WIP: implement text selection across multiple labels

Author: emilk

crates/egui/src/context.rs

@@ -625,7 +625,7 @@ impl Context {
     /// ```
     pub fn begin_frame(&self, new_input: RawInput) {
         crate::profile_function!();
-
+        crate::text_selection::LabelSelectionState::begin_frame(self);
         self.write(|ctx| ctx.begin_frame_mut(new_input));
     }
 }
@@ -1610,6 +1610,8 @@ impl Context {
             crate::gui_zoom::zoom_with_keyboard(self);
         }
 
+        crate::text_selection::LabelSelectionState::end_frame(self);
+
         let debug_texts = self.write(|ctx| std::mem::take(&mut ctx.debug_texts));
         if !debug_texts.is_empty() {
             // Show debug-text next to the cursor.
@@ -2346,6 +2348,15 @@ impl Context {
                 let font_image_size = self.fonts(|f| f.font_image_size());
                 crate::introspection::font_texture_ui(ui, font_image_size);
             });
+
+        CollapsingHeader::new("Label text selection state")
+            .default_open(false)
+            .show(ui, |ui| {
+                ui.label(format!(
+                    "{:#?}",
+                    crate::text_selection::LabelSelectionState::load(ui.ctx())
+                ));
+            });
     }
 
     /// Show stats about the allocated textures.

crates/egui/src/input_state.rs

@@ -840,6 +840,7 @@ impl PointerState {
     }
 
     /// Was any pointer button pressed (`!down -> down`) this frame?
+    ///
     /// This can sometimes return `true` even if `any_down() == false`
     /// because a press can be shorted than one frame.
     pub fn any_pressed(&self) -> bool {

crates/egui/src/text_selection/cursor_range.rs

@@ -234,10 +234,10 @@ impl CCursorRange {
     }
 
     #[inline]
-    pub fn two(min: CCursor, max: CCursor) -> Self {
+    pub fn two(min: impl Into<CCursor>, max: impl Into<CCursor>) -> Self {
         Self {
-            primary: max,
-            secondary: min,
+            primary: max.into(),
+            secondary: min.into(),
         }
     }