Clean up text widget.

This fixes a visual bug where the highlighted area wouldn't update
when the widget was reshaped, and fixes some weirdness with local
functions in preparation for exposing them as part of a rich API
for the text widget.

luigi/widget/text.lua

@@ -8,47 +8,38 @@ local ROOT = (...):gsub('[^.]*.[^.]*$', '')
 local utf8 = require(ROOT .. 'utf8')
 local Backend = require(ROOT .. 'backend')
 
+local function updateHighlight (self)
+    local value = self.value
+    local font = self:getFont()
+    local startIndex, endIndex = self.startIndex, self.endIndex
+    local offset = self:getRectangle(true, true) - self.scrollX
+    self.startX = font:getAdvance(value:sub(1, startIndex)) + offset
+    self.endX = font:getAdvance(value:sub(1, endIndex)) + offset
+end
+
 local function scrollToCaret (self)
     local x1, y1, w, h = self:getRectangle(true, true)
     local x2, y2 = x1 + w, y1 + h
-    local oldX = self.endX
-    local newX
+    local oldX = self.endX or x1
 
     if oldX <= x1 then
         self.scrollX = self.scrollX - (x1 - oldX)
-        newX = x1
     elseif oldX >= x2 then
         self.scrollX = self.scrollX + (oldX - x2 + 1)
-        newX = x2 - 1
     end
 
-    if newX then
-        self.endX = newX
-        self.startX = self.startX + (newX - oldX)
-    end
+    updateHighlight(self)
 end
 
-local function findCaretFromText (self, text)
-    local font = self:getFont()
-    local x = self:getRectangle(true, true)
-    return #text, font:getAdvance(text) + x - self.scrollX
-end
-
-local function setCaretFromText (self, text, mode)
-    local index, x = findCaretFromText(self, text)
-
-    if mode == 'start' or not mode then
-        self.startIndex, self.startX = index, x
-    end
-    if mode == 'end' or not mode then
-        self.endIndex, self.endX = index, x
-    end
+local function selectRange (self, startIndex, endIndex)
+    if startIndex then self.startIndex = startIndex end
+    if endIndex then self.endIndex = endIndex end
 
     scrollToCaret(self)
 end
 
--- return caret index and x position
-local function findCaretFromPoint (self, x, y)
+-- return caret index
+local function findIndexFromPoint (self, x, y)
     local x1 = self:getRectangle(true, true)
 
     local font = self.fontData
@@ -61,54 +52,46 @@ local function findCaretFromPoint (self, x, y)
         width = font:getAdvance(text)
         if width > x + self.scrollX - x1 then
             if position == 1 then
-                return 0, x1 - self.scrollX
+                return 0
             end
-            return lastPosition, lastWidth + x1 - self.scrollX
+            return lastPosition
         end
         lastPosition = position - 1
     end
 
     for position in utf8.codes(self.value) do
-        local a, b = checkPosition(position)
-        if a then return a, b end
+        local index = checkPosition(position)
+        if index then return index end
     end
 
-    local a, b = checkPosition(#self.value + 1)
-    if a then return a, b end
+    local index = checkPosition(#self.value + 1)
+    if index then return index end
 
-    return #self.value, width + x1 - self.scrollX
+    return #self.value
 end
 
 -- move the caret one character to the left
 local function moveCaretLeft (self, alterRange)
     local text, endIndex = self.value, self.endIndex
 
-    -- if cursor is at beginning, do nothing
-    if endIndex < 1 then
-        return false
-    end
+    -- clamp caret to beginning
+    if endIndex < 1 then endIndex = 1 end
 
     -- move left
-    local mode = alterRange and 'end'
-    local offset = utf8.offset(text, -1, endIndex + 1) or 0
-
-    setCaretFromText(self, text:sub(1, offset - 1), mode)
+    local index = (utf8.offset(text, -1, endIndex + 1) or 0) - 1
+    selectRange(self, not alterRange and index, index)
 end
 
