Added PowerPoint templates to the Slide Assistant (#1055)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Tools/PowerPoint/TemplateSlideShapes.cs

@@ -0,0 +1,78 @@
+using DocumentFormat.OpenXml;
+
+using A = DocumentFormat.OpenXml.Drawing;
+using P = DocumentFormat.OpenXml.Presentation;
+
+namespace AIStudio.Tools.PowerPoint;
+
+/// <summary>
+/// Which shapes of a slide fill which slots of its layout.
+/// </summary>
+/// <remarks>
+/// Reading a template and editing one of its slides ask the same question, so they share the answer:
+/// what the model is told a slot holds is what a new content replaces.
+/// </remarks>
+internal static class TemplateSlideShapes
+{
+    /// <summary>
+    /// Finds the shapes of a slide which fill the slots of its layout.
+    /// </summary>
+    /// <remarks>
+    /// A placeholder fills the slot of its type and index; of two placeholders for one slot, the
+    /// first counts, while the second may be read as a copy of the slot, as a text box copied from
+    /// the placeholder is. A table slot whose placeholder holds no table, or which the slide leaves out,
+    /// takes a table which is no placeholder at all: an author who pastes a table onto the slide,
+    /// or whose table lost the link to its placeholder on the way, still means it as the table of
+    /// the slide. Such tables fill these table slots in the order of the slide.
+    /// </remarks>
+    /// <param name="shapeTree">The shape tree of the slide.</param>
+    /// <param name="layout">The layout the slide is based on.</param>
+    /// <returns>The top-level shape filling each slot; slots the slide leaves out are missing.</returns>
+    public static Dictionary<TemplateSlot, OpenXmlElement> SlotShapesOf(P.ShapeTree? shapeTree, TemplateLayout layout)
+    {
+        var elements = shapeTree?.Elements().ToList() ?? [];
+        var shapesBySlot = new Dictionary<TemplateSlot, OpenXmlElement>();
+        foreach (var element in elements)
+        {
+            if (PlaceholderOf(element) is { } placeholder && layout.SlotOf(placeholder.Type?.InnerText ?? "obj", placeholder.Index?.Value) is { } slot)
+                shapesBySlot.TryAdd(slot, element);
+        }
+
+        var freeTables = new Queue<OpenXmlElement>(elements.Where(element => PlaceholderOf(element) is null && HoldsTable(element)));
+        foreach (var slot in layout.Slots.Where(slot => slot.Role is PlaceholderRole.TABLE && !(shapesBySlot.GetValueOrDefault(slot) is { } shape && HoldsTable(shape))))
+        {
+            if (!freeTables.TryDequeue(out var table))
+                break;
+
+            shapesBySlot[slot] = table;
+        }
+
+        return shapesBySlot;
+    }
+
+    private static bool HoldsTable(OpenXmlElement element) => element is P.GraphicFrame frame && frame.Graphic?.GraphicData?.GetFirstChild<A.Table>() is not null;
+
+    /// <summary>
+    /// The ID of a top-level element of a slide: a shape, a picture, a graphic frame, a group, a
+    /// connector, or something wrapped for newer versions of PowerPoint.
+    /// </summary>
+    /// <returns>The ID, or null for anything else, e.g., the properties of the shape tree itself.</returns>
+    public static uint? ShapeIdOf(OpenXmlElement element) => element switch
+    {
+        P.Shape or P.Picture or P.GraphicFrame or P.GroupShape or P.ConnectionShape or AlternateContent => element.Descendants<P.NonVisualDrawingProperties>().FirstOrDefault()?.Id?.Value,
+
+        _ => null,
+    };
+
+    /// <summary>
+    /// The placeholder a shape, a picture or a table of a slide fills; null for anything else.
+    /// </summary>
+    public static P.PlaceholderShape? PlaceholderOf(OpenXmlElement element) => element switch
+    {
+        P.Shape shape => shape.NonVisualShapeProperties?.ApplicationNonVisualDrawingProperties?.PlaceholderShape,
+        P.Picture picture => picture.NonVisualPictureProperties?.ApplicationNonVisualDrawingProperties?.PlaceholderShape,
+        P.GraphicFrame frame => frame.NonVisualGraphicFrameProperties?.ApplicationNonVisualDrawingProperties?.PlaceholderShape,
+
+        _ => null,
+    };
+}