checkbox: Adding third state (Indeterminate) support in checkbox

Summary:
Checkbox should support a third state "indeterminate" along with "Checked" and "Unchecked"
This third state is a state of checkbox which is shown when checkbox is neither Checked nor Unchecked.

- Added this new feature on the basis of a boolean variable's value.
- By default this boolean variable is disabled and checkbox will treat like old way.
- While adding this, I kept in mind, that applications which are already using checkbox, should not be affected, so I used 0=False=Unchecked, 1=True=Checked, and 2=Indeterminate
- Also added an example check_example_o2.c, which is using checkbox with both ways, using boolean, and using enum.
- Now also values can be set using boolean values, but it will give a type casting warning. As a boolean doen't support third state, so I used an enum int like.

- Added APIs to enable disable third state mode. elm_check_three_state_mode_set(check_obj, bool_val), and elm_check_three_state_mode_get(check_obj)
- Modified old APIs which were setting or getting states of checkbox.
- Added a state in theme of checkbox, with third state image.

Reviewers: seoz, raster, Sergeant_Whitespace, Hermet

Subscribers: Hermet, Sergeant_Whitespace, sachin.dev

Differential Revision: https://phab.enlightenment.org/D2249

8 files changed, 297 insertions, 42 deletions

diff --git a/data/themes/Makefile.am b/data/themes/Makefile.am
index 8237c67b4..64a137562 100644
--- a/data/themes/Makefile.am
+++ b/data/themes/Makefile.am
@@ -586,6 +586,7 @@ img/split_v_glow.png \
 img/split_v_hilight.png \
 img/split_v_inset.png \
 img/sym_check_alum.png \
+img/sym_check_indeterminate.png \
 img/sym_close_dark_normal.png \
 img/sym_close_dark_selected.png \
 img/sym_close_light_normal.png \
diff --git a/data/themes/edc/elm/check.edc b/data/themes/edc/elm/check.edc
index 431cdc769..9b3068ee6 100644
--- a/data/themes/edc/elm/check.edc
+++ b/data/themes/edc/elm/check.edc
@@ -2,6 +2,7 @@ group { name: "elm/check/base/default";
    images.image: "inset_shadow_tiny.png" COMP;
    images.image: "bevel_in.png" COMP;
    images.image: "sym_check_alum.png" COMP;
+   images.image: "sym_check_indeterminate.png" COMP;
 #define ICON     1
 #define LABEL    2
 #define MASK     3
@@ -144,6 +145,11 @@ group { name: "elm/check/base/default";
             inherit: "default" 0.0;
             visible: 1;
          }
+         description { state: "mixed" 0.0;
+            inherit: "default" 0.0;
+            image.normal: "sym_check_indeterminate.png";
+            visible: 1;
+         }
       }
       part { name: "clip"; type: RECT;
          description { state: "default" 0.0;
@@ -270,6 +276,11 @@ group { name: "elm/check/base/default";
          target: "indicator";
       }
       program {
+         signal: "elm,state,check,indeterminate"; source: "elm";
+         action:  STATE_SET "mixed" 0.0;
+         target: "indicator";
+      }
+      program {
          signal: "elm,state,text,visible"; source: "elm";
          script {
             new m = get_int(btmode);
diff --git a/data/themes/img/sym_check_indeterminate.png b/data/themes/img/sym_check_indeterminate.png
new file mode 100755
index 000000000..3b2c0eac9
--- /dev/null
+++ b/data/themes/img/sym_check_indeterminate.png
diff --git a/src/examples/check_example_02.c b/src/examples/check_example_02.c
new file mode 100644
index 000000000..6aa0a1cfd
--- /dev/null
+++ b/src/examples/check_example_02.c
@@ -0,0 +1,111 @@
+//Compile with:
+//gcc -o check_example_02  check_example_02.c -g `pkg-config --cflags --libs elementary` && ./check_example_02
+
+#include <Elementary.h>
+
+Evas_Object *cb, *cb1, *cb2, *cb3;
+
+static void
+_print(void *data, Evas_Object *obj, void *event_info)
+{
+   if (!elm_check_three_state_mode_get(cb))
+     {
