feat(core): add window center API, closes #1822

.changes/api-window-center.md

@@ -0,0 +1,5 @@
+---
+"api": patch
+---
+
+Adds `center?: boolean` to `WindowOptions` and `center()` API to the `appWindow`.

.changes/window-center.md

@@ -0,0 +1,7 @@
+---
+"tauri-runtime": patch
+"tauri-runtime-wry": patch
+"tauri-runtime": patch
+---
+
+Adds `Window#center` API.

core/tauri-runtime-wry/src/lib.rs

@@ -243,6 +243,7 @@ impl From<Position> for PositionWrapper {
 #[derive(Debug, Clone, Default)]
 pub struct WindowBuilderWrapper {
   inner: WryWindowBuilder,
+  center: bool,
   #[cfg(feature = "menu")]
   menu_items: HashMap<u32, WryCustomMenuItem>,
 }
@@ -295,6 +296,11 @@ impl WindowBuilder for WindowBuilderWrapper {
     self
   }
 
+  fn center(mut self) -> Self {
+    self.center = true;
+    self
+  }
+
   fn position(mut self, x: f64, y: f64) -> Self {
     self.inner = self.inner.with_position(WryLogicalPosition::new(x, y));
     self
@@ -453,6 +459,7 @@ enum WindowMessage {
   #[cfg(windows)]
   Hwnd(Sender<Hwnd>),
   // Setters
+  Center(Sender<Result<()>>),
   SetResizable(bool),
   SetTitle(String),
   Maximize,
@@ -638,6 +645,10 @@ impl Dispatch for WryDispatcher {
 
   // Setters
 
+  fn center(&self) -> Result<()> {
+    dispatcher_getter!(self, WindowMessage::Center)
+  }
+
   fn print(&self) -> Result<()> {
     self
       .context
@@ -1278,6 +1289,9 @@ fn handle_event_loop(
               tx.send(Hwnd(window.hwnd())).unwrap()
             }
             // Setters
+            WindowMessage::Center(tx) => {
+              tx.send(center_window(window)).unwrap();
+            }
             WindowMessage::SetResizable(resizable) => window.set_resizable(resizable),
             WindowMessage::SetTitle(title) => window.set_title(&title),
             WindowMessage::Maximize => window.set_maximized(true),
@@ -1409,6 +1423,19 @@ fn handle_event_loop(
   }
 }
 
+fn center_window(window: &Window) -> Result<()> {
+  if let Some(monitor) = window.current_monitor() {
+    let screen_size = monitor.size();
+    let window_size = window.inner_size();
+    let x = (screen_size.width - window_size.width) / 2;
+    let y = (screen_size.height - window_size.height) / 2;
+    window.set_outer_position(WryPhysicalPosition::new(x, y));
+    Ok(())
+  } else {
+    Err(Error::FailedToGetMonitor)
+  }
+}
+
 fn create_webview<P: Params<Runtime = Wry>>(
   event_loop: &EventLoopWindowTarget<Message>,
   context: DispatcherContext,
@@ -1428,6 +1455,9 @@ fn create_webview<P: Params<Runtime = Wry>>(
   #[cfg(feature = "menu")]
   let menu_items = window_builder.menu_items;
   let window = window_builder.inner.build(event_loop).unwrap();
+  if window_builder.center {
+    let _ = center_window(&window);
+  }
   let mut webview_builder = WebViewBuilder::new(window)
     .map_err(|e| Error::CreateWebview(Box::new(e)))?
     .with_url(&url)

core/tauri-runtime/src/lib.rs

@@ -99,6 +99,9 @@ pub enum Error {
   /// Failed to load window icon.
   #[error("invalid icon: {0}")]
   InvalidIcon(Box<dyn std::error::Error + Send>),
+  /// Failed to get monitor on window operation.
+  #[error("failed to get monitor")]
+  FailedToGetMonitor,
 }
 
 /// Result type.
@@ -317,6 +320,9 @@ pub trait Dispatch: Clone + Send + Sized + 'static {
 
   // SETTERS
 
+  /// Centers the window.
+  fn center(&self) -> crate::Result<()>;
+
   /// Opens the dialog to prints the contents of the webview.
   fn print(&self) -> crate::Result<()>;
 

core/tauri-runtime/src/webview.rs

@@ -103,6 +103,9 @@ pub trait WindowBuilder: WindowBuilderBase {
   #[cfg_attr(doc_cfg, doc(cfg(feature = "menu")))]
   fn menu<I: MenuId>(self, menu: Menu<I>) -> Self;
 
