[gimp] app: remove code duplication in the histogram and curve views

[Michael Natterer <mitch src gnome org>]

commit 4466b3a35bbec72a24ca0bb373d505945a24b7ed
Author: Michael Natterer <mitch gimp org>
Date:   Fri Jul 30 12:51:03 2010 +0200

    app: remove code duplication in the histogram and curve views
    
    by letting the histogram view always draw the background and the outer
    borders. Also fix a lot of off-by-one problems in the curve view which
    occur due to the 0.5,0.5 offset of cairo line drawing.

 app/widgets/gimpcurveview.c     |   59 ++++++++++++++-------------------------
 app/widgets/gimphistogramview.c |   23 ++++++++------
 2 files changed, 34 insertions(+), 48 deletions(-)
---
diff --git a/app/widgets/gimpcurveview.c b/app/widgets/gimpcurveview.c
index 0b181a4..f02aeb9 100644
--- a/app/widgets/gimpcurveview.c
+++ b/app/widgets/gimpcurveview.c
@@ -345,7 +345,7 @@ gimp_curve_view_draw_grid (GimpCurveView *view,
 
   for (i = 1; i < view->grid_rows; i++)
     {
-      gint y = i * height / view->grid_rows;
+      gint y = i * (height - 1) / view->grid_rows;
 
       if ((view->grid_rows % 2) == 0 && (i == view->grid_rows / 2))
         continue;
@@ -356,7 +356,7 @@ gimp_curve_view_draw_grid (GimpCurveView *view,
 
   for (i = 1; i < view->grid_columns; i++)
     {
-      gint x = i * width / view->grid_columns;
+      gint x = i * (width - 1) / view->grid_columns;
 
       if ((view->grid_columns % 2) == 0 && (i == view->grid_columns / 2))
         continue;
@@ -376,7 +376,7 @@ gimp_curve_view_draw_grid (GimpCurveView *view,
 
   if ((view->grid_rows % 2) == 0)
     {
-      gint y = height / 2;
+      gint y = (height - 1) / 2;
 
       cairo_move_to (cr, border,             border + y);
       cairo_line_to (cr, border + width - 1, border + y);
@@ -384,7 +384,7 @@ gimp_curve_view_draw_grid (GimpCurveView *view,
 
   if ((view->grid_columns % 2) == 0)
     {
-      gint x = width / 2;
+      gint x = (width - 1) / 2;
 
       cairo_move_to (cr, border + x, border);
       cairo_line_to (cr, border + x, border + height - 1);
@@ -414,11 +414,11 @@ gimp_curve_view_draw_point (GimpCurveView *view,
 #define RADIUS 3
 
   cairo_move_to (cr,
-                 border + (gdouble) width  * x + RADIUS,
-                 border + (gdouble) height * y);
+                 border + (gdouble) (width  - 1) * x + RADIUS,
+                 border + (gdouble) (height - 1) * y);
   cairo_arc (cr,
-             border + (gdouble) width  * x,
-             border + (gdouble) height * y,
+             border + (gdouble) (width  - 1) * x,
+             border + (gdouble) (height - 1) * y,
              RADIUS,
              0, 2 * G_PI);
 }
@@ -438,8 +438,8 @@ gimp_curve_view_draw_curve (GimpCurveView *view,
   y = 1.0 - gimp_curve_map_value (curve, 0.0);
 
   cairo_move_to (cr,
-                 border + (gdouble) width  * x,
-                 border + (gdouble) height * y);
+                 border + (gdouble) (width  - 1) * x,
+                 border + (gdouble) (height - 1)* y);
 
   for (i = 1; i < 256; i++)
     {
@@ -447,8 +447,8 @@ gimp_curve_view_draw_curve (GimpCurveView *view,
       y = 1.0 - gimp_curve_map_value (curve, x);
 
       cairo_line_to (cr,
-                     border + (gdouble) width  * x,
-                     border + (gdouble) height * y);
+                     border + (gdouble) (width  - 1) * x,
+                     border + (gdouble) (height - 1) * y);
     }
 
   cairo_stroke (cr);
@@ -478,34 +478,17 @@ gimp_curve_view_expose (GtkWidget      *widget,
   gtk_widget_get_allocation (widget, &allocation);
 
   border = GIMP_HISTOGRAM_VIEW (view)->border_width;
-  width  = allocation.width  - 2 * border - 1;
-  height = allocation.height - 2 * border - 1;
+  width  = allocation.width  - 2 * border;
+  height = allocation.height - 2 * border;
 
   cr = gdk_cairo_create (gtk_widget_get_window (widget));
 
   gdk_cairo_region (cr, event->region);
   cairo_clip (cr);
 
