[gimp] libgimpwidgets: improving (kinda) GimpSpinScale in RTL layout.

[Jehan <jehanp src gnome org>]

commit c93742f1788dadc0141b0ff98a9556f7790a526a
Author: Jehan <jehan girinstud io>
Date:   Wed Feb 16 18:46:13 2022 +0100

    libgimpwidgets: improving (kinda) GimpSpinScale in RTL layout.
    
    The label was simply completely invisible because of broken progress
    computation. Now it is visible at least when the progress fully cover
    the label, but a part of the label is not drawn when the progression is
    smaller than the label. I still have not figured out how to fix this,
    though I am starting to wonder if we should not just drop this 2-color
    fancy drawing of the label. Clearly the fact we can't get the exact
    progression gadget dimension is biting us.
    
    Another issue I noticed when playing with RTL layout is that when
    editing the value, it gets printed on the right side (together with the
    label) which gets messy. This is also something to figure out, hoping we
    get an API for this on the GTK side.
    
    Also I am setting "auto dir" to FALSE on the Pango layout, making sure
    it follows the widget direction, whatsoever. In particular, even if the
    contents is not RTL characters, we should keep a RTL layout to avoid
    completely broken layout.

 libgimpwidgets/gimpspinscale.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)
---
diff --git a/libgimpwidgets/gimpspinscale.c b/libgimpwidgets/gimpspinscale.c
index f9b6a8a8de..57143211f8 100644
--- a/libgimpwidgets/gimpspinscale.c
+++ b/libgimpwidgets/gimpspinscale.c
@@ -399,6 +399,12 @@ gimp_spin_scale_draw (GtkWidget *widget,
           private->layout = gtk_widget_create_pango_layout (widget,
                                                             private->label_text);
           pango_layout_set_ellipsize (private->layout, PANGO_ELLIPSIZE_END);
+          /* Needing to force right-to-left layout when the widget is
+           * set so, even when the text is not RTL text. Without this,
+           * such case is broken because on the left side, we'd have
+           * both the value and the label texts.
+           */
+          pango_layout_set_auto_dir (private->layout, FALSE);
 
           if (private->mnemonics_visible)
             {
@@ -436,23 +442,14 @@ gimp_spin_scale_draw (GtkWidget *widget,
       gtk_style_context_restore (style);
 
       progress_fraction = gtk_entry_get_progress_fraction (GTK_ENTRY (widget));
+      progress_y        = 0.0;
+      progress_width    = (gdouble) text_area.width * progress_fraction;
+      progress_height   = text_area.height;
 
       if (gtk_widget_get_direction (widget) == GTK_TEXT_DIR_RTL)
-        {
-          progress_fraction = 1.0 - progress_fraction;
-
-          progress_x      = (gdouble) text_area.width * progress_fraction + text_area.x;
-          progress_y      = 0.0;
-          progress_width  = text_area.width - progress_x;
-          progress_height = text_area.height;
-        }
+        progress_x = text_area.width + text_area.x - progress_width;
       else
-        {
-          progress_x      = text_area.x;
-          progress_y      = 0.0;
-          progress_width  = (gdouble) text_area.width * progress_fraction;
-          progress_height = text_area.height;
-        }
+        progress_x = text_area.x;
 
       cairo_save (cr);