fix: size and center the main window relative to the actual monitor

src-tauri/src/lib.rs

@@ -1,16 +1,60 @@
+use tauri::{LogicalSize, Manager, WebviewWindow};
+
 // Learn more about Tauri commands at https://tauri.app/develop/calling-rust/
 #[tauri::command]
 fn greet(name: &str) -> String {
     format!("Hello, {}! You've been greeted from Rust!", name)
 }
 
+// tauri.conf.json's width/height (1200x800) are only used as a fallback for
+// the brief moment before this runs, and as the size on platforms where
+// monitor info is unavailable at startup. The window starts hidden
+// (`visible: false` in tauri.conf.json) so the resize below never causes a
+// visible flash.
+const TARGET_WORK_AREA_RATIO: f64 = 0.75;
+const MIN_LOGICAL_WIDTH: f64 = 1000.0;
+const MIN_LOGICAL_HEIGHT: f64 = 700.0;
+const MAX_LOGICAL_WIDTH: f64 = 1600.0;
+const MAX_LOGICAL_HEIGHT: f64 = 1000.0;
+
+/// Resizes and centers the window relative to the current monitor's
+/// available work area (screen size minus taskbars/docks), scaled for its
+/// DPI, and clamped to a sane min/max so it is never unusably small on a
+/// dense display nor absurdly large on an ultrawide one.
+fn size_window_for_monitor(window: &WebviewWindow) {
+    let monitor = match window.primary_monitor() {
+        Ok(Some(monitor)) => monitor,
+        _ => return,
+    };
+
+    let scale_factor = monitor.scale_factor();
+    let work_area_logical: LogicalSize<f64> = monitor.work_area().size.to_logical(scale_factor);
+
+    let target_width =
+        (work_area_logical.width * TARGET_WORK_AREA_RATIO).clamp(MIN_LOGICAL_WIDTH, MAX_LOGICAL_WIDTH);
+    let target_height = (work_area_logical.height * TARGET_WORK_AREA_RATIO)
+        .clamp(MIN_LOGICAL_HEIGHT, MAX_LOGICAL_HEIGHT);
+
+    let _ = window.set_size(LogicalSize::new(target_width, target_height));
+    let _ = window.center();
+}
+
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
     tauri::Builder::default()
         .plugin(tauri_plugin_opener::init())
         .plugin(tauri_plugin_process::init())
         .plugin(tauri_plugin_updater::Builder::new().build())
         .invoke_handler(tauri::generate_handler![greet])
+        .setup(|app| {
+            if let Some(window) = app.get_webview_window("main") {
+                size_window_for_monitor(&window);
+                // Always show, even if monitor detection above failed —
+                // the window must never stay hidden.
+                let _ = window.show();
+            }
+            Ok(())
+        })
         .run(tauri::generate_context!())
         .expect("error while running tauri application");
 }

src-tauri/tauri.conf.json

@@ -18,8 +18,12 @@
         "title": "CommDesk",
         "width": 1200,
         "height": 800,
+        "minWidth": 1000,
+        "minHeight": 700,
         "resizable": true,
-        "fullscreen": false
+        "fullscreen": false,
+        "center": true,
+        "visible": false
       }
     ],