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TextBoxWidget: use xtext for text shaping

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Alternative code to size, split lines and draw text with
the help of the xtext Lua C module.
Enabled by default (can be disabled via an added menu
item in "Developer options").

New properties can be specified by calling widgets, only
used when xtext is used:
- lang: use specified language instead of the UI language
- para_direction_rtl: true/false to override the default
  direction for the UI language
- auto_para_direction: detect direction of each paragraph
  in text
- alignment_strict: prevent the inversion of the specified
  alignment= that is done when a paragraph direction is
  set or detected as RTL.

Also: fix possible memory leak (present even when not using xtext)
by calling :free() in onCloseWidget() like it's done in ImageWidget.
This commit is contained in:
poire-z
2019-11-15 15:14:40 +01:00
parent 22e3e34c45
commit e699a1ee22
2 changed files with 409 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

385
frontend/ui/widget/textboxwidget.lua
View File

@@ -77,11 +77,23 @@ local TextBoxWidget = InputContainer:new{
-- when bb or hi_bb is nil: its job is to load/build bb or hi_bb.
-- The page will refresh itself when load_bb_func returns.
images = nil, -- list of such images
line_num_to_image = nil, -- will be filled by self:_splitCharWidthList()
line_num_to_image = nil, -- will be filled by self:_splitToLines()
image_padding_left = Screen:scaleBySize(10),
image_padding_bottom = Screen:scaleBySize(3),
image_alt_face = Font:getFace("xx_smallinfofont"),
image_alt_fgcolor = Blitbuffer.COLOR_BLACK,
-- Additional properties only used when using xtext
use_xtext = G_reader_settings:nilOrTrue("use_xtext"),
lang = nil, -- use this language (string) instead of the UI language
para_direction_rtl = nil, -- use true/false to override the default direction for the UI language
auto_para_direction = false, -- detect direction of each paragraph in text
-- (para_direction_rtl or UI language is then only
-- used as a weak hint about direction)
alignment_strict = false, -- true to force the alignemnt set by the alignment= attribute.
-- When false, specified alignment is inverted when para direction is RTL
_xtext = nil, -- for internal use
_alt_color_for_rtl = nil, -- (for debugging) draw LTR glyphs in black, RTL glyphs in gray
}
function TextBoxWidget:init()
@@ -98,12 +110,18 @@ function TextBoxWidget:init()
if self.height < self.line_height_px then
self.height = self.line_height_px
end
-- if no self.height, these will be set just after self:_splitCharWidthList()
-- if no self.height, these will be set just after self:_splitToLines()
self.lines_per_page = math.floor(self.height / self.line_height_px)
self.text_height = self.lines_per_page * self.line_height_px
end
self:_evalCharWidthList()
self:_splitCharWidthList()
if self.use_xtext then
self:_measureWithXText()
else
self:_evalCharWidthList()
end
self:_splitToLines()
if self.charpos and self.charpos > #self.charlist+1 then
self.charpos = #self.charlist+1
end
@@ -168,8 +186,32 @@ function TextBoxWidget:_evalCharWidthList()
self.idx_pad = {}
end
function TextBoxWidget:_measureWithXText()
if not self._xtext_loaded then
require("libs/libkoreader-xtext")
TextBoxWidget._xtext_loaded = true
end
if type(self.charlist) == "table" then
self._xtext = xtext.new(self.charlist, self.face, self.auto_para_direction,
self.para_direction_rtl, self.lang)
else
if not self.text then
self.text = ""
elseif type(self.text) ~= "string" then
self.text = tostring(self.text)
end
self._xtext = xtext.new(self.text, self.face, self.auto_para_direction,
self.para_direction_rtl, self.lang)
self.charlist = self._xtext
-- Just to have many common bits of code using #self.charlist work
-- as expected (will crash if used as a real table with "table
-- expected, got userdata", so we know)
end
self._xtext:measure()
end
-- Split the text into logical lines to fit into the text box.