 -- move the caret one character to the right
 local function moveCaretRight (self, alterRange)
     local text, endIndex = self.value, self.endIndex
 
-    -- if cursor is at end, do nothing
-    if endIndex == #text then
-        return false
-    end
-
-    local mode = alterRange and 'end'
-    local offset = utf8.offset(text, 2, endIndex + 1) or #text
+    -- clamp caret to end
+    if endIndex >= #text then endIndex = #text - 1 end
 
     -- move right
-    setCaretFromText(self, text:sub(1, offset - 1), mode)
+    local index = (utf8.offset(text, 2, endIndex + 1) or #text) - 1
+    selectRange(self, not alterRange and index, index)
 end
 
 local function getRange (self)
@@ -126,9 +109,9 @@ local function deleteRange (self)
     -- if expanded range is selected, delete text in range
     if first ~= last then
         local left = text:sub(1, first)
-        text = left .. text:sub(last + 1)
-        self.value = text
-        setCaretFromText(self, left)
+        local index = #left
+        self.value = left .. text:sub(last + 1)
+        selectRange(self, index, index)
         return true
     end
 end
@@ -145,9 +128,9 @@ local function deleteCharacterLeft (self)
     -- delete character to the left
     local offset = utf8.offset(text, -1, last + 1) or 0
     local left = text:sub(1, offset - 1)
-    text = left .. text:sub(first + 1)
-    self.value = text
-    setCaretFromText(self, left)
+    local index = #left
+    self.value = left .. text:sub(first + 1)
+    selectRange(self, index, index)
 end
 
 local function copyRangeToClipboard (self)
@@ -163,21 +146,24 @@ local function pasteFromClipboard (self)
     local pasted = Backend.getClipboardText() or ''
     local first, last = getRange(self)
     local left = text:sub(1, first) .. pasted
-    text = left .. text:sub(last + 1)
-    self.value = text
-    setCaretFromText(self, left)
+    local index = #left
+    self.value = left .. text:sub(last + 1)
+    selectRange(self, index, index)
 end
 
 local function insertText (self, newText)
     local text = self.value
     local first, last = getRange(self)
     local left = text:sub(1, first) .. newText
-
+    local index = #left
     self.value = left .. text:sub(last + 1)
-    setCaretFromText(self, left)
+    selectRange(self, index, index)
 end
 
 return function (self)
+    self.startIndex, self.endIndex = 0, 0
+    self.startX, self.endX = -1, -1
+    self.scrollX = 0
     self.value = tostring(self.value or self.text or '')
     self.text = ''
 
@@ -203,19 +189,16 @@ This color is used to indicate the selected range of text.
 @section end
 --]]--
 
-    self.scrollX = 0
-
-    setCaretFromText(self, self.value)
-
     self:onPressStart(function (event)
         if event.button ~= 'left' then return end
-        self.startIndex, self.startX = findCaretFromPoint(self, event.x)
-        self.endIndex, self.endX = self.startIndex, self.startX
+        self.startIndex = findIndexFromPoint(self, event.x)
+        self.endIndex = self.startIndex
+        scrollToCaret(self)
     end)
 
     self:onPressDrag(function (event)
         if event.button ~= 'left' then return end
-        self.endIndex, self.endX = findCaretFromPoint(self, event.x)
+        self.endIndex = findIndexFromPoint(self, event.x)
         scrollToCaret(self)
     end)
 
@@ -270,7 +253,7 @@ This color is used to indicate the selected range of text.
     end)
 
     self:onDisplay(function (event)
-        local startX, endX = self.startX or 0, self.endX or 0
+        local startX, endX = self.startX, self.endX
         local x, y, w, h = self:getRectangle(true, true)
         local width, height = endX - startX, h
         local font = self:getFont()
@@ -302,4 +285,8 @@ This color is used to indicate the selected range of text.
 
         Backend.pop()
     end)
+
+    self:onReshape(function ()
+        updateHighlight(self)
+    end)
 end