[gthumb] histogram view: use cairo_save and cairo_restore

[Paolo Bacchilega <paobac src gnome org>]

commit 29e6dfa75931a9fcf76c0282c182a4928987dda8
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Wed Jan 7 13:05:26 2015 +0100

    histogram view: use cairo_save and cairo_restore

 gthumb/gth-histogram-view.c |   45 ++++++++++++++++++++++++++----------------
 1 files changed, 28 insertions(+), 17 deletions(-)
---
diff --git a/gthumb/gth-histogram-view.c b/gthumb/gth-histogram-view.c
index 96d5539..7a0e91c 100644
--- a/gthumb/gth-histogram-view.c
+++ b/gthumb/gth-histogram-view.c
@@ -56,7 +56,7 @@ struct _GthHistogramViewPrivate {
        GthHistogramChannel  current_channel;
        guchar               selection_start;
        guchar               selection_end;
-       GtkWidget           *histogram_view;
+       GtkWidget           *view;
        GtkWidget           *linear_histogram_button;
        GtkWidget           *logarithmic_histogram_button;
        GtkWidget           *channel_combo_box;
@@ -356,6 +356,8 @@ gth_histogram_paint_channel (GthHistogramView *self,
        if (channel > gth_histogram_get_nchannels (self->priv->histogram))
                return;
 
+       cairo_save (cr);
+
        _cairo_set_source_color_from_channel (cr, channel);
 
        if (self->priv->display_mode == GTH_HISTOGRAM_MODE_ALL_CHANNELS)
@@ -385,6 +387,7 @@ gth_histogram_paint_channel (GthHistogramView *self,
                                 y);
        }
        cairo_fill (cr);
+       cairo_restore (cr);
 }
 
 
@@ -398,6 +401,8 @@ gth_histogram_paint_rgb (GthHistogramView *self,
        double step;
        int    i;
 
+       cairo_save (cr);
+
        max = MAX (gth_histogram_get_channel_max (self->priv->histogram, 1), gth_histogram_get_channel_max 
(self->priv->histogram, 2));
        max = MAX (max, gth_histogram_get_channel_max (self->priv->histogram, 3));
        if (max > 0.0)
@@ -496,6 +501,8 @@ gth_histogram_paint_rgb (GthHistogramView *self,
                                 y);
                cairo_fill (cr);
        }
+
+       cairo_restore (cr);
 }
 
 
@@ -509,6 +516,7 @@ gth_histogram_paint_grid (GthHistogramView *self,
        double  grid_step;
        int     i;
 
+       cairo_save (cr);
        gtk_style_context_get_border_color (style_context,
                                            gtk_widget_get_state_flags (GTK_WIDGET (self)),
                                            &color);
@@ -525,6 +533,7 @@ gth_histogram_paint_grid (GthHistogramView *self,
        }
 
        cairo_stroke (cr);
+       cairo_restore (cr);
 }
 
 
@@ -537,6 +546,7 @@ gth_histogram_paint_selection (GthHistogramView *self,
        GdkRGBA color;
        double  step;
 
+       cairo_save (cr);
        cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
        cairo_set_line_width (cr, 0.5);
 
@@ -550,6 +560,7 @@ gth_histogram_paint_selection (GthHistogramView *self,
                         (self->priv->selection_end - self->priv->selection_start) * step,
                         allocation->height);
        cairo_fill (cr);
+       cairo_restore (cr);
 }
 
 
@@ -649,14 +660,14 @@ histogram_view_button_press_event_cb (GtkWidget      *widget,
        if (! gtk_widget_get_visible (GET_WIDGET ("histogram_info")))
                return TRUE;
 
