[PATCH 0/3] color: add support for 12-bit RGB colors

[PATCH 0/3] color: add support for 12-bit RGB colors

[Beat Bolli]

 * The color parsing code learned to handle 12-bit RGB colors.

The first commit fixes a typo, the second one adds some test coverage
for invalid RGB colors, and the final one extends the RGB color parser
to recognize 12-bit colors, as in #f0f.

Beat Bolli (3):
  t/t4026-color: remove an extra double quote character
  t/t4026-color: add test coverage for invalid RGB colors
  color: add support for 12-bit RGB colors

 Documentation/config.txt |  3 ++-
 color.c                  | 21 ++++++++++++++-------
 color.h                  |  3 ++-
 t/t4026-color.sh         | 18 +++++++++++++++---
 4 files changed, 33 insertions(+), 12 deletions(-)

-- 
2.44.0

[PATCH 1/3] t/t4026-color: remove an extra double quote character

[Beat Bolli]

This is most probably just an editing left-over from cb357221a4 (t4026:
test "normal" color, 2014-11-20) which added this test.

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
---
 t/t4026-color.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/t/t4026-color.sh b/t/t4026-color.sh
index cc3f60d468f4..37622451fc23 100755
--- a/t/t4026-color.sh
+++ b/t/t4026-color.sh
@@ -112,7 +112,7 @@ test_expect_success '"default" can be combined with attributes' '
 	color "default default no-reverse bold" "[1;27;39;49m"
 '
 
-test_expect_success '"normal" yields no color at all"' '
+test_expect_success '"normal" yields no color at all' '
 	color "normal black" "[40m"
 '
 
-- 
2.44.0

Re: [PATCH 1/3] t/t4026-color: remove an extra double quote character

[Jeff King]

On Mon, Apr 29, 2024 at 06:48:47PM +0200, Beat Bolli wrote:

> This is most probably just an editing left-over from cb357221a4 (t4026:
> test "normal" color, 2014-11-20) which added this test.

Yeah, I suspect that is correct. Modulo a minor comment I left on the
third patch, the whole series looks good to me.

-Peff

[PATCH 2/3] t/t4026-color: add test coverage for invalid RGB colors

[Beat Bolli]

Make sure that the RGB color parser rejects invalid characters.

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
---
 t/t4026-color.sh | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/t/t4026-color.sh b/t/t4026-color.sh
index 37622451fc23..0c39bd74a613 100755
--- a/t/t4026-color.sh
+++ b/t/t4026-color.sh
@@ -140,6 +140,15 @@ test_expect_success 'extra character after attribute' '
 	invalid_color "dimX"
 '
 
+test_expect_success 'non-hex character in RGB color' '
+	invalid_color "#x23456" &&
+	invalid_color "#1x3456" &&
+	invalid_color "#12x456" &&
+	invalid_color "#123x56" &&
+	invalid_color "#1234x6" &&
+	invalid_color "#12345x"
+'
+
 test_expect_success 'unknown color slots are ignored (diff)' '
 	git config color.diff.nosuchslotwilleverbedefined white &&
 	git diff --color
-- 
2.44.0

[PATCH 3/3] color: add support for 12-bit RGB colors

[Beat Bolli]

RGB color parsing currently supports 24-bit values in the form #RRGGBB.

As in Cascading Style Sheets (CSS [1]), also allow to specify an RGB color
using only three digits with #RGB.

In this shortened form, each of the digits is – again, as in CSS –
duplicated to convert the color to 24 bits, e.g. #f1b specifies the same
color as #ff11bb.

In color.h, remove the '0x' prefix in the example to match the actual
syntax.

[1] https://developer.mozilla.org/en-US/docs/Web/CSS/hex-color

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
---
 Documentation/config.txt |  3 ++-
 color.c                  | 21 ++++++++++++++-------
 color.h                  |  3 ++-
 t/t4026-color.sh         |  9 ++++++---
 4 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 70b448b13262..6f649c997c0f 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -316,7 +316,8 @@ terminals, this is usually not the same as setting to "white black".
 Colors may also be given as numbers between 0 and 255; these use ANSI
 256-color mode (but note that not all terminals may support this).  If
 your terminal supports it, you may also specify 24-bit RGB values as
-hex, like `#ff0ab3`.
+hex, like `#ff0ab3`, or 12-bit RGB values like `#f1b`, which is
+equivalent to the 24-bit color `#ff11bb`.
 +
 The accepted attributes are `bold`, `dim`, `ul`, `blink`, `reverse`,
 `italic`, and `strike` (for crossed-out or "strikethrough" letters).
diff --git a/color.c b/color.c
index f663c06ac4ed..227a5ab2f42e 100644
--- a/color.c
+++ b/color.c
@@ -64,12 +64,16 @@ static int match_word(const char *word, int len, const char *match)
 	return !strncasecmp(word, match, len) && !match[len];
 }
 