function TextBoxWidget:_splitCharWidthList()
function TextBoxWidget:_splitToLines()
self.vertical_string_list = {}
local idx = 1
@@ -180,7 +222,7 @@ function TextBoxWidget:_splitCharWidthList()
local image_num = 0
local targeted_width = self.width
local image_lines_remaining = 0
while idx <= size do
while idx and idx <= size do
-- Every scrolled page, we want to add the next (if any) image at its top right
-- (if not scrollable, we will display only the first image)
-- We need to make shorter lines and leave room for the image
@@ -219,6 +261,45 @@ function TextBoxWidget:_splitCharWidthList()
-- end_offset will be the idx of char at end of line
offset = idx -- idx of char at start of line
if self.use_xtext then
-- All of what's done below when use_xtext=false is done by the C++ module.
local line = self._xtext:makeLine(offset, targeted_width)
-- logger.dbg("makeLine", ln, line)
-- We get a line such as this:
-- {
-- ["next_start_offset"] = 9272,
-- ["width"] = 511,
-- ["end_offset"] = 9270,
-- ["targeted_width"] = 548,
-- ["offset"] = 9208,
-- ["can_be_justified"] = true
-- },
-- Notes:
-- - next_start_offset is nil when reaching end of text
-- - On empty lines made from a standalone \n\n, we get end_offset = offset-1,
-- which is a bit strange but that's what the use_xtext=false does.
-- - Between a line end_offset= and the next line offset=, there may be only
-- a single indice not included: the \n or the space that allowed the break.
self.vertical_string_list[ln] = line
if line.hard_newline_at_eot and not line.next_start_offset then
-- Add an empty line to reprensent the \n at end of text
-- and allow positionning cursor after it
self.vertical_string_list[ln+1] = {
offset = size+1,
end_offset = nil,
width = 0,
}
end
ln = ln + 1
idx = line.next_start_offset -- nil when end of text reached
-- Skip the whole following non-use_xtext code, to continue
-- this 'while' loop (to avoid indentation diff on the
-- following code if we were using a 'else'...)
goto idx_continue
end
-- Only when not self.use_xtext:
-- We append chars until the accumulated width exceeds `targeted_width`,
-- or a newline occurs, or no more chars to consume.
cur_line_width = 0
@@ -333,6 +414,8 @@ function TextBoxWidget:_splitCharWidthList()
end
ln = ln + 1
-- Make sure `idx` point to the next char to be processed in the next loop.
::idx_continue:: -- (Label for goto when use_xtext=true)
end
end
@@ -350,6 +433,146 @@ function TextBoxWidget:_getLinePads(vertical_string)
return pads
end
-- XText: shape a line into positionned glyphs
function TextBoxWidget:_shapeLine(line)
-- line is an item from self.vertical_string_list
if not line.end_offset then
return -- empty line (hard newline at end of file)
end
if line.end_offset < line.offset then
return -- empty line (hard newline while not at end of file)
end
if line.xglyphs then
return -- already done
end
-- Get glyphs, shaped and possibly substituted by Harfbuzz and re-ordered by FriBiDi.
-- We'll add to 'line' this table of glyphs, with some additional
-- computed x and advance keys
local xshaping = self._xtext:shapeLine(line.offset, line.end_offset)
-- logger.dbg(xshaping)
-- We get an array of tables looking like this:
-- [1] = {
-- ["y_offset"] = 0,
-- ["x_advance"] = 10,
-- ["can_extend"] = false,
-- ["can_extend_fallback"] = false,
-- ["is_rtl"] = false,
-- ["text_index"] = 1,
-- ["glyph"] = 68,
-- ["font_num"] = 0,
-- ["x_offset"] = 0,
-- ["is_cluster_start"] = true,
-- ["cluster_len"] = 1
-- },
-- [...]
