[gimp] app: Add drag-to-zoom speed preference

[Jehan <jehanp src gnome org>]

commit eb58b277d22e0d02fd0c43db0dfccdc73b1fa16b
Author: woob <thetoastcaper gmail com>
Date:   Tue Mar 1 20:08:42 2022 -0500

    app: Add drag-to-zoom speed preference
    
    Adds the new configuration option "drag-zoom-speed" to adjust the rate
    at which mouse movement can zoom the canvas, ranging from 25% to 300%
    of the base rate and applying to both drag-to-zoom modes.
    This option can be found in the preferences dialog as:
      Image Windows -> Zoom & Resize Behavior -> Drag-to-zoom speed

 app/config/gimpdisplayconfig.c       | 14 ++++++++++++++
 app/config/gimpdisplayconfig.h       |  1 +
 app/config/gimprc-blurbs.h           |  4 ++++
 app/dialogs/preferences-dialog.c     |  6 ++++++
 app/display/gimpdisplayshell-scale.c |  7 ++++---
 5 files changed, 29 insertions(+), 3 deletions(-)
---
diff --git a/app/config/gimpdisplayconfig.c b/app/config/gimpdisplayconfig.c
index e2c51d0ecc..d77f021335 100644
--- a/app/config/gimpdisplayconfig.c
+++ b/app/config/gimpdisplayconfig.c
@@ -55,6 +55,7 @@ enum
   PROP_DEFAULT_DOT_FOR_DOT,
   PROP_INITIAL_ZOOM_TO_FIT,
   PROP_DRAG_ZOOM_MODE,
+  PROP_DRAG_ZOOM_SPEED,
   PROP_CURSOR_MODE,
   PROP_CURSOR_UPDATING,
   PROP_SHOW_BRUSH_OUTLINE,
@@ -190,6 +191,13 @@ gimp_display_config_class_init (GimpDisplayConfigClass *klass)
                          PROP_DRAG_ZOOM_MODE_DISTANCE,
                          GIMP_PARAM_STATIC_STRINGS);
 
+  GIMP_CONFIG_PROP_DOUBLE(object_class, PROP_DRAG_ZOOM_SPEED,
+                          "drag-zoom-speed",
+                          "Drag-to-zoom speed",
+                          DRAG_ZOOM_SPEED_BLURB,
+                          25.0, 300.0, 100.0,
+                          GIMP_PARAM_STATIC_STRINGS);
+
   GIMP_CONFIG_PROP_ENUM (object_class, PROP_CURSOR_MODE,
                          "cursor-mode",
                          "Cursor mode",
@@ -438,6 +446,9 @@ gimp_display_config_set_property (GObject      *object,
     case PROP_DRAG_ZOOM_MODE:
       display_config->drag_zoom_mode = g_value_get_enum (value);
       break;
+    case PROP_DRAG_ZOOM_SPEED:
+      display_config->drag_zoom_speed = g_value_get_double (value);
+      break;
     case PROP_CURSOR_MODE:
       display_config->cursor_mode = g_value_get_enum (value);
       break;
@@ -553,6 +564,9 @@ gimp_display_config_get_property (GObject    *object,
     case PROP_DRAG_ZOOM_MODE:
       g_value_set_enum (value, display_config->drag_zoom_mode);
       break;
+    case PROP_DRAG_ZOOM_SPEED:
+      g_value_set_double (value, display_config->drag_zoom_speed);
+      break;
     case PROP_CURSOR_MODE:
       g_value_set_enum (value, display_config->cursor_mode);
       break;
diff --git a/app/config/gimpdisplayconfig.h b/app/config/gimpdisplayconfig.h
index 1de8bffe89..0deab5f08b 100644
--- a/app/config/gimpdisplayconfig.h
+++ b/app/config/gimpdisplayconfig.h
@@ -51,6 +51,7 @@ struct _GimpDisplayConfig
   gboolean            default_dot_for_dot;
   gboolean            initial_zoom_to_fit;
   GimpDragZoomMode    drag_zoom_mode;
+  gboolean            drag_zoom_speed;
   GimpCursorMode      cursor_mode;
   gboolean            cursor_updating;
   gboolean            show_brush_outline;
diff --git a/app/config/gimprc-blurbs.h b/app/config/gimprc-blurbs.h
index 00726264df..73487fa0d7 100644
--- a/app/config/gimprc-blurbs.h
+++ b/app/config/gimprc-blurbs.h
@@ -261,6 +261,10 @@ _("When enabled, this will ensure that the full image is visible after a " \
 _("Whether to zoom based on distance moved or time spent moving, when " \
   "zooming via dragging the mouse.")
 
+#define DRAG_ZOOM_SPEED_BLURB \
+_("Adjusts the rate at which dragging the mouse will zoom the canvas, " \
+  "in percentage.")
+
 #define INTERPOLATION_TYPE_BLURB \
 _("Sets the level of interpolation used for scaling and other " \
   "transformations.")
diff --git a/app/dialogs/preferences-dialog.c b/app/dialogs/preferences-dialog.c
index 6d50f1aba3..a9a418c18c 100644
--- a/app/dialogs/preferences-dialog.c
+++ b/app/dialogs/preferences-dialog.c
@@ -2939,6 +2939,12 @@ prefs_dialog_new (Gimp       *gimp,
                             _("Dra_g-to-zoom behavior:"),
                             GTK_GRID (grid), 0, size_group);
 
+  grid = prefs_grid_new (GTK_CONTAINER (vbox2));
+
+  prefs_spin_button_add (object, "drag-zoom-speed", 5.0, 25.0, 0,
+                         _("Drag-to-zoom spe_ed:"),
+                         GTK_GRID (grid), 0, size_group);
+
   /*  Space Bar  */
   vbox2 = prefs_frame_new (_("Space Bar"),
                            GTK_CONTAINER (vbox), FALSE);
diff --git a/app/display/gimpdisplayshell-scale.c b/app/display/gimpdisplayshell-scale.c
index c840f962f9..a3875aa437 100644
--- a/app/display/gimpdisplayshell-scale.c
+++ b/app/display/gimpdisplayshell-scale.c
@@ -812,6 +812,7 @@ gimp_display_shell_scale_drag (GimpDisplayShell *shell,
   if (delta_y != 0.0)
     {
       GimpDisplayConfig *config = shell->display->config;
+      gdouble            speed  = config->drag_zoom_speed * 0.01;
 
       gimp_display_shell_push_zoom_focus_pointer_pos (shell, start_x, start_y);
 
@@ -819,21 +820,21 @@ gimp_display_shell_scale_drag (GimpDisplayShell *shell,
         {
           gimp_display_shell_scale (shell,
                                     GIMP_ZOOM_TO,
-                                    scale * exp (0.005 * delta_y),
+                                    scale * exp (0.005 * speed * delta_y),
                                     GIMP_ZOOM_FOCUS_POINTER);
         }
       else if (delta_y > 0.0) /* drag_zoom_mode == PROP_DRAG_ZOOM_MODE_DURATION */
         {
           gimp_display_shell_scale (shell,
                                     GIMP_ZOOM_TO,
-                                    scale * 1.1,
+                                    scale * (1 + 0.1 * speed),
                                     GIMP_ZOOM_FOCUS_POINTER);
         }
       else /* delta_y < 0.0 */
         {
           gimp_display_shell_scale (shell,
                                     GIMP_ZOOM_TO,
-                                    scale * 0.9,
+                                    scale * (1 - 0.1 * speed),
                                     GIMP_ZOOM_FOCUS_POINTER);
         }