[feat, UX] frontlighwidget: Support for automatic warmth

If the device supports it, add a checkbox for enabling automatic
warmth, and a widget for setting the hour at which warmth should be
maximal ("bedtime").

The hour can be changed through +/- buttons; holding them will change
with 30min steps. As soon as automatic warmth is enabled, the 'warmth'
cannot be changed manually anymore, so we make its widget grey, but
the current value is still displayed correctly. Changing the hour
changes warmth accordingly.

frontend/ui/widget/frontlightwidget.lua

@@ -1,6 +1,7 @@
 local Blitbuffer = require("ffi/blitbuffer")
 local Button = require("ui/widget/button")
 local CenterContainer = require("ui/widget/container/centercontainer")
+local CheckButton = require("ui/widget/checkbutton")
 local CloseButton = require("ui/widget/closebutton")
 local Device = require("device")
 local FrameContainer = require("ui/widget/container/framecontainer")
@@ -34,6 +35,7 @@ local FrontLightWidget = InputContainer:new{
 
 function FrontLightWidget:init()
     self.medium_font_face = Font:getFace("ffont")
+    self.larger_font_face = Font:getFace("cfont")
     self.light_bar = {}
     self.screen_width = Screen:getWidth()
     self.screen_height = Screen:getHeight()
@@ -56,6 +58,7 @@ function FrontLightWidget:init()
     local button_margin = Size.margin.tiny
     local button_padding = Size.padding.button
     local button_bordersize = Size.border.button
+    self.auto_nl = false
     self.button_width = math.floor(self.screen_width * 0.9 / self.steps) -
             2 * (button_margin + button_padding + button_bordersize)
 
@@ -276,19 +279,32 @@ function FrontLightWidget:addWarmthWidgets(num_warmth, step, vertical_group)
     local button_group_down = HorizontalGroup:new{ align = "center" }
     local button_group_up = HorizontalGroup:new{ align = "center" }
     local warmth_group = HorizontalGroup:new{ align = "center" }
+    local auto_nl_group = HorizontalGroup:new{ align = "center" }
     local padding_span = VerticalSpan:new{ width = self.span }
     local enable_button_plus = true
     local enable_button_minus = true
+    local button_color = Blitbuffer.COLOR_WHITE
 
     if self[1] then
         self.powerd:setWarmth(num_warmth)
     end
 
+    if self.powerd.auto_warmth then
+        enable_button_plus = false
+        enable_button_minus = false
+        button_color = Blitbuffer.COLOR_GREY
+    else
+        if num_warmth == self.fl_max then enable_button_plus = false end
+        if num_warmth == self.fl_min then enable_button_minus = false end
+    end
+
     if self.natural_light and num_warmth then
         for i = 0, math.floor(num_warmth / step) do
             table.insert(warmth_group, self.fl_prog_button:new{
                              text = "",
                              preselect = true,
+                             enabled = not self.powerd.auto_warmth,
+                             background = button_color,
                              callback = function()
                                  self:setProgress(self.fl_cur, step, i * step)
                              end
@@ -298,6 +314,7 @@ function FrontLightWidget:addWarmthWidgets(num_warmth, step, vertical_group)
         for i = math.floor(num_warmth / step) + 1, self.steps - 1 do
             table.insert(warmth_group, self.fl_prog_button:new{
                              text="",
+                             enabled = not self.powerd.auto_warmth,
                              callback = function()
                                  self:setProgress(self.fl_cur, step, i * step)
                              end
@@ -305,9 +322,6 @@ function FrontLightWidget:addWarmthWidgets(num_warmth, step, vertical_group)
         end
     end
 
