[Rust - agx] Cleanly interpolate scroll bar from ‘tuck in’ to expande…

…d scroll

.github/workflows/main.yml

@@ -14,7 +14,7 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
-  
+
     steps:
       # Checks out repo at $GITHUB_WORKSPACE
       - uses: actions/checkout@v2
@@ -47,7 +47,7 @@ jobs:
           python3 scripts/install_dependencies.py
           python3 scripts/build_os_toolchain.py
           echo "Toolchain built successfully"
-      
+
       - name: Build Rust toolchain
         shell: bash
         run: |

bootloader/main.c

@@ -248,8 +248,7 @@ int main(int argc, char** argv) {
 	draw(boot_info,   0x00e3a3d4);
 
 	printf("axle OS bootloader init...\n");
-	printf("Desired aspect ratio: %f\n", desired_aspect_ratio);
-	printf("Selected Mode %ld: %ldx%ld, %ld bpp\n", best_mode, gop_mode_info->HorizontalResolution, gop_mode_info->VerticalResolution, gop_mode_info->PixelFormat);
+	printf("Selected GOP mode #%ld: %ldx%ld, (pixel format #%ld)\n", best_mode, gop_mode_info->HorizontalResolution, gop_mode_info->VerticalResolution, gop_mode_info->PixelFormat);
 
 	pml4e_t* page_mapping_level4 = map2();
 	boot_info->boot_pml4 = (uint64_t)page_mapping_level4;

rust_programs/agx_definitions/src/lib.rs

@@ -973,7 +973,7 @@ mod test {
             TileSegments(vec![TileSegment::new(
                 Rect::new(0, 0, 300, 300),
                 Rect::new(0, 0, 300, 300),
-                &tiles[0]
+                &tiles[0],
             )])
         );
         assert_eq!(
@@ -982,12 +982,12 @@ mod test {
                 TileSegment::new(
                     Rect::new(0, 0, 300, 290),
                     Rect::new(0, 10, 300, 290),
-                    &tiles[0]
+                    &tiles[0],
                 ),
                 TileSegment::new(
                     Rect::new(0, 290, 300, 10),
                     Rect::new(0, 0, 300, 10),
-                    &tiles[1]
+                    &tiles[1],
                 ),
             ])
         );
@@ -1072,7 +1072,7 @@ mod test {
                 // Left edge
                 Rect::new(0, 100, 50, 50),
                 // Right edge
-                Rect::new(350, 100, 50, 50)
+                Rect::new(350, 100, 50, 50),
             ]
         );
 

rust_programs/libgui/src/bordered.rs

@@ -238,6 +238,6 @@ pub trait Bordered: Drawable + UIElement {
             true,
             self.currently_contains_mouse(),
         )
-            .1
+        .1
     }
 }

rust_programs/libgui/src/scroll_view.rs

@@ -1,6 +1,8 @@
 use core::{cell::RefCell, fmt::Display};
 
-use crate::bordered::{compute_inner_margin_and_content_frames, draw_border_with_insets, draw_outer_mouse_highlight};
+use crate::bordered::{
+    compute_inner_margin_and_content_frames, draw_border_with_insets, draw_outer_mouse_highlight,
+};
 use crate::window_events::KeyCode;
 use crate::{
     bordered::Bordered,
@@ -980,17 +982,24 @@ fn compute_scrollbar_attributes(
     };
 
     let scrollable_region_size = scrollable_region_size(viewport_size, content_size);
-    let scrolled_proportion = (scroll_position.y as f64 / scrollable_region_size.height as f64);
+    let scrolled_proportion = scroll_position.y as f64 / scrollable_region_size.height as f64;
     let scrollbar_width = (scroll_bar_onto_size.width as f64 * 0.4) as isize;
 
     let scrollbar_tuck_in_proportion = 0.2;
     let max_scrollbar_y = viewport_size.height - scrollbar_vertical_padding;
     let max_nominal_scrollbar_origin_y = max_scrollbar_y as f64 - nominal_scrollbar_height;
-    let max_nominal_scrollbar_y = max_nominal_scrollbar_origin_y + nominal_scrollbar_height;
+    // Slightly tricky bit ahead: 
+    // When not in the 'tuck in regions', the scrollbar should be linearly proportional to the scrolled proportion
+    // We need to find the slope and y-intercept of the line that crosses (0, scrollbar_vertical_padding) and (1, max_nominal_scrollbar_origin_y)
+    // Simplified slope intercept form
+    let slope = 1.0 / (1.0 - (scrollbar_tuck_in_proportion * 2.0));
+    let intercept = -slope * scrollbar_tuck_in_proportion;
+    // And ensure we never cross the [0, 1] bounds
+    let normalized_proportion = (intercept + (slope * scrolled_proportion)).max(0.0).min(1.0);
     let nominal_scrollbar_origin_y = lerp(
         scrollbar_vertical_padding as f64,
-        max_nominal_scrollbar_y,
-        scrolled_proportion - scrollbar_tuck_in_proportion,
+        max_nominal_scrollbar_origin_y,
+        normalized_proportion,
     );
 
     // The scroll bar should 'tuck in' if the user is near either extrema

rust_programs/libgui/src/text_view.rs

@@ -218,7 +218,7 @@ impl TextView {
         let is_inserting_at_end = cursor_pos.0 == text.len();
 
         if !is_inserting_at_end {
-            todo!("re-enable, disabled just while checking if this code path is hit");
+            //todo!("re-enable, disabled just while checking if this code path is hit");
             // If we just inserted a newline, we need to adjust our cursor position
             let mut cursor_point =
                 Self::next_cursor_pos_for_char(cursor_pos.1, ch, &font, font_size, onto);