What logic does P.P. use to move elements on theme change?

[Malcom]

Hello.

I need to know what logic does P.P. use to move slide elements (shapes) on theme change.
I have created a "template" PPTX with a master slide and some layouts and I use it with Aspose to generate a new PPTX.
Most of the layouts I created do not correspond to an existing layout predefined in P.P., meaning that I have slides with 6 charts and a table and other unusual configurations.
As far as I saw, one factor affecting the application of a layout defined in a theme (on theme change) is the current layout name of the slide. I mean, in order for a slide using a layout of mine to follow the element positions of a layout defined in the new theme, my layout should use the same name to the theme's layout.
What I haven't figured out yet, is how it decides which shape to move and based on which placeholder (especially when the number of shapes in the two slides do not match).

I you can enlighten me on this issue it would be great. Otherwise, at least help me with this (which is my main problem):

I have a custom layout defined in a master slide (no content match to any predefined P.P. layout) and I need to make sure that when the user changes the theme, some specific elements of the slide do not move. I have a problem with this because, despite the fact that I use a custom name for my layout and a custom name for my placeholder, somehow, some (but not all) of the predefined themes change the position of that shape.

Thanks in advance,


Kostas

[JohnWilson]

Sadly this is a VERY badly thought out feature. The order that placeholders are populated when you switch themes can only be accessed in the XML code and even then the logic is quite twisted!

IF you understand how to access and edit the XML for the custom layouts the value you are looking for is idx but don't go there if you don't understand - you must use the values that exist but change the placeholders they relate to. Potential for problems is high!

We have several major clients who are pee'd off with this and have asked us to write code to replace "Apply Theme" which makes sure the content goes where it is intended. Not a solution unless you have a big budget!

Sorry I cannot be more helpful.

[Malcom]

Thank you for all your help John.
I will see what I can do based on your information.

Best Regards,
Kostas