-static int get_hex_color(const char *in, unsigned char *out)
+static int get_hex_color(const char **inp, int width, unsigned char *out)
 {
+	const char *in = *inp;
 	unsigned int val;
-	val = (hexval(in[0]) << 4) | hexval(in[1]);
+
+	assert(width == 1 || width == 2);
+	val = (hexval(in[0]) << 4) | hexval(in[width - 1]);
 	if (val & ~0xff)
 		return -1;
+	*inp += width;
 	*out = val;
 	return 0;
 }
@@ -135,11 +139,14 @@ static int parse_color(struct color *out, const char *name, int len)
 		return 0;
 	}
 
-	/* Try a 24-bit RGB value */
-	if (len == 7 && name[0] == '#') {
-		if (!get_hex_color(name + 1, &out->red) &&
-		    !get_hex_color(name + 3, &out->green) &&
-		    !get_hex_color(name + 5, &out->blue)) {
+	/* Try a 24- or 12-bit RGB value prefixed with '#' */
+	if ((len == 7 || len == 4) && name[0] == '#') {
+		int width_per_color = (len == 7) ? 2 : 1;
+		const char *color = name + 1;
+
+		if (!get_hex_color(&color, width_per_color, &out->red) &&
+		    !get_hex_color(&color, width_per_color, &out->green) &&
+		    !get_hex_color(&color, width_per_color, &out->blue)) {
 			out->type = COLOR_RGB;
 			return 0;
 		}
diff --git a/color.h b/color.h
index bb28343be210..7ed259a35bb4 100644
--- a/color.h
+++ b/color.h
@@ -112,7 +112,8 @@ int want_color_fd(int fd, int var);
  * Translate a Git color from 'value' into a string that the terminal can
  * interpret and store it into 'dst'. The Git color values are of the form
  * "foreground [background] [attr]" where fore- and background can be a color
- * name ("red"), a RGB code (#0xFF0000) or a 256-color-mode from the terminal.
+ * name ("red"), a RGB code (#FF0000 or #F00) or a 256-color-mode from the
+ * terminal.
  */
 int color_parse(const char *value, char *dst);
 int color_parse_mem(const char *value, int len, char *dst);
diff --git a/t/t4026-color.sh b/t/t4026-color.sh
index 0c39bd74a613..9a6f8a4bc5bf 100755
--- a/t/t4026-color.sh
+++ b/t/t4026-color.sh
@@ -96,8 +96,8 @@ test_expect_success '256 colors' '
 	color "254 bold 255" "[1;38;5;254;48;5;255m"
 '
 
-test_expect_success '24-bit colors' '
-	color "#ff00ff black" "[38;2;255;0;255;40m"
+test_expect_success 'RGB colors' '
+	color "#ff00ff #0f0" "[38;2;255;0;255;48;2;0;255;0m"
 '
 
 test_expect_success '"default" foreground' '
@@ -146,7 +146,10 @@ test_expect_success 'non-hex character in RGB color' '
 	invalid_color "#12x456" &&
 	invalid_color "#123x56" &&
 	invalid_color "#1234x6" &&
-	invalid_color "#12345x"
+	invalid_color "#12345x" &&
+	invalid_color "#x23" &&
+	invalid_color "#1x3" &&
+	invalid_color "#12x"
 '
 
 test_expect_success 'unknown color slots are ignored (diff)' '
-- 
2.44.0

Re: [PATCH 3/3] color: add support for 12-bit RGB colors

[Junio C Hamano]

"Beat Bolli" <bb@drbeat.li> writes:

> +static int get_hex_color(const char **inp, int width, unsigned char *out)
>  {
> +	const char *in = *inp;
>  	unsigned int val;
> -	val = (hexval(in[0]) << 4) | hexval(in[1]);
> +
> +	assert(width == 1 || width == 2);
> +	val = (hexval(in[0]) << 4) | hexval(in[width - 1]);

So this makes #111111 out of #111 and #ffffff out of #fff.  Nice.