-  if (! gimp_histogram_view_get_histogram (GIMP_HISTOGRAM_VIEW (view)) &&
-      ! gimp_histogram_view_get_background (GIMP_HISTOGRAM_VIEW (view)))
-    {
-      gdk_cairo_set_source_color (cr, &style->base[GTK_STATE_NORMAL]);
-      cairo_rectangle (cr, 0, 0,
-                       allocation.width,
-                       allocation.height);
-      cairo_fill (cr);
-
-      cairo_translate (cr, 0.5, 0.5);
-
-      gdk_cairo_set_source_color (cr, &style->dark[GTK_STATE_NORMAL]);
-      cairo_rectangle (cr, border, border,
-                       width - 1, height - 1);
-      cairo_stroke (cr);
-    }
-  else
-    {
-      cairo_translate (cr, 0.5, 0.5);
-    }
+  cairo_set_line_width (cr, 1.0);
+  cairo_set_line_cap (cr, CAIRO_LINE_CAP_SQUARE);
+  cairo_translate (cr, 0.5, 0.5);
 
   if (gtk_widget_has_focus (widget))
     {
@@ -513,7 +496,7 @@ gimp_curve_view_expose (GtkWidget      *widget,
                        gtk_widget_get_state (widget),
                        &event->area, widget, NULL,
                        border - 2, border - 2,
-                       width + 5, height + 5);
+                       width + 4, height + 4);
     }
 
   /*  Draw the grid lines  */
@@ -575,10 +558,10 @@ gimp_curve_view_expose (GtkWidget      *widget,
 
       /* draw the color line */
       cairo_move_to (cr,
-                     border + ROUND ((gdouble) width * view->xpos),
-                     border);
+                     border + ROUND ((gdouble) (width - 1) * view->xpos),
+                     border + 1);
       cairo_line_to (cr,
-                     border + ROUND ((gdouble) width * view->xpos),
+                     border + ROUND ((gdouble) (width - 1) * view->xpos),
                      border + height - 1);
       cairo_stroke (cr);
 
diff --git a/app/widgets/gimphistogramview.c b/app/widgets/gimphistogramview.c
index d6f3578..6d14756 100644
--- a/app/widgets/gimphistogramview.c
+++ b/app/widgets/gimphistogramview.c
@@ -297,27 +297,21 @@ gimp_histogram_view_expose (GtkWidget      *widget,
   GdkColor          *bg_color_out;
   GdkColor           rgb_color[3];
 
-  if (! view->histogram && ! view->bg_histogram)
-    return FALSE;
-
   cr = gdk_cairo_create (gtk_widget_get_window (widget));
 
   gdk_cairo_region (cr, event->region);
   cairo_clip (cr);
 
+  /*  Draw the background  */
+  gdk_cairo_set_source_color (cr, &style->base[GTK_STATE_NORMAL]);
+  cairo_paint (cr);
+
   gtk_widget_get_allocation (widget, &allocation);
 
   border = view->border_width;
   width  = allocation.width  - 2 * border;
   height = allocation.height - 2 * border;
 
-  x1 = CLAMP (MIN (view->start, view->end), 0, 255);
-  x2 = CLAMP (MAX (view->start, view->end), 0, 255);
-
-  /*  Draw the background  */
-  gdk_cairo_set_source_color (cr, &style->base[GTK_STATE_NORMAL]);
-  cairo_paint (cr);
-
   cairo_set_line_width (cr, 1.0);
   cairo_set_line_cap (cr, CAIRO_LINE_CAP_SQUARE);
   cairo_translate (cr, 0.5, 0.5);
@@ -328,6 +322,15 @@ gimp_histogram_view_expose (GtkWidget      *widget,
                    width - 1, height - 1);
   cairo_stroke (cr);
 
+  if (! view->histogram && ! view->bg_histogram)
+    {
+      cairo_destroy (cr);
+      return FALSE;
+    }
+
+  x1 = CLAMP (MIN (view->start, view->end), 0, 255);
+  x2 = CLAMP (MAX (view->start, view->end), 0, 255);
+
   if (view->histogram)
     max = gimp_histogram_view_get_maximum (view, view->histogram,
                                            view->channel);