The following is based on JRiver v19.0.108
A [Theater View:SKIN] defines the 'layout' of the screen components in [Theater View]
For example, it defines where
Buttons/Rollers are located, such as Movies, Audio, Images, Exit
Text is located, such as headers and footer text
Where pics are located on roller/menu pages and info pages
A [Theater View:THEME] provides a set of background images that are displayed while navigating [Theater View]
As best as I can tell, there is no technical inter-relationship between a SKIN and a THEME, although they are often created in conjuntion with one another.
The theme folder structure, and names of the folders are key to get the images to display while navigating within [Theater View]
Having played around with the folders a little, this is what I have found the following. Please feel free to correct me where I am wrong.
To create a new theme, create a new folder within the Themes folder.
The default folder location is C:\Program Files\J River\Media Center 19\Skins\Theater View\Themes
For this example, i'll create a theme called "MyTheme"
Once created, it will show up as an avaiable theme for selection from within Tools > Options > Theater View > Appearance > Theme :
Now, if you copy a background image file into the \MyTheme folder, that image will show up in [Theater View] behind the roller menus, and on all Info pages.
If you copy a second (or third, etc) image file into the \MyTheme folder, JRiver will randomly display one of the images each time you enter [Theater View].
However, if you would like diplay a specific image for each menu item on the roller, you need to :
1) create a sub-folder named \Root within your them folder ie: \MyTheme\Root
2) create a subfolder underneath \Root, named exactly the same as the Menu item name.
eg: if the button on your roller menu is named "Audio", create a subfolder named \Audio. If the button on the your roller menu is named "Music", create a subfolder named \Music.
3) copy a unique background image into each subfolder.
Now, when you move between roller menu items, the image you placed under the respecitive subfolder will be displayed in the background
In the situation where you have roller menu items for which you DO NOT have a subfolder created under the \Root folder, then an image from either within the \Root folder, or the \MyTheme folder will be displayed.
If you DO NOT have an image file in either the \Root folder, or the \MyTheme folder, then the background will be blank for that menu item.
Now, if you would like to display a specific background image for the Info pages, which is different from the background on the roller view, you need to:
1) create a subfolder from within the \MyTheme folder, named exactly the same as the roller menu item eg: \MyTheme\Movies
2) copy an image file into the folder
Now, when you open the Info page from the roller menu, the image file you copied into the folder will be displayed
In the situation where you have roller menu items for which you DO NOT have a subfolder created under the \MyTheme folder, then an image from either within the \MyTheme folder will be displayed.
If you DO NOT have an image file in either the \Root folder, or the \MyTheme folder, then the background will be blank for that menu item.
IMPORTANT TO NOTE: If you have Online Media SlideShow enabled, (with a content provider selected), and content is found, then your background image will not be displayed.
If content is not found, then your background image will be displayed.
Online Media SlideShow can be found from Tools > Options > Theater View > Appearance > Theme : > Online Media SlideShow
Finally, if any of the directories has more than one image file stored within it, JRiver will randomly pick one of the files to display from within the folder.
Each time the image changes, the image file displayed will be randomly selected again.
So, in summary......
\MyTheme <===== Name of theme
\Root <===== Subfolder to store background images for roller menu items.... folder must be named "Root"
\Movies <===== Background images for each individual roller menu it.... must be named exactly the same as Roller menu name
\Music <===== as above
\Images <===== as above
\Playlist <===== as above
\TV Shows <===== as above
\Movies <===== Background images for info pages ... must be named exactly the same as Roller menu name
\Music <===== as above
\Images <===== as above
\Playlist <===== as above
\TV Shows <===== as above
BE AWARE: If you wish to re-use a theme, make sure that the folder names match your menu names.
You can change menu names from within Tools > Options > Theater View > Items to Show (listbox)
Having learnt this, I have constructed my own custom theme, re-using images I like from various other themes.