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How to: Move a slide to a new position in a presentation |
office |
o365devx |
o365devx |
conceptual |
11/01/2017 |
medium |
This topic shows how to use the classes in the Open XML SDK for Office to move a slide to a new position in a presentation programmatically.
In the Open XML SDK, the PresentationDocument class represents a presentation document package. To work with a presentation document, first create an instance of the PresentationDocument class, and then work with that instance. To create the class instance from the document call the Open(String, Boolean) method that uses a file path, and a Boolean value as the second parameter to specify whether a document is editable. In order to count the number of slides in a presentation, it is best to open the file for read-only access in order to avoid accidental writing to the file. To do that, specify the value false for the Boolean parameter as shown in the following using statement. In this code, the presentationFile parameter is a string that represents the path for the file from which you want to open the document.
// Open the presentation as read-only.
using (PresentationDocument presentationDocument = PresentationDocument.Open(presentationFile, false))
{
// Insert other code here.
} ' Open the presentation as read-only.
Using presentationDocument As PresentationDocument = PresentationDocument.Open(presentationFile, False)
' Insert other code here.
End UsingThe using statement provides a recommended alternative to the typical .Open, .Save, .Close sequence. It ensures that the Dispose method (internal method used by the Open XML SDK to clean up resources) is automatically called when the closing brace is reached. The block that follows the using statement establishes a scope for the object that is created or named in the using statement, in this case presentationDocument.
[!includeStructure]
In order to move a specific slide in a presentation file to a new position, you need to know first the number of slides in the presentation. Therefore, the code in this topic is divided into two parts. The first is counting the number of slides, and the second is moving a slide to a new position.
The sample code for counting the number of slides consists of two overloads of the method CountSlides. The first overload uses a string parameter and the second overload uses a PresentationDocument parameter. In the first CountSlides method, the sample code opens the presentation document in the using statement. Then it passes the PresentationDocument object to the second CountSlides method, which returns an integer number that represents the number of slides in the presentation.
// Pass the presentation to the next CountSlides method
// and return the slide count.
return CountSlides(presentationDocument); ' Pass the presentation to the next CountSlides method
' and return the slide count.
Return CountSlides(presentationDocument)In the second CountSlides method, the code verifies that the PresentationDocument object passed in is not null, and if it is not, it gets a PresentationPart object from the PresentationDocument object. By using the SlideParts the code gets the slideCount and returns it.
// Check for a null document object.
if (presentationDocument == null)
{
throw new ArgumentNullException("presentationDocument");
}
int slidesCount = 0;
// Get the presentation part of document.
PresentationPart presentationPart = presentationDocument.PresentationPart;
// Get the slide count from the SlideParts.
if (presentationPart != null)
{
slidesCount = presentationPart.SlideParts.Count();
}
// Return the slide count to the previous method.
return slidesCount; ' Check for a null document object.
If presentationDocument Is Nothing Then
Throw New ArgumentNullException("presentationDocument")
End If
Dim slidesCount As Integer = 0
' Get the presentation part of document.
Dim presentationPart As PresentationPart = presentationDocument.PresentationPart
' Get the slide count from the SlideParts.
If presentationPart IsNot Nothing Then
slidesCount = presentationPart.SlideParts.Count()
End If
' Return the slide count to the previous method.
Return slidesCountMoving a slide to a new position requires opening the file for read/write access by specifying the value true to the Boolean parameter as shown in the following using statement. The code for moving a slide consists of two overloads of the MoveSlide method. The first overloaded MoveSlide method takes three parameters: a string that represents the presentation file name and path and two integers that represent the current index position of the slide and the index position to which to move the slide respectively. It opens the presentation file, gets a PresentationDocument object, and then passes that object and the two integers, from and to, to the second overloaded MoveSlide method, which performs the actual move.
// Move a slide to a different position in the slide order in the presentation.
public static void MoveSlide(string presentationFile, int from, int to)
{
using (PresentationDocument presentationDocument = PresentationDocument.Open(presentationFile, true))
{
MoveSlide(presentationDocument, from, to);
}
} ' Move a slide to a different position in the slide order in the presentation.
