Color problem on Windows 7

[gwsw]

Copying from rivy/less#9 (comment)

For your information, Less v643 by @gwsw and @jftuga is the last version that colors properly on Windows 7. Subsequent versions (including, for example, v668) still run, but the coloring is broken. See sharkdp/bat#954 (comment).

[gwsw]

@sergeevabc, can you confirm that this problem happens on Windows 7 but does not happen on Windows 10 or later?

Also, can you provide a sample file that demonstrates the problem when input into less? That is, I'd like a test case that doesn't involve running bat or any other program besides less itself.

cc @avih

[sergeevabc]

Less v668 itself looks different than v643 on Windows 7.

$ less --help

v668

v643

Bat can color piped input and files and then it uses Less as a pager by default to output data page by page (screen by screen), rather than as a whole. Since Bat, executed without Less by means of --paging=never, colors the input as expected, the conclusion is that the latest versions of Less incorrectly process the data from Bat, depriving it of colors.

Bat with Less v668 (source: about.md).

Bat with Less v643 or without Less (the output is colored the same way).

Can you confirm that this problem happens on Windows 7 but does not happen on Windows 10 or later?

I have no access to Windows 10 or later, but I'm happy with Windows 7 SP1 x64, so you can count on me when testing Less on this OS.

[avih]

Less v668 itself looks different than v643 on Windows 7.

That is expected. The default colors were changed at b931818 to the colors you see (after v643, before v644).

This is more similar to the default colors on unix and linux, with the exception (compared to unix) that underline is cyan, and I don't recall how it looks on unix if the terminal doesn't support underline.

Bat about.md with Less v668.

Bat with Less v643 or without Less.

My guess is that both of these screenshots show broken colors, just in different ways.

Can you please post a screenshot of how that file looks on win10, or linux or something which supports it correctly?

The issue is that in 643 there was a bug which ended up with pretty much random colors when trying to display 256 colors in win7, and this bug was fixed, so now it shows only supported colors, and anything which can't be displayed correctly is now ignored correctly, instead of producing a random color.

However, 8/16 colors should work fine, because this is what win7 console supports, so you need to choose a theme (in bat) of 8/16 colors. Maybe it's called "ansi"? I don't recall.

I think they had some issues with that too, that some themes which are supposed to be 8 colors ended up using the 256 colors palette, but at least you should try that first.

[gwsw]

Yes, colors were changed after v643, so the difference in the help file is expected. I'm not yet sure about the difference in the about.md file. Can you run less -R color-test-1.txt using the attached file and see what you see? It should display orange text. Also, try less -R -Da color-test-1.txt and see if that makes any difference.

color-test-1.txt

[gwsw]

Re avih's comment, the escape sequence for the first line is ESC[38;2;253;151;31mHaroopadESC[m, so it should be orange but in less-643 it's apparently displaying as red. On Windows 10 I think it displays the same as on Linux, although I don't have a Windows version of bat so I'm not 100% sure.

[avih]

the escape sequence for the first line is ESC[38;2;253;151;31mHaroopadESC[m,

Right, so it's not even 256 colors. It's true colors, which just can't work on win7, and we don't currently have auto-conversion to 8 colors. True colors also had this issue of random colors, it can't be displayed correctly, so "less" just gives up and it ends up with random thing.

You need to change the bat theme to ansi or something else which is 8/16 colors, which is what your win7 console supports.

[avih]

the escape sequence for the first line is ESC[38;2;253;151;31mHaroopadESC[m

Where did you get this from? Are you running bat with default config on some system? Which system?

[avih]

the escape sequence for the first line is ESC[38;2;253;151;31mHaroopadESC[m,

Right, so it's not even 256 colors. It's true colors, which just can't work on win7, and we don't currently have auto-conversion to 8 colors. True colors also had this issue of random colors,

And this random color in this case is the "31" there. Instead of RGB of 253;151;31 which is red-ish thing, it doesn't know what to do with 253 and 151, but it takes the value of 31 - which is red in 8/16 colors, and displays it incorrectly, while in fact it was supposed to be the blue value in that RGB triplet.

It was a bug which is fixed. Choose a theme which is appropriate for win7.

[gwsw]

Where did you get this from? Are you running bat with default config on some system?

Yeah, I ran bat on Linux under the script command and extracted it from the typescript file.

[avih]

Yeah, I ran bat on Linux

Right, so if this is indeed the same output on win7 then it's exactly what I described that it only takes the 31 from that RGB triplet.

But we don't know that for a fact, yet. It's possible that it uses a different theme on win7.

Though still, the symptoms fit what I know changed, so my bet so far is that my initial assessment was correct and it's an inadequate theme for this system.

[sergeevabc]

By default I have access to 16 colors, right. But with the help of ConEmu (wrapper that extends Windows cmd.exe capabilities) I can see 256 xterm palette. However, Less v668 does not output colors as expected even in the latter case.

$ less.exe -R color-test-1.txt

$ bat.exe color-test-1.txt

v643, 16 colors	v643, 256 colors	v668, 16 or 256 colors
red	orange	grey

[avih]

Next time please mention from the beginning the factors which are involved in what you're doing.

Anyway, show us the bug without conemu and with 16 color theme in bat, and then we can assess that.

643 was buggy with 256/true colors. It just didn't do the right thing, and it was broken in sort of random ways. Even if it looked like it worked, it didn't.

Later versions improved and currently only 8/16 colors can work on win7, which is the correct thing to do on win7.

[sergeevabc]

Next time please mention from the beginning the factors which are involved in what you're doing.

I did. You know my OS and versions of Less in question, other tools are not used until required for troubleshooting. For example, I mentioned ConEmu just to let you know there is a way for me to see more than 16 colors. And it didn't help with Less.

Anyway, show us the bug without conemu and with 16 color theme in bat, and then we can assess that.

I did. less.exe -R color-test-1.txt does not involve bat. Less v643 outputs red (broken or not, but it's colored output) or orange (as it should, based on ANSI sequence in that text file), whereas v668 outputs grey (essentially it means no coloring, although some color is expected).

[gwsw]

The color-test-1.txt file contains a full-color (24-bit color) sequence, the same as bat is using with the theme you're using. The Windows 7 terminal doesn't support that. This is the first I've heard of ConEmu, but it sounds like it doesn't support 24-bit color either, just 8-bit. The only way less could support 24-bit sequences is to do a full emulation, mapping each 24-bit color to the nearest 4-bit color. There has been some discussion about it, but that has never been supported.

As avih explained, older versions of less do random things with such sequences, so it looks like there is color, but the color is random and unrelated to the expected color. Newer versions of less just ignore 24-bit sequences, which is .why you see grey. This is a better and more deterministic behavior. For your use case, you should use a bat theme that uses 4-bit color.

[avih]

I did. less.exe -R color-test-1.txt does not involve bat. Less v643 outputs red (broken or not, but it's colored output) or orange (as it should, based on ANSI sequence in that text file),

That was a bug. This files has the true color sequence RGB of 253;151;31 .

It should not have shown anything because it can't work on win7. Interpreting only some values of a sequence which is not decoded correctly is a bug.

If this is what you want to argue then it is by design that less 688 doesn't try to display true colors on win7.

Maybe it will work with conemu and -r, not sure, and it's not great either.