> diff --git a/color.h b/color.h
> index bb28343be210..7ed259a35bb4 100644
> --- a/color.h
> +++ b/color.h
> @@ -112,7 +112,8 @@ int want_color_fd(int fd, int var);
>   * Translate a Git color from 'value' into a string that the terminal can
>   * interpret and store it into 'dst'. The Git color values are of the form
>   * "foreground [background] [attr]" where fore- and background can be a color
> - * name ("red"), a RGB code (#0xFF0000) or a 256-color-mode from the terminal.
> + * name ("red"), a RGB code (#FF0000 or #F00) or a 256-color-mode from the
> + * terminal.
>   */

Good.  Hopefully we do not have such extra 0x in our end-user facing
documentation?

> diff --git a/t/t4026-color.sh b/t/t4026-color.sh
> index 0c39bd74a613..9a6f8a4bc5bf 100755
> --- a/t/t4026-color.sh
> +++ b/t/t4026-color.sh
> @@ -96,8 +96,8 @@ test_expect_success '256 colors' '
>  	color "254 bold 255" "[1;38;5;254;48;5;255m"
>  '
>  
> -test_expect_success '24-bit colors' '
> -	color "#ff00ff black" "[38;2;255;0;255;40m"
> +test_expect_success 'RGB colors' '
> +	color "#ff00ff #0f0" "[38;2;255;0;255;48;2;0;255;0m"
>  '
>  
>  test_expect_success '"default" foreground' '
> @@ -146,7 +146,10 @@ test_expect_success 'non-hex character in RGB color' '
>  	invalid_color "#12x456" &&
>  	invalid_color "#123x56" &&
>  	invalid_color "#1234x6" &&
> -	invalid_color "#12345x"
> +	invalid_color "#12345x" &&
> +	invalid_color "#x23" &&
> +	invalid_color "#1x3" &&
> +	invalid_color "#12x"
>  '

OK, looking good.

Thanks.

Re: [PATCH 3/3] color: add support for 12-bit RGB colors

[Beat Bolli]

On 29.04.2024 19:23, Junio C Hamano wrote:
> "Beat Bolli" <bb@drbeat.li> writes:
> 
>> diff --git a/color.h b/color.h
>> index bb28343be210..7ed259a35bb4 100644
>> --- a/color.h
>> +++ b/color.h
>> @@ -112,7 +112,8 @@ int want_color_fd(int fd, int var);
>>    * Translate a Git color from 'value' into a string that the terminal can
>>    * interpret and store it into 'dst'. The Git color values are of the form
>>    * "foreground [background] [attr]" where fore- and background can be a color
>> - * name ("red"), a RGB code (#0xFF0000) or a 256-color-mode from the terminal.
>> + * name ("red"), a RGB code (#FF0000 or #F00) or a 256-color-mode from the
>> + * terminal.
>>    */
> 
> Good.  Hopefully we do not have such extra 0x in our end-user facing
> documentation?

No, this was the only '#0x' I found. config.txt is fine as per the first 
hunk.

Re: [PATCH 3/3] color: add support for 12-bit RGB colors

[Jeff King]

On Mon, Apr 29, 2024 at 06:48:49PM +0200, Beat Bolli wrote:

> -test_expect_success '24-bit colors' '
> -	color "#ff00ff black" "[38;2;255;0;255;40m"
> +test_expect_success 'RGB colors' '
> +	color "#ff00ff #0f0" "[38;2;255;0;255;48;2;0;255;0m"
>  '

Heh, I would still think of it as a shorthand for 24-bit color, but I
guess you could argue it is now 12-bit color. :)

(Only observing, I think the new name is fine).

>  test_expect_success '"default" foreground' '
> @@ -146,7 +146,10 @@ test_expect_success 'non-hex character in RGB color' '
>  	invalid_color "#12x456" &&
>  	invalid_color "#123x56" &&
>  	invalid_color "#1234x6" &&
> -	invalid_color "#12345x"
> +	invalid_color "#12345x" &&
> +	invalid_color "#x23" &&
> +	invalid_color "#1x3" &&
> +	invalid_color "#12x"
>  '

This made me wonder what we'd do with "#1", "#12", "#1234", etc. Looking
at the code change, I think we'd continue to reject them. I wonder if it
is worth covering here.

