OleEmbeddedDataInfo(File.ReadAllBytes("embedOle.zip"), "zip"));
   
    pres.Save("embeddedChanged.pptx", SaveFormat.Pptx);
}

Setting Icon Images and Titles for Embedded Objects

After you embed an OLE object, a preview consisting of an icon image and title gets added automatically. The preview is what users see before they access or open the OLE object.

If you want to use a specific image and text as elements in the preview, you can set the icon image and title using Aspose.Slides for .NET.

This C# code shows you how to set the icon image and title for an embedded object:

using (Presentation pres = new Presentation("embeddedOle.pptx"))
{
    ISlide slide = pres.Slides[0];
    IOleObjectFrame oleObjectFrame = (IOleObjectFrame)slide.Shapes[0];

    IPPImage oleImage = pres.Images.AddImage(File.ReadAllBytes("image.png"));
    oleObjectFrame.SubstitutePictureTitle = "My title";
    oleObjectFrame.SubstitutePictureFormat.Picture.Image = oleImage;
    oleObjectFrame.IsObjectIcon = false;

    pres.Save("embeddedOle-newImage.pptx", SaveFormat.Pptx);
}

Prevent an OLE Object Frame from Being Resized and Pepositioned

After you add a linked OLE object to a presentation slide, when you open the presentation in PowerPoint, you might see a message asking you to update the links. Clicking the “Update Links” button may change the size and position of the OLE object frame because PowerPoint updates the data from the linked OLE object and refreshes the object preview. To prevent PowerPoint from prompting to update the object’s data, set the UpdateAutomatic property of the IOleObjectFrame interface to false:

oleObjectFrame.UpdateAutomatic = false;

Extracting Embedded Files

Aspose.Slides for .NET allows you to extract the files embedded in slides as OLE objects this way:

Create an instance of the Presentation class containing the OLE object you intend to extract.
Loop through all the shapes in the presentation and access the OLEObjectFrame shape.
Access the embedded file’s data from the OLE Object Frame and write it to disk. This C# code shows you how to extract a file embedded in a slide as an OLE object:

using (Presentation pres = new Presentation("embeddedOle.pptx"))
{
    ISlide slide = pres.Slides[0];

    for (var index = 0; index < slide.Shapes.Count; index++)
    {
        IShape shape = slide.Shapes[index];
        
        IOleObjectFrame oleFrame = shape as IOleObjectFrame;
        
        if (oleFrame != null)
        {
            byte[] data = oleFrame.EmbeddedData.EmbeddedFileData;
            string extension = oleFrame.EmbeddedData.EmbeddedFileExtension;
            
            File.WriteAllBytes($"oleFrame{index}{extension}", data);
        }
    }
}

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