[gnome-system-monitor] Added option to disable smooth cpu chart (bgo#778470)

[Robert Roth <robertroth src gnome org>]

commit e60c3860b7c45043e6eab52a51ebefeeeaf53a77
Author: Robert Roth <robert roth off gmail com>
Date:   Mon Feb 13 23:58:40 2017 +0200

    Added option to disable smooth cpu chart (bgo#778470)

 data/preferences.ui                                |   20 ++++++++++++++++++-
 src/application.cpp                                |   13 ++++++++++++
 src/application.h                                  |    2 +
 src/load-graph.cpp                                 |   21 +++++++++++++------
 ...rg.gnome.gnome-system-monitor.gschema.xml.in.in |    8 +++++++
 src/prefsdialog.cpp                                |    5 ++++
 src/settings-keys.h                                |    1 +
 7 files changed, 62 insertions(+), 8 deletions(-)
---
diff --git a/data/preferences.ui b/data/preferences.ui
index 55436ab..a2676b3 100644
--- a/data/preferences.ui
+++ b/data/preferences.ui
@@ -398,6 +398,24 @@
                               </packing>
                             </child>
                             <child>
+                              <object class="GtkCheckButton" id="draw_smooth_button">
+                                <property name="label" translatable="yes">Draw CPU chart as s_mooth 
graph</property>
+                                <property name="visible">True</property>
+                                <property name="can_focus">True</property>
+                                <property name="receives_default">False</property>
+                                <property name="hexpand">True</property>
+                                <property name="use_underline">True</property>
+                                <property name="halign">start</property>
+                                <property name="draw_indicator">True</property>
+                              </object>
+                              <packing>
+                                <property name="left_attach">0</property>
+                                <property name="top_attach">2</property>
+                                <property name="width">1</property>
+                                <property name="height">1</property>
+                              </packing>
+                            </child>
+                            <child>
                               <object class="GtkCheckButton" id="bits_button">
                                 <property name="label" translatable="yes">_Show network speed in 
bits</property>
                                 <property name="visible">True</property>
@@ -410,7 +428,7 @@
                               </object>
                               <packing>
                                 <property name="left_attach">0</property>
-                                <property name="top_attach">2</property>
+                                <property name="top_attach">3</property>
                                 <property name="width">1</property>
                                 <property name="height">1</property>
                               </packing>
diff --git a/src/application.cpp b/src/application.cpp
index facdf3a..d5a5e57 100644
--- a/src/application.cpp
+++ b/src/application.cpp
@@ -39,6 +39,14 @@ cb_draw_stacked_changed (Gio::Settings& settings, Glib::ustring key, GsmApplicat
 }
 
 static void
+cb_draw_smooth_changed (Gio::Settings& settings, Glib::ustring key, GsmApplication* app)
+{
+    app->config.draw_smooth = settings.get_boolean(key);
+    app->cpu_graph->clear_background();
+    load_graph_reset(app->cpu_graph);
+}
+
+static void
 cb_network_in_bits_changed (Gio::Settings& settings, Glib::ustring key, GsmApplication* app)
 {
     app->config.network_in_bits = settings.get_boolean(key);
@@ -156,6 +164,11 @@ GsmApplication::load_settings()
         cb_draw_stacked_changed (*this->settings.operator->(), key, this);
     });
 
+    config.draw_smooth = this->settings->get_boolean (GSM_SETTING_DRAW_SMOOTH);
+    this->settings->signal_changed(GSM_SETTING_DRAW_SMOOTH).connect ([this](const Glib::ustring& key) {
+        cb_draw_smooth_changed (*this->settings.operator->(), key, this);
+    });
+
     config.network_in_bits = this->settings->get_boolean (GSM_SETTING_NETWORK_IN_BITS);
     this->settings->signal_changed (GSM_SETTING_NETWORK_IN_BITS).connect ([this](const Glib::ustring& key) {
         cb_network_in_bits_changed (*this->settings.operator->(), key, this);
diff --git a/src/application.h b/src/application.h
index 68eff87..730b9c5 100644
--- a/src/application.h
+++ b/src/application.h
@@ -43,6 +43,7 @@ struct ProcConfig
        num_cpus(0),
        solaris_mode(false),
        draw_stacked(false),
+       draw_smooth(true),
        network_in_bits(false)
     {
       std::fill(&this->cpu_color[0], &this->cpu_color[GLIBTOP_NCPU], GdkRGBA());
@@ -61,6 +62,7 @@ struct ProcConfig
     gint            num_cpus;
     bool solaris_mode;
     bool draw_stacked;
+    bool draw_smooth;
     bool network_in_bits;
 };
 