-- [12] = {
-- ["y_offset"] = 0,
-- ["x_advance"] = 0,
-- ["can_extend"] = false,
-- ["can_extend_fallback"] = false,
-- ["is_rtl"] = true,
-- ["text_index"] = 8,
-- ["glyph"] = 1292,
-- ["font_num"] = 3,
-- ["x_offset"] = -2,
-- ["is_cluster_start"] = true,
-- ["cluster_len"] = 2
-- },
-- [13] = {
-- ["y_offset"] = 0,
-- ["x_advance"] = 10,
-- ["can_extend"] = false,
-- ["can_extend_fallback"] = false,
-- ["is_rtl"] = true,
-- ["text_index"] = 8,
-- ["glyph"] = 1321,
-- ["font_num"] = 3,
-- ["x_offset"] = 0,
-- ["is_cluster_start"] = false,
-- ["cluster_len"] = 2
-- },
-- With some additional keys about the line itself, that will help
-- with alignment and justification:
-- ["para_is_rtl"] = true,
-- ["nb_can_extend"] = 6,
-- ["nb_can_extend_fallback"] = 0,
-- ["width"] = 457
local alignment = self.alignment
if not self.alignment_strict and xshaping.para_is_rtl then
if alignment == "left" then
alignment = "right"
elseif alignment == "right" then
alignment = "left"
end
end
local pen_x = 0 -- when alignment == "left"
if alignment == "center" then
pen_x = (line.targeted_width - line.width)/2 or 0
elseif alignment == "right" then
pen_x = (line.targeted_width - line.width)
end
local space_add_w = 0
local space_add1_nb = 0
local use_can_extend_fallback = false
if self.justified and line.can_be_justified then
local space_to_fill = line.targeted_width - xshaping.width
if xshaping.nb_can_extend > 0 then
space_add_w = math.floor(space_to_fill / xshaping.nb_can_extend)
-- nb of spaces to which we'll add 1 more pixel
space_add1_nb = space_to_fill - space_add_w * xshaping.nb_can_extend
line.justified = true
line.width = line.targeted_width
pen_x = 0 -- reset alignment
elseif xshaping.nb_can_extend_fallback > 0 then
use_can_extend_fallback = true
space_add_w = math.floor(space_to_fill / xshaping.nb_can_extend_fallback)
-- nb of spaces to which we'll add 1 more pixel
space_add1_nb = space_to_fill - space_add_w * xshaping.nb_can_extend_fallback
line.justified = true
line.width = line.targeted_width
pen_x = 0 -- reset alignment
end
end
local prev_cluster_start_xglyph
for i, xglyph in ipairs(xshaping) do
xglyph.x0 = pen_x
pen_x = pen_x + xglyph.x_advance -- advance from Harfbuzz
if xglyph.can_extend or (use_can_extend_fallback and xglyph.can_extend_fallback) then
-- add some pixels for justification
pen_x = pen_x + space_add_w
if space_add1_nb > 0 then
pen_x = pen_x + 1
space_add1_nb = space_add1_nb - 1
end
end
-- These will be used by _getXYForCharPos() and getCharPosAtXY():
xglyph.x1 = pen_x
xglyph.w = xglyph.x1 - xglyph.x0
-- Because of glyph substitution and merging (one to many, many to one, many to many,
-- with advance or zero-advance...), glyphs may not always be fine to position
-- the cursor caret. For X/Y/Charpos positionning/guessing, we'll ignore
-- glyphs that are not cluster_start, and we build here the full cluster x0/x1/w
-- by mergin them from all glyphs part of this cluster
if xglyph.is_cluster_start then
prev_cluster_start_xglyph = xglyph
else
if xglyph.x1 > prev_cluster_start_xglyph.x1 then
prev_cluster_start_xglyph.x1 = xglyph.x1
prev_cluster_start_xglyph.w = prev_cluster_start_xglyph.x1 - prev_cluster_start_xglyph.x0
end
-- We don't update/decrease prev_cluster_start_xglyph.x0, even if one of its glyph
-- has a backward advance that go back the 1st glyph x0, to not mess positionning.
end
end
line.xglyphs = xshaping
--- @todo Should we drop these when no more displayed in the page to reclaim memory,
-- at the expense of recomputing it when back to this page?
end
---- Lays out text.