-Peff

Re: [PATCH 3/3] color: add support for 12-bit RGB colors

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

> On Mon, Apr 29, 2024 at 06:48:49PM +0200, Beat Bolli wrote:
>
>> -test_expect_success '24-bit colors' '
>> -	color "#ff00ff black" "[38;2;255;0;255;40m"
>> +test_expect_success 'RGB colors' '
>> +	color "#ff00ff #0f0" "[38;2;255;0;255;48;2;0;255;0m"
>>  '
>
> Heh, I would still think of it as a shorthand for 24-bit color, but I
> guess you could argue it is now 12-bit color. :)
>
> (Only observing, I think the new name is fine).
>
>>  test_expect_success '"default" foreground' '
>> @@ -146,7 +146,10 @@ test_expect_success 'non-hex character in RGB color' '
>>  	invalid_color "#12x456" &&
>>  	invalid_color "#123x56" &&
>>  	invalid_color "#1234x6" &&
>> -	invalid_color "#12345x"
>> +	invalid_color "#12345x" &&
>> +	invalid_color "#x23" &&
>> +	invalid_color "#1x3" &&
>> +	invalid_color "#12x"
>>  '
>
> This made me wonder what we'd do with "#1", "#12", "#1234", etc. Looking
> at the code change, I think we'd continue to reject them. I wonder if it
> is worth covering here.

Worth covering in this test, yes, but I am perfectly OK with leaving
it outside the series as a #leftoverbit clean-up.

Re: [PATCH 3/3] color: add support for 12-bit RGB colors

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

>>> @@ -146,7 +146,10 @@ test_expect_success 'non-hex character in RGB color' '
>>>  	invalid_color "#12x456" &&
>>>  	invalid_color "#123x56" &&
>>>  	invalid_color "#1234x6" &&
>>> -	invalid_color "#12345x"
>>> +	invalid_color "#12345x" &&
>>> +	invalid_color "#x23" &&
>>> +	invalid_color "#1x3" &&
>>> +	invalid_color "#12x"
>>>  '
>>
>> This made me wonder what we'd do with "#1", "#12", "#1234", etc. Looking
>> at the code change, I think we'd continue to reject them. I wonder if it
>> is worth covering here.
>
> Worth covering in this test, yes, but I am perfectly OK with leaving
> it outside the series as a #leftoverbit clean-up.

Ah, I take it back.  The preimage was added by [2/3] so it is fair
to say that that step would be the right place to do that from the
get-go.

Re: [PATCH 3/3] color: add support for 12-bit RGB colors

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

> Ah, I take it back.  The preimage was added by [2/3] so it is fair
> to say that that step would be the right place to do that from the
> get-go.

Perhaps something like this can be squashed in.

Subject: [PATCH] fixup! t/t4026-color: add test coverage for invalid RGB colors

---
 t/t4026-color.sh | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/t/t4026-color.sh b/t/t4026-color.sh
index 9a6f8a4bc5..e60aa588c2 100755
--- a/t/t4026-color.sh
+++ b/t/t4026-color.sh
@@ -140,6 +140,14 @@ test_expect_success 'extra character after attribute' '
 	invalid_color "dimX"
 '
 
+test_expect_success 'wrong number of letters in RGB color' '
+	invalid_color "#1" &&
+	invalid_color "#23" &&
+	invalid_color "#4567" &&
+	invalid_color "#89abc" &&
+	invalid_color "#def0123"
+'
+
 test_expect_success 'non-hex character in RGB color' '
 	invalid_color "#x23456" &&
 	invalid_color "#1x3456" &&
-- 
2.45.0

Re: [PATCH 3/3] color: add support for 12-bit RGB colors

[Jeff King]

On Tue, Apr 30, 2024 at 12:01:54PM -0700, Junio C Hamano wrote:

> Junio C Hamano <gitster@pobox.com> writes:
> 
> > Ah, I take it back.  The preimage was added by [2/3] so it is fair
> > to say that that step would be the right place to do that from the
> > get-go.
> 
> Perhaps something like this can be squashed in.
> 
> Subject: [PATCH] fixup! t/t4026-color: add test coverage for invalid RGB colors

Yup, that looks good to me.

