Implement tooltip level on Windows platform (#1737)

Implement `WindowLevel::Tooltip` on Windows platform. Before change: - Tooltip window appear in taskbar - Window has strange min-size (probably due to OS min constraints) - Window steals focus from main app window After change: - Tooltip window doesn't appear in taskbar - Window fits any size (tested with nursery's `tooltip.rs`) - Window doesn't steal focus from main app window
linebender · May 2, 2021 · 2ab1d75 · 2ab1d75
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,13 +3,15 @@
 The latest published Druid release is [0.7.0](#070---2021-01-01) which was released on 2021-01-01.
 You can find its changes [documented below](#070---2021-01-01).
 
-# Unreleased
+## Unreleased
 
 ### Highlights
+
 - International text input support (IME) on macOS.
 - Rich text and complex script support on Linux.
 
 ### Added
+
 - Add `scroll()` method in WidgetExt ([#1600] by [@totsteps])
 - `write!` for `RichTextBuilder` ([#1596] by [@Maan2003])
 - Sub windows: Allow opening windows that share state with arbitrary parts of the widget hierarchy ([#1254] by [@rjwittams])
@@ -56,13 +58,15 @@ You can find its changes [documented below](#070---2021-01-01).
 ### Removed
 
 ### Fixed
+
 - `Notification`s will not be delivered to the widget that sends them ([#1640] by [@cmyr])
 - `TextBox` can handle standard keyboard shortcuts without needing menus ([#1660] by [@cmyr])
 - GTK Shell: Prevent mangling of newline characters in clipboard ([#1695] by [@ForLoveOfCats])
 - Use correct fill rule when rendering SVG paths ([#1606] by [@SecondFlight])
 - Correctly capture and use stroke properties when rendering SVG paths ([#1647] by [@SecondFlight])
 - focus-chain now only includes non hidden (`should_propagate_to_hidden()` on `Event` and `Lifecylce`) widgets ([#1724] by [@xarvic])
 - Fixed layout of scrollbar with very small viewports ([#1715] by [@andrewhickman])
+- Fixed `WindowLevel::Tooltip` on Windows platform ([#1737] by [@djeedai])
 
 ### Visual
 
@@ -463,6 +467,7 @@ Last release without a changelog :(
 [@ccqpein]: https://github.com/ccqpein
 [@RichardPoole42]: https://github.com/RichardPoole42
 [@r-ml]: https://github.com/r-ml
+[@djeedai]: https://github.com/djeedai
 
 [#599]: https://github.com/linebender/druid/pull/599
 [#611]: https://github.com/linebender/druid/pull/611
@@ -692,6 +697,7 @@ Last release without a changelog :(
 [#1722]: https://github.com/linebender/druid/pull/1722
 [#1724]: https://github.com/linebender/druid/pull/1724
 [#1730]: https://github.com/linebender/druid/pull/1730
+[#1737]: https://github.com/linebender/druid/pull/1737
 [#1743]: https://github.com/linebender/druid/pull/1743
 
 [Unreleased]: https://github.com/linebender/druid/compare/v0.7.0...master

diff --git a/druid-shell/src/platform/windows/window.rs b/druid-shell/src/platform/windows/window.rs
@@ -98,6 +98,7 @@ pub(crate) struct WindowBuilder {
     transparent: bool,
     min_size: Option<Size>,
     position: Option<Point>,
+    level: Option<WindowLevel>,
     state: window::WindowState,
 }
 
@@ -223,6 +224,9 @@ struct WindowState {
     is_resizable: Cell<bool>,
     handle_titlebar: Cell<bool>,
     active_text_input: Cell<Option<TextFieldToken>>,
+    // Is the window focusable ("activatable" in Win32 terminology)?
+    // False for tooltips, to prevent stealing focus from owner window.
+    is_focusable: bool,
 }
 