+        printf("check0 %smarked\n", *((Eina_Bool*)data) ? "" : "un");
+     }
+   else
+     {
+        printf("check0 elm_check_state_get() value is %d (%s)\n", elm_check_state_get(cb), *((Eina_Bool*)data) ? "EINA_TRUE" : "EINA_FALSE");
+     }
+}
+
+static void
+_print1(void *data, Evas_Object *obj, void *event_info)
+{
+   Check_State st = elm_check_state_get(cb1);
+   if (st == _CHECK_STATE_CHECKED)
+     printf("check1 elm_check_state_get() value is %d (%s)\n", st, "_CHECK_STATE_CHECKED");
+   else if (st == _CHECK_STATE_INDETERMINATE)
+     printf("check1 elm_check_state_get() value is %d (%s)\n", st, "_CHECK_STATE_INDETERMINATE");
+   else
+     printf("check1 elm_check_state_get() value is %d (%s)\n", st, "_CHECK_STATE_UNCHECKED");
+}
+
+static void
+_print2(void *data, Evas_Object *obj, void *event_info)
+{
+   printf("Currently three state mode is: %s\n", elm_check_three_state_mode_get(cb) ? "On" : "Off");
+   elm_check_three_state_mode_set(cb, elm_check_state_get(cb2));
+   elm_check_three_state_mode_set(cb1, elm_check_state_get(cb2));
+   printf("Three state mode is changed to: %s\n", elm_check_three_state_mode_get(cb) ? "On" : "Off");
+}
+
+static void
+_print3(void *data, Evas_Object *obj, void *event_info)
+{
+   elm_object_disabled_set(cb, elm_check_state_get(cb3));
+   elm_object_disabled_set(cb1, elm_check_state_get(cb3));
+   printf("Checkbox disable mode is : %s\n", elm_check_state_get(cb3) ? "Enabled" : "Disabled");
+}
+
+EAPI_MAIN int
+elm_main(int argc, char **argv)
+{
+   Evas_Object *win, *icon;
+   Eina_Bool value, *value2, *value3;
+   Check_State *value1;
+
+   elm_policy_set(ELM_POLICY_QUIT, ELM_POLICY_QUIT_LAST_WINDOW_CLOSED);
+
+   win = elm_win_util_standard_add("check", "Check");
+   elm_win_autodel_set(win, EINA_TRUE);
+
+   cb = elm_check_add(win);
+   elm_object_text_set(cb, "check0 using bool");
+   elm_check_state_pointer_set(cb, &value);
+   elm_check_state_set(cb, EINA_FALSE);
+   evas_object_smart_callback_add(cb, "changed", _print, &value);
+   evas_object_move(cb, 10, 10);
+   evas_object_resize(cb, 250, 30);
+   evas_object_show(cb);
+
+   cb1 = elm_check_add(win);
+   elm_object_text_set(cb1, "check1 using enum");
+   elm_check_state_pointer_set(cb1, (Check_State *)&value1);
+   elm_check_state_set(cb1, (Check_State)_CHECK_STATE_CHECKED);
+   evas_object_smart_callback_add(cb1, "changed", _print1, &value1);
+   evas_object_move(cb1, 10, 50);
+   evas_object_resize(cb1, 250, 30);
+   evas_object_show(cb1);
+
+   icon = evas_object_rectangle_add(evas_object_evas_get(win));
+   evas_object_color_set(icon, 0, 255, 0, 255);
+   evas_object_resize(icon, 20, 20);
+   evas_object_show(icon);
+
+   cb2 = elm_check_add(win);
+   elm_object_text_set(cb2, "Enable three state mode in above checkboxes");
+   elm_check_state_pointer_set(cb2, (Check_State *)&value2);
+   elm_check_state_set(cb2, (Check_State)_CHECK_STATE_UNCHECKED);
+   evas_object_smart_callback_add(cb2, "changed", _print2, &value2);
+   elm_object_part_content_set(cb2, "icon", icon);
+   evas_object_move(cb2, 10, 90);
+   evas_object_resize(cb2, 250, 30);
+   evas_object_show(cb2);
+
+   cb3 = elm_check_add(win);
+   elm_object_text_set(cb3, "Enable/Disable checkboxes");
+   elm_check_state_pointer_set(cb3, (Check_State *)&value3);
+   elm_check_state_set(cb3, (Check_State)_CHECK_STATE_UNCHECKED);
+   evas_object_smart_callback_add(cb3, "changed", _print3, &value3);
+   evas_object_move(cb3, 10, 130);
+   evas_object_resize(cb3, 250, 30);
+   evas_object_show(cb3);
+
+   evas_object_resize(win, 200, 190);
+   evas_object_show(win);
+
+   elm_run();
+
+   return 0;
+}
+ELM_MAIN()
diff --git a/src/lib/elm_check.c b/src/lib/elm_check.c
index 27f38d05a..a7bbfb520 100644
--- a/src/lib/elm_check.c
+++ b/src/lib/elm_check.c
@@ -53,19 +53,57 @@ _activate(Evas_Object *obj)
 {
    ELM_CHECK_DATA_GET(obj, sd);
 
