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CommonTraps.md

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Common PowerPoint Add-in Development Traps

This document details the common pitfalls when developing for PowerPointLabs, so that these mistakes can be noted/avoided by future contributors.

  1. The index of an Office collection starts from 1, however note that the index of a collection provided by .NET starts from 0 ShapeRange range = getCurrentSelectedShapes(); range[1] ... ; //the first element

  2. When you delete, cut, or ungroup a shape programmatically, and you undo this change from the PowerPoint UI, then that shape will become corrupted. For a corrupted shape, accessing attributes programatically other than it's left/top/width/height/name would throw an exception.

    One possible solution would be re-allocate the shape’s memory; copy and paste it programmatically before you handle the shape.

    Another possible solution would be to use the method called CorruptionCorrection, located in ShapeUtil, for fixing corrupted shapes although it may not work for every type of corruption

  3. When dealing with pictures or shapes, your features should not override user's clipboard contents. Use the RestoreClipboardAfterAction method in ClipboardUtil if your feature requires copying/pasting to maintain user's clipboard contents

  4. When pasting a shape programmatically, it is not selected in Office 2010, but selected in Office 2013

  5. When using shape.Duplicate(), the animations are copied in Office 2013 but not 2016. Recommended to use slide.RemoveAnimationsForShape() to remove animations

  6. When pasting a shape in the current slide, its naming mechanism is like this:

    1. Index increment for default name. E.g. Rectangle 1 -> Rectangle 2
    2. Unchanged for non-default name. E.g. MyRectangle -> MyRectangle

  7. Some Office APIs are not supported for Office 2010, e.g. MergeShape. When developing, special attention needs to be given to APIs available for Office 2010

  8. Some Office APIs may not work correctly, e.g. WindowBeforeDoubleClick event. You may have to use a workaround. Be sure to include a short comment in the code if a non-conventional workaround is used

  9. When a shape is rotated, its position attributes, i.e. left and top, will always return the value when its rotation angle is at zero. Thus to get the rotated position, you may calculate it using its rotation matrix

  10. When you need to convert Shape(s) to a ShapeRange object, you can consider using the ToShapeRange method in PowerPointSlide

  11. Effects rendering is slow, especially for pictures and 3D images. You may try to avoid it, or make it rendered (e.g. export the picture with effects, and then insert it again)

  12. When you copy and paste a slide, the slide name will be lost:

    1. Original slide name = “My slide”
    2. After paste slide name = “Slide\d+”

  13. Event triggering order of WindowDeactivated and PresentationClose is different between PowerPoint 2010 and 2013. In 2010, PresentationClose will be triggered before WindowDeactivated, but this order is reversed in 2013

  14. Accessing the ActivePresentation.Saved property on a new, unsaved presentation, always results in the ActivePresentation.Saved property returning msoFalse, regardless of whether the new presentation contains any valid changes to be saved.