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bug#26909: 25.1; A face for margins
From: |
Clément Pit-Claudel |
Subject: |
bug#26909: 25.1; A face for margins |
Date: |
Mon, 11 May 2020 17:01:23 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 |
Hi Eli and Yuri,
On 13/05/2017 10.27, Eli Zaretskii wrote:>> From: Yuri Khan
<yuri.v.khan@gmail.com>
>> Date: Sat, 13 May 2017 21:07:03 +0700
>>
>> The last two actions demonstrate that customizing the faces of
>> whatever is displayed in the margin is not sufficient. A mechanism is
>> needed that will allow customization of the margin where nothing is
>> displayed. A new face would serve nicely.
>
> A face can only affect places where something is displayed using that
> face. Display margins only display text if the buffer specifies text
> properties or overlays which display in the margins. But what you
> would like to do calls for having a face that would affect screen
> space where _nothing_ is displayed, and such screen space in Emacs is
> always displayed using the frame's background color, not by using some
> face.
>
> IOW, I don't think introducing a new face would help here. Some
> additional mechanism would be necessary.
A margin face would be great to have.
How reasonable would it be to fill the margins with a stretched space? Would
it be too costly?
Currently we almost do that in extend_face_to_end_of_line, but short-circuits
earlier in that function mean that this part is only applicable when there is
e.g. a region.
if (WINDOW_LEFT_MARGIN_WIDTH (it->w) > 0
&& it->glyph_row->used[LEFT_MARGIN_AREA] == 0)
{
it->glyph_row->glyphs[LEFT_MARGIN_AREA][0] = space_glyph;
it->glyph_row->glyphs[LEFT_MARGIN_AREA][0].face_id =
default_face->id;
it->glyph_row->used[LEFT_MARGIN_AREA] = 1;
}
if (WINDOW_RIGHT_MARGIN_WIDTH (it->w) > 0
&& it->glyph_row->used[RIGHT_MARGIN_AREA] == 0)
{
it->glyph_row->glyphs[RIGHT_MARGIN_AREA][0] = space_glyph;
it->glyph_row->glyphs[RIGHT_MARGIN_AREA][0].face_id =
default_face->id;
it->glyph_row->used[RIGHT_MARGIN_AREA] = 1;
}
The (silly) attached patch confirms that removing the short-circuits makes it
possible to set a face in the margins, but besides the performance aspect it
only applies to lines that have contents.
Is this a reasonable way to go? If not, what might be better way?
Clément.
0001-Add-a-margin-face-remove-short-circuits-in-extend_fa.patch
Description: Text Data
- bug#26909: 25.1; A face for margins,
Clément Pit-Claudel <=