refactor(ui): one empty state, and loading is not one of them

crates/hidegit-ui/src/widget/common.rs

@@ -19,7 +19,7 @@
 //! a real obstacle and is not: a rule emits nothing, so the message type is
 //! free and these are generic over it.
 
-use iced::widget::{Space, container};
+use iced::widget::{Space, container, text};
 use iced::{Fill, Length};
 
 use crate::Element;
@@ -51,6 +51,42 @@ fn rule<'a, M: 'a>(palette: &Palette, width: Length, height: Length) -> Element<
         .into()
 }
 
+/// What a pane shows when it holds nothing yet.
+///
+/// Three of these existed — `empty` in the diff, `placeholder` in the detail
+/// pane and a third `placeholder` in staging — rendering the same centred muted
+/// line three ways.
+///
+/// `UI_SPEC.md` asks empty states to "carry the next action, not just an
+/// absence", and most of these do not yet. Giving them one is a separate change;
+/// what this does is make there be one place to give it to.
+pub fn empty<'a, M: 'a>(message: impl text::IntoFragment<'a>, palette: &Palette) -> Element<'a, M> {
+    centred(message, palette)
+}
+
+/// What a pane shows while it is still reading.
+///
+/// The same picture as [`empty`] and deliberately not the same function. A pane
+/// with nothing in it and a pane that has not finished looking are different
+/// states, and the difference is about to matter: an empty state is getting the
+/// next action, and "Loading…" has no next action to offer. Two of the seven
+/// call sites this replaced were this state wearing the other one's name.
+pub fn loading<'a, M: 'a>(
+    message: impl text::IntoFragment<'a>,
+    palette: &Palette,
+) -> Element<'a, M> {
+    centred(message, palette)
+}
+
+fn centred<'a, M: 'a>(message: impl text::IntoFragment<'a>, palette: &Palette) -> Element<'a, M> {
+    let muted = palette.muted;
+    container(text(message).size(metrics::text::BODY).color(muted))
+        .width(Fill)
+        .height(Fill)
+        .center(Fill)
+        .into()
+}
+
 /// How a button is drawn, by what pressing it does.
 ///
 /// Four designs for "the primary button" existed at once and disagreed about
@@ -202,6 +238,7 @@ mod tests {
                 "fn divider",
                 "fn vertical_rule",
                 "fn horizontal_rule",
+                "fn placeholder",
                 "fn accent_style",
                 "fn danger_style",
                 "fn quiet_style",

crates/hidegit-ui/src/widget/detail.rs

@@ -14,8 +14,8 @@ use crate::widget::common;
 
 pub fn view<'a>(repo: &'a OpenRepo, palette: &'a Palette) -> Element<'a, RepoMessage> {
     let body: Element<'a, RepoMessage> = match &repo.detail {
-        DetailPane::Empty => placeholder("Select a commit to read its message and diff", palette),
-        DetailPane::Loading => placeholder("Loading…", palette),
+        DetailPane::Empty => common::empty("Select a commit to read its message and diff", palette),
+        DetailPane::Loading => common::loading("Loading…", palette),
         DetailPane::Failed(error) => failure(error, palette),
         DetailPane::Commit { detail, diff, file } => {
             // A stash *is* a commit, which is what lets it reuse all of this — but
@@ -413,18 +413,6 @@ fn commit<'a>(
     .into()
 }
 
-fn placeholder<'a>(message: &str, palette: &Palette) -> Element<'a, RepoMessage> {
-    container(
-        text(message.to_owned())
-            .size(metrics::text::BODY)
-            .color(palette.muted),
-    )
-    .width(Fill)
-    .height(Fill)
-    .center(Fill)
-    .into()
-}
-
 /// A failure shown where the action was attempted, with Git's own words rather
 /// than a paraphrase.
 fn failure<'a>(error: &UiError, palette: &Palette) -> Element<'a, RepoMessage> {

crates/hidegit-ui/src/widget/diff.rs

@@ -17,6 +17,7 @@ use crate::message::RepoMessage;
 use crate::metrics;
 use crate::state::DiffMode;
 use crate::theme::Palette;
+use crate::widget::common;
 
 const GUTTER_WIDTH: f32 = 44.0;
 
