font scaling now also resizes the window for opengl+software frontend

src/frontend/software/termwindow.rs

@@ -565,7 +565,13 @@ impl TermWindow {
     fn scaling_changed(&mut self, dimensions: Dimensions, font_scale: f64) {
         let mux = Mux::get().unwrap();
         if let Some(window) = mux.get_window(self.mux_window_id) {
-            if dimensions.dpi != self.dimensions.dpi || font_scale != self.fonts.get_font_scale() {
+            let cols = self.dimensions.pixel_width / self.render_metrics.cell_size.width as usize;
+            let rows = self.dimensions.pixel_height / self.render_metrics.cell_size.height as usize;
+
+            let scale_changed =
+                dimensions.dpi != self.dimensions.dpi || font_scale != self.fonts.get_font_scale();
+
+            if scale_changed {
                 self.fonts
                     .change_scaling(font_scale, dimensions.dpi as f64 / 96.);
                 self.render_metrics = RenderMetrics::new(&self.fonts);
@@ -593,6 +599,16 @@ impl TermWindow {
             for tab in window.iter() {
                 tab.resize(size).ok();
             }
+
+            // Queue up a speculative resize in order to preserve the number of rows+cols
+            if scale_changed {
+                if let Some(window) = self.window.as_ref() {
+                    window.set_inner_size(
+                        cols * self.render_metrics.cell_size.width as usize,
+                        rows * self.render_metrics.cell_size.height as usize,
+                    );
+                }
+            }
         };
     }
 

window/src/lib.rs

@@ -169,6 +169,9 @@ pub trait WindowOps {
     /// Change the titlebar text for the window
     fn set_title(&self, title: &str);
 
+    /// Resize the inner or client area of the window
+    fn set_inner_size(&self, width: usize, height: usize);
+
     /// Schedule a callback on the data associated with the window.
     /// The `Any` that is passed in corresponds to the WindowCallbacks
     /// impl you passed to `new_window`, pre-converted to Any so that
@@ -208,4 +211,7 @@ pub trait WindowOpsMut {
 
     /// Change the titlebar text for the window
     fn set_title(&mut self, title: &str);
+
+    /// Resize the inner or client area of the window
+    fn set_inner_size(&self, width: usize, height: usize);
 }

window/src/os/macos/window.rs

@@ -296,6 +296,10 @@ impl WindowOps for Window {
         Connection::with_window_inner(self.0, move |inner| inner.set_title(&title));
     }
 
+    fn set_inner_size(&self, width: usize, height: usize) {
+        Connection::with_window_inner(self.0, move |inner| inner.set_inner_size(width, height));
+    }
+
     fn apply<F: Send + 'static + Fn(&mut dyn Any, &dyn WindowOps)>(&self, func: F)
     where
         Self: Sized,
@@ -381,6 +385,19 @@ impl WindowOpsMut for WindowInner {
             NSWindow::setTitle_(*self.window, *title);
         }
     }
+
+    fn set_inner_size(&self, width: usize, height: usize) {
+        unsafe {
+            let frame = NSView::frame(*self.view as *mut _);
+            let backing_frame = NSView::convertRectToBacking(*self.view as *mut _, frame);
+            let scale = backing_frame.size.width / frame.size.width;
+
+            NSWindow::setContentSize_(
+                *self.window,
+                NSSize::new(width as f64 / scale, height as f64 / scale),
+            );
+        }
+    }
 }
 
 struct Inner {

window/src/os/windows/window.rs

@@ -239,6 +239,8 @@ impl WindowOpsMut for WindowInner {
         }
     }
 
+    fn set_inner_size(&self, _width: usize, _height: usize) {}
+
     fn set_title(&mut self, title: &str) {
         let title = wide_string(title);
         unsafe {
@@ -271,6 +273,8 @@ impl WindowOps for Window {
         Connection::with_window_inner(self.0, move |inner| inner.set_title(&title));
     }
 
+    fn set_inner_size(&self, _width: usize, _height: usize) {}
+
     fn apply<F: Send + 'static + Fn(&mut dyn Any, &dyn WindowOps)>(&self, func: F)
     where
         Self: Sized,

window/src/os/x11/window.rs

@@ -466,6 +466,8 @@ impl WindowOpsMut for WindowInner {
         self.paint_all = true;
     }
 
+    fn set_inner_size(&self, _width: usize, _height: usize) {}
+
     /// Change the title for the window manager
     fn set_title(&mut self, title: &str) {
         xcb_util::icccm::set_wm_name(self.conn.conn(), self.window_id, title);
@@ -494,6 +496,9 @@ impl WindowOps for Window {
         let title = title.to_owned();
         Connection::with_window_inner(self.0, move |inner| inner.set_title(&title));
     }
+
+    fn set_inner_size(&self, _width: usize, _height: usize) {}
+
     fn apply<F: Send + 'static + Fn(&mut dyn Any, &dyn WindowOps)>(&self, func: F)
     where
         Self: Sized,