Softwrapping improvements (#5893)

* use max_line_width + 1 during softwrap to account for newline char

Helix softwrap implementation always wraps lines so that the newline
character doesn't get cut off so he line wraps one chars earlier then
in other editors. This is necessary, because newline chars are always
selecatble in helix and must never be hidden.

However That means that `max_line_width` currently wraps one char
earlier than expected. The typical definition of line width does not
include the newline character and other helix commands like `:reflow`
also don't count the newline character here.

This commit makes softwrap use `max_line_width + 1` instead of
`max_line_width` to correct the impedance missmatch.

* fix typos

Co-authored-by: Jonathan Lebon <jonathan@jlebon.com>

* Add text-width to config.toml

* text-width: update setting documentation

* rename leftover config item

* remove leftover max-line-length occurrences

* Make `text-width` optional in editor config

When it was only used for `:reflow` it made sense to have a default
value set to `80`, but now that soft-wrapping uses this setting, keeping
a default set to `80` would make soft-wrapping behave more aggressively.

* Allow softwrapping to ignore `text-width`

Softwrapping wraps by default to the viewport width or a configured
`text-width` (whichever's smaller). In some cases we only want to set
`text-width` to use for hard-wrapping and let longer lines flow if they
have enough space. This setting allows that.

* Revert "Make `text-width` optional in editor config"

This reverts commit b247d526d69adf41434b6fd9c4983369c785aa22.

* soft-wrap: allow per-language overrides

* Update book/src/configuration.md

Co-authored-by: Pascal Kuthe <pascal.kuthe@semimod.de>

* Update book/src/languages.md

Co-authored-by: Pascal Kuthe <pascal.kuthe@semimod.de>

* Update book/src/configuration.md

Co-authored-by: Pascal Kuthe <pascal.kuthe@semimod.de>

---------

Co-authored-by: Pascal Kuthe <pascal.kuthe@semimod.de>
Co-authored-by: Jonathan Lebon <jonathan@jlebon.com>
Co-authored-by: Alex Boehm <alexb@ozrunways.com>
Co-authored-by: Blaž Hrastnik <blaz@mxxn.io>

2 files changed, 50 insertions, 47 deletions

diff --git a/helix-view/src/document.rs b/helix-view/src/document.rs
index 579c6725..4d3586f1 100644
--- a/helix-view/src/document.rs
+++ b/helix-view/src/document.rs
@@ -1238,24 +1238,61 @@ impl Document {
     }
 
