agx: don't activate the pivot pickers until the user starts dragging the mouse, to avoid first picking a pivot based on the whole image

Author: kofa73

src/gui/color_picker_proxy.c

@@ -73,6 +73,11 @@ gboolean dt_iop_color_picker_is_visible(const dt_develop_t *dev)
   return module_picker || primary_picker;
 }
 
+gboolean dt_iop_color_picker_is_area_empty(const dt_pickerbox_t box)
+{
+  return (fabsf(box[2] - box[0]) < 1e-5f || fabsf(box[3] - box[1]) < 1e-5f);
+}
+
 static gboolean _record_point_area(dt_iop_color_picker_t *self)
 {
   const dt_colorpicker_sample_t *const sample =
@@ -201,7 +206,13 @@ static gboolean _color_picker_callback_button_press(GtkWidget *button,
     // pull picker's last recorded positions
     if(kind & DT_COLOR_PICKER_AREA)
     {
-      if(   self->pick_box[0] == 0.0f && self->pick_box[1] == 0.0f
+      if(flags & DT_COLOR_PICKER_NO_AUTO)
+      {
+        // reset coordinates to 0.0f to create a zero-area box,
+        // requiring the user to drag-select manually
+        memset(self->pick_box, 0, sizeof(self->pick_box));
+      }
+      else if(   self->pick_box[0] == 0.0f && self->pick_box[1] == 0.0f
          && self->pick_box[2] == 1.0f && self->pick_box[3] == 1.0f)
       {
         dt_boundingbox_t reset = { 0.02f, 0.02f, 0.98f, 0.98f };
@@ -317,6 +328,13 @@ static void _iop_color_picker_pickerdata_ready_callback(gpointer instance,
   // iops only need new picker data if the pointer has moved
   if(_record_point_area(picker))
   {
+    // in Area mode, ignore updates where the area is empty (e.g. when using DT_COLOR_PICKER_NO_AUTO
+    // and the user has not started dragging yet)
+    if((picker->flags & DT_COLOR_PICKER_AREA) && dt_iop_color_picker_is_area_empty(picker->pick_box))
+    {
+      return;
+    }
+
     if(!module->blend_data || !blend_color_picker_apply(module, picker->colorpick, pipe))
     {
       if(module->color_picker_apply)

src/gui/color_picker_proxy.h

@@ -40,7 +40,9 @@ typedef enum _iop_color_picker_flags_t
   // only works with 4-channel images
   DT_COLOR_PICKER_DENOISE = 1 << 2,
   // all pickers sample input, only ones with this flag set sample output
-  DT_COLOR_PICKER_IO = 1 << 3
+  DT_COLOR_PICKER_IO = 1 << 3,
+  // don't auto-expand the area, wait for user selection via dragging
+  DT_COLOR_PICKER_NO_AUTO = 1 << 4
 } dt_iop_color_picker_flags_t;
 
 typedef struct dt_iop_color_picker_t
@@ -71,6 +73,8 @@ typedef struct dt_iop_color_picker_t
 
 gboolean dt_iop_color_picker_is_visible(const dt_develop_t *dev);
 
+gboolean dt_iop_color_picker_is_area_empty(const dt_pickerbox_t box);
+
 //* reset current color picker if not keep-active or not keep */
 void dt_iop_color_picker_reset(dt_iop_module_t *module,
                                const gboolean keep);

src/iop/agx.c

@@ -1815,7 +1815,7 @@ static GtkWidget* _create_basic_curve_controls_box(dt_iop_module_t *self,
   dt_iop_basic_curve_controls_t *controls = &g->basic_curve_controls;
 
   // curve_pivot_x_relative_ev with picker
-  slider = dt_color_picker_new(self, DT_COLOR_PICKER_AREA | DT_COLOR_PICKER_DENOISE, dt_bauhaus_slider_from_params(section, "curve_pivot_x"));
+  slider = dt_color_picker_new(self, DT_COLOR_PICKER_AREA | DT_COLOR_PICKER_DENOISE | DT_COLOR_PICKER_NO_AUTO, dt_bauhaus_slider_from_params(section, "curve_pivot_x"));
   controls->curve_pivot_x = slider;
   dt_bauhaus_slider_set_format(slider, _(" EV"));
   dt_bauhaus_slider_set_digits(slider, 2);
@@ -1824,7 +1824,7 @@ static GtkWidget* _create_basic_curve_controls_box(dt_iop_module_t *self,
                                                "used to set the pivot relative to mid-gray"));
 
   // curve_pivot_y_linear
-  slider = dt_color_picker_new(self, DT_COLOR_PICKER_AREA | DT_COLOR_PICKER_DENOISE, dt_bauhaus_slider_from_params(section, "curve_pivot_y_linear_output"));
+  slider = dt_color_picker_new(self, DT_COLOR_PICKER_AREA | DT_COLOR_PICKER_DENOISE | DT_COLOR_PICKER_NO_AUTO, dt_bauhaus_slider_from_params(section, "curve_pivot_y_linear_output"));
   controls->curve_pivot_y_linear = slider;
   dt_bauhaus_slider_set_format(slider, "%");
   dt_bauhaus_slider_set_digits(slider, 2);

src/views/darkroom.c

@@ -310,6 +310,10 @@ static void _darkroom_pickers_draw(dt_view_t *self,
     // overlays are aligned with pixels for a clean look
     if(sample->size == DT_LIB_COLORPICKER_SIZE_BOX)
     {
+      // do not draw if the area is empty
+      if(dt_iop_color_picker_is_area_empty(sample->box))
+        continue;
+
       dt_boundingbox_t fbox;
       dt_color_picker_transform_box(dev, 2, sample->box, fbox, FALSE);
       x = fbox[0];