 /// Generic handler trait for the winapi window procedure entry point.
@@ -385,7 +389,13 @@ fn set_style(hwnd: HWND, resizable: bool, titlebar: bool) {
             0,
             0,
             0,
-            SWP_SHOWWINDOW | SWP_NOMOVE | SWP_NOZORDER | SWP_FRAMECHANGED | SWP_NOSIZE,
+            SWP_SHOWWINDOW
+                | SWP_NOMOVE
+                | SWP_NOZORDER
+                | SWP_FRAMECHANGED
+                | SWP_NOSIZE
+                | SWP_NOOWNERZORDER
+                | SWP_NOACTIVATE,
         ) == 0
         {
             warn!(
@@ -543,7 +553,7 @@ impl MyWndProc {
                         0,
                         size_px.width.round() as i32,
                         size_px.height.round() as i32,
-                        SWP_NOMOVE | SWP_NOZORDER,
+                        SWP_NOMOVE | SWP_NOZORDER | SWP_NOOWNERZORDER | SWP_NOACTIVATE,
                     ) == 0
                     {
                         warn!(
@@ -561,7 +571,7 @@ impl MyWndProc {
                         pos_px.y.round() as i32,
                         0,
                         0,
-                        SWP_NOSIZE | SWP_NOZORDER,
+                        SWP_NOSIZE | SWP_NOZORDER | SWP_NOOWNERZORDER | SWP_NOACTIVATE,
                     ) == 0
                     {
                         warn!(
@@ -578,14 +588,20 @@ impl MyWndProc {
                     self.with_window_state(|s| s.is_resizable.set(resizable));
                     set_style(hwnd, resizable, self.has_titlebar());
                 }
-                DeferredOp::SetWindowState(val) => unsafe {
-                    let s = match val {
-                        window::WindowState::Maximized => SW_MAXIMIZE,
-                        window::WindowState::Minimized => SW_MINIMIZE,
-                        window::WindowState::Restored => SW_RESTORE,
+                DeferredOp::SetWindowState(val) => {
+                    let show = if self.handle.borrow().is_focusable() {
+                        match val {
+                            window::WindowState::Maximized => SW_MAXIMIZE,
+                            window::WindowState::Minimized => SW_MINIMIZE,
+                            window::WindowState::Restored => SW_RESTORE,
+                        }
+                    } else {
+                        SW_SHOWNOACTIVATE
                     };
-                    ShowWindow(hwnd, s);
-                },
+                    unsafe {
+                        ShowWindow(hwnd, show);
+                    }
+                }
                 DeferredOp::SaveAs(options, token) => {
                     let info = unsafe {
                         get_file_dialog_path(hwnd, FileDialogType::Save, options)
@@ -747,7 +763,9 @@ impl WndProc for MyWndProc {
                                 | SWP_NOMOVE
                                 | SWP_NOZORDER
                                 | SWP_FRAMECHANGED
-                                | SWP_NOSIZE,
+                                | SWP_NOSIZE
+                                | SWP_NOOWNERZORDER
+                                | SWP_NOACTIVATE,
                         ) == 0
                         {
                             warn!(
@@ -813,7 +831,11 @@ impl WndProc for MyWndProc {
                     (*rect).top,
                     (*rect).right - (*rect).left,
                     (*rect).bottom - (*rect).top,
-                    SWP_NOZORDER | SWP_FRAMECHANGED | SWP_DRAWFRAME,
+                    SWP_NOZORDER
+                        | SWP_FRAMECHANGED
+                        | SWP_DRAWFRAME
+                        | SWP_NOOWNERZORDER
+                        | SWP_NOACTIVATE,
                 );
                 Some(0)
             },
@@ -1233,6 +1255,7 @@ impl WindowBuilder {
             size: None,
             min_size: None,
             position: None,
+            level: None,
             state: window::WindowState::Restored,
         }
     }
@@ -1287,8 +1310,13 @@ impl WindowBuilder {
         self.state = state;
     }
 
