Partially implement new UI mockup

The GiveBack flag now has a dedicated row with a switch, rather than a
toggle button the row labeled "Flags".  That GiveBack is one of several
flags seems like an implementation detail from the high level of a GUI.

There is now a combo box to select the dimension of the current-setting
value.  Changing this combo box automatically changes the value to keep
the current the same at the present voltage.  The correct item is
selected when a Sink is chosen from the list, and the unit label always
updates to match the dimension.

data/pd-buddy-gtk.ui

                                                 <property name="label" translatable="yes">_Voltage</property>
                                                 <property name="use_underline">True</property>
                                                 <property name="justify">right</property>
+                                                <property name="mnemonic_widget">voltage-spinbutton</property>
                                               </object>
                                               <packing>
                                                 <property name="left_attach">0</property>
                                                 <property name="can_focus">False</property>
                                                 <property name="halign">start</property>
                                                 <property name="label" translatable="yes">V</property>
+                                                <property name="width_chars">2</property>
                                               </object>
                                               <packing>
                                                 <property name="left_attach">2</property>
                                               <object class="GtkSpinButton" id="voltage-spinbutton">
                                                 <property name="visible">True</property>
                                                 <property name="can_focus">True</property>
-                                                <property name="width_chars">5</property>
+                                                <property name="width_chars">6</property>
                                                 <property name="text" translatable="yes">0.00</property>
                                                 <property name="xalign">1</property>
                                                 <property name="input_purpose">number</property>
                                             <property name="margin_top">6</property>
                                             <property name="margin_bottom">6</property>
                                             <property name="column_spacing">12</property>
-                                            <child>
-                                              <object class="GtkLabel">
-                                                <property name="visible">True</property>
-                                                <property name="can_focus">False</property>
-                                                <property name="halign">start</property>
-                                                <property name="hexpand">True</property>
-                                                <property name="label" translatable="yes">_Current</property>
-                                                <property name="use_underline">True</property>
-                                                <property name="justify">right</property>
-                                                <property name="mnemonic_widget">current-spinbutton</property>
-                                              </object>
-                                              <packing>
-                                                <property name="left_attach">0</property>
-                                                <property name="top_attach">0</property>
-                                              </packing>
-                                            </child>
                                             <child>
                                               <object class="GtkSpinButton" id="current-spinbutton">
                                                 <property name="visible">True</property>
                                                 <property name="can_focus">True</property>
                                                 <property name="margin_left">12</property>
-                                                <property name="width_chars">5</property>
+                                                <property name="width_chars">6</property>
                                                 <property name="xalign">1</property>
                                                 <property name="input_purpose">number</property>
                                                 <property name="adjustment">current-adjustment</property>
                                               </packing>
                                             </child>
                                             <child>
-                                              <object class="GtkLabel">
+                                              <object class="GtkLabel" id="current-unit">
                                                 <property name="visible">True</property>
                                                 <property name="can_focus">False</property>
                                                 <property name="halign">start</property>
                                                 <property name="label" translatable="yes">A</property>
+                                                <property name="width_chars">2</property>
                                               </object>
                                               <packing>
                                                 <property name="left_attach">2</property>
                                                 <property name="top_attach">0</property>
                                               </packing>
                                             </child>
+                                            <child>
+                                              <object class="GtkComboBoxText" id="current-dimension">
+                                                <property name="visible">True</property>
+                                                <property name="can_focus">False</property>
+                                                <property name="halign">start</property>
+                                                <property name="hexpand">True</property>
+                                                <property name="active_id">idim-current</property>
+                                                <items>
+                                                  <item id="idim-current" translatable="yes">Current</item>
+                                                  <item id="idim-power" translatable="yes">Power</item>
+                                                  <item id="idim-resistance" translatable="yes">Resistance</item>
+                                                </items>
+                                                <signal name="changed" handler="on_current_dimension_changed" swapped="no"/>
+                                              </object>
+                                              <packing>
+                                                <property name="left_attach">0</property>
+                                                <property name="top_attach">0</property>
+                                              </packing>
+                                            </child>
                                           </object>
                                         </child>
                                       </object>
                                                 <property name="can_focus">False</property>
                                                 <property name="halign">start</property>
                                                 <property name="hexpand">True</property>
-                                                <property name="label" translatable="yes">Flags</property>
+                                                <property name="label" translatable="yes">_GiveBack</property>
+                                                <property name="use_underline">True</property>
                                                 <property name="justify">right</property>
+                                                <property name="mnemonic_widget">giveback-switch</property>
                                               </object>
                                               <packing>
                                                 <property name="left_attach">0</property>
                                               </packing>
                                             </child>
                                             <child>
-                                              <object class="GtkButtonBox">
+                                              <object class="GtkSwitch" id="giveback-switch">
                                                 <property name="visible">True</property>
-                                                <property name="can_focus">False</property>
-                                                <property name="halign">start</property>
-                                                <property name="layout_style">expand</property>
-                                                <child>
-                                                  <object class="GtkToggleButton" id="giveback-toggle">
-                                                    <property name="label" translatable="yes">_GiveBack</property>
-                                                    <property name="visible">True</property>
-                                                    <property name="can_focus">True</property>
-                                                    <property name="receives_default">True</property>
-                                                    <property name="use_underline">True</property>
-                                                    <signal name="toggled" handler="on_giveback_toggle_toggled" swapped="no"/>
-                                                  </object>
-                                                  <packing>
-                                                    <property name="expand">True</property>
-                                                    <property name="fill">True</property>
-                                                    <property name="position">0</property>
-                                                  </packing>
-                                                </child>
+                                                <property name="can_focus">True</property>
+                                                <signal name="state-set" handler="on_giveback_switch_state_set" swapped="no"/>
                                               </object>
                                               <packing>
                                                 <property name="left_attach">1</property>
                                                 <property name="visible">True</property>
                                                 <property name="can_focus">False</property>
                                                 <property name="halign">start</property>
-                                                <property name="label" translatable="yes">_Source Capabilities</property>
+                                                <property name="label" translatable="yes">Source _Capabilities</property>
                                                 <property name="use_underline">True</property>
                                                 <property name="justify">right</property>
                                                 <property name="mnemonic_widget">source-cap-row</property>