-Peff

Re: [PATCH 0/3] color: add support for 12-bit RGB colors

[Taylor Blau]

On Mon, Apr 29, 2024 at 06:48:46PM +0200, Beat Bolli wrote:
>  Documentation/config.txt |  3 ++-
>  color.c                  | 21 ++++++++++++++-------
>  color.h                  |  3 ++-
>  t/t4026-color.sh         | 18 +++++++++++++++---
>  4 files changed, 33 insertions(+), 12 deletions(-)

Looks very nice. The first two patches are trivially correct, and I took
a close look at 3/3 and couldn't find any errors.

    Reviewed-by: Taylor Blau <me@ttaylorr.com>

Thanks,
Taylor

[PATCH v2 0/3] color: add support for 12-bit RGB colors

[Beat Bolli]

 * The color parsing code learned to handle 12-bit RGB colors.

The first commit fixes a typo, the second one adds some test coverage
for invalid RGB colors, and the final one extends the RGB color parser
to recognize 12-bit colors, as in #f0f.
---

Changes against v1:
- add test coverage for invalid RGB color lengths

1:  25da18f71e2c = 1:  25da18f71e2c t/t4026-color: remove an extra double quote character
2:  fb9a6ed05279 ! 2:  352fa4c91aa0 t/t4026-color: add test coverage for invalid RGB colors
    @@ Metadata
      ## Commit message ##
         t/t4026-color: add test coverage for invalid RGB colors
     
    -    Make sure that the RGB color parser rejects invalid characters.
    +    Make sure that the RGB color parser rejects invalid characters and
    +    invalid lengths.
     
      ## t/t4026-color.sh ##
     @@ t/t4026-color.sh: test_expect_success 'extra character after attribute' '
    @@ t/t4026-color.sh: test_expect_success 'extra character after attribute' '
     +	invalid_color "#1234x6" &&
     +	invalid_color "#12345x"
     +'
    ++
    ++test_expect_success 'wrong number of letters in RGB color' '
    ++	invalid_color "#1" &&
    ++	invalid_color "#23" &&
    ++	invalid_color "#456" &&
    ++	invalid_color "#789a" &&
    ++	invalid_color "#bcdef" &&
    ++	invalid_color "#1234567"
    ++'
     +
      test_expect_success 'unknown color slots are ignored (diff)' '
      	git config color.diff.nosuchslotwilleverbedefined white &&
3:  9d109fadcdb1 ! 3:  9147902f698f color: add support for 12-bit RGB colors
    @@ t/t4026-color.sh: test_expect_success 'non-hex character in RGB color' '
     +	invalid_color "#12x"
      '
      
    - test_expect_success 'unknown color slots are ignored (diff)' '
    + test_expect_success 'wrong number of letters in RGB color' '
    + 	invalid_color "#1" &&
    + 	invalid_color "#23" &&
    +-	invalid_color "#456" &&
    + 	invalid_color "#789a" &&
    + 	invalid_color "#bcdef" &&
    + 	invalid_color "#1234567"


Beat Bolli (3):
  t/t4026-color: remove an extra double quote character
  t/t4026-color: add test coverage for invalid RGB colors
  color: add support for 12-bit RGB colors

 Documentation/config.txt |  3 ++-
 color.c                  | 21 ++++++++++++++-------
 color.h                  |  3 ++-
 t/t4026-color.sh         | 26 +++++++++++++++++++++++---
 4 files changed, 41 insertions(+), 12 deletions(-)

-- 
2.44.0

[PATCH v2 1/3] t/t4026-color: remove an extra double quote character

[Beat Bolli]

This is most probably just an editing left-over from cb357221a4 (t4026:
test "normal" color, 2014-11-20) which added this test.

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
---
 t/t4026-color.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/t/t4026-color.sh b/t/t4026-color.sh
index cc3f60d468f4..37622451fc23 100755
--- a/t/t4026-color.sh
+++ b/t/t4026-color.sh
@@ -112,7 +112,7 @@ test_expect_success '"default" can be combined with attributes' '
 	color "default default no-reverse bold" "[1;27;39;49m"
 '
 
-test_expect_success '"normal" yields no color at all"' '
+test_expect_success '"normal" yields no color at all' '
 	color "normal black" "[40m"
 '
 
-- 
2.44.0

[PATCH v2 2/3] t/t4026-color: add test coverage for invalid RGB colors

[Beat Bolli]

Make sure that the RGB color parser rejects invalid characters and
invalid lengths.