-   sd->state = !sd->state;
+   if (!sd->three_state_mode)
+     {
+        sd->state = !sd->state;
+     }
+   else
+     {
+        if (sd->state == _CHECK_STATE_UNCHECKED)
+          sd->state = _CHECK_STATE_CHECKED;
+        else if (sd->state == _CHECK_STATE_CHECKED)
+          sd->state = _CHECK_STATE_INDETERMINATE;
+        else
+          sd->state = _CHECK_STATE_UNCHECKED;
+     }
+
    if (sd->statep) *sd->statep = sd->state;
-   if (sd->state)
+
+   if (!sd->three_state_mode)
      {
-        elm_layout_signal_emit(obj, "elm,state,check,on", "elm");
-        if (_elm_config->access_mode != ELM_ACCESS_MODE_OFF)
-             _elm_access_say(E_("State: On"));
+        if (sd->state)
+          {
+             elm_layout_signal_emit(obj, "elm,state,check,on", "elm");
+             if (_elm_config->access_mode != ELM_ACCESS_MODE_OFF)
+               _elm_access_say(E_("State: On"));
+          }
+        else
+          {
+             elm_layout_signal_emit(obj, "elm,state,check,off", "elm");
+             if (_elm_config->access_mode != ELM_ACCESS_MODE_OFF)
+               _elm_access_say(E_("State: Off"));
+          }
      }
    else
      {
-        elm_layout_signal_emit(obj, "elm,state,check,off", "elm");
-        if (_elm_config->access_mode != ELM_ACCESS_MODE_OFF)
-             _elm_access_say(E_("State: Off"));
+        if (sd->state == _CHECK_STATE_CHECKED)
+          {
+             elm_layout_signal_emit(obj, "elm,state,check,on", "elm");
+             if (_elm_config->access_mode != ELM_ACCESS_MODE_OFF)
+               _elm_access_say(E_("State: On"));
+          }
+        else if (sd->state == _CHECK_STATE_UNCHECKED)
+          {
+             elm_layout_signal_emit(obj, "elm,state,check,off", "elm");
+             if (_elm_config->access_mode != ELM_ACCESS_MODE_OFF)
+               _elm_access_say(E_("State: Off"));
+          }
+        else
+          {
+             elm_layout_signal_emit(obj, "elm,state,check,indeterminate", "elm");
+             if (_elm_config->access_mode != ELM_ACCESS_MODE_OFF)
+               _elm_access_say(E_("State: Indeterminate"));
+          }
      }
 
    evas_object_smart_callback_call(obj, SIG_CHANGED, NULL);
@@ -99,8 +137,10 @@ _elm_check_elm_interface_atspi_accessible_state_set_get(Eo *obj, Elm_Check_Data
 
    eo_do_super(obj, ELM_CHECK_CLASS, states = elm_interface_atspi_accessible_state_set_get());
 
-   if (elm_check_state_get(obj))
-       STATE_TYPE_SET(states, ELM_ATSPI_STATE_CHECKED);
+   if (elm_check_state_get(obj) == _CHECK_STATE_CHECKED)
+     STATE_TYPE_SET(states, ELM_ATSPI_STATE_CHECKED);
+   else if (elm_check_state_get(obj) == _CHECK_STATE_INDETERMINATE)
+     STATE_TYPE_SET(states, ELM_ATSPI_STATE_INDETERMINATE);
 
    return states;
 }
@@ -198,8 +238,9 @@ _elm_check_elm_widget_theme_apply(Eo *obj, Elm_Check_Data *sd)
    eo_do_super(obj, MY_CLASS, int_ret = elm_obj_widget_theme_apply());
    if (!int_ret) return EINA_FALSE;
 