diff --git a/src/load-graph.cpp b/src/load-graph.cpp
index 85264fe..4ad0f7e 100644
--- a/src/load-graph.cpp
+++ b/src/load-graph.cpp
@@ -252,6 +252,7 @@ load_graph_draw (GtkWidget *widget,
     cairo_clip(cr);
 
     bool drawStacked = graph->type == LOAD_GRAPH_CPU && GsmApplication::get()->config.draw_stacked;
+    bool drawSmooth = graph->type == LOAD_GRAPH_CPU && GsmApplication::get()->config.draw_smooth;
     for (j = graph->n-1; j >= 0; j--) {
         gdk_cairo_set_source_rgba (cr, &(graph->colors [j]));
         if (drawStacked) {
@@ -262,13 +263,19 @@ load_graph_draw (GtkWidget *widget,
         for (i = 1; i < LoadGraph::NUM_POINTS; ++i) {
             if (graph->data[i][j] == -1.0f)
                 continue;
-            cairo_curve_to (cr,
-                            x_offset - ((i - 0.5f) * graph->graph_delx),
-                            (1.0f - graph->data[i-1][j]) * graph->real_draw_height + 3.5f,
-                            x_offset - ((i - 0.5f) * graph->graph_delx),
-                            (1.0f - graph->data[i][j]) * graph->real_draw_height + 3.5f,
-                            x_offset - (i * graph->graph_delx),
-                            (1.0f - graph->data[i][j]) * graph->real_draw_height + 3.5f);
+            if (drawSmooth) {
+              cairo_curve_to (cr,
+                              x_offset - ((i - 0.5f) * graph->graph_delx),
+                              (1.0f - graph->data[i-1][j]) * graph->real_draw_height + 3.5f,
+                              x_offset - ((i - 0.5f) * graph->graph_delx),
+                              (1.0f - graph->data[i][j]) * graph->real_draw_height + 3.5f,
+                              x_offset - (i * graph->graph_delx),
+                              (1.0f - graph->data[i][j]) * graph->real_draw_height + 3.5f);
+            } else {
+              cairo_line_to (cr, x_offset - (i * graph->graph_delx),
+                              (1.0f - graph->data[i][j]) * graph->real_draw_height + 3.5f);
+            }
+
         }
         if (drawStacked) {
             cairo_rel_line_to (cr, 0, graph->real_draw_height + 3.5f);
diff --git a/src/org.gnome.gnome-system-monitor.gschema.xml.in.in 
b/src/org.gnome.gnome-system-monitor.gschema.xml.in.in
index 383377d..6095749 100644
--- a/src/org.gnome.gnome-system-monitor.gschema.xml.in.in
+++ b/src/org.gnome.gnome-system-monitor.gschema.xml.in.in
@@ -36,6 +36,14 @@
       </_description>
     </key>
 
+    <key type="b" name="cpu-smooth-graph">
+      <default>true
+      </default>
+      <_summary>Show CPU chart as smooth graph using Bezier curves</_summary>
+      <_description>If TRUE, system-monitor shows the CPU chart as a smoothed graph, otherwise as a line 
chart.
+      </_description>
+    </key>
+
     <key name="smooth-refresh" type="b">
       <default>true
       </default>
diff --git a/src/prefsdialog.cpp b/src/prefsdialog.cpp
index 1e24b34..9f18fd7 100644
--- a/src/prefsdialog.cpp
+++ b/src/prefsdialog.cpp
@@ -250,6 +250,11 @@ create_preferences_dialog (GsmApplication *app)
                      draw_stacked_button, "active",
                      G_SETTINGS_BIND_DEFAULT);
 
+    GtkCheckButton *draw_smooth_button = GTK_CHECK_BUTTON (gtk_builder_get_object (builder, 
"draw_smooth_button"));
+    g_settings_bind (app->settings->gobj (), GSM_SETTING_DRAW_SMOOTH,
+                     draw_smooth_button, "active",
+                     G_SETTINGS_BIND_DEFAULT);
+
     create_field_page (builder, GTK_TREE_VIEW (app->tree), "proctree");
 
     update = (gfloat) app->config.graph_update_interval;
diff --git a/src/settings-keys.h b/src/settings-keys.h
index 2ef20cc..87fbb9f 100644
--- a/src/settings-keys.h
+++ b/src/settings-keys.h
@@ -24,6 +24,7 @@
 #define GSM_SETTING_NET_IN_COLOR            "net-in-color"
 #define GSM_SETTING_NET_OUT_COLOR           "net-out-color"
 #define GSM_SETTING_DRAW_STACKED            "cpu-stacked-area-chart"
+#define GSM_SETTING_DRAW_SMOOTH             "cpu-smooth-graph"
 #define GSM_SETTING_NETWORK_IN_BITS         "network-in-bits"
 #define GSM_SETTING_SHOW_CPU                "show-cpu"
 #define GSM_SETTING_SHOW_MEM                "show-mem"