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
---
 t/t4026-color.sh | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/t/t4026-color.sh b/t/t4026-color.sh
index 37622451fc23..c41138031989 100755
--- a/t/t4026-color.sh
+++ b/t/t4026-color.sh
@@ -140,6 +140,24 @@ test_expect_success 'extra character after attribute' '
 	invalid_color "dimX"
 '
 
+test_expect_success 'non-hex character in RGB color' '
+	invalid_color "#x23456" &&
+	invalid_color "#1x3456" &&
+	invalid_color "#12x456" &&
+	invalid_color "#123x56" &&
+	invalid_color "#1234x6" &&
+	invalid_color "#12345x"
+'
+
+test_expect_success 'wrong number of letters in RGB color' '
+	invalid_color "#1" &&
+	invalid_color "#23" &&
+	invalid_color "#456" &&
+	invalid_color "#789a" &&
+	invalid_color "#bcdef" &&
+	invalid_color "#1234567"
+'
+
 test_expect_success 'unknown color slots are ignored (diff)' '
 	git config color.diff.nosuchslotwilleverbedefined white &&
 	git diff --color
-- 
2.44.0

[PATCH v2 3/3] color: add support for 12-bit RGB colors

[Beat Bolli]

RGB color parsing currently supports 24-bit values in the form #RRGGBB.

As in Cascading Style Sheets (CSS [1]), also allow to specify an RGB color
using only three digits with #RGB.

In this shortened form, each of the digits is – again, as in CSS –
duplicated to convert the color to 24 bits, e.g. #f1b specifies the same
color as #ff11bb.

In color.h, remove the '0x' prefix in the example to match the actual
syntax.

[1] https://developer.mozilla.org/en-US/docs/Web/CSS/hex-color

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
---
 Documentation/config.txt |  3 ++-
 color.c                  | 21 ++++++++++++++-------
 color.h                  |  3 ++-
 t/t4026-color.sh         | 10 ++++++----
 4 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 70b448b13262..6f649c997c0f 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -316,7 +316,8 @@ terminals, this is usually not the same as setting to "white black".
 Colors may also be given as numbers between 0 and 255; these use ANSI
 256-color mode (but note that not all terminals may support this).  If
 your terminal supports it, you may also specify 24-bit RGB values as
-hex, like `#ff0ab3`.
+hex, like `#ff0ab3`, or 12-bit RGB values like `#f1b`, which is
+equivalent to the 24-bit color `#ff11bb`.
 +
 The accepted attributes are `bold`, `dim`, `ul`, `blink`, `reverse`,
 `italic`, and `strike` (for crossed-out or "strikethrough" letters).
diff --git a/color.c b/color.c
index f663c06ac4ed..227a5ab2f42e 100644
--- a/color.c
+++ b/color.c
@@ -64,12 +64,16 @@ static int match_word(const char *word, int len, const char *match)
 	return !strncasecmp(word, match, len) && !match[len];
 }
 
-static int get_hex_color(const char *in, unsigned char *out)
+static int get_hex_color(const char **inp, int width, unsigned char *out)
 {
+	const char *in = *inp;
 	unsigned int val;
-	val = (hexval(in[0]) << 4) | hexval(in[1]);
+
+	assert(width == 1 || width == 2);
+	val = (hexval(in[0]) << 4) | hexval(in[width - 1]);
 	if (val & ~0xff)
 		return -1;
+	*inp += width;
 	*out = val;
 	return 0;
 }
@@ -135,11 +139,14 @@ static int parse_color(struct color *out, const char *name, int len)
 		return 0;
 	}
 
