Access Slide in Presentation

Access Slides in Presentation

In this topic, we will introduce the possible ways to access a slide from a presentation file. Each slide in a presentation has a unique Id. On the other hand, all the slides in the presentation are arranged in the order of the slide position starting from 0, that is, slide at position 1 will be accessible through 0 index of ISlideCollection associated with a Presentation object.

Aspose.Slides for Java provides Presentation class that can be used to find and access any desired slide present in the presentation. Currently, developers can access a slide in two ways:

1. Accessing Slide by Index
2. Accessing Slide by ID

Access Slide by Index

Presentation class represents a presentation file and exposes all slides in it as a ISlideCollection collection (that is a collection of ISlide objects). All of these slides can be accessed from this Slides collection using a slide index as shown below in the example.

// Instantiate a Presentation object that represents a presentation file
Presentation pres = new Presentation("demo.pptx");
try {
    // Accessing a slide using its slide index
    ISlide slide = pres.getSlides().get_Item(0);
} finally {
    pres.dispose();
}

Access Slide by ID

Every slide in the presentation has a unique ID associated with it. The Presentation class exposes the getSlideById(id) method that can be used to access the slide by ID. All you need to do is to provide the valid slide ID and access that slide using getSlideById(id) method as shown below in the example.

// Instantiate a Presentation object that represents a presentation file
Presentation pres = new Presentation("demo.pptx");
try {
    // Getting Slide ID
    int id = (int) pres.getSlides().get_Item(0).getSlideId();
    
    // Accessing Slide by ID
    IBaseSlide slide = pres.getSlideById(id);
} finally {
    pres.dispose();
}

Change Slide Position

If you create a presentation using MS PowerPoint, you would have experienced that whenever you add a new slide to your presentation, it is appended at the end of the presentation by default. Using MS PowerPoint, you can drag a selected slide to any other position of the presentation. Aspose.Slides for Java also allows developers to change the position of a slide within the presentation. Let’s see how to get it done.

It’s very simple to change the position of a slide in the presentation. Just follow the steps below:

• Create an instance of Presentation class.
• Obtain the reference of a slide by using its Index.
• Change the SlideNumber of the referenced slide.
• Write the modified presentation file.

In the example given below, we have changed the position of a slide (lying at the zero index position 1) of the presentation) to index 1 (Position 2).

// Instantiate Presentation class to load the source presentation file
Presentation pres = new Presentation("Presentation.pptx");
try {
    // Get the slide whose position is to be changed
    ISlide sld = pres.getSlides().get_Item(0);
    
    // Set the new position for the slide
    sld.setSlideNumber(2);
    
    // Write the presentation to disk
    pres.save("helloworld_Pos.pptx", SaveFormat.Pptx);
} finally {
    pres.dispose();
}

The example above moves the slide (that was at position 1 to the second position and the slide that was at a second position, is moved to the first position and so on. In this way, all slides are adjusted automatically by Aspose.Slides for Java.

Set Slide Number

Aspose.Slides for Java now supports, setting the Slide Number. In this topic, we will see with example how to get and set the slide number property in Aspose.Slides.

The new methods added to Presentation class allow to get or to set the number of the first slide in a presentation. When a new FirstSlideNumber value is specified all slide numbers are recalculated. In order to get or set the Slide Number, please follow the steps below:

1. Create an instance of Presentation class
2. Get the slide number
3. Set the slide number
4. Write the presentation as a PPTX file In the example given below, we have get and set the slide number.

// Instantiate a Presentation object that represents a presentation file
Presentation pres = new Presentation("HelloWorld.pptx");
try {
    // Get the slide number
    int firstSlideNumber = pres.getFirstSlideNumber();

    // Set the slide number
    pres.setFirstSlideNumber(10);

    pres.save("Set_Slide_Number_out.pptx", SaveFormat.Pptx);
} finally {
    pres.dispose();
}