-       gtk_widget_get_allocation (self->priv->histogram_view, &allocation);
+       gtk_widget_get_allocation (self->priv->view, &allocation);
        value = CLAMP (event->x / allocation.width * 256 + .5, 0, 255);
        self->priv->selecting = TRUE;
        self->priv->tmp_selection_start = value;
        self->priv->tmp_selection_end = self->priv->tmp_selection_start;
        self->priv->selection_start = MIN (self->priv->tmp_selection_start, self->priv->tmp_selection_end);
        self->priv->selection_end = MAX (self->priv->tmp_selection_start, self->priv->tmp_selection_end);
-       gtk_widget_queue_draw (self->priv->histogram_view);
+       gtk_widget_queue_draw (self->priv->view);
 
        return TRUE;
 }
@@ -677,7 +688,7 @@ histogram_view_button_release_event_cb (GtkWidget      *widget,
        if (self->priv->selection_start == self->priv->selection_end) {
                self->priv->selection_start = 0;
                self->priv->selection_end = 255;
-               gtk_widget_queue_draw (self->priv->histogram_view);
+               gtk_widget_queue_draw (self->priv->view);
        }
 
        if (gtk_widget_get_visible (GET_WIDGET ("histogram_info")))
@@ -699,12 +710,12 @@ histogram_view_motion_notify_event_cb (GtkWidget      *widget,
        if (! self->priv->selecting)
                return TRUE;
 
-       gtk_widget_get_allocation (self->priv->histogram_view, &allocation);
+       gtk_widget_get_allocation (self->priv->view, &allocation);
        value = CLAMP (event->x / allocation.width * 256 + .5, 0, 255);
        self->priv->tmp_selection_end = value;
        self->priv->selection_start = MIN (self->priv->tmp_selection_start, self->priv->tmp_selection_end);
        self->priv->selection_end = MAX (self->priv->tmp_selection_start, self->priv->tmp_selection_end);
-       gtk_widget_queue_draw (self->priv->histogram_view);
+       gtk_widget_queue_draw (self->priv->view);
 
        return TRUE;
 }
@@ -923,28 +934,28 @@ gth_histogram_view_init (GthHistogramView *self)
        gtk_widget_set_vexpand (view_container, TRUE);
        gtk_widget_show (view_container);
 
-       self->priv->histogram_view = gtk_drawing_area_new ();
-       gtk_widget_add_events (self->priv->histogram_view, GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK | 
GDK_POINTER_MOTION_MASK | GDK_STRUCTURE_MASK);
-       gtk_widget_show (self->priv->histogram_view);
-       gtk_container_add (GTK_CONTAINER (view_container), self->priv->histogram_view);
+       self->priv->view = gtk_drawing_area_new ();
+       gtk_widget_add_events (self->priv->view, GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK | 
GDK_POINTER_MOTION_MASK | GDK_STRUCTURE_MASK);
+       gtk_widget_show (self->priv->view);
+       gtk_container_add (GTK_CONTAINER (view_container), self->priv->view);
 
-       g_signal_connect (self->priv->histogram_view,
+       g_signal_connect (self->priv->view,
                          "draw",
                          G_CALLBACK (histogram_view_draw_cb),
                          self);
-       g_signal_connect (self->priv->histogram_view,
+       g_signal_connect (self->priv->view,
                          "scroll-event",
                          G_CALLBACK (histogram_view_scroll_event_cb),
                          self);
-       g_signal_connect (self->priv->histogram_view,
+       g_signal_connect (self->priv->view,
                          "button-press-event",
                          G_CALLBACK (histogram_view_button_press_event_cb),
                          self);
-       g_signal_connect (self->priv->histogram_view,
+       g_signal_connect (self->priv->view,
                          "button-release-event",
                          G_CALLBACK (histogram_view_button_release_event_cb),
                          self);
-       g_signal_connect (self->priv->histogram_view,
+       g_signal_connect (self->priv->view,
                          "motion-notify-event",
                          G_CALLBACK (histogram_view_motion_notify_event_cb),
                          self);
@@ -1000,10 +1011,10 @@ update_sensitivity (GthHistogramView *self)
        if ((self->priv->histogram == NULL)
            || ((int) self->priv->current_channel > gth_histogram_get_nchannels (self->priv->histogram)))
        {
-               gtk_widget_set_sensitive (self->priv->histogram_view, FALSE);
+               gtk_widget_set_sensitive (self->priv->view, FALSE);
        }
        else
-               gtk_widget_set_sensitive (self->priv->histogram_view, TRUE);
+               gtk_widget_set_sensitive (self->priv->view, TRUE);
 
        /* channel combobox */