[feat, UX] SDL: add Gtk3 filechooser (#3827)

The specifics for other implementations are easy to change in the backend.

frontend/device/input.lua

@@ -114,6 +114,7 @@ local Input = {
     -- keyboard state:
     modifiers = {
         Alt = false,
+        Ctrl = false,
         Shift = false,
     },
 
@@ -301,9 +302,22 @@ function Input:handleKeyBoardEv(ev)
         end
     end
 
+    local FileChooser = self.file_chooser
+    if FileChooser and self:isEvKeyPress(ev)
+    and self.modifiers["Ctrl"] and keycode == "O" then
+        logger.dbg("Opening FileChooser:", FileChooser.type)
+        local file_path = FileChooser:open()
+
+        if file_path then
+            local ReaderUI = require("apps/reader/readerui")
+            ReaderUI:doShowReader(file_path)
+        end
+        return
+    end
+
     -- quit on Alt + F4
     -- this is also emitted by the close event in SDL
-    if self.modifiers["Alt"] and keycode == "F4" then
+    if self:isEvKeyPress(ev) and self.modifiers["Alt"] and keycode == "F4" then
         local Device = require("frontend/device")
         local UIManager = require("ui/uimanager")
 

frontend/device/sdl/device.lua

@@ -49,6 +49,7 @@ function Device:init()
 
                 -- SDL events can remain cdata but are almost completely transparent
                 local SDL_MOUSEWHEEL = 1027
+                local SDL_MULTIGESTURE = 2050
                 local SDL_DROPFILE = 4096
                 local SDL_WINDOWEVENT_RESIZED = 5
 
@@ -99,6 +100,9 @@ function Device:init()
                         UIManager:broadcastEvent(fake_pan_ev)
                         UIManager:broadcastEvent(fake_release_ev)
                     end
+                elseif ev.code == SDL_MULTIGESTURE then
+                    -- no-op for now
+                    do end -- luacheck: ignore 541
                 elseif ev.code == SDL_DROPFILE then
                     local dropped_file_path = ev.value
                     if dropped_file_path and dropped_file_path ~= "" then
@@ -132,6 +136,7 @@ function Device:init()
             setClipboardText = function(text)
                 return input.setClipboardText(text)
             end,
+            file_chooser = input.file_chooser,
         }
     else
         self.screen = require("ffi/framebuffer_SDL1_2"):new{device = self, debug = logger.dbg}

frontend/device/sdl/event_map_sdl2.lua

@@ -32,4 +32,7 @@ return {
     [81] = "Down", -- arrow down
     [78] = "RPgFwd", -- normal PageDown
     [76] = "Del", -- Delete
+    [101] = "ContextMenu", -- Context menu key
+    [224] = "Ctrl", -- Left Ctrl
+    [228] = "Ctrl", -- Right Ctrl
 }