go.*,text,widget{,/material}: implement text truncators

This commit adds support for the idea of a text "Truncator", a string
that is shown at the end of truncated text to indicate that it has been
shortened because it would not fit within the requested number of lines.

When specifying a maximum number of lines, a truncator symbol is always
used. If the user does not provide one, the rune `…` is used. This
requirement results in a better user experience and significantly simpler
code, as we can rely upon the presence of one or more truncator glyphs in
the output glyph stream when truncation has occurred.

When interacting with truncated text, the truncator glyphs all act as
a single, indivisible unit. They can be selected or not, and if selected
they act as the entire contents of the truncated portion of the text.
This means that copying all of a truncated label will copy the entire
label text content, with the truncator symbol not appearing at all.

Concretely, the exposed text API now accepts a Truncator string in
text.Parameters, and there is a new glyph flag FlagTruncator which indicates
that the glyph is part of the truncator run. The truncator run will only
have a single FlagClusterBreak (even if the run would usually have many),
and the glyph with both FlagClusterBreak and FlagTruncator will have the
quantity of truncated runes in its Runes field. This necessitated increasing
the size of the Runes field from a byte to an int, as it's theoretically possible
for quite a lot of text to be truncated.

This commit necessarily bumps our go-text/typesetting dependency to the version
exposing truncation in the exported API.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

This commit is contained in:

Chris Waldon

2023-03-22 15:19:04 -04:00

committed by

Elias Naur

parent 5c54268d40

commit 959f5889a1

11 changed files with 171 additions and 52 deletions

									
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				@@ -6,7 +6,7 @@ require (

					eliasnaur.com/font v0.0.0-20230308162249-dd43949cb42d

					gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2

					gioui.org/shader v1.0.6

					github.com/go-text/typesetting v0.0.0-20230327140021-5bac583ebb4f

					github.com/go-text/typesetting v0.0.0-20230327141846-b6333f70ed72

					golang.org/x/exp v0.0.0-20221012211006-4de253d81b95

					golang.org/x/exp/shiny v0.0.0-20220827204233-334a2380cb91

					golang.org/x/image v0.5.0