Screenshoter: propose to set as screensaver image (#4113)

frontend/ui/widget/screenshoter.lua

@@ -1,13 +1,12 @@
-local InputContainer = require("ui/widget/container/inputcontainer")
-local InfoMessage = require("ui/widget/infomessage")
-local GestureRange = require("ui/gesturerange")
+local ConfirmBox = require("ui/widget/confirmbox")
 local DataStorage = require("datastorage")
+local GestureRange = require("ui/gesturerange")
+local InputContainer = require("ui/widget/container/inputcontainer")
 local UIManager = require("ui/uimanager")
 local Screen = require("device").screen
 local T = require("ffi/util").template
 local _ = require("gettext")
 
-
 local Screenshoter = InputContainer:new{
     prefix = 'Screenshot',
 }
@@ -39,10 +38,16 @@ end
 
 function Screenshoter:onScreenshot(filename)
     local screenshot_name = filename or os.date(self.screenshot_fn_fmt)
-    UIManager:show(InfoMessage:new{
-        text = T( _("Saving screenshot to %1."), screenshot_name),
-        timeout = 3,
-    })
+    local widget = ConfirmBox:new{
+        text = T( _("Saving screenshot to %1.\nWould you like to set it as screensaver?"), screenshot_name),
+        ok_text = _("Yes"),
+        ok_callback = function()
+            G_reader_settings:saveSetting("screensaver_type", "image_file")
+            G_reader_settings:saveSetting("screensaver_image", screenshot_name)
+        end,
+        cancel_text = _("No"),
+    }
+    UIManager:show(widget)
     Screen:shot(screenshot_name)
     -- trigger full refresh
     UIManager:setDirty(nil, "full")