Improved text layout support when inserting runs/text or splitting lines on runs that were non-text (images or widgets). The text layout now inserts an extra text run when splitting a non-text run, which avoids issues where text was either being inserted into a non-text run (and vanishing), or an image run was being cloned (and appearing twice).
This also fixes the cursor movement in the multiline editable text when selecting over images or widgets (the cursor would jump to the start of the document as GetTextIndexAt hadn't been implemented. Additionally, it also fixes an issue where Measure was always trying to place the cursor at the end of an image run (ignoring the values of BeginIndex and EndIndex) which made the cursor offset draw in the wrong place.
These changes required the text layout to be able to create a default text run, which involved refactoring the text marshallers as the Slate text run now knows about the default text style, taking that responsibility away from the marshallers
Added tutorial-specific image decorator that accepts a content-relative or engine relative image path.
Added button to tutorial rich text editor to add new images.
All previously-imported images should still 'work'.
reviewed by Jamie.Dale,Nick.Atamas,Justin.Sargent
[CL 2302278 by Thomas Sarkanen in Main branch]
Refactored handling of decorators into new utility class FTutorialText.
Added tooltip (and rich tooltip) support to hyperlink runs.
#codereview Jamie.Dale
[CL 2294907 by Thomas Sarkanen in Main branch]
Added asset, code, tutorial and UDN hyperlinks. Tweaked UI to use combo box instead of the large amount of radio buttons it was using before.
Made sure importer & content use correct text styles.
Defaulted to rich text for content.
[CL 2284444 by Thomas Sarkanen in Main branch]
Removed ability to independently set font size & colour etc. and replaced with a set of font styles we can use (and style appropriately). Added legacy code to deal with old-style text as best it can.
[CL 2282800 by Thomas Sarkanen in Main branch]
Icon is only visible if content is available for the editor in question.
Split editor settings into two groups - one is persistent settings and one is progress/state.
Tutorials record their dismissed state, so users can permenantly disable the 'nag' for a particular tutorial.
Tutorial content now solidifies when the mouse is hovered over it, so it can be made easier to read.
Fixed crash on startup if an intro tutorial was displaying rich text.
Also fixed crash for TTP# 345094, where a zero-length tutorial was being accessed.
[CL 2275934 by Thomas Sarkanen in Main branch]
