Handle generic joystick input

Unmapped handheld controllers emit joystick events, leaving the launcher
cursor and in-game input inactive.

main.lua

@@ -331,6 +331,30 @@ function love.gamepadaxis(joystick, axis, value)
   Game:gamepadaxis(joystick, axis, value)
 end
 
+function love.joystickpressed(joystick, button)
+  if editorMode then return end
+  if Importer then return Importer:joystickpressed(joystick, button) end
+  Game:joystickpressed(joystick, button)
+end
+
+function love.joystickreleased(joystick, button)
+  if editorMode then return end
+  if Importer then return Importer:joystickreleased(joystick, button) end
+  Game:joystickreleased(joystick, button)
+end
+
+function love.joystickaxis(joystick, axis, value)
+  if editorMode then return end
+  if Importer then return Importer:joystickaxis(joystick, axis, value) end
+  Game:joystickaxis(joystick, axis, value)
+end
+
+function love.joystickhat(joystick, hat, direction)
+  if editorMode then return end
+  if Importer then return Importer:joystickhat(joystick, hat, direction) end
+  Game:joystickhat(joystick, hat, direction)
+end
+
 function love.joystickremoved(joystick)
   if editorMode then return end
   if Importer then return end

src/core/Game.lua

@@ -491,6 +491,25 @@ function Game:gamepadaxis(joystick, axis, value)
   Input:gamepadaxis(joystick, axis, value)
 end
 
+function Game:joystickpressed(joystick, button)
+  TouchControls:noteGamepad()
+  Input:joystickpressed(joystick, button)
+end
+
+function Game:joystickreleased(joystick, button)
+  Input:joystickreleased(joystick, button)
+end
+
+function Game:joystickaxis(joystick, axis, value)
+  if math.abs(value) > 0.5 then TouchControls:noteGamepad() end
+  Input:joystickaxis(joystick, axis, value)
+end
+
+function Game:joystickhat(joystick, hat, direction)
+  if direction ~= "c" then TouchControls:noteGamepad() end
+  Input:joystickhat(joystick, hat, direction)
+end
+
 -- Window focus/visibility flips: a release due while unfocused/hidden can
 -- be swallowed by the OS. Reset on both edges -- gaining focus with a
 -- physically held key won't re-fire keypressed, so trusting leftover

src/core/Input.lua

@@ -39,6 +39,20 @@ local DEFAULT_GAMEPAD_BINDINGS = {
 local STICK_ON = 0.5
 local STICK_OFF = 0.3
 
+-- Generic SDL joysticks expose the left stick as the first two numbered
+-- axes and the D-pad as a hat.  This is common on Linux handhelds whose
+-- controller has no game-controller database entry.
+local RAW_BUTTON_BINDINGS = {
+  [1] = "a", [2] = "b",
+  [7] = "select", [8] = "start", [9] = "select", [10] = "start",
+}
+
+local HAT_DIRECTIONS = {
+  u = { "up" }, d = { "down" }, l = { "left" }, r = { "right" },
+  lu = { "left", "up" }, ru = { "right", "up" },
+  ld = { "left", "down" }, rd = { "right", "down" },
+}
+
 function Input:init()
   self:applyBindings(nil)
   self:reset()
@@ -79,6 +93,7 @@ function Input:reset()
   self.sources = {}
   self.stickAxis = { x = 0, y = 0 }
   self.stickDir = nil
+  self.hatDirs = {}
 end
 
 -- Multiple physical sources (W + Up, d-pad + stick, etc.) can claim the
@@ -179,6 +194,16 @@ function Input:gamepadreleased(joystick, button)
   end
 end
 
+function Input:joystickpressed(joystick, button)
+  local btn = RAW_BUTTON_BINDINGS[button]
+  if btn then press(self, btn, "joy:" .. button) end
+end
+
+function Input:joystickreleased(joystick, button)
+  local btn = RAW_BUTTON_BINDINGS[button]
+  if btn then release(self, btn, "joy:" .. button) end
+end
+
 -- left stick treated as a continuous held direction, same 4-way rule as
 -- the touch swipe d-pad: whichever axis has the larger magnitude wins.
 function Input:gamepadaxis(joystick, axis, value)
@@ -214,6 +239,26 @@ function Input:gamepadaxis(joystick, axis, value)
   end
 end
 
+function Input:joystickaxis(joystick, axis, value)
+  if axis == 1 then
+    self:gamepadaxis(joystick, "leftx", value)
+  elseif axis == 2 then
+    self:gamepadaxis(joystick, "lefty", value)
+  end
+end
+
+function Input:joystickhat(joystick, hat, direction)
+  local source = "hat:" .. hat
+  for _, btn in ipairs(self.hatDirs[hat] or {}) do
+    release(self, btn, source)
+  end
+  local dirs = HAT_DIRECTIONS[direction] or {}
+  for _, btn in ipairs(dirs) do
+    press(self, btn, source)
+  end
+  self.hatDirs[hat] = dirs
+end
+
 function Input:isDown(btn)
   return self.state[btn] or false
 end

src/import/RomImporter.lua

@@ -540,6 +540,7 @@ function RomImporter.new(onComplete, opts)
     _padCursorActive = false,
     _padAxis = { leftx = 0, lefty = 0, righty = 0 },
     _padDir = {},
+    _rawHatDirs = {},
     _padInited = false,
   }, RomImporter)
 