     pub fn text_format(&self, mut viewport_width: u16, theme: Option<&Theme>) -> TextFormat {
-        if let Some(max_line_len) = self
+        let config = self.config.load();
+        let text_width = self
             .language_config()
-            .and_then(|config| config.max_line_length)
-        {
-            viewport_width = viewport_width.min(max_line_len as u16)
+            .and_then(|config| config.text_width)
+            .unwrap_or(config.text_width);
+        let soft_wrap_at_text_width = self
+            .language_config()
+            .and_then(|config| {
+                config
+                    .soft_wrap
+                    .as_ref()
+                    .and_then(|soft_wrap| soft_wrap.wrap_at_text_width)
+            })
+            .or(config.soft_wrap.wrap_at_text_width)
+            .unwrap_or(false);
+        if soft_wrap_at_text_width {
+            // We increase max_line_len by 1 because softwrap considers the newline character
+            // as part of the line length while the "typical" expectation is that this is not the case.
+            // In particular other commands like :reflow do not count the line terminator.
+            // This is technically inconsistent for the last line as that line never has a line terminator
+            // but having the last visual line exceed the width by 1 seems like a rare edge case.
+            viewport_width = viewport_width.min(text_width as u16 + 1)
         }
         let config = self.config.load();
-        let soft_wrap = &config.soft_wrap;
+        let editor_soft_wrap = &config.soft_wrap;
+        let language_soft_wrap = self
+            .language
+            .as_ref()
+            .and_then(|config| config.soft_wrap.as_ref());
+        let enable_soft_wrap = language_soft_wrap
+            .and_then(|soft_wrap| soft_wrap.enable)
+            .or(editor_soft_wrap.enable)
+            .unwrap_or(false);
+        let max_wrap = language_soft_wrap
+            .and_then(|soft_wrap| soft_wrap.max_wrap)
+            .or(config.soft_wrap.max_wrap)
+            .unwrap_or(20);
+        let max_indent_retain = language_soft_wrap
+            .and_then(|soft_wrap| soft_wrap.max_indent_retain)
+            .or(editor_soft_wrap.max_indent_retain)
+            .unwrap_or(40);
+        let wrap_indicator = language_soft_wrap
+            .and_then(|soft_wrap| soft_wrap.wrap_indicator.clone())
+            .or_else(|| config.soft_wrap.wrap_indicator.clone())
+            .unwrap_or_else(|| "↪ ".into());
         let tab_width = self.tab_width() as u16;
         TextFormat {
-            soft_wrap: soft_wrap.enable && viewport_width > 10,
+            soft_wrap: enable_soft_wrap && viewport_width > 10,
             tab_width,
-            max_wrap: soft_wrap.max_wrap.min(viewport_width / 4),
-            max_indent_retain: soft_wrap.max_indent_retain.min(viewport_width * 2 / 5),
+            max_wrap: max_wrap.min(viewport_width / 4),
+            max_indent_retain: max_indent_retain.min(viewport_width * 2 / 5),
             // avoid spinning forever when the window manager
             // sets the size to something tiny
             viewport_width,
-            wrap_indicator: soft_wrap.wrap_indicator.clone().into_boxed_str(),
+            wrap_indicator: wrap_indicator.into_boxed_str(),
             wrap_indicator_highlight: theme
                 .and_then(|theme| theme.find_scope_index("ui.virtual.wrap"))
                 .map(Highlight),
diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index b96eec8d..5b819b33 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -42,7 +42,7 @@ pub use helix_core::diagnostic::Severity;
 pub use helix_core::register::Registers;
 use helix_core::{
     auto_pairs::AutoPairs,
-    syntax::{self, AutoPairConfig},
+    syntax::{self, AutoPairConfig, SoftWrap},
     Change,
 };
 use helix_core::{Position, Selection};
@@ -241,6 +241,8 @@ pub struct Config {
     pub auto_format: bool,
     /// Automatic save on focus lost. Defaults to false.
     pub auto_save: bool,
+    /// Set a global text_width
+    pub text_width: usize,
     /// Time in milliseconds since last keypress before idle timers trigger.
     /// Used for autocompletion, set to 0 for instant. Defaults to 400ms.
     #[serde(
@@ -276,43 +278,6 @@ pub struct Config {
     pub soft_wrap: SoftWrap,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(default, rename_all = "kebab-case", deny_unknown_fields)]
-pub struct SoftWrap {
-    /// Soft wrap lines that exceed viewport width. Default to off
-    pub enable: bool,
-    /// Maximum space left free at the end of the line.
-    /// This space is used to wrap text at word boundaries. If that is not possible within this limit
-    /// the word is simply split at the end of the line.
-    ///
-    /// This is automatically hard-limited to a quarter of the viewport to ensure correct display on small views.
-    ///
-    /// Default to 20
-    pub max_wrap: u16,
-    /// Maximum number of indentation that can be carried over from the previous line when softwrapping.
-    /// If a line is indented further then this limit it is rendered at the start of the viewport instead.
-    ///
-    /// This is automatically hard-limited to a quarter of the viewport to ensure correct display on small views.
-    ///
-    /// Default to 40
-    pub max_indent_retain: u16,
-    /// Indicator placed at the beginning of softwrapped lines
-    ///
-    /// Defaults to ↪
-    pub wrap_indicator: String,
-}
-
-impl Default for SoftWrap {
-    fn default() -> Self {
-        SoftWrap {
-            enable: false,
-            max_wrap: 20,
-            max_indent_retain: 40,
-            wrap_indicator: "↪ ".into(),
-        }
-    }
-}
-
 #[derive(Debug, Default, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case", deny_unknown_fields)]
 pub struct TerminalConfig {
@@ -772,6 +737,7 @@ impl Default for Config {
             indent_guides: IndentGuidesConfig::default(),
             color_modes: false,
             soft_wrap: SoftWrap::default(),
+            text_width: 80,
         }
     }
 }