frontlightwidget: Add widgets for changing 'warmth' if available

If the device supports natural light (currently only KA1), extend the
frontlight widget to also allow for changing the 'warmth' value. We
more or less duplicate the widget for 'brightness', with the exception
that we drop the 'toggle' button, which does not make much sense for
the frontlight's warmth. Also, we add captions 'Brightness' and
'Warmth' for clarity.

frontend/ui/widget/frontlightwidget.lua

@@ -47,6 +47,7 @@ function FrontLightWidget:init()
         self.steps = self.steps + 1
     end
     self.steps = math.min(self.steps , steps_fl)
+    self.natural_light = Device:isKobo() and Device:hasNaturalLight()
 
     -- button width to fit screen size
     local button_margin = Size.margin.tiny
@@ -95,7 +96,7 @@ function FrontLightWidget:generateProgressGroup(width, height, fl_level, step)
     return self.fl_container
 end
 
-function FrontLightWidget:setProgress(num, step)
+function FrontLightWidget:setProgress(num, step, num_warmth)
     self.fl_container:clear()
     local padding_span = VerticalSpan:new{ width = self.span }
     local button_group_down = HorizontalGroup:new{ align = "center" }
@@ -107,6 +108,9 @@ function FrontLightWidget:setProgress(num, step)
     local enable_button_minus = true
     local step_num = math.floor(num / step)
     local step_min = math.floor(self.fl_min / step)
+    if self.natural_light then
+        num_warmth = num_warmth or self.powerd.fl_warmth
+    end
     if num then
         self.fl_cur = num
         set_fl = math.min(self.fl_cur, self.fl_max)
@@ -147,6 +151,13 @@ function FrontLightWidget:setProgress(num, step)
             callback = function() self:setProgress(i * step, step) end
         })
     end
+    local text_br = TextBoxWidget:new{
+        text = _("Brightness"),
+        face = self.medium_font_face,
+        bold = true,
+        alignment = "center",
+        width = self.screen_width * 0.95
+    }
     local button_minus = Button:new{
         text = "-1",
         margin = Size.margin.small,
@@ -217,6 +228,11 @@ function FrontLightWidget:setProgress(num, step)
         empty_space,
         button_max,
     }
+    if self.natural_light then
+        -- Only insert 'brightness' caption if we also add 'warmth'
+        -- widgets below.
+        table.insert(vertical_group,text_br)
+    end
     table.insert(button_group_up, button_table_up)
     table.insert(button_group_down, button_table_down)
     table.insert(vertical_group,padding_span)
@@ -226,6 +242,10 @@ function FrontLightWidget:setProgress(num, step)
     table.insert(vertical_group,padding_span)
     table.insert(vertical_group,button_group_down)
     table.insert(vertical_group,padding_span)
+    if self.natural_light then
+        -- If the device supports natural light, add the widgets for 'warmth'.
+        self:addWarmthWidgets(num_warmth, step, vertical_group)
+    end
     table.insert(self.fl_container, vertical_group)
     -- Reset container height to what it actually contains
     self.fl_container.dimen.h = vertical_group:getSize().h
@@ -234,6 +254,120 @@ function FrontLightWidget:setProgress(num, step)
     return true
 end
 
+-- Currently, we are assuming the 'warmth' has the same min/max limits
+-- as 'brightness'.
+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 padding_span = VerticalSpan:new{ width = self.span }
+    local enable_button_plus = true
+    local enable_button_minus = true
+
+    if self[1] then
+        self.powerd:setWarmth(num_warmth)
+    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,
+                             callback = function()
+                                 self:setProgress(self.fl_cur, step, i * step)
+                             end
+            })
+        end
+
+        for i = math.floor(num_warmth / step) + 1, self.steps - 1 do
+            table.insert(warmth_group, self.fl_prog_button:new{
+                             text="",
+                             callback = function()
+                                 self:setProgress(self.fl_cur, step, i * step)
+                             end
+            })
+        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,
+        bold = true,
+        alignment = "center",
+        width = self.screen_width * 0.95
+    }
+    local button_minus = Button:new{
+        text = "-1",
+        margin = Size.margin.small,
+        radius = 0,
+        enabled = enable_button_minus,
+        width = self.screen_width * 0.20,
+        show_parent = self,
+        callback = function()  self:setProgress(self.fl_cur, step, num_warmth - 1) end,
+    }
+    local button_plus = Button:new{
+        text = "+1",
+        margin = Size.margin.small,
+        radius = 0,
+        enabled = enable_button_plus,
+        width = self.screen_width * 0.20,
+        show_parent = self,
+        callback = function() self:setProgress(self.fl_cur, step, num_warmth + 1) end,
+    }
+    local item_level = TextBoxWidget:new{
+        text = num_warmth,
+        face = self.medium_font_face,
+        alignment = "center",
+        width = self.screen_width * 0.95 - 1.275 * button_minus.width - 1.275 * button_plus.width,
+    }
+    local button_min = Button:new{
+        text = _("Min"),
+        margin = Size.margin.small,
+        radius = 0,
+        enabled = true,
+        width = self.screen_width * 0.20,
+        show_parent = self,
+        callback = function() self:setProgress(self.fl_cur, step, self.fl_min) end,
+    }
+    local button_max = Button:new{
+        text = _("Max"),
+        margin = Size.margin.small,
+        radius = 0,
+        enabled = true,
+        width = self.screen_width * 0.20,
+        show_parent = self,
+        callback = function() self:setProgress(self.fl_cur, step, self.fl_max) end,
+    }
+    local empty_space = HorizontalSpan:new{
+        width = (self.screen_width * 0.95 - 1.2 * button_minus.width - 1.2 * button_plus.width) / 2,
+    }
+    local button_table_up = HorizontalGroup:new{
+        align = "center",
+        button_minus,
+        item_level,
+        button_plus,
+    }
+    local button_table_down = HorizontalGroup:new{
+        align = "center",
+        button_min,
+        empty_space,
+        button_max,
+    }
+    table.insert(vertical_group,text_warmth)
+    table.insert(button_group_up, button_table_up)
+    table.insert(button_group_down, button_table_down)
+    table.insert(vertical_group,padding_span)
+    table.insert(vertical_group,button_group_up)
+    table.insert(vertical_group,padding_span)
+    table.insert(vertical_group,warmth_group)
+    table.insert(vertical_group,padding_span)
+    table.insert(vertical_group,button_group_down)
+    table.insert(vertical_group,padding_span)
+end
+
 function FrontLightWidget:update()
     -- header
     self.light_title = FrameContainer:new{