[planner: 15/32] charts: Restore default white background via GtkStyleContext

[Mart Raudsepp <mraudsepp src gnome org>]

commit 4374f46714944cda77c1239403ab3f73cf29ba8c
Author: Mart Raudsepp <leio gentoo org>
Date:   Sun May 30 23:30:40 2021 +0300

    charts: Restore default white background via GtkStyleContext

 src/planner-gantt-chart.c | 22 +++++++++++++++++-----
 src/planner-usage-chart.c | 24 ++++++++++++++++++------
 2 files changed, 35 insertions(+), 11 deletions(-)
---
diff --git a/src/planner-gantt-chart.c b/src/planner-gantt-chart.c
index f8dd7418..36a12f77 100644
--- a/src/planner-gantt-chart.c
+++ b/src/planner-gantt-chart.c
@@ -574,8 +574,10 @@ gantt_chart_realize (GtkWidget *widget)
 {
        PlannerGanttChart     *chart;
        PlannerGanttChartPriv *priv;
-       GtkStyle              *style;
+       GtkCssProvider        *css_provider;
+       GtkStyleContext       *style_context;
        GtkWidget             *canvas;
+       GError                *error = NULL;
 
        chart = PLANNER_GANTT_CHART (widget);
        priv = chart->priv;
@@ -587,10 +589,20 @@ gantt_chart_realize (GtkWidget *widget)
        }
 
        /* Set the background to white. */
-       style = gtk_style_copy (gtk_widget_get_style (canvas));
-       gdk_color_parse ("white", &style->bg[GTK_STATE_NORMAL]);
-       gtk_widget_set_style (canvas, style);
-       g_object_unref (style);
+       css_provider = gtk_css_provider_new ();
+       gtk_css_provider_load_from_data (css_provider,
+                                        "@define-color theme_bg_color white;",
+                                        -1, &error);
+       style_context = gtk_widget_get_style_context (canvas);
+       if (error == NULL) {
+               gtk_style_context_add_provider (style_context,
+                                               GTK_STYLE_PROVIDER (css_provider),
+                                               GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+       } else {
+               g_warning ("%s: %s", G_STRFUNC, error->message);
+               g_clear_error (&error);
+       }
+       g_object_unref (css_provider);
 
        gantt_chart_set_zoom (chart, priv->zoom);
 }
diff --git a/src/planner-usage-chart.c b/src/planner-usage-chart.c
index dacfc6b6..32e3c06d 100644
--- a/src/planner-usage-chart.c
+++ b/src/planner-usage-chart.c
@@ -683,8 +683,10 @@ usage_chart_realize (GtkWidget *widget)
 {
        PlannerUsageChart     *chart;
        PlannerUsageChartPriv *priv;
-       GtkWidget              *canvas;
-       GtkStyle               *style;
+       GtkWidget             *canvas;
+       GtkStyleContext       *style_context;
+       GtkCssProvider        *css_provider;
+       GError                *error = NULL;
 
        chart = PLANNER_USAGE_CHART (widget);
        priv = chart->priv;
@@ -696,10 +698,20 @@ usage_chart_realize (GtkWidget *widget)
        }
 
        /* Set the background to white. */
-       style = gtk_style_copy (gtk_widget_get_style (canvas));
-       gdk_color_parse ("white", &style->bg[GTK_STATE_NORMAL]);
-       gtk_widget_set_style (canvas, style);
-       g_object_unref (style);
+       css_provider = gtk_css_provider_new ();
+       gtk_css_provider_load_from_data (css_provider,
+                                        "@define-color theme_bg_color white;",
+                                        -1, &error);
+       style_context = gtk_widget_get_style_context (canvas);
+       if (error == NULL) {
+               gtk_style_context_add_provider (style_context,
+                                               GTK_STYLE_PROVIDER (css_provider),
+                                               GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+       } else {
+               g_warning ("%s: %s", G_STRFUNC, error->message);
+               g_clear_error (&error);
+       }
+       g_object_unref (css_provider);
 
        usage_chart_set_zoom (chart, priv->zoom);
 }