-   if (!sd->state) elm_layout_signal_emit(obj, "elm,state,check,off", "elm");
-   else elm_layout_signal_emit(obj, "elm,state,check,on", "elm");
+   if (sd->state == _CHECK_STATE_UNCHECKED) elm_layout_signal_emit(obj, "elm,state,check,off", "elm");
+   else if (sd->state == _CHECK_STATE_CHECKED) elm_layout_signal_emit(obj, "elm,state,check,on", "elm");
+   else elm_layout_signal_emit(obj, "elm,state,check,indeterminate", "elm");
 
    edje_object_message_signal_process(wd->resize_obj);
 
@@ -228,11 +269,11 @@ static char *
 _access_state_cb(void *data, Evas_Object *obj)
 {
    Elm_Check_Data *sd = eo_data_scope_get(data, MY_CLASS);
-   const char *on_text, *off_text;
+   const char *on_text, *off_text, *indeterminate_text;
 
    if (elm_widget_disabled_get(obj))
      return strdup(E_("State: Disabled"));
-   if (sd->state)
+   if (sd->state == _CHECK_STATE_CHECKED)
      {
         on_text = elm_layout_text_get(data, "on");
 
@@ -246,17 +287,30 @@ _access_state_cb(void *data, Evas_Object *obj)
         else
           return strdup(E_("State: On"));
      }
+   else if (sd->state == _CHECK_STATE_UNCHECKED)
+     {
+        off_text = elm_layout_text_get(data, "off");
 
-   off_text = elm_layout_text_get(data, "off");
-
-   if (off_text)
+        if (off_text)
+          {
+             char buf[1024];
+             snprintf(buf, sizeof(buf), "%s: %s", E_("State"), off_text);
+             return strdup(buf);
+          }
+        return strdup(E_("State: Off"));
+     }
+   else
      {
-        char buf[1024];
+        indeterminate_text = elm_layout_text_get(data, "indeterminate");
 
-        snprintf(buf, sizeof(buf), "%s: %s", E_("State"), off_text);
-        return strdup(buf);
+        if (indeterminate_text)
+          {
+             char buf[1024];
+             snprintf(buf, sizeof(buf), "%s: %s", E_("State"), indeterminate_text);
+             return strdup(buf);
+          }
+        return strdup(E_("State: indeterminate"));
      }
-   return strdup(E_("State: Off"));
 }
 
 static void
@@ -269,7 +323,7 @@ _on_check_off(void *data,
 
    ELM_CHECK_DATA_GET(obj, sd);
 
-   sd->state = EINA_FALSE;
+   sd->state = _CHECK_STATE_UNCHECKED;
    if (sd->statep) *sd->statep = sd->state;
 
    elm_layout_signal_emit(obj, "elm,state,check,off", "elm");
@@ -291,15 +345,36 @@ _on_check_on(void *data,
 
    ELM_CHECK_DATA_GET(obj, sd);
 
-   sd->state = EINA_TRUE;
+   sd->state = _CHECK_STATE_CHECKED;
    if (sd->statep) *sd->statep = sd->state;
    elm_layout_signal_emit(obj, "elm,state,check,on", "elm");
    evas_object_smart_callback_call(data, SIG_CHANGED, NULL);
 
    if (_elm_config->atspi_mode)
-       elm_interface_atspi_accessible_state_changed_signal_emit(data,
-                                                                ELM_ATSPI_STATE_CHECKED,
-                                                                sd->state);
+     elm_interface_atspi_accessible_state_changed_signal_emit(data,
+                                                              ELM_ATSPI_STATE_CHECKED,
+                                                              sd->state);
+}
+
+static void
+_on_check_indeterminate(void *data,
+             Evas_Object *o EINA_UNUSED,
+             const char *emission EINA_UNUSED,
+             const char *source EINA_UNUSED)
+{
+   Evas_Object *obj = data;
+
+   ELM_CHECK_DATA_GET(obj, sd);
+
+   sd->state = _CHECK_STATE_INDETERMINATE;
+   if (sd->statep) *sd->statep = sd->state;
+   elm_layout_signal_emit(obj, "elm,state,check,indeterminate", "elm");
+   evas_object_smart_callback_call(data, SIG_CHANGED, NULL);
+
+   if (_elm_config->atspi_mode)
+     elm_interface_atspi_accessible_state_changed_signal_emit(data,
+                                                              ELM_ATSPI_STATE_CHECKED,
+                                                              sd->state);
 }
 
