[gnome-software] gs-star-widget: Split out rating refresh from other refresh

[Philip Withnall <pwithnall src gnome org>]

commit d5eca468d0556a5b02e4a90083993f73ff2301c1
Author: Philip Withnall <withnall endlessm com>
Date:   Tue Jun 2 13:53:37 2020 +0100

    gs-star-widget: Split out rating refresh from other refresh
    
    It’s quite expensive to destroy and recreate all the child widgets of a
    `GsStarRating` every time its rating is changed. In particular, doing so
    means re-loading the `starred-symbolic` image a lot.
    
    Avoid that by separating refreshing the `rating` property from
    refreshing everything else.
    
    This avoids around 115KB of object allocations through refreshes.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>

 src/gs-star-widget.c | 38 +++++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)
---
diff --git a/src/gs-star-widget.c b/src/gs-star-widget.c
index e2570786..3c44adde 100644
--- a/src/gs-star-widget.c
+++ b/src/gs-star-widget.c
@@ -19,6 +19,7 @@ typedef struct
        gint             rating;
        guint            icon_size;
        GtkWidget       *box1;
+       GtkImage        *images[5];
 } GsStarWidgetPrivate;
 
 G_DEFINE_TYPE_WITH_PRIVATE (GsStarWidget, gs_star_widget, GTK_TYPE_BIN)
@@ -37,6 +38,8 @@ enum {
 static GParamSpec *properties[PROP_RATING + 1] = { 0, };
 static guint signals [SIGNAL_LAST] = { 0 };
 
+const gint rate_to_star[] = {20, 40, 60, 80, 100, -1};
+
 static void gs_star_widget_refresh (GsStarWidget *star);
 
 gint
@@ -79,11 +82,33 @@ gs_star_widget_button_clicked_cb (GtkButton *button, GsStarWidget *star)
        g_signal_emit (star, signals[RATING_CHANGED], 0, priv->rating);
 }
 
+/* Update the star styles to display the new rating */
+static void
+gs_star_widget_refresh_rating (GsStarWidget *star)
+{
+       GsStarWidgetPrivate *priv = gs_star_widget_get_instance_private (star);
+
+       if (!gtk_widget_get_realized (GTK_WIDGET (star)))
+               return;
+
+       for (guint i = 0; i < G_N_ELEMENTS (priv->images); i++) {
+               GtkWidget *im = GTK_WIDGET (priv->images[i]);
+               gboolean enabled;
+
+               /* add fudge factor so we can actually get 5 stars in reality */
+               enabled = priv->rating >= rate_to_star[i] - 10;
+
+               gtk_style_context_add_class (gtk_widget_get_style_context (im),
+                                            enabled ? "star-enabled" : "star-disabled");
+               gtk_style_context_remove_class (gtk_widget_get_style_context (im),
+                                               enabled ? "star-disabled" : "star-enabled");
+       }
+}
+
 static void
 gs_star_widget_refresh (GsStarWidget *star)
 {
        GsStarWidgetPrivate *priv = gs_star_widget_get_instance_private (star);
-       const gint rate_to_star[] = {20, 40, 60, 80, 100, -1};
 
        if (!gtk_widget_get_realized (GTK_WIDGET (star)))
                return;
@@ -91,7 +116,7 @@ gs_star_widget_refresh (GsStarWidget *star)
        /* remove all existing widgets */
        gs_container_remove_all (GTK_CONTAINER (priv->box1));
 
-       for (guint i = 0; i < 5; i++) {
+       for (guint i = 0; i < G_N_ELEMENTS (priv->images); i++) {
                GtkWidget *w;
                GtkWidget *im;
 
@@ -99,6 +124,7 @@ gs_star_widget_refresh (GsStarWidget *star)
                im = gtk_image_new_from_icon_name ("starred-symbolic",
                                                   GTK_ICON_SIZE_DIALOG);
                gtk_image_set_pixel_size (GTK_IMAGE (im), (gint) priv->icon_size);
+               priv->images[i] = GTK_IMAGE (im);
 
                /* create button */
                if (priv->interactive) {
@@ -115,13 +141,11 @@ gs_star_widget_refresh (GsStarWidget *star)
                }
                gtk_widget_set_sensitive (w, priv->interactive);
                gtk_style_context_add_class (gtk_widget_get_style_context (w), "star");
-               /* add fudge factor so we can actually get 5 stars in reality */
-               gtk_style_context_add_class (gtk_widget_get_style_context (im),
-                                            priv->rating >= rate_to_star[i] - 10 ?
-                                            "star-enabled" : "star-disabled");
                gtk_widget_set_visible (w, TRUE);
                gtk_container_add (GTK_CONTAINER (priv->box1), w);
        }
+
+       gs_star_widget_refresh_rating (star);
 }
 
 void
@@ -152,7 +176,7 @@ gs_star_widget_set_rating (GsStarWidget *star,
 
        priv->rating = rating;
        g_object_notify_by_pspec (G_OBJECT (star), properties[PROP_RATING]);
-       gs_star_widget_refresh (star);
+       gs_star_widget_refresh_rating (star);
 }
 
 static void