Don't do unnecessary font scaling

Turns out that we removed and added a CSS provider on every size allocate
even when it had the same style content. This bug was exposed by using
Adwaita's spinner theming because the animation caused too many
relayouts. Instead, only change the CSS provider if the calculated font
scaling factor has actually changed. This should improve performance by
quite a bit.

[endlessm/eos-sdk#3634]

1 files changed, 36 insertions, 27 deletions

diff --git a/endless/eoswindow.c b/endless/eoswindow.c
index 3080ad6..2a24de2 100644
--- a/endless/eoswindow.c
+++ b/endless/eoswindow.c
@@ -482,44 +482,53 @@ eos_window_finalize (GObject *object)
   G_OBJECT_CLASS (eos_window_parent_class)->finalize (object);
 }
 
-/* Updates the base font size depending on the window size. */
 static void
-eos_window_size_allocate (GtkWidget *window, GtkAllocation *allocation)
+eos_window_font_scale (EosWindow *self,
+                       gint       allocated_height)
 {
-  EosWindow *self = EOS_WINDOW (window);
   EosWindowPrivate *priv = eos_window_get_instance_private (self);
 
-  if (priv->font_scaling_active)
-    {
-      GtkStyleProvider *provider = GTK_STYLE_PROVIDER (priv->font_size_provider);
-      priv->font_scaling_calculated_font_size = (gdouble) priv->font_scaling_default_size *
-                                ((gdouble) allocation->height / (gdouble) priv->font_scaling_default_window_size);
+  if (!priv->font_scaling_active)
+    return;
 
-      if (priv->font_scaling_calculated_font_size < priv->font_scaling_min_font_size)
-        priv->font_scaling_calculated_font_size = priv->font_scaling_min_font_size;
+  GtkStyleProvider *provider = GTK_STYLE_PROVIDER (priv->font_size_provider);
+  gdouble new_size = priv->font_scaling_default_size *
+    ((gdouble) allocated_height / priv->font_scaling_default_window_size);
 
-      GError *error = NULL;
+  new_size = MIN (new_size, priv->font_scaling_min_font_size);
 
-      /* A float will only have one decimal point when printed as a string.
-       * The decimal point can be represented as a comma or period when using
-       * either Imperial or metric units. However, the CSS parser only recognizes
-       * periods as valid decimal points. Therefore, we convert the float to a
-       * string using a period as the decimal point. */
-      gchar font_size_float_str [G_ASCII_DTOSTR_BUF_SIZE];
-      g_ascii_dtostr (font_size_float_str, G_ASCII_DTOSTR_BUF_SIZE, priv->font_scaling_calculated_font_size);
+  if (new_size == priv->font_scaling_calculated_font_size)
+    return;
 
-      gchar *font_size_css = g_strdup_printf (FONT_SIZE_TEMPLATE, font_size_float_str);
-      GdkScreen *screen = gdk_screen_get_default ();
+  priv->font_scaling_calculated_font_size = new_size;
 
-      gtk_style_context_remove_provider_for_screen (screen, provider);
-      gtk_css_provider_load_from_data (GTK_CSS_PROVIDER (provider),
-                                       font_size_css, -1, &error);
-      gtk_style_context_add_provider_for_screen (screen, provider,
-                                                 GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+  /* A float will only have one decimal point when printed as a string. The
+   * decimal point can be represented as a comma or period when using either
+   * Imperial or metric units. However, the CSS parser only recognizes periods
+   * as valid decimal points. Therefore, we convert the float to a string using
+   * a period as the decimal point. */
+  gchar font_size_float_str[G_ASCII_DTOSTR_BUF_SIZE];
+  g_ascii_dtostr (font_size_float_str, G_ASCII_DTOSTR_BUF_SIZE,
+                  priv->font_scaling_calculated_font_size);
 
-      g_free(font_size_css);
-    }
+  gchar *font_size_css = g_strdup_printf (FONT_SIZE_TEMPLATE,
+                                          font_size_float_str);
+  GdkScreen *screen = gdk_screen_get_default ();
 
+  gtk_style_context_remove_provider_for_screen (screen, provider);
+  gtk_css_provider_load_from_data (GTK_CSS_PROVIDER (provider), font_size_css,
+                                   -1, NULL);  /* ignore error */
+  gtk_style_context_add_provider_for_screen (screen, provider,
+                                             GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+
+  g_free (font_size_css);
+}
+
+/* Updates the base font size depending on the window size. */
+static void
+eos_window_size_allocate (GtkWidget *window, GtkAllocation *allocation)
+{
+  eos_window_font_scale (EOS_WINDOW (window), allocation->height);
   GTK_WIDGET_CLASS (eos_window_parent_class)->size_allocate (window, allocation);
 }