-    if num_warmth == self.fl_max then enable_button_plus = false end
-    if num_warmth == self.fl_min then enable_button_minus = false end
-
     local text_warmth = TextBoxWidget:new{
         text = "\n" .. _("Warmth"),
         face = self.medium_font_face,
@@ -343,7 +357,7 @@ function FrontLightWidget:addWarmthWidgets(num_warmth, step, vertical_group)
         text = _("Min"),
         margin = Size.margin.small,
         radius = 0,
-        enabled = true,
+        enabled = not self.powerd.auto_warmth,
         width = self.screen_width * 0.20,
         show_parent = self,
         callback = function() self:setProgress(self.fl_cur, step, self.fl_min) end,
@@ -352,7 +366,7 @@ function FrontLightWidget:addWarmthWidgets(num_warmth, step, vertical_group)
         text = _("Max"),
         margin = Size.margin.small,
         radius = 0,
-        enabled = true,
+        enabled = not self.powerd.auto_warmth,
         width = self.screen_width * 0.20,
         show_parent = self,
         callback = function() self:setProgress(self.fl_cur, step, self.fl_max) end,
@@ -372,9 +386,86 @@ function FrontLightWidget:addWarmthWidgets(num_warmth, step, vertical_group)
         empty_space,
         button_max,
     }
+    local checkbutton_auto_nl = CheckButton:new({
+            text = _("Automatic warmth"),
+            checked = self.powerd.auto_warmth,
+            callback = function()
+                if self.powerd.auto_warmth then
+                    self.powerd.auto_warmth = false
+                else
+                    self.powerd.auto_warmth = true
+                    self.powerd:calculateAutoWarmth()
+                end
+                self:setProgress(self.fl_cur, step)
+            end
+        })
+
+    local text_auto_nl = TextBoxWidget:new{
+        text = _("Maximum at:  "),
+        face = self.larger_font_face,
+        alignment = "right",
+        fgcolor = self.powerd.auto_warmth and Blitbuffer.COLOR_BLACK or
+            Blitbuffer.COLOR_GREY,
+        width = self.screen_width * 0.3
+    }
+    local text_hour = TextBoxWidget:new{
+        text = " " .. math.floor(self.powerd.max_warmth_hour) .. ":" ..
+            self.powerd.max_warmth_hour % 1 * 6 .. "0",
+        face = self.larger_font_face,
+        fgcolor =self.powerd.auto_warmth and Blitbuffer.COLOR_BLACK or
+            Blitbuffer.COLOR_GREY,
+        width = self.screen_width * 0.1
+    }
+    local button_minus_one_hour = Button:new{
+        text = "−",
+        margin = Size.margin.small,
+        radius = 0,
+        enabled = self.powerd.auto_warmth,
+        width = self.screen_width * 0.1,
+        show_parent = self,
+        callback = function()
+            self.powerd.max_warmth_hour =
+                (self.powerd.max_warmth_hour - 1) % 24
+            self.powerd:calculateAutoWarmth()
+            self:setProgress(self.fl_cur, step)
+        end,
+        hold_callback = function()
+            self.powerd.max_warmth_hour =
+                (self.powerd.max_warmth_hour - 0.5) % 24
+            self.powerd:calculateAutoWarmth()
+            self:setProgress(self.fl_cur, step)
+        end,
+    }
+    local button_plus_one_hour = Button:new{
+        text = "+",
+        margin = Size.margin.small,
+        radius = 0,
+        enabled = self.powerd.auto_warmth,
+        width = self.screen_width * 0.1,
+        show_parent = self,
+        callback = function()
+            self.powerd.max_warmth_hour =
+                (self.powerd.max_warmth_hour + 1) % 24
+            self.powerd:calculateAutoWarmth()
+            self:setProgress(self.fl_cur, step)
+        end,
+        hold_callback = function()
+            self.powerd.max_warmth_hour =
+                (self.powerd.max_warmth_hour + 0.5) % 24
+            self.powerd:calculateAutoWarmth()
+            self:setProgress(self.fl_cur, step)
+        end,
+    }
+
     table.insert(vertical_group,text_warmth)
     table.insert(button_group_up, button_table_up)
     table.insert(button_group_down, button_table_down)
+    table.insert(auto_nl_group, checkbutton_auto_nl)
+    table.insert(auto_nl_group, text_auto_nl)
+    table.insert(auto_nl_group, button_minus_one_hour)
+    table.insert(auto_nl_group, text_hour)
+    table.insert(auto_nl_group, button_plus_one_hour)
+
     table.insert(vertical_group,padding_span)
     table.insert(vertical_group,button_group_up)
     table.insert(vertical_group,padding_span)
@@ -382,6 +473,7 @@ function FrontLightWidget:addWarmthWidgets(num_warmth, step, vertical_group)
     table.insert(vertical_group,padding_span)
     table.insert(vertical_group,button_group_down)
     table.insert(vertical_group,padding_span)
+    table.insert(vertical_group,auto_nl_group)
 end
 
 function FrontLightWidget:update()