Master Slide

Master slides form the top level of the slide inheritance hierarchy in PowerPoint. A master slide defines common design elements such as backgrounds, logos, and text formatting. Layout slides inherit from master slides, and normal slides inherit from layout slides.

This article demonstrates how to create, modify, and manage master slides using Aspose.Slides for .NET.

Add a Master Slide

This example shows how to create a new master slide by cloning the default one. It then adds a company name banner to all slides through layout inheritance.

static void Add_Master_Slide()
{
    using var pres = new Presentation();

    // Clone the default master slide
    var defaultMasterSlide = pres.Masters[0];
    var newMaster = pres.Masters.AddClone(defaultMasterSlide);

    // Add a banner with company name to the top of the master slide
    var textBox = newMaster.Shapes.AddAutoShape(ShapeType.Rectangle, x: 0, y: 0, width: 720, height: 25);
    textBox.TextFrame.Text = "Company Name";
    textBox.TextFrame.Paragraphs[0].ParagraphFormat.DefaultPortionFormat.FillFormat.FillType = FillType.Solid;
    textBox.TextFrame.Paragraphs[0].ParagraphFormat.DefaultPortionFormat.FillFormat.SolidFillColor.Color = Color.Black;
    textBox.FillFormat.FillType = FillType.NoFill;

    // Assign the new master slide to a layout slide
    var layoutSlide = pres.LayoutSlides[0];
    layoutSlide.MasterSlide = newMaster;

    // Assign the layout slide to the first slide in the presentation
    pres.Slides[0].LayoutSlide = layoutSlide;
}

💡 Tip 1: Master slides provide a way to apply consistent branding or shared design elements across all slides. Any changes made to the master will automatically reflect on dependent layout and normal slides.

💡 Tip 2: Any shapes or formatting added to a master slide are inherited by layout slides and, in turn, all normal slides using those layouts. The image below illustrates how a text box added on a master slide is automatically rendered on the final slide.

Access a Master Slide

You can access master slides using the Presentation.Masters collection. Here’s how to retrieve and work with them:

static void Access_Master_Slide()
{
    using var pres = new Presentation();

    // Access the first master slide
    var firstMasterSlide = pres.Masters[0];

    // Change the background type
    firstMasterSlide.Background.Type = BackgroundType.OwnBackground;
}

Remove a Master Slide

Master slides can be removed either by index or by reference.

static void Remove_Master_Slide()
{
    using var pres = new Presentation();

    // Remove by index
    pres.Masters.RemoveAt(0);

    // Or remove by reference
    var firstMasterSlide = pres.Masters[0];
    pres.Masters.Remove(firstMasterSlide);
}

Remove Unused Master Slides

Some presentations contain master slides that are not in use. Removing these slides can help reduce file size.

static void RemoveUnused_Master_Slide()
{
    using var pres = new Presentation();

    // Remove all unused master slides (even those marked as Preserve)
    pres.Masters.RemoveUnused(ignorePreserveField: true);
}

⚙️ Tip: Use RemoveUnused(true) to clean up unused master slides and minimize the presentation size.