 static void
@@ -326,6 +401,9 @@ _elm_check_evas_object_smart_add(Eo *obj, Elm_Check_Data *_pd EINA_UNUSED)
      (wd->resize_obj, "elm,action,check,off", "*",
      _on_check_off, obj);
    edje_object_signal_callback_add
+     (wd->resize_obj, "elm,action,check,indeterminate", "*",
+     _on_check_indeterminate, obj);
+   edje_object_signal_callback_add
      (wd->resize_obj, "elm,action,check,toggle", "*",
      _on_check_toggle, obj);
 
@@ -376,7 +454,7 @@ _elm_check_eo_base_constructor(Eo *obj, Elm_Check_Data *_pd EINA_UNUSED)
 }
 
 EOLIAN static void
-_elm_check_state_set(Eo *obj, Elm_Check_Data *sd, Eina_Bool state)
+_elm_check_state_set(Eo *obj, Elm_Check_Data *sd, Check_State state)
 {
    ELM_WIDGET_DATA_GET_OR_RETURN(obj, wd);
 
@@ -384,23 +462,25 @@ _elm_check_state_set(Eo *obj, Elm_Check_Data *sd, Eina_Bool state)
      {
         sd->state = state;
         if (sd->statep) *sd->statep = sd->state;
-        if (sd->state)
+        if (sd->state == _CHECK_STATE_UNCHECKED)
+          elm_layout_signal_emit(obj, "elm,state,check,off", "elm");
+        else if ((sd->state == _CHECK_STATE_CHECKED) || (!sd->three_state_mode))
           elm_layout_signal_emit(obj, "elm,state,check,on", "elm");
         else
-          elm_layout_signal_emit(obj, "elm,state,check,off", "elm");
+          elm_layout_signal_emit(obj, "elm,state,check,indeterminate", "elm");
      }
 
    edje_object_message_signal_process(wd->resize_obj);
 }
 
-EOLIAN static Eina_Bool
+EOLIAN static Check_State
 _elm_check_state_get(Eo *obj EINA_UNUSED, Elm_Check_Data *sd)
 {
    return sd->state;
 }
 
 EOLIAN static void
-_elm_check_state_pointer_set(Eo *obj, Elm_Check_Data *sd, Eina_Bool *statep)
+_elm_check_state_pointer_set(Eo *obj, Elm_Check_Data *sd, Check_State *statep)
 {
    if (statep)
      {
@@ -408,16 +488,39 @@ _elm_check_state_pointer_set(Eo *obj, Elm_Check_Data *sd, Eina_Bool *statep)
         if (*sd->statep != sd->state)
           {
              sd->state = *sd->statep;
-             if (sd->state)
+             if (sd->state == _CHECK_STATE_CHECKED)
                elm_layout_signal_emit(obj, "elm,state,check,on", "elm");
-             else
+             else if (sd->state == _CHECK_STATE_UNCHECKED)
                elm_layout_signal_emit(obj, "elm,state,check,off", "elm");
+             else
+               elm_layout_signal_emit(obj, "elm,state,check,indeterminate", "elm");
           }
      }
    else
      sd->statep = NULL;
 }
 
