server-context-service: optimize height calculation

Even though proper size management is being worked on, this patch
proposes a simple and easily revertable solution to device-dependent
sizing issues.

First, it provides different calculations based on the display
orientation. In landscape mode, this allows us to have a sensible
keyboard size while leaving enough screen estate for apps to be able to
display useful information.

Then, it gets rid of the weird calculation for display widths between
360 and 540px. While having some continuity is a pleasant idea, in the
real world in doesn't work, as shown by port attempts to other devices:
a 480x800 display (scale 1) would show an unusable 190px-high keyboard
(about half the size of the Librem 5 on-screen keyboard on a device I
own).

Finally, this commit makes sure we never use a hardcoded size.

Tested on the PinePhone, PineTab and Librem 5.

Note: Current behavior is preserved on the L5 in portrait mode, but
keyboard is a bit smaller in landscape mode; this is deliberate, as it
was previously using too much space (causing some apps, such as chatty,
to be unusable).

src/server-context-service.c

@@ -85,13 +85,20 @@ on_notify_unmap (ServerContextService *self, GtkWidget *widget)
 }
 
 static uint32_t
-calculate_height(int32_t width)
+calculate_height(int32_t width, GdkRectangle *geometry)
 {
-    uint32_t height = 180;
+    uint32_t height;
-    if (width < 360 && width > 0) {
+    if (geometry->width > geometry->height) {
-        height = ((unsigned)width * 7 / 12); // to match 360×210
+        // 1:5 ratio works fine on lanscape mode, and makes sure there's
-    } else if (width < 540) {
+        // room left for the app window
-        height = 180 + (540 - (unsigned)width) * 30 / 180; // smooth transition
+        height = width / 5;
+    } else {
+        if (width < 540 && width > 0) {
+            height = ((unsigned)width * 7 / 12); // to match 360×210
+        } else {
+            // Here we switch to wide layout, less height needed
+            height = ((unsigned)width * 7 / 22);
+        }
     }
     return height;
 }
@@ -99,6 +106,10 @@ calculate_height(int32_t width)
 static void
 on_surface_configure(ServerContextService *self, PhoshLayerSurface *surface)
 {
+    GdkDisplay *display = NULL;
+    GdkWindow *window = NULL;
+    GdkMonitor *monitor = NULL;
+    GdkRectangle geometry;
     gint width;
     gint height;
 
@@ -110,11 +121,24 @@ on_surface_configure(ServerContextService *self, PhoshLayerSurface *surface)
                  "configured-height", &height,
                  NULL);
 
-    // When the geometry event comes after surface.configure,
+    // In order to improve height calculation, we need the monitor geometry so
-    // this entire height calculation does nothing.
+    // we can use different algorithms for portrait and landscape mode.
-    // guint desired_height = squeek_uiman_get_perceptual_height(context->manager);
+    // Note: this is a temporary fix until the size manager is complete.
-    // Temporarily use old method, until the size manager is complete.
+    display = gdk_display_get_default ();
-    guint desired_height = calculate_height(width);
+    if (display)
+        window = gtk_widget_get_window (GTK_WIDGET (surface));
+    if (window)
+        monitor = gdk_display_get_monitor_at_window (display, window);
+    if (monitor)
+        gdk_monitor_get_geometry (monitor, &geometry);
+    else
+        geometry.width = geometry.height = 0;
+
+     // When the geometry event comes after surface.configure,
+     // this entire height calculation does nothing.
+     // guint desired_height = squeek_uiman_get_perceptual_height(context->manager);
+     // Temporarily use old method, until the size manager is complete.
+    guint desired_height = calculate_height(width, &geometry);
 
     guint configured_height = (guint)height;
     // if height was already requested once but a different one was given