@@ -1184,6 +1185,36 @@ function RomImporter:gamepadaxis(_, axis, value)
   end
 end
 
+function RomImporter:joystickpressed(joystick, button)
+  if button == 1 then self:gamepadpressed(joystick, "a") end
+end
+
+function RomImporter:joystickreleased(joystick, button)
+  if button == 1 then self:gamepadreleased(joystick, "a") end
+end
+
+function RomImporter:joystickaxis(joystick, axis, value)
+  if axis == 1 then
+    self:gamepadaxis(joystick, "leftx", value)
+  elseif axis == 2 then
+    self:gamepadaxis(joystick, "lefty", value)
+  end
+end
+
+function RomImporter:joystickhat(_, hat, direction)
+  for _, dir in ipairs(self._rawHatDirs[hat] or {}) do
+    self._padDir[dir] = nil
+  end
+  local dirs = ({
+    u = { "dpup" }, d = { "dpdown" }, l = { "dpleft" }, r = { "dpright" },
+    lu = { "dpleft", "dpup" }, ru = { "dpright", "dpup" },
+    ld = { "dpleft", "dpdown" }, rd = { "dpright", "dpdown" },
+  })[direction] or {}
+  for _, dir in ipairs(dirs) do self._padDir[dir] = true end
+  self._rawHatDirs[hat] = dirs
+  if #dirs > 0 then self:_activatePadCursor() end
+end
+
 -- Player pressed Play on a game whose ROM is imported: hand off to boot.
 function RomImporter:play(version)
   if self.workState == "working" then return end

src/update/Boot.lua

@@ -50,7 +50,9 @@ local CALLBACK_NAMES = {
   "keypressed", "keyreleased", "textinput",
   "mousepressed", "mousereleased", "mousemoved", "wheelmoved",
   "touchpressed", "touchmoved", "touchreleased",
-  "gamepadpressed", "gamepadreleased", "gamepadaxis", "joystickremoved",
+  "gamepadpressed", "gamepadreleased", "gamepadaxis",
+  "joystickpressed", "joystickreleased", "joystickaxis", "joystickhat",
+  "joystickremoved",
   "focus", "visible", "resize", "filedropped", "directorydropped",
   "errorhandler", "threaderror", "lowmemory",
 }

tests/input_hold_test.lua

@@ -46,6 +46,51 @@ Input:step()
 check(Input:wasPressed("left"), "stick flick edges wasPressed")
 check(not Input:isDown("left"), "stick flick does not stick isDown")
 
+-- Linux handhelds without an SDL game-controller mapping send raw joystick
+-- axes and D-pad hats instead of gamepad events.
+Input:reset()
+Input:joystickaxis(nil, 1, -0.9)
+Input:step()
+check(Input:isDown("left"), "raw joystick left axis holds left")
+Input:joystickaxis(nil, 1, 0)
+check(not Input:isDown("left"), "raw joystick axis release clears left")
+
+Input:reset()
+Input:joystickhat(nil, 1, "u")
+Input:step()
+check(Input:isDown("up"), "raw joystick hat holds up")
+Input:joystickhat(nil, 1, "c")
+check(not Input:isDown("up"), "raw joystick hat release clears up")
+
+Input:reset()
+Input:joystickpressed(nil, 1)
+Input:step()
+check(Input:isDown("a"), "raw joystick primary button presses A")
+
+-- The launcher has a separate virtual cursor, so prove generic joystick
+-- events reach its left-stick and D-pad state too.
+local RomImporter = require("src.import.RomImporter")
+local importer = setmetatable({
+  _padCursor = { x = 0, y = 0 }, _padCursorActive = false,
+  _padAxis = { leftx = 0, lefty = 0, righty = 0 },
+  _padDir = {}, _rawHatDirs = {}, _padInited = true,
+}, RomImporter)
+local clicked = false
+function importer:mousepressed(_, _, button)
+  clicked = button == 1
+end
+importer:joystickaxis(nil, 1, -0.8)
+check(importer._padAxis.leftx == -0.8,
+  "raw joystick left axis reaches the launcher cursor")
+importer:joystickhat(nil, 1, "r")
+check(importer._padDir.dpright,
+  "raw joystick hat reaches the launcher cursor")
+importer:joystickhat(nil, 1, "c")
+check(not importer._padDir.dpright,
+  "raw joystick hat release clears the launcher cursor")
+importer:joystickpressed(nil, 1)
+check(clicked, "raw joystick primary button clicks the launcher cursor")
+
 -- Drivers that only inject pressQueue still get a one-step hold.
 Input:reset()
 table.insert(Input.pressQueue, "down")