-    pub fn set_level(&mut self, _level: WindowLevel) {
-        warn!("WindowBuilder::set_level  is currently unimplemented for Windows platforms.");
+    pub fn set_level(&mut self, level: WindowLevel) {
+        match level {
+            WindowLevel::AppWindow | WindowLevel::Tooltip => self.level = Some(level),
+            _ => {
+                warn!("WindowBuilder::set_level({:?}) is currently unimplemented for Windows platforms.", level);
+            }
+        }
     }
 
     pub fn build(self) -> Result<WindowHandle, Error> {
@@ -1330,6 +1358,28 @@ impl WindowBuilder {
                 None => (0 as HMENU, None, false),
             };
 
+            let mut dwStyle = WS_OVERLAPPEDWINDOW;
+            let mut dwExStyle: DWORD = 0;
+            let mut focusable = true;
+            if let Some(level) = self.level {
+                match level {
+                    WindowLevel::AppWindow => (),
+                    WindowLevel::Tooltip => {
+                        dwStyle = WS_POPUP;
+                        dwExStyle = WS_EX_NOACTIVATE | WS_EX_TOOLWINDOW;
+                        focusable = false;
+                    }
+                    WindowLevel::DropDown => {
+                        dwStyle = WS_CHILD;
+                        dwExStyle = 0;
+                    }
+                    WindowLevel::Modal => {
+                        dwStyle = WS_OVERLAPPED;
+                        dwExStyle = WS_EX_TOPMOST;
+                    }
+                }
+            }
+
             let window = WindowState {
                 hwnd: Cell::new(0 as HWND),
                 scale: Cell::new(scale),
@@ -1345,6 +1395,7 @@ impl WindowBuilder {
                 is_transparent: Cell::new(self.transparent),
                 handle_titlebar: Cell::new(false),
                 active_text_input: Cell::new(None),
+                is_focusable: focusable,
             };
             let win = Rc::new(window);
             let handle = WindowHandle {
@@ -1367,14 +1418,13 @@ impl WindowBuilder {
             };
             win.wndproc.connect(&handle, state);
 
-            let mut dwStyle = WS_OVERLAPPEDWINDOW;
             if !self.resizable {
                 dwStyle &= !(WS_THICKFRAME | WS_MAXIMIZEBOX);
             }
             if !self.show_titlebar {
                 dwStyle &= !(WS_MINIMIZEBOX | WS_SYSMENU | WS_OVERLAPPED);
             }
-            let mut dwExStyle = 0;
+
             if self.present_strategy == PresentStrategy::Flip {
                 dwExStyle |= WS_EX_NOREDIRECTIONBITMAP;
             }
@@ -1413,7 +1463,7 @@ impl WindowBuilder {
                         0,
                         size_px.width.round() as i32,
                         size_px.height.round() as i32,
-                        SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE,
+                        SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE | SWP_NOOWNERZORDER,
                     ) == 0
                     {
                         warn!(
@@ -1681,12 +1731,16 @@ impl WindowHandle {
     pub fn show(&self) {
         if let Some(w) = self.state.upgrade() {
             let hwnd = w.hwnd.get();
-            unsafe {
-                let show = match self.get_window_state() {
+            let show = if w.is_focusable {
+                match self.get_window_state() {
                     window::WindowState::Maximized => SW_MAXIMIZE,
                     window::WindowState::Minimized => SW_MINIMIZE,
                     _ => SW_SHOWNORMAL,
-                };
+                }
+            } else {
+                SW_SHOWNOACTIVATE
+            };
+            unsafe {
                 ShowWindow(hwnd, show);
                 UpdateWindow(hwnd);
             }
@@ -2061,6 +2115,12 @@ impl WindowHandle {
         self.state.upgrade().map(|w| w.hwnd.get())
     }
 
+    /// Check whether the window can receive keyboard focus. This is generally true,
+    /// except for special windows like tooltips.
+    pub fn is_focusable(&self) -> bool {
+        self.state.upgrade().map(|w| w.is_focusable).unwrap_or(true)
+    }
+
     /// Get a handle that can be used to schedule an idle task.
     pub fn get_idle_handle(&self) -> Option<IdleHandle> {
         self.state.upgrade().map(|w| IdleHandle {