From 33dbbf271e0d7ddb3b7defda3d047e51091145cf Mon Sep 17 00:00:00 2001
From: Nathan Sobo <nathan@zed.dev>
Date: Tue, 24 Aug 2021 18:16:31 -0600
Subject: [PATCH] WIP

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>
---
 gpui/src/elements.rs      |   2 +
 gpui/src/elements/text.rs | 166 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 168 insertions(+)
 create mode 100644 gpui/src/elements/text.rs

diff --git a/gpui/src/elements.rs b/gpui/src/elements.rs
index c3053c9fa1655882dfbc75e3fb1c0a02132ec82c..d7d042617fe7f8a74b09bc1d28a98aef8fb7a19c 100644
--- a/gpui/src/elements.rs
+++ b/gpui/src/elements.rs
@@ -11,6 +11,7 @@ mod list;
 mod mouse_event_handler;
 mod stack;
 mod svg;
+mod text;
 mod uniform_list;
 
 pub use crate::presenter::ChildView;
@@ -27,6 +28,7 @@ pub use list::*;
 pub use mouse_event_handler::*;
 pub use stack::*;
 pub use svg::*;
+pub use text::*;
 pub use uniform_list::*;
 
 use crate::{
diff --git a/gpui/src/elements/text.rs b/gpui/src/elements/text.rs
new file mode 100644
index 0000000000000000000000000000000000000000..78e9d0d3a48a916756641403ab35d35cfc90d2f9
--- /dev/null
+++ b/gpui/src/elements/text.rs
@@ -0,0 +1,166 @@
+use crate::{
+    color::Color,
+    font_cache::FamilyId,
+    fonts::{FontId, TextStyle},
+    geometry::{
+        rect::RectF,
+        vector::{vec2f, Vector2F},
+    },
+    json::{ToJson, Value},
+    text_layout::Line,
+    DebugContext, Element, Event, EventContext, FontCache, LayoutContext, PaintContext,
+    SizeConstraint,
+};
+use serde::Deserialize;
+use serde_json::json;
+use smallvec::{smallvec, SmallVec};
+
+pub struct Text {
+    text: String,
+    family_id: FamilyId,
+    font_size: f32,
+    style: TextStyle,
+}
+
+impl Text {
+    pub fn new(text: String, family_id: FamilyId, font_size: f32) -> Self {
+        Self {
+            text,
+            family_id,
+            font_size,
+            style: Default::default(),
+        }
+    }
+
+    pub fn with_style(mut self, style: &TextStyle) -> Self {
+        self.style = style.clone();
+        self
+    }
+
+    pub fn with_default_color(mut self, color: Color) -> Self {
+        self.style.color = color;
+        self
+    }
+}
+
+impl Element for Text {
+    type LayoutState = Line;
+    type PaintState = ();
+
+    fn layout(
+        &mut self,
+        constraint: SizeConstraint,
+        cx: &mut LayoutContext,
+    ) -> (Vector2F, Self::LayoutState) {
+        let font_id = cx
+            .font_cache
+            .select_font(self.family_id, &self.style.font_properties)
+            .unwrap();
+        let line =
+            cx.text_layout_cache
+                .layout_str(self.text.as_str(), self.font_size, runs.as_slice());
+
+        let size = vec2f(
+            line.width().max(constraint.min.x()).min(constraint.max.x()),
+            cx.font_cache.line_height(font_id, self.font_size).ceil(),
+        );
+
+        (size, line)
+    }
+
+    fn paint(
+        &mut self,
+        bounds: RectF,
+        line: &mut Self::LayoutState,
+        cx: &mut PaintContext,
+    ) -> Self::PaintState {
+        line.paint(
+            bounds.origin(),
+            RectF::new(vec2f(0., 0.), bounds.size()),
+            cx,
+        )
+    }
+
+    fn dispatch_event(
+        &mut self,
+        _: &Event,
+        _: RectF,
+        _: &mut Self::LayoutState,
+        _: &mut Self::PaintState,
+        _: &mut EventContext,
+    ) -> bool {
+        false
+    }
+
+    fn debug(
+        &self,
+        bounds: RectF,
+        _: &Self::LayoutState,
+        _: &Self::PaintState,
+        cx: &DebugContext,
+    ) -> Value {
+        json!({
+            "type": "Label",
+            "bounds": bounds.to_json(),
+            "text": &self.text,
+            "highlight_indices": self.highlight_indices,
+            "font_family": cx.font_cache.family_name(self.family_id).unwrap(),
+            "font_size": self.font_size,
+            "style": self.style.to_json(),
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::fonts::{Properties as FontProperties, Weight};
+
+    #[crate::test(self)]
+    fn test_layout_label_with_highlights(cx: &mut crate::MutableAppContext) {
+        let menlo = cx.font_cache().load_family(&["Menlo"]).unwrap();
+        let menlo_regular = cx
+            .font_cache()
+            .select_font(menlo, &FontProperties::new())
+            .unwrap();
+        let menlo_bold = cx
+            .font_cache()
+            .select_font(menlo, FontProperties::new().weight(Weight::BOLD))
+            .unwrap();
+        let black = Color::black();
+        let red = Color::new(255, 0, 0, 255);
+
+        let label = Text::new(".αβγδε.ⓐⓑⓒⓓⓔ.abcde.".to_string(), menlo, 12.0)
+            .with_style(&TextStyle {
+                text: TextStyle {
+                    color: black,
+                    font_properties: Default::default(),
+                },
+                highlight_text: Some(TextStyle {
+                    color: red,
+                    font_properties: *FontProperties::new().weight(Weight::BOLD),
+                }),
+            })
+            .with_highlights(vec![
+                ".α".len(),
+                ".αβ".len(),
+                ".αβγδ".len(),
+                ".αβγδε.ⓐ".len(),
+                ".αβγδε.ⓐⓑ".len(),
+            ]);
+
+        let runs = label.compute_runs(cx.font_cache().as_ref(), menlo_regular);
+        assert_eq!(
+            runs.as_slice(),
+            &[
+                (".α".len(), menlo_regular, black),
+                ("βγ".len(), menlo_bold, red),
+                ("δ".len(), menlo_regular, black),
+                ("ε".len(), menlo_bold, red),
+                (".ⓐ".len(), menlo_regular, black),
+                ("ⓑⓒ".len(), menlo_bold, red),
+                ("ⓓⓔ.abcde.".len(), menlo_regular, black),
+            ]
+        );
+    }
+}