Flesh out bgmap viewer

src/window/vram/utils.rs

@@ -1,3 +1,5 @@
+use egui::{Color32, Image, ImageSource, Response, Sense, TextureOptions, Ui, Widget};
+
 pub const GENERIC_PALETTE: [u8; 4] = [0, 64, 128, 255];
 
 pub fn parse_palette(palette: u8, brts: &[u8]) -> [u8; 4] {
@@ -14,3 +16,100 @@ pub fn parse_palette(palette: u8, brts: &[u8]) -> [u8; 4] {
         shades[(palette >> 6) as usize & 0x03],
     ]
 }
+
+pub struct CharacterGrid<'a> {
+    source: ImageSource<'a>,
+    scale: f32,
+    show_grid: bool,
+    selected: Option<usize>,
+}
+
+impl<'a> CharacterGrid<'a> {
+    pub fn new(source: impl Into<ImageSource<'a>>) -> Self {
+        Self {
+            source: source.into(),
+            scale: 1.0,
+            show_grid: false,
+            selected: None,
+        }
+    }
+
+    pub fn with_scale(self, scale: f32) -> Self {
+        Self { scale, ..self }
+    }
+
+    pub fn with_grid(self, show_grid: bool) -> Self {
+        Self { show_grid, ..self }
+    }
+
+    pub fn with_selected(self, selected: usize) -> Self {
+        Self {
+            selected: Some(selected),
+            ..self
+        }
+    }
+
+    pub fn show(self, ui: &mut Ui) -> Option<usize> {
+        let start_pos = ui.cursor().min;
+        let cell_size = 8.0 * self.scale;
+
+        let res = self.ui(ui);
+
+        let grid_width_cells = ((res.rect.max.x - res.rect.min.x) / cell_size).round() as usize;
+
+        if res.clicked() {
+            let click_pos = res.interact_pointer_pos()?;
+            let grid_pos = (click_pos - start_pos) / cell_size;
+            Some((grid_pos.y as usize * grid_width_cells) + grid_pos.x as usize)
+        } else {
+            None
+        }
+    }
+}
+
+impl Widget for CharacterGrid<'_> {
+    fn ui(self, ui: &mut Ui) -> Response {
+        let image = Image::new(self.source)
+            .fit_to_original_size(self.scale)
+            .tint(Color32::RED)
+            .texture_options(TextureOptions::NEAREST)
+            .sense(Sense::click());
+        let res = ui.add(image);
+
+        let cell_size = 8.0 * self.scale;
+        let grid_width_cells = ((res.rect.max.x - res.rect.min.x) / cell_size).round() as usize;
+        let grid_height_cells = ((res.rect.max.y - res.rect.min.y) / cell_size).round() as usize;
+
+        let painter = ui.painter_at(res.rect);
+        if self.show_grid {
+            let stroke = ui.style().visuals.widgets.noninteractive.fg_stroke;
+            for x in (1..grid_width_cells).map(|i| (i as f32) * cell_size) {
+                let p1 = (res.rect.min.x + x, res.rect.min.y).into();
+                let p2 = (res.rect.min.x + x, res.rect.max.y).into();
+                painter.line(vec![p1, p2], stroke);
+            }
+            for y in (1..grid_height_cells).map(|i| (i as f32) * cell_size) {
+                let p1 = (res.rect.min.x, res.rect.min.y + y).into();
+                let p2 = (res.rect.max.x, res.rect.min.y + y).into();
+                painter.line(vec![p1, p2], stroke);
+            }
+        }
+        if let Some(selected) = self.selected {
+            let x1 = (selected % grid_width_cells) as f32 * cell_size;
+            let x2 = x1 + cell_size;
+            let y1 = (selected / grid_width_cells) as f32 * cell_size;
+            let y2 = y1 + cell_size;
+            painter.line(
+                vec![
+                    (res.rect.min + (x1, y1).into()),
+                    (res.rect.min + (x2, y1).into()),
+                    (res.rect.min + (x2, y2).into()),
+                    (res.rect.min + (x1, y2).into()),
+                    (res.rect.min + (x1, y1).into()),
+                ],
+                ui.style().visuals.widgets.active.fg_stroke,
+            );
+        }
+        res
+    }
+}