pd-buddy-gtk.py

         # Get relevant widgets
         voltage = self.builder.get_object("voltage-adjustment")
         current = self.builder.get_object("current-adjustment")
-        giveback = self.builder.get_object("giveback-toggle")
+        current_dim = self.builder.get_object("current-dimension")
+        giveback = self.builder.get_object("giveback-switch")
         pd_frame = self.builder.get_object("power-delivery-frame")
         output = self.builder.get_object("output-switch")
         cap_row = self.builder.get_object("source-cap-row")
         self._store_device_settings()
         self._set_save_button_visibility()
 
-        # Set giveback button state
+        # Set giveback switch state
         giveback.set_active(bool(self.cfg.flags & pdbuddy.SinkFlags.GIVEBACK))
 
         # Get voltage and current from device and load them into the GUI
         voltage.set_value(self.cfg.v/1000)
 
+        if self.cfg.idim == pdbuddy.SinkDimension.CURRENT:
+            current_dim.set_active_id("idim-current")
+        elif self.cfg.idim == pdbuddy.SinkDimension.POWER:
+            current_dim.set_active_id("idim-power")
+        elif self.cfg.idim == pdbuddy.SinkDimension.RESISTANCE:
+            current_dim.set_active_id("idim-resistance")
         current.set_value(self.cfg.i/1000)
 
         # Set PD frame visibility and output switch state
 
         self._set_save_button_visibility()
 
+    def on_current_dimension_changed(self, cb):
+        item = cb.get_active_id()
+        value = self.builder.get_object("current-adjustment")
+        unit = self.builder.get_object("current-unit")
+
+        if item == "idim-current":
+            if self.cfg.idim == pdbuddy.SinkDimension.POWER:
+                self.cfg = self.cfg._replace(i=self.cfg.i/self.cfg.v*1000.0)
+            elif self.cfg.idim == pdbuddy.SinkDimension.RESISTANCE:
+                self.cfg = self.cfg._replace(i=self.cfg.v/self.cfg.i*1000.0)
+            value.configure(self.cfg.i / 1000.0, 0, 5, 0.1, 1, 0)
+            idim = pdbuddy.SinkDimension.CURRENT
+            unit.set_text("A")
+        if item == "idim-power":
+            if self.cfg.idim == pdbuddy.SinkDimension.CURRENT:
+                self.cfg = self.cfg._replace(i=self.cfg.i*self.cfg.v/1000.0)
+            elif self.cfg.idim == pdbuddy.SinkDimension.RESISTANCE:
+                self.cfg = self.cfg._replace(
+                        i=self.cfg.v*self.cfg.v/self.cfg.i)
+            idim = pdbuddy.SinkDimension.POWER
+            value.configure(self.cfg.i / 1000.0, 0, 100, 1, 10, 0)
+            unit.set_text("W")
+        if item == "idim-resistance":
+            if self.cfg.idim == pdbuddy.SinkDimension.CURRENT:
+                self.cfg = self.cfg._replace(i=self.cfg.v/self.cfg.i*1000.0)
+            elif self.cfg.idim == pdbuddy.SinkDimension.POWER:
+                self.cfg = self.cfg._replace(
+                        i=self.cfg.v*self.cfg.v/self.cfg.i)
+            idim = pdbuddy.SinkDimension.RESISTANCE
+            value.configure(self.cfg.i / 1000.0, 0, 655.35, 1, 10, 0)
+            unit.set_text("\u03a9")
+
+        self.cfg = self.cfg._replace(idim=idim)
+
+        self._set_save_button_visibility()
+
     def on_current_adjustment_value_changed(self, adj):
         self.cfg = self.cfg._replace(i=int(adj.get_value() * 1000))
 
         self._set_save_button_visibility()
 
-    def on_giveback_toggle_toggled(self, toggle):
-        if toggle.get_active():
+    def on_giveback_switch_state_set(self, switch, state):
+        if state:
             self.cfg = self.cfg._replace(flags=self.cfg.flags|pdbuddy.SinkFlags.GIVEBACK)
         else:
             self.cfg = self.cfg._replace(flags=self.cfg.flags&~pdbuddy.SinkFlags.GIVEBACK)