@@ -103,16 +104,16 @@ pub fn view<'a>(
     staging: Option<Staging<'a>>,
 ) -> Element<'a, RepoMessage> {
     let Some(file) = diff.files.get(file) else {
-        return empty("Select a file to see its changes", palette);
+        return common::empty("Select a file to see its changes", palette);
     };
 
     match &file.content {
-        FileDiffContent::Binary => empty(
-            &format!("{} is binary — no text to show", file.path.display()),
+        FileDiffContent::Binary => common::empty(
+            format!("{} is binary — no text to show", file.path.display()),
             palette,
         ),
-        FileDiffContent::TooLarge { bytes } => empty(
-            &format!(
+        FileDiffContent::TooLarge { bytes } => common::empty(
+            format!(
                 "{} is {} — too large to diff without stalling",
                 file.path.display(),
                 format::bytes(*bytes)
@@ -122,8 +123,8 @@ pub fn view<'a>(
         // The size, not the pointer. Three lines of `oid sha256:…` are what
         // Git stores, not what changed — and "4.2 MB → 5.1 MB" is the most a
         // diff can honestly say about a file whose content it does not have.
-        FileDiffContent::Lfs { old, new, fetched } => empty(
-            &format!(
+        FileDiffContent::Lfs { old, new, fetched } => common::empty(
+            format!(
                 "{} is stored with Git LFS — {}{}",
                 file.path.display(),
                 lfs_summary(old.as_ref(), new.as_ref()),
@@ -132,7 +133,7 @@ pub fn view<'a>(
             palette,
         ),
         FileDiffContent::Text { hunks } if hunks.is_empty() => {
-            empty("No textual changes — the file's mode changed", palette)
+            common::empty("No textual changes — the file's mode changed", palette)
         }
         FileDiffContent::Text { hunks } => match mode {
             DiffMode::Unified => unified(file, hunks, palette, staging),
@@ -660,18 +661,6 @@ fn gutter<'a>(lineno: Option<u32>, palette: &Palette) -> Element<'a, RepoMessage
     .into()
 }
 
-fn empty<'a>(message: &str, palette: &Palette) -> Element<'a, RepoMessage> {
-    container(
-        text(message.to_owned())
-            .size(metrics::text::BODY)
-            .color(palette.muted),
-    )
-    .width(Fill)
-    .height(Fill)
-    .center(Fill)
-    .into()
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

crates/hidegit-ui/src/widget/staging.rs

@@ -143,7 +143,7 @@ fn pane<'a>(
     palette: &'a Palette,
 ) -> Element<'a, RepoMessage> {
     let Some(row) = selected else {
-        return placeholder("Select a file to see its changes", palette);
+        return common::empty("Select a file to see its changes", palette);
     };
 
     let staging = |is_staged: bool| {
@@ -159,15 +159,15 @@ fn pane<'a>(
         Section::Unstaged => diff::view(unstaged, row.index, mode, palette, staging(false)),
         // An untracked file has no diff to show: nothing in the repository has
         // ever seen it, so every line would be an addition against nothing.
-        Section::Untracked => placeholder("Untracked — stage it to see it as a diff", palette),
+        Section::Untracked => common::empty("Untracked — stage it to see it as a diff", palette),
         // The resolver loads its file asynchronously, so between selecting the
         // row and the file arriving there is genuinely nothing to show. Saying
         // so beats an empty pane that looks broken.
         Section::Conflicted => match resolver {
             Some(resolver) => {
                 crate::widget::resolver::view(resolver, state, conflicted_paths, palette)
             }
-            None => placeholder("Reading the conflicted file…", palette),
+            None => common::loading("Reading the conflicted file…", palette),
         },
     }
 }
@@ -403,14 +403,6 @@ fn clean<'a>(palette: &Palette) -> Element<'a, RepoMessage> {
     .into()
 }
 
-fn placeholder<'a>(message: &'a str, palette: &Palette) -> Element<'a, RepoMessage> {
-    let muted = palette.muted;
-    container(text(message).size(metrics::text::BODY).color(muted))
-        .center_x(Fill)
-        .center_y(Fill)
-        .into()
-}
-
 /// The commit message editor, and the button that acts on it.
 ///
 /// Sits under the file lists rather than in the diff pane, because it is about

docs/UI_SPEC.md

@@ -932,6 +932,15 @@ on screen and taken nowhere. Copying does not dismiss the toast.
 PRs → connect GitHub, or "you have no open pull requests"; clean working directory → the last
 commit.
 
+They are drawn by `widget/common::empty`, which replaced three helpers rendering the same centred
+muted line three ways. **Most of them do not carry an action yet** — the welcome screen and the PR
+panel do, and the panes that say "Select a file to see its changes" or "Nothing to commit" only
+describe the absence. That gap is real and named here rather than left to be discovered.
+
+**A pane that is still reading is not an empty pane.** `common::loading` draws the same picture and
+is deliberately a different function: an empty state is getting a next action and "Loading…" has
+none to offer. Two of the seven call sites were this state wearing the other one's name.
+
 **Drag and drop** on the graph performs merge and rebase. Drag a branch badge onto another and the
 action sheet opens naming both branches on every entry; nothing runs until one is chosen. The
 discoverability of the gesture is the point, but not at the cost of an unintended rebase.