Public Shared Sub MoveSlide(ByVal presentationFile As String, ByVal [from] As Integer, ByVal [to] As Integer)
Using presentationDocument As PresentationDocument = PresentationDocument.Open(presentationFile, True)
MoveSlide(presentationDocument, From, [to])
End Using
End SubIn the second overloaded MoveSlide method, the CountSlides method is called to get the number of slides in the presentation. The code then checks if the zero-based indexes, from and to, are within the range and different from one another.
public static void MoveSlide(PresentationDocument presentationDocument, int from, int to)
{
if (presentationDocument == null)
{
throw new ArgumentNullException("presentationDocument");
}
// Call the CountSlides method to get the number of slides in the presentation.
int slidesCount = CountSlides(presentationDocument);
// Verify that both from and to positions are within range and different from one another.
if (from < 0 || from >= slidesCount)
{
throw new ArgumentOutOfRangeException("from");
}
if (to < 0 || from >= slidesCount || to == from)
{
throw new ArgumentOutOfRangeException("to");
} Public Shared Sub MoveSlide(ByVal presentationDocument As PresentationDocument, ByVal [from] As Integer, ByVal [to] As Integer)
If presentationDocument Is Nothing Then
Throw New ArgumentNullException("presentationDocument")
End If
' Call the CountSlides method to get the number of slides in the presentation.
Dim slidesCount As Integer = CountSlides(presentationDocument)
' Verify that both from and to positions are within range and different from one another.
If
From < 0 OrElse
From >= slidesCount Then
Throw New ArgumentOutOfRangeException("from")
End If
If [to] < 0 OrElse
From >= slidesCount OrElse [to] =
From Then
Throw New ArgumentOutOfRangeException("to")
End IfA PresentationPart object is declared and set equal to the presentation part of the PresentationDocument object passed in. The PresentationPart object is used to create a Presentation object, and then create a SlideIdList object that represents the list of slides in the presentation from the Presentation object. A slide ID of the source slide (the slide to move) is obtained, and then the position of the target slide (the slide after which in the slide order to move the source slide) is identified.
// Get the presentation part from the presentation document.
PresentationPart presentationPart = presentationDocument.PresentationPart;
// The slide count is not zero, so the presentation must contain slides.
Presentation presentation = presentationPart.Presentation;
SlideIdList slideIdList = presentation.SlideIdList;
// Get the slide ID of the source slide.
SlideId sourceSlide = slideIdList.ChildElements[from] as SlideId;
SlideId targetSlide = null;
// Identify the position of the target slide after which to move the source slide.
if (to == 0)
{
targetSlide = null;
}
else if (from < to)
{
targetSlide = slideIdList.ChildElements[to] as SlideId;
}
else
{
targetSlide = slideIdList.ChildElements[to - 1] as SlideId;
} ' Get the presentation part from the presentation document.
Dim presentationPart As PresentationPart = presentationDocument.PresentationPart
' The slide count is not zero, so the presentation must contain slides.
Dim presentation As Presentation = presentationPart.Presentation
Dim slideIdList As SlideIdList = presentation.SlideIdList
' Get the slide ID of the source slide.
Dim sourceSlide As SlideId = TryCast(slideIdList.ChildElements(From), SlideId)
Dim targetSlide As SlideId = Nothing
' Identify the position of the target slide after which to move the source slide.
If to = 0 Then
targetSlide = Nothing
ElseIf From < to Then
targetSlide = TryCast(slideIdList.ChildElements(to), SlideId)
Else
targetSlide = TryCast(slideIdList.ChildElements(to - 1), SlideId)
End IfThe Remove method of the SlideID object is used to remove the source slide from its current position, and then the InsertAfter method of the SlideIdList object is used to insert the source slide in the index position after the target slide. Finally, the modified presentation is saved.
// Remove the source slide from its current position.
sourceSlide.Remove();
// Insert the source slide at its new position after the target slide.
slideIdList.InsertAfter(sourceSlide, targetSlide);
// Save the modified presentation.
presentation.Save(); ' Remove the source slide from its current position.
sourceSlide.Remove()
' Insert the source slide at its new position after the target slide.
slideIdList.InsertAfter(sourceSlide, targetSlide)
' Save the modified presentation.
presentation.Save()Following is the complete sample code that you can use to move a slide from one position to another in the same presentation file. For instance, you can use the following call in your program to move a slide from position 0 to position 1 in a presentation file named "Myppt11.pptx".
MoveSlide(@"C:\Users\Public\Documents\Myppt11.pptx", 0, 1); MoveSlide("C:\Users\Public\Documents\Myppt11.pptx", 0, 1)After you run the program, check your presentation file to see the new positions of the slides.
Following is the complete sample code in both C# and Visual Basic.