There are a number of changes in Tcell v3, mostly aimed at simplifying things for applications, but some also intended to reduce the burden for support. Every application will need at least some changes, but it is expected that those changes will be small, possibly even mechanical in nature.
In order to improve support for multi-rune grapheme clusters, and to provide an experience that reduces friction when using it, some APIs have been removed, and newer APIs exist in their place.
SetCell and SetContents are removed. Use Put instead.GetContents is removed. Use Get instead.The event channel is now directly exposed via EventQ, and events may be read from or written
directly to the channel in the standard Go fashion. This should help applications that want to
integrate into select statements (e.g. for timed key presses).
The ChannelEvents, PollEvent, PostEvent, and PostEventWait functions are removed, as
applications can now just access the event channel directly.
EventKey now carries a string for KeyRune instead of a single rune.
As a result the old Rune method for EventKey is replaced by Str.
The main difference for most users will be that Str returns a string, and most
of the time that string will consist of only a single rune. However, it is possible
now to inject synthetic key strokes consisting of multi-rune grapheme clusters.
Additionally the following special keys are removed, as they are delivered
instead as KeyRune with the relevant rune, and the ModCtrl modifier:
KeyCtrlSpace, KeyCtrlLeftSq, KeyCtrlRightSq, KeyCtrlBackslash, and
KeyCtrlUnderscore.
Note that KeyRune will never have a ModShift applied unless it is applied
also with other modifiers.
The KeyCtrlA through KeyCtrlZ keys are delivered, but will also carry
the associated lower case rune (e.g. “a”, “b”, etc.) and ModCtrl.
The KeyBackspace2 key is no longer delivered, but is converted to
KeyBackspace. (This resolves some inconsistency around e.g. CTRL-H vs DELETE.)
The termbox compatibility package is removed. Few applications were using it,
and the compatibility was imperfect. Also the package had limited support for many
newer features. Further, Termbox itself is no longer being maintained.
Applications that still need this should keep using Tcell v2.
The Terminfo subsystem has been removed entirely. Essentially the old terminfo based design has long proved to be inferior for modern terminal applications, and has not kept up with newer terminal features such as 24-bit color, different mouse reporting modes, bracketed paste, advanced text styling, and so forth.
As part of this, we’re removing the parsed terminfo logic entirely. It turns out that pretty much all of the terminal logic can be consolidated to just a few classes of terminals with substantial overlap.
A consequence of this is that support for some legacy terminals that are either functionally extinct (such as hpterm) or unlikely to be found outside of a museum (such as VT52, Wyse50, or anything produced more than 40 years ago.)
Note that VT100 and later will work in emulation, and VT220 and later physical terminals should still work. VT100 physical terminals may not work, as the padding delays that existed for them are removed. Those delays hurt emulations that do not need them, and existed only to accommodate limitations found on the physical hardware from the 1970s.
Note that we still examine $TERM when appropriate, but if the value is not one we recognize,
then we will assume something reasonably capable and compatible at some level with xterm or
at least ECMA-48.
The Color type is now only 32-bits, which should save some memory on large terminal windows.
The AttrMask type is now only 16-bits, and the UnderlineStyle is now 8 bits.
All these lead to further savings in the memory per cell.
AttrUnderline is gone. It was not sufficient to describe styled and colored underlines.
Deprecated APIs HasKey, HasMouse, and CanDisplay are removed.
These functions weren’t reliable and served no useful purpose.
NewConsoleScreen is removed as is support for Windows console mode.
Instead this uses the more modern Windows VT modes. As a consequence, this means that Tcell on Windows requires at least Winows 10 build 1703 (the Creators Update). If you are using a version of Windows 10 older than that, you should really upgrade for many reasons, not just because Tcell doesn’t support it anymore.
This structure, and the associated NewInputProcessor function, were made public incorrectly.
They are not part of our public API going forward, and are now private symbols.