function TextBoxWidget:_renderText(start_row_idx, end_row_idx)
local font_height = self.face.size
@@ -367,6 +590,34 @@ function TextBoxWidget:_renderText(start_row_idx, end_row_idx)
self._bb = Blitbuffer.new(self.width, h, bbtype)
self._bb:fill(Blitbuffer.COLOR_WHITE)
local y = font_height
if self.use_xtext then
for i = start_row_idx, end_row_idx do
local line = self.vertical_string_list[i]
self:_shapeLine(line)
if line.xglyphs then -- non-empty line
for __, xglyph in ipairs(line.xglyphs) do
local face = self.face.getFallbackFont(xglyph.font_num) -- callback (not a method)
local glyph = RenderText:getGlyphByIndex(face, xglyph.glyph, self.bold)
local color = self.fgcolor
if self._alt_color_for_rtl then
color = xglyph.is_rtl and Blitbuffer.COLOR_DARK_GRAY or Blitbuffer.COLOR_BLACK
end
self._bb:colorblitFrom(glyph.bb,
xglyph.x0 + glyph.l + xglyph.x_offset,
y - glyph.t + xglyph.y_offset,
0, 0, glyph.bb:getWidth(), glyph.bb:getHeight(), color)
end
end
y = y + self.line_height_px
end
-- Render image if any
self:_renderImage(start_row_idx)
return
end
-- Only when not self.use_xtext:
for i = start_row_idx, end_row_idx do
local line = self.vertical_string_list[i]
local pen_x = 0 -- when alignment == "left"
@@ -375,8 +626,8 @@ function TextBoxWidget:_renderText(start_row_idx, end_row_idx)
elseif self.alignment == "right" then
pen_x = (self.width - line.width)
end
--- @todo don't use kerning for monospaced fonts. (houqp)
--- refer to [cb25029dddc42693cc7aaefbe47e9bd3b7e1a750](https://github.com/koreader/koreader/commit/cb25029dddc42693cc7aaefbe47e9bd3b7e1a750) in master tree
-- Note: we use kerning=true in all RenderText calls
-- (But kerning should probably not be used with monospaced fonts.)
RenderText:renderUtf8Text(self._bb, pen_x, y, self.face, self:_getLineText(line), true, self.bold, self.fgcolor, nil, self:_getLinePads(line))
y = y + self.line_height_px
end
@@ -580,6 +831,19 @@ function TextBoxWidget:paintTo(bb, x, y)
bb:blitFrom(self._bb, x, y, 0, 0, self.width, self._bb:getHeight())
end
function TextBoxWidget:onCloseWidget()
-- Free all resources (BlitBuffers, XText) when UIManager closes this
-- widget (as it won't be painted anymore), without waiting for Lua gc()
-- to kick in.
-- Free the between-renderings (between page scrolls) freeable resources
self:free()
if self.use_xtext and self._xtext then
-- Free our self._xtext (that we can't free in :free()
-- as we need to keep it across renderings)
self._xtext:free()
end
end
function TextBoxWidget:free()
logger.dbg("TextBoxWidget:free called")
-- :free() is called when our parent widget is closing, and
@@ -792,6 +1056,45 @@ function TextBoxWidget:_getXYForCharPos(charpos)
local y = (ln - self.virtual_line_num) * self.line_height_px
-- Find the x offset in the current line.
local x = 0
if self.use_xtext then
local line = self.vertical_string_list[ln]
self:_shapeLine(line)
if line.xglyphs then -- non-empty line
for i, xglyph in ipairs(line.xglyphs) do
if xglyph.is_cluster_start then -- ignore non-start cluster glyphs
if charpos >= xglyph.text_index and charpos < xglyph.text_index + xglyph.cluster_len then
--- @todo Be more clever with RTL, and at bidi boundaries,
-- may be depending on line.xglyphs.para_is_rtl.
if xglyph.is_rtl then
x = xglyph.x1 -- draw cursor on the right of this RTL glyph
else
x = xglyph.x0
end
if xglyph.cluster_len > 1 then
-- Adjust x so we move the cursor along this single glyph width
-- depending on charpos position inside this cluster
local dx = math.floor(xglyph.w * (charpos - xglyph.text_index) / xglyph.cluster_len)
if xglyph.is_rtl then
x = x - dx
else
x = x + dx
end
end
break
end
x = xglyph.x1
--- @todo When line.xglyphs.para_is_rtl and no x found, it should
-- be the first line glyph's x0
end
end
end
-- logger.dbg("_getXYForCharPos(", charpos, "):", x, y)
return x, y
end
-- Only when not self.use_xtext:
local offset = self.vertical_string_list[ln].offset
local nbchars = #self.charlist
while offset < charpos do
@@ -822,7 +1125,7 @@ function TextBoxWidget:getCharPosAtXY(x, y)
end
if x > self.vertical_string_list[ln].width then -- no need to loop thru chars
local pos = self.vertical_string_list[ln].end_offset
if not pos then -- empty line
if not pos then -- empty last line
return self.vertical_string_list[ln].offset
end
return pos + 1 -- after last char
@@ -832,6 +1135,41 @@ function TextBoxWidget:getCharPosAtXY(x, y