+  /// Show window in the center of the screen.
+  fn center(self) -> Self;
+
   /// The initial position of the window's.
   fn position(self, x: f64, y: f64) -> Self;
 

core/tauri-utils/src/config.rs

@@ -42,6 +42,9 @@ pub struct WindowConfig {
   /// The window webview URL.
   #[serde(default)]
   pub url: WindowUrl,
+  /// Center the window.
+  #[serde(default)]
+  pub center: bool,
   /// The horizontal position of the window's top left corner
   pub x: Option<f64>,
   /// The vertical position of the window's top left corner
@@ -125,6 +128,7 @@ impl Default for WindowConfig {
     Self {
       label: default_window_label(),
       url: WindowUrl::default(),
+      center: false,
       x: None,
       y: None,
       width: default_width(),
@@ -649,6 +653,7 @@ mod build {
     fn to_tokens(&self, tokens: &mut TokenStream) {
       let label = str_lit(&self.label);
       let url = &self.url;
+      let center = self.center;
       let x = opt_lit(self.x.as_ref());
       let y = opt_lit(self.y.as_ref());
       let width = self.width;
@@ -673,6 +678,7 @@ mod build {
         WindowConfig,
         label,
         url,
+        center,
         x,
         y,
         width,
@@ -937,6 +943,7 @@ mod test {
       windows: vec![WindowConfig {
         label: "main".to_string(),
         url: WindowUrl::default(),
+        center: false,
         x: None,
         y: None,
         width: 800f64,

core/tauri/src/endpoints/window.rs

@@ -53,6 +53,7 @@ pub enum Cmd {
   PrimaryMonitor,
   AvailableMonitors,
   // Setters
+  Center,
   SetResizable(bool),
   SetTitle(String),
   Maximize,
@@ -141,6 +142,7 @@ impl Cmd {
         Self::PrimaryMonitor => return Ok(window.primary_monitor()?.into()),
         Self::AvailableMonitors => return Ok(window.available_monitors()?.into()),
         // Setters
+        Self::Center => window.center()?,
         Self::SetResizable(resizable) => window.set_resizable(resizable)?,
         Self::SetTitle(title) => window.set_title(&title)?,
         Self::Maximize => window.maximize()?,

core/tauri/src/window.rs

@@ -403,6 +403,11 @@ impl<P: Params> Window<P> {
 
   // Setters
 
+  /// Centers the window.
+  pub fn center(&self) -> crate::Result<()> {
+    self.window.dispatcher.center().map_err(Into::into)
+  }
+
   /// Opens the dialog to prints the contents of the webview.
   /// Currently only supported on macOS on `wry`.
   /// `window.print()` works on all platforms.

examples/api/src/components/Window.svelte

@@ -20,6 +20,7 @@
     setPosition,
     setFullscreen,
     setIcon,
+    center,
   } = appWindow;
 
   export let onMessage;
@@ -95,6 +96,9 @@
       <input type="checkbox" bind:checked={maximized} />
       Maximize
     </label>
+    <button title="Unminimizes after 2 seconds" on:click={center}>
+      Center
+    </button>
     <button title="Unminimizes after 2 seconds" on:click={minimize_}>
       Minimize
     </button>

tooling/api/src/window.ts

@@ -394,6 +394,21 @@ class WindowManager {
 
   // Setters
 
+  /**
+   * Centers the window.
+   *
+   * @param resizable
+   * @returns A promise indicating the success or failure of the operation.
+   */
+  async center(): Promise<void> {
+    return invokeTauriCommand({
+      __tauriModule: 'Window',
+      message: {
+        cmd: 'center'
+      }
+    })
+  }
+
   /**
    * Updates the window resizable flag.
    *
@@ -613,12 +628,12 @@ class WindowManager {
         cmd: 'setMinSize',
         data: size
           ? {
-              type: size.type,
-              data: {
-                width: size.width,
-                height: size.height
-              }
+            type: size.type,
+            data: {
+              width: size.width,
+              height: size.height
             }
+          }
           : null
       }
     })
@@ -649,12 +664,12 @@ class WindowManager {
         cmd: 'setMaxSize',
         data: size
           ? {
-              type: size.type,
-              data: {
-                width: size.width,
-                height: size.height
-              }
+            type: size.type,
+            data: {
+              width: size.width,
+              height: size.height
             }
+          }
           : null
       }
     })
@@ -785,6 +800,8 @@ interface WindowOptions {
    * Remote URL or local file path to open, e.g. `https://github.com/tauri-apps` or `path/to/page.html`.
    */
   url?: string
+  /** Show window in the center of the screen.. */
+  center?: boolean
   /** The initial vertical position. Only applies if `y` is also set. */
   x?: number
   /** The initial horizontal position. Only applies if `x` is also set. */