-	/* Try a 24-bit RGB value */
-	if (len == 7 && name[0] == '#') {
-		if (!get_hex_color(name + 1, &out->red) &&
-		    !get_hex_color(name + 3, &out->green) &&
-		    !get_hex_color(name + 5, &out->blue)) {
+	/* Try a 24- or 12-bit RGB value prefixed with '#' */
+	if ((len == 7 || len == 4) && name[0] == '#') {
+		int width_per_color = (len == 7) ? 2 : 1;
+		const char *color = name + 1;
+
+		if (!get_hex_color(&color, width_per_color, &out->red) &&
+		    !get_hex_color(&color, width_per_color, &out->green) &&
+		    !get_hex_color(&color, width_per_color, &out->blue)) {
 			out->type = COLOR_RGB;
 			return 0;
 		}
diff --git a/color.h b/color.h
index bb28343be210..7ed259a35bb4 100644
--- a/color.h
+++ b/color.h
@@ -112,7 +112,8 @@ int want_color_fd(int fd, int var);
  * Translate a Git color from 'value' into a string that the terminal can
  * interpret and store it into 'dst'. The Git color values are of the form
  * "foreground [background] [attr]" where fore- and background can be a color
- * name ("red"), a RGB code (#0xFF0000) or a 256-color-mode from the terminal.
+ * name ("red"), a RGB code (#FF0000 or #F00) or a 256-color-mode from the
+ * terminal.
  */
 int color_parse(const char *value, char *dst);
 int color_parse_mem(const char *value, int len, char *dst);
diff --git a/t/t4026-color.sh b/t/t4026-color.sh
index c41138031989..b05f2a9b6075 100755
--- a/t/t4026-color.sh
+++ b/t/t4026-color.sh
@@ -96,8 +96,8 @@ test_expect_success '256 colors' '
 	color "254 bold 255" "[1;38;5;254;48;5;255m"
 '
 
-test_expect_success '24-bit colors' '
-	color "#ff00ff black" "[38;2;255;0;255;40m"
+test_expect_success 'RGB colors' '
+	color "#ff00ff #0f0" "[38;2;255;0;255;48;2;0;255;0m"
 '
 
 test_expect_success '"default" foreground' '
@@ -146,13 +146,15 @@ test_expect_success 'non-hex character in RGB color' '
 	invalid_color "#12x456" &&
 	invalid_color "#123x56" &&
 	invalid_color "#1234x6" &&
-	invalid_color "#12345x"
+	invalid_color "#12345x" &&
+	invalid_color "#x23" &&
+	invalid_color "#1x3" &&
+	invalid_color "#12x"
 '
 
 test_expect_success 'wrong number of letters in RGB color' '
 	invalid_color "#1" &&
 	invalid_color "#23" &&
-	invalid_color "#456" &&
 	invalid_color "#789a" &&
 	invalid_color "#bcdef" &&
 	invalid_color "#1234567"
-- 
2.44.0

Re: [PATCH v2 0/3] color: add support for 12-bit RGB colors

[Junio C Hamano]

"Beat Bolli" <bb@drbeat.li> writes:

>  * The color parsing code learned to handle 12-bit RGB colors.
>
> The first commit fixes a typo, the second one adds some test coverage
> for invalid RGB colors, and the final one extends the RGB color parser
> to recognize 12-bit colors, as in #f0f.

Thanks.

Re: [PATCH v2 0/3] color: add support for 12-bit RGB colors

[Jeff King]

On Thu, May 02, 2024 at 01:03:28PM +0200, Beat Bolli wrote:

>  * The color parsing code learned to handle 12-bit RGB colors.
> 
> The first commit fixes a typo, the second one adds some test coverage
> for invalid RGB colors, and the final one extends the RGB color parser
> to recognize 12-bit colors, as in #f0f.
> ---
> 
> Changes against v1:
> - add test coverage for invalid RGB color lengths

Ah, I missed that you had sent a new version when I responded to Junio.
Yeah, this whole thing looks good to me!

-Peff

Re: [PATCH v2 0/3] color: add support for 12-bit RGB colors

[Beat Bolli]

On 03.05.2024 19:48, Jeff King wrote:
> On Thu, May 02, 2024 at 01:03:28PM +0200, Beat Bolli wrote:
> 
>>   * The color parsing code learned to handle 12-bit RGB colors.
>>
>> The first commit fixes a typo, the second one adds some test coverage
>> for invalid RGB colors, and the final one extends the RGB color parser
>> to recognize 12-bit colors, as in #f0f.
>> ---
>>
>> Changes against v1:
>> - add test coverage for invalid RGB color lengths
> 
> Ah, I missed that you had sent a new version when I responded to Junio.
> Yeah, this whole thing looks good to me!

All good ;-)

Thanks for reviewing!

Cheers, Beat