Add support for the DECAC escape sequence #13058

j4james · 2022-05-08T16:34:10Z

The DECAC (Assign Colors) escape sequence controls which color table
entries are associated with the default foreground and background
colors. This is how you would change the default colors on the the
original DEC VT525 terminals.

But DECAC also allows you to assign the color table entries for the
"window frame", which in our case is mapped to the tab color (just the
background for now). So this now gives us a way to control the tab color
via an escape sequence as well.

DETAILS

The way this works is there are now two new entries in the color table
for the frame colors, and two new aliases in the color alias table that
are mapped to those color table entries. As previously mentioned, only
the background is used for now.

By default, the colors are set to INVALID_COLOR, which indicates that
the system colors should be used. But if the user has set a tabColor
property in their profile, the frame background will be initialized with
that value instead.

And note that some of the existing color table entries are now
renumbered for compatibility with XTerm, which uses entries 256 to 260
for special colors which we don't yet support. Our default colors are
now at 261 and 262, the frame colors are 263 and 264, and the cursor
color is 265.

So at runtime, you can change the tab color programmatically by setting
the color table entry at index 262 using OSC 4 (assuming you need a
specific RGB value). Otherwise if you just want to set the tab color to
an existing color index, you can use DECAC 2.

You can even make the tab color automatically match background color by
mapping the frame background alias to the color table entry for the
default background, using DECAC 2;261;262 (technically this is mapping
both the the foreground and background).

This PR doesn't include support for querying the color mapping with
DECRQSS, and doesn't support resetting the colors with RIS, but
hopefully those can be figured out in a future PR - there are some
complications that'll need to be resolved first.

Validation Steps Performed

I've added a basic unit test that confirms the DECAC escape sequence
updates the color aliases in the render settings as expected. I've also
manually confirmed that the tab color in Windows Terminal is updated by
DECAC 2, and the default colors are updated in both conhost and WT
using DECAC 1.

Closes #6574

zadjii-msft · 2022-05-09T18:14:43Z

You cool if this misses the 1.14 release train? We're trying to stabilize that build up right now for release in about a weekish. That might mean a little bit delayed review on this one 😬

j4james · 2022-05-09T19:20:43Z

You cool if this misses the 1.14 release train?

@zadjii-msft Not a problem at all. I only did this now because I thought it might be a quick route to replacing the PowerShell VT quirk, and then we wouldn't have to worry about fixing #13037. But it turns out that's going to be a little more complicated than I had thought, so for now this is just a fun feature.

zadjii-msft · 2022-05-09T21:14:53Z

for now this is just a fun feature

You sure got that right ☺️ I'll toss it in with the rest of 1.15. Thanks!

src/terminal/adapter/adaptDispatch.cpp

lhecker · 2022-05-10T19:14:59Z

The border color can be implemented in conhost with DWMWA_BORDER_COLOR, DWMWA_CAPTION_COLOR and DWMWA_TEXT_COLOR I believe.

j4james · 2022-05-10T19:57:08Z

The border color can be implemented in conhost with DWMWA_BORDER_COLOR, DWMWA_CAPTION_COLOR and DWMWA_TEXT_COLOR I believe.

That's a nice idea. I'll have a play around with that when I get a chance and see how it looks.

j4james · 2022-05-12T18:26:55Z

FYI, I tried to get the border color working in conhost, only to discover that those particular DWM attributes are only supported on Windows 11, and I'm still on Windows 10. So I'm going to leave that for someone else to follow up on.

DHowett · 2022-05-12T18:56:49Z

src/cascadia/TerminalCore/Terminal.cpp

    }
    else
    {
-        _tabColor = settings.TabColor().Value();
+        _renderSettings.SetColorTableEntry(TextColor::FRAME_BACKGROUND, til::color{ settings.TabColor().Value() });


I don't 100% understand the color table vs alias thing right now, but should this use SetColorAlias to both (1) point FrameBackground at FRAME_BACKGROUND and (2) set FRAME_BACKGROUND to the new tab color?

Or is the intent that once redirected via DECAC, user-specified tab color cannot override application-specified tab color?

(And keeping with my (potential mis-)understanding of color aliases:) If that is the intent, then updating only the FRAME_BACKGROUND color but not re-pointing FrameBackground back to it is in line with that intent (?)

I'm glad you raised this, because I had meant to bring it up myself. I'm open to changing this, but I did it this way because it lets you map the frame background alias to the default background color table (using DECAC 2;261;262), and then switch your color scheme in the settings and still have both remain in sync. If we reset the frame alias here then we lose that ability.

But further down the line I'm assuming you might add an option for users to explicitly request that behavior (to support #702), and then the decision as to what should happen here would probably be controlled by that setting.

Does that make sense?

Does that make sense?

100%. We can refine this if/when we add this part of 702. For now, I like how it is. Thanks!

Mike may be changing the default s.t. Terminal always acts like DECAC 2;261;262 over in #12992, or shortly after. /cc @zadjii-msft for this discussion.

DHowett · 2022-05-12T20:17:59Z

there are some complications that'll need to be resolved first.

If you wouldn't mind documenting these in an issue, I'd appreciate it!

DHowett

Thanks again!

ghost · 2022-05-12T20:18:29Z

Hello @DHowett!