+EOLIAN static void
+_elm_check_three_state_mode_set(Eo *obj, Elm_Check_Data *sd, Eina_Bool is_enabled)
+{
+   ELM_WIDGET_DATA_GET_OR_RETURN(obj, wd);
+
+   if (is_enabled != sd->three_state_mode)
+     {
+        sd->three_state_mode = is_enabled;
+        if ((!sd->three_state_mode) && (sd->state == _CHECK_STATE_INDETERMINATE))
+          elm_layout_signal_emit(obj, "elm,state,check,on", "elm");
+     }
+
+   edje_object_message_signal_process(wd->resize_obj);
+}
+
+EOLIAN static Eina_Bool
+_elm_check_three_state_mode_get(Eo *obj EINA_UNUSED, Elm_Check_Data *sd)
+{
+   return sd->three_state_mode;
+}
+
 EOLIAN static Eina_Bool
 _elm_check_elm_widget_focus_next_manager_is(Eo *obj EINA_UNUSED, Elm_Check_Data *_pd EINA_UNUSED)
 {
diff --git a/src/lib/elm_check.eo b/src/lib/elm_check.eo
index 17d49ee8c..f7d74df55 100644
--- a/src/lib/elm_check.eo
+++ b/src/lib/elm_check.eo
@@ -1,3 +1,9 @@
+      type Check_State: enum _Check_State {
+         Unchecked,
+         Checked,
+         Indeterminate
+      };
+
 class Elm_Check (Elm_Layout, Elm_Interface_Atspi_Widget_Action)
 {
    eo_prefix: elm_obj_check;
@@ -17,30 +23,52 @@ class Elm_Check (Elm_Layout, Elm_Interface_Atspi_Widget_Action)
             /*@
             @brief Get the state of the check object
 
-            @return The boolean state
+            @return The enum of states, first two states(Unchecked and checked) can be treated as boolean.
 
             @ingroup Check */
          }
          values {
-            bool state; /*@ The state to use (1 == on, 0 == off) */
+            Check_State state; /*@ The state to use (0 == off, 1 == on, 2 == indeterminate) */
          }
       }
       state_pointer {
          set {
             /*@
-            @brief Set a convenience pointer to a boolean to change
+            @brief Set a convenience pointer to a enum of state to change
 
-            This sets a pointer to a boolean, that, in addition to the check objects
+            This sets a pointer to a enum of state, that, in addition to the check objects
             state will also be modified directly. To stop setting the object pointed
             to simply use NULL as the @p statep parameter. If @p statep is not NULL,
             then when this is called, the check objects state will also be modified to
-            reflect the value of the boolean @p statep points to, just like calling
+            reflect the value of the enum of states @p statep points to, just like calling
             elm_check_state_set().
 
             @ingroup Check */
          }
          values {
-            bool *statep; /*@ Pointer to the boolean to modify */
+            Check_State *statep; /*@ Pointer to the boolean to modify */
+         }
+      }
+      three_state_mode {
+         set {
+            /*@
+            @brief Set the enable/disable of three state mode of the check object
+
+            This enables the three state mode. By default any checkbox will be changing states in two states. i.e. Checked and Unchecked
+            On enabling this, it will start rotation of states into three states. Checked, Unchecked and Indeterminate
+
+            @ingroup Check */
+         }
+         get {
+            /*@
+            @brief Get the enable/disable of three state mode of the check object
+
+            @return The boolean value of enable/disable of three mode state change.
+
+            @ingroup Check */
+         }
+         values {
+            bool three_state_mode; /*@ The state to use (0 == Disabled, 1 == Enabled) */
          }
       }
    }
diff --git a/src/lib/elm_interface_atspi_accessible.h b/src/lib/elm_interface_atspi_accessible.h
index acd152e1b..da5a48699 100644
--- a/src/lib/elm_interface_atspi_accessible.h
+++ b/src/lib/elm_interface_atspi_accessible.h
@@ -221,7 +221,7 @@ typedef enum _Elm_Atspi_Relation_Type Elm_Atspi_Relation_Type;
 struct _Elm_Atspi_Event_State_Changed_Data
 {
    Elm_Atspi_State_Type type;
-   Eina_Bool new_value;
+   int new_value;
 };
 
 
diff --git a/src/lib/elm_widget_check.h b/src/lib/elm_widget_check.h
index bcf3eac1f..edeb3767e 100644
--- a/src/lib/elm_widget_check.h
+++ b/src/lib/elm_widget_check.h
@@ -26,8 +26,9 @@
 typedef struct _Elm_Check_Data Elm_Check_Data;
 struct _Elm_Check_Data
 {
-   Eina_Bool             state;
-   Eina_Bool            *statep;
+   Check_State             state;
+   Check_State            *statep;
+   Eina_Bool               three_state_mode;
 };
 
 /**