TextWidget: small refactoring, better handle max_width (#5503)

Lots of code was doing some renderText calls to get the size
of some text string, and truncate it to some width if needed,
with or without an added ellipsis, before instantiating
a TextWidget with that tweaked text string.

This PR fixes/adds some properties and methods to TextWidget
so all that can be done by it. It makes the calling code
simpler, as they don't need to use RenderText directly.
(Additionally, when we go at using Harfbuzz for text rendering,
we'll just have to update or replace textwidget.lua without
the need to update any higher level code.)

Also:
- RenderText: removed the space added by truncateTextByWidth
  after the ellipsis, as it doesn't feel needed, and break
  right alignment of the ellipsis with other texts.
- KeyValuePage: fix some subtle size and alignment issues.
- NumberPickerWidget: fix font size (provided font size was
  not used)

frontend/ui/widget/textwidget.lua

@@ -19,39 +19,76 @@ local RenderText = require("ui/rendertext")
 local Size = require("ui/size")
 local Widget = require("ui/widget/widget")
 local Screen = require("device").screen
+local util = require("util")
 
 local TextWidget = Widget:new{
     text = nil,
     face = nil,
-    bold = nil,
+    bold = false, -- synthetized/fake bold (use a bold face for nicer bold)
     fgcolor = Blitbuffer.COLOR_BLACK,
-    padding = Size.padding.small, -- should padding be function of face.size ?
+    padding = Size.padding.small, -- vertical padding (should it be function of face.size ?)
+                                  -- (no horizontal padding is added)
     max_width = nil,
-    _bb = nil,
+    truncate_with_ellipsis = true, -- when truncation at max_width needed, add "…"
+    truncate_left = false, -- truncate on the right by default
+
+    _updated = nil,
+    _text_to_draw = nil,
     _length = 0,
     _height = 0,
     _baseline_h = 0,
     _maxlength = 1200,
 }
 
---function TextWidget:_render()
-    --local h = self.face.size * 1.3
-    --self._bb = Blitbuffer.new(self._maxlength, h)
-    --self._bb:fill(Blitbuffer.COLOR_WHITE)
-    --self._length = RenderText:renderUtf8Text(self._bb, 0, h*0.8, self.face, self.text, true, self.bold)
---end
-
 function TextWidget:updateSize()
-    local tsize = RenderText:sizeUtf8Text(0, self.max_width and self.max_width or Screen:getWidth(), self.face, self.text, true, self.bold)
-    if tsize.x == 0 then
-        self._length = 0
-    else
-        -- As text length includes last glyph pen "advance" (for positionning
-        -- next char), it's best to use math.floor() instead of math.ceil()
-        -- to get rid of a fraction of it in case this text is to be
-        -- horizontally centered
+    if self._updated then
+        return
+    end
+    self._updated = true
+
+    -- In case we draw truncated text, keep original self.text
+    -- so caller can fetch it again
+    self._text_to_draw = self.text
+
+    -- Note: we use kerning=true in all RenderText calls
+    --- @todo Don't use kerning for monospaced fonts. (houqp)
+
+    -- Compute width:
+    -- We never need to draw/size more than one screen width, so limit computation
+    -- to that width in case we are given some huge string
+    local tsize = RenderText:sizeUtf8Text(0, Screen:getWidth(), self.face, self._text_to_draw, true, self.bold)
+    -- As text length includes last glyph pen "advance" (for positionning
+    -- next char), it's best to use math.floor() instead of math.ceil()
+    -- to get rid of a fraction of it in case this text is to be
+    -- horizontally centered
+    self._length = math.floor(tsize.x)
+
+    -- Ensure max_width, and truncate text if needed
+    if self.max_width and self._length > self.max_width then
+        if self.truncate_left then
+            -- We want to truncate text on the left, so work with the reverse of text.
+            -- We don't use kerning in this measurement as it might be different
+            -- on the reversed text. The final text will use kerning, and might get
+            -- a smaller width than the one found out here.
+            -- Also, not sure if this is correct when diacritics/clustered glyphs
+            -- happen at truncation point. But it will do for now.
+            local reversed_text = util.utf8Reverse(self._text_to_draw)
+            if self.truncate_with_ellipsis then
+                reversed_text = RenderText:truncateTextByWidth(reversed_text, self.face, self.max_width, false, self.bold)
+            else
+                reversed_text = RenderText:getSubTextByWidth(reversed_text, self.face, self.max_width, false, self.bold)
+            end
+            self._text_to_draw = util.utf8Reverse(reversed_text)
+        elseif self.truncate_with_ellipsis then
+            self._text_to_draw = RenderText:truncateTextByWidth(self._text_to_draw, self.face, self.max_width, true, self.bold)
+        end
+        -- Get the adjusted width when limiting to max_width (it might be
+        -- smaller than max_width when dropping the truncated glyph).
+        tsize = RenderText:sizeUtf8Text(0, self.max_width, self.face, self._text_to_draw, true, self.bold)
         self._length = math.floor(tsize.x)
     end
+
+    -- Compute height:
     -- Used to be:
     --   self._height = math.ceil(self.face.size * 1.5)
     --   self._baseline_h = self._height*0.7
@@ -68,10 +105,6 @@ function TextWidget:updateSize()
 end
 
 function TextWidget:getSize()
-    --if not self._bb then
-        --self:_render()
-    --end
-    --return { w = self._length, h = self._bb:getHeight() }
     self:updateSize()
     return Geom:new{
         w = self._length,
@@ -79,6 +112,11 @@ function TextWidget:getSize()
     }
 end
 
+function TextWidget:getWidth()
+    self:updateSize()
+    return self._length
+end
+
 function TextWidget:getBaseline()
     self:updateSize()
     return self._baseline_h
@@ -86,27 +124,18 @@ end
 
 function TextWidget:setText(text)
     self.text = text
-    self:updateSize()
+    self._updated = false
+end
+
+function TextWidget:setMaxWidth(max_width)
+    self.max_width = max_width
+    self._updated = false
 end
 
 function TextWidget:paintTo(bb, x, y)
-    --if not self._bb then
-        --self:_render()
-    --end
-    --bb:blitFrom(self._bb, x, y, 0, 0, self._length, self._bb:getHeight())
-    --- @todo Don't use kerning for monospaced fonts.    (houqp)
-    if self.max_width and RenderText:sizeUtf8Text(0, Screen:getWidth(), self.face, self.text, true, self.bold).x > self.max_width then
-        self.text = RenderText:truncateTextByWidth(self.text, self.face, self.max_width, true)
-    end
-    RenderText:renderUtf8Text(bb, x, y+self._baseline_h, self.face, self.text, true, self.bold,
-                self.fgcolor, self.max_width and self.max_width or self.width)
-end
-
-function TextWidget:free()
-    if self._bb then
-        self._bb:free()
-        self._bb = nil
-    end
+    self:updateSize()
+    RenderText:renderUtf8Text(bb, x, y+self._baseline_h, self.face, self._text_to_draw, true, self.bold,
+                self.fgcolor, self._length)
 end
 
 return TextWidget