Because this pull request has the AutoMerge label, I will be glad to assist with helping to merge this pull request once all check-in policies pass.

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DHowett · 2022-05-16T22:06:29Z

Playing around with this now and I love it! I also somewhat wonder if there's a place for a terminal emulator to extend it. Like, eventually we'll have customizable cursor colors (akin to xterm OSC 12 or whichever it is), but DECAC only specifies text and frame.

It puts me in mind of DECSET/DECRST (and I must admit that I don't understand why DECSET's modes aren't just part of SM...)

j4james · 2022-05-16T23:37:26Z

I also somewhat wonder if there's a place for a terminal emulator to extend it. Like, eventually we'll have customizable cursor colors (akin to xterm OSC 12 or whichever it is), but DECAC only specifies text and frame.

Possibly, but I'm not sure the cursor color is a good example of something you'd want to link to an existing color index, rather than just giving it an RGB value. In general, though, I'm not opposed to the idea if there was a good use case for it.

It puts me in mind of DECSET/DECRST (and I must admit that I don't understand why DECSET's modes aren't just part of SM...)

Technically DECSET and DECRST are the same sequences as SM and RM. Its just that there are multiple categories of modes. The ones defined by ANSI have no prefix, while the ones defined by DEC use a ? private parameter prefix (other vendors would typically have had their own prefix).

There are only a few possible prefixes, so there were bound to be conflicts, but modern terminal emulators didn't even make an attempt to segregate their modes. They just lumped everything into the DEC category, often overwriting existing DEC modes, so it's a bit of mess at this point.

So coming back to the idea of extending DECAC to set the colors for other UI elements, we could potentially just use item numbers 3 and above, but another possibility would be to use a private parameter prefix for anything that is WT-specific. Anyway, it's not something we need to decide now, but I thought it quite pertinent to your question of DECSET vs SM.

ghost · 2022-07-06T18:08:33Z

🎉Windows Terminal Preview v1.15.186 has been released which incorporates this pull request.:tada:

Handy links:

@al20878

This PR adds support for querying the color indices set by the `DECAC` control, using the existing `DECRQSS` implementation. ## References and Relevant Issues The initial `DECRQSS` support was added in PR #11152. The `DECAC` functionality was added in PR #13058, but at the time we didn't know how to format the associated `DECRQSS` query. ## Detailed Description of the Pull Request / Additional comments For most `DECRQSS` queries, the setting being requested is identified by the final characters of its escape sequence. However, for the `DECAC` settings, you also need to include a parameter value, to indicate which color item you're querying. This meant we needed to extend the `DECRQSS` parser, so I also took this opportunity to ensure we correctly parsed any parameter prefix chars. We don't yet support any setting requiring a prefix, but this makes sure we don't respond incorrectly if an app does query such a setting. ## Validation Steps Performed Thanks to @al20878, we've been able to test how these queries are parsed on a real VT525 terminal, and I've manually verified our implementation matches that behavior. I've also extended the existing `DECRQSS` unit test to confirm that we are responding to the `DECAC` queries as expected. Closes #13091

j4james added 5 commits May 7, 2022 14:22

Hook up the DECAC sequence to the dispatch class.

6eb4301

Implement color assignment operation.

d184ef7

Link the frame background to the tab color.

f5468f4

Reserve color table entries for XTerm compatibility.

b875b4d

Add a basic test for the DECAC sequence.

ffaf52c

ghost added Area-VT Virtual Terminal sequence support Issue-Task It's a feature request, but it doesn't really need a major design. Product-Terminal The new Windows Terminal. labels May 8, 2022

Make audit mode happy.

4f57ee0

zadjii-msft added this to the Terminal v1.15 milestone May 9, 2022

lhecker reviewed May 10, 2022

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src/terminal/adapter/adaptDispatch.cpp Outdated Show resolved Hide resolved

j4james added 2 commits May 12, 2022 15:37

Move index validity check into SetColorAliasIndex.

1008586

Use a more generic name for the frame color callback.

21cf16c

j4james marked this pull request as ready for review May 12, 2022 18:26

lhecker approved these changes May 12, 2022

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DHowett reviewed May 12, 2022

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DHowett approved these changes May 12, 2022

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DHowett added the AutoMerge Marked for automatic merge by the bot when requirements are met label May 12, 2022

ghost merged commit a69ce89 into microsoft:main May 12, 2022

j4james mentioned this pull request May 12, 2022

Add support for querying DECAC with DECRQSS #13091

Closed

j4james deleted the feature-decac branch May 14, 2022 12:44

ghost mentioned this pull request Jul 6, 2022

Feature Request: command or proprietary escape codes to set a tab's color #6574

Closed

zadjii-msft mentioned this pull request Jul 6, 2022

DECAC support needs to be documented MicrosoftDocs/Console-Docs#267

Open

j4james mentioned this pull request Mar 14, 2023

Add support for querying the DECAC settings #14990

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Add support for the DECAC escape sequence #13058

Add support for the DECAC escape sequence #13058

j4james commented May 8, 2022 •

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Add support for the DECAC escape sequence #13058

Add support for the DECAC escape sequence #13058

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DETAILS

Validation Steps Performed

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