Add cursor overlay in beta (#65)

lib/accessibility_buffer.lua

@@ -169,6 +169,21 @@ function AccessibilityBuffer:getRangeForLineNumber(lineNumber)
   return Selection.fromRange(range)
 end
 
+function AccessibilityBuffer:isAtLastVisibleCharacter()
+  local visibleRange = self
+    :getCurrentElement()
+    :attributeValue("AXVisibleCharacterRange")
+
+  if not visibleRange then return false end
+
+  local selection = self:getSelectionRange()
+  if not selection then return false end
+
+  local lastVisibleIndex = visibleRange.length + visibleRange.location
+
+  return lastVisibleIndex <= selection.location
+end
+
 function AccessibilityBuffer.getCurrentApplication()
   return ax.applicationElement(hs.application.frontmostApplication())
 end

lib/block_cursor.lua

@@ -0,0 +1,85 @@
+local AccessibilityBuffer = dofile(vimModeScriptPath .. "lib/accessibility_buffer.lua")
+
+local BlockCursor = {}
+
+function BlockCursor:new()
+  local canvas = hs.canvas.new({ x = 0, y = 0, h = 1, w = 1 })
+  local rectangleElementIndex = 1
+
+  canvas:level('overlay')
+  canvas:insertElement(
+    {
+      type = 'rectangle',
+      action = 'fill',
+      fillColor = { red = 0, green = 0, blue = 0, alpha = 0.2 },
+      frame = { x = "0%", y = "0%", h = "100%", w = "100%", },
+      withShadow = false
+    },
+    rectangleElementIndex
+  )
+
+  local cursor = {
+    canvas = canvas,
+  }
+
+  setmetatable(cursor, self)
+  self.__index = self
+
+  cursor.redrawTimer = hs.timer.new(1 / 60, function()
+    local result = cursor:_renderFrame()
+
+    if not result then
+      cursor:hide()
+    end
+  end)
+
+  return cursor
+end
+
+function BlockCursor:show()
+  if self.canvas:isShowing() then return nil end
+
+  self.redrawTimer:start()
+  self.canvas:show()
+end
+
+function BlockCursor:hide()
+  if not self.canvas:isShowing() then return nil end
+
+  self.canvas:hide()
+  self.redrawTimer:stop()
+end
+
+-- Renders a single frame. Returns `true` if successful.
+function BlockCursor:_renderFrame()
+  local buffer = AccessibilityBuffer:new()
+  if not buffer:isValid() then return false end
+
+  local currentElement = buffer:getCurrentElement()
+
+  -- We don't want to draw the cursor if we're at the end of the textbox (or
+  -- past the end!)
+  if buffer:isAtLastVisibleCharacter() then return false end
+
+  -- Get the range for the next character after the blinking cursor
+  local range = buffer:getSelectionRange()
+  local caretRange = {
+    location = range.location,
+    length = 1,
+  }
+
+  -- Get the { h, w, x, y } bounding box for the next character's range so we
+  -- can draw over it.
+  local bounds = currentElement:parameterizedAttributeValue(
+    "AXBoundsForRange",
+    caretRange
+  )
+
+  -- move the position and resize
+  self.canvas:topLeft({ x = bounds.x, y = bounds.y })
+  self.canvas:size({ h = bounds.h, w = bounds.w })
+
+  return true
+end
+
+return BlockCursor

lib/config.lua

@@ -8,8 +8,9 @@ function Config:new(options)
     alert = {
       font = "Courier New"
     },
+    betaFeatures = {},
     shouldShowAlertInNormalMode = true,
-    shouldDimScreenInNormalMode = true
+    shouldDimScreenInNormalMode = true,
   }
 
   setmetatable(config, self)
@@ -26,4 +27,16 @@ function Config:setOptions(options)
   end
 end
 
+function Config:isBetaFeatureEnabled(feature)
+  return not not self.betaFeatures[feature]
+end
+
+function Config:enableBetaFeature(feature)
+  self.betaFeatures[feature] = true
+end
+
+function Config:disableBetaFeature(feature)
+  self.betaFeatures[feature] = false
+end
+
 return Config

lib/state.lua

@@ -29,13 +29,15 @@ local function createStateMachine(vim)
     },
     callbacks = {
       onenterNormal = function()
+        vim:enableBlockCursor()
         vim:disableSequence()
         vim:resetCommandState()
         vim:setNormalMode()
         vim:enterModal('normal')
       end,
       onenterInsert = function()
         vim.visualCaretPosition = nil
+        vim:disableBlockCursor()
         vim:exitAllModals()
         vim:setInsertMode()
         vim:resetCommandState()

lib/vim.lua

@@ -20,6 +20,7 @@ dofile(vimModeScriptPath .. "lib/utils/benchmark.lua")
 local AccessibilityBuffer = dofile(vimModeScriptPath .. "lib/accessibility_buffer.lua")
 local AccessibilityStrategy = dofile(vimModeScriptPath .. "lib/strategies/accessibility_strategy.lua")
 local AppWatcher = dofile(vimModeScriptPath .. "lib/app_watcher.lua")
+local BlockCursor = dofile(vimModeScriptPath .. "lib/block_cursor.lua")
 local CommandState = dofile(vimModeScriptPath .. "lib/command_state.lua")
 local Config = dofile(vimModeScriptPath .. "lib/config.lua")
 local KeySequence = dofile(vimModeScriptPath .. "lib/key_sequence.lua")
@@ -51,6 +52,7 @@ function VimMode:new()
 
   vim:resetCommandState()
 
+  vim.blockCursor = BlockCursor:new()
   vim.config = Config:new()
   vim.enabled = true
   vim.mode = 'insert'
@@ -98,6 +100,10 @@ end
 
 ---------------------------
 
+function VimMode:enableBetaFeature(feature)
+  self.config:enableBetaFeature(feature)
+end
+
 function VimMode:shouldShowAlertInNormalMode(showAlert)
   self.config.shouldShowAlertInNormalMode = showAlert
   return self
@@ -220,6 +226,18 @@ function VimMode:exit()
   self.state:enterInsert()
 end
 
+function VimMode:enableBlockCursor()
+  if not self.config:isBetaFeatureEnabled('block_cursor_overlay') then return end
+
+  self.blockCursor:show()
+end
+
+function VimMode:disableBlockCursor()
+  if not self.config:isBetaFeatureEnabled('block_cursor_overlay') then return end
+
+  self.blockCursor:hide()
+end
+
 function VimMode:setInsertMode()
   self.mode = "insert"