## Summary of the Pull Request
This adds a new action, `clearBuffer`. It accepts 3 values for the `clear` type:
* `"clear": "screen"`: Clear the terminal viewport content. Leaves the scrollback untouched. Moves the cursor row to the top of the viewport (unmodified).
* `"clear": "scrollback"`: Clear the scrollback. Leaves the viewport untouched.
* `"clear": "all"`: (**default**) Clear the scrollback and the visible viewport. Moves the cursor row to the top of the viewport (unmodified).
"Clear Buffer" has also been added to `defaults.json`.
## References
* From microsoft/vscode#75141 originally
## PR Checklist
* [x] Closes#1193
* [x] Closes#1882
* [x] I work here
* [x] Tests added/passed
* [ ] Requires documentation to be updated
## Detailed Description of the Pull Request / Additional comments
This is a bit tricky, because we need to plumb it all the way through conpty to clear the buffer. If we don't, then conpty will immediately just redraw the screen. So this sends a signal to the attached conpty, and then waits for conpty to draw the updated, cleared, screen back to us.
## Validation Steps Performed
* works for each of the three clear types as expected
* tests pass.
* works even with `ping -t 8.8.8.8` as you'd hope.
[Defapp] Use real HPCON for PTY management; Have Monarch always listen for connections
## PR Checklist
* [x] Closes#9464
* [x] Related to #9475 - incomplete fix
* [x] I work here.
* [x] Manual test
## Detailed Description of the Pull Request / Additional comments
- Sometimes peasants can't manage to accept a connection appropriately because I wrote defterm before @zadjii-msft's monarch/peasant architecture. The simple solution here is to just make the monarch always be listening for inbound connections. Then COM won't start a peasant with -Embedding just to ask the monarch where it should go. It'll just join the active window. I didn't close 9475 because it should follow monarch policies on which window to join... and it doesn't yet.
- A lot of interesting things are happening because this didn't have a real HPCON. So I passed through the remaining handles (and re-GUID-ed the interface) that made it possible for me to pack the right process handles and such into an HPCON on the inbound connection and monitor that like any other ConptyConnection. This should resolve some of the process exit behaviors and signal channel things like resizing.
Adds support for `win32-input-mode` to conhost, conpty, and the Windows
Terminal.
* The shared `terminalInput` class supports sending these sequences when
a VT client application requests this mode.
* ConPTY supports synthesizing `INPUT_RECORD`s from the input sent to it
from a terminal
* ConPTY requests this mode immediately on startup (if started with a
new flag, `PSEUDOCONSOLE_WIN32_INPUT_MODE`)
* The Terminal now supports sending this input as well, when conpty asks
for it.
Also adds a new ConPTY flag `PSEUDOCONSOLE_WIN32_INPUT_MODE` which
requests this functionality from conpty, and the Terminal requests this
by default.
Also adds `experimental.input.forceVT` as a global setting to let a user
opt-out of this behavior, if they don't want it / this ends up breaking
horribly.
## Validation Steps Performed
* played with this mode in vtpipeterm
* played with this mode in Terminal
* checked a bunch of scenarios, as outlined in a [comment] on #4999
[comment]: https://github.com/microsoft/terminal/issues/4999#issuecomment-628718631
References #4999: The megathread
References #5887: The spec
Closes#879Closes#2865Closes#530Closes#3079Closes#1119Closes#1694Closes#3608Closes#4334Closes#4446
This PR adds support for "Resize with Reflow" to the Terminal. In
conhost, `ResizeWithReflow` is the function that's responsible for
reflowing wrapped lines of text as the buffer gets resized. Now that
#4415 has merged, we can also implement this in the Terminal. Now, when
the Terminal is resized, it will reflow the lines of it's buffer in the
same way that conhost does. This means, the terminal will no longer chop
off the ends of lines as the buffer is too small to represent them.
As a happy side effect of this PR, it also fixed#3490. This was a bug
that plagued me during the investigation into this functionality. The
original #3490 PR, #4354, tried to fix this bug with some heavy conpty
changes. Turns out, that only made things worse, and far more
complicated. When I really got to thinking about it, I realized "conhost
can handle this right, why can't the Terminal?". Turns out, by adding
resize with reflow, I was also able to fix this at the same time.
Conhost does a little bit of math after reflowing to attempt to keep the
viewport in the same relative place after a reflow. By re-using that
logic in the Terminal, I was able to fix#3490.
I also included that big ole test from #3490, because everyone likes
adding 60 test cases in a PR.
## References
* #4200 - this scenario
* #405/#4415 - conpty emits wrapped lines, which was needed for this PR
* #4403 - delayed EOL wrapping via conpty, which was also needed for
this
* #4354 - we don't speak of this PR anymore
## PR Checklist
* [x] Closes#1465
* [x] Closes#3490
* [x] Closes#4771
* [x] Tests added/passed
## EDIT: Changes to this PR on 5 March 2020
I learned more since my original version of this PR. I wrote that in
January, and despite my notes that say it was totally working, it
_really_ wasn't.
Part of the hard problem, as mentioned in #3490, is that the Terminal
might request a resize to (W, H-1), and while conpty is preparing that
frame, or before the terminal has received that frame, the Terminal
resizes to (W, H-2). Now, there aren't enough lines in the terminal
buffer to catch all the lines that conpty is about to emit. When that
happens, lines get duplicated in the buffer. From a UX perspective, this
certainly looks a lot worse than a couple lost lines. It looks like
utter chaos.
So I've introduced a new mode to conpty to try and counteract this
behavior. This behavior I'm calling "quirky resize". The **TL;DR** of
quirky resize mode is that conpty won't emit the entire buffer on a
resize, and will trust that the terminal is prepared to reflow it's
buffer on it's own.
This will enable the quirky resize behavior for applications that are
prepared for it. The "quirky resize" is "don't `InvalidateAll` when the
terminal resizes". This is added as a quirk as to not regress other
terminal applications that aren't prepared for this behavior
(gnome-terminal, conhost in particular). For those kinds of terminals,
when the buffer is resized, it's just going to lose lines. That's what
currently happens for them.
When the quirk is enabled, conpty won't repaint the entire buffer. This
gets around the "duplicated lines" issue that requesting multiple
resizes in a row can cause. However, for these terminals that are
unprepared, the conpty cursor might end up in the wrong position after a
quirky resize.
The case in point is maximizing the terminal. For maximizing
(height->50) from a buffer that's 30 lines tall, with the cursor on
y=30, this is what happens:
* With the quirk disabled, conpty reprints the entire buffer. This is
60 lines that get printed. This ends up blowing away about 20 lines
of scrollback history, as the terminal app would have tried to keep
the text pinned to the bottom of the window. The term. app moved the
viewport up 20 lines, and then the 50 lines of conpty output (30
lines of text, and 20 blank lines at the bottom) overwrote the lines
from the scrollback. This is bad, but not immediately obvious, and
is **what currently happens**.
* With the quirk enabled, conpty doesn't emit any lines, but the
actual content of the window is still only in the top 30 lines.
However, the terminal app has still moved 20 lines down from the
scrollback back into the viewport. So the terminal's cursor is at
y=50 now, but conpty's is at 30. This means that the terminal and
conpty are out of sync, and there's not a good way of re-syncing
these. It's very possible (trivial in `powershell`) that the new
output will jump up to y=30 override the existing output in the
terminal buffer.
The Windows Terminal is already prepared for this quirky behavior, so it
doesn't keep the output at the bottom of the window. It shifts it's
viewport down to match what conpty things the buffer looks like.
What happens when we have passthrough mode and WT is like "I would like
quirky resize"? I guess things will just work fine, cause there won't be
a buffer behind the passthrough app that the terminal cares about. Sure,
in the passthrough case the Terminal could _not_ quirky resize, but the
quirky resize won't be wrong.
This commit renames the functions in conpty.lib to Conpty* so that they
can be explicitly linked and introduces a header so they can be located.
It also updates the DEF for conpty.dll to reexport them with their
original names.
The crux of the issue here is that TerminalConnection is consuming the
_import_ symbols for the *PseudoConsole family of APIs, which simply
cannot be supplanted by a static library.
Avenues explored: * Exporting __imp_x from the static library to get all
up in kernel32's business. * Using /ALTERNATENAME:__imp_X=StaticX. It
turns out ALTERNATENAME is only consulted when the symbol isn't found
through traditional means.
This, renaming them, is the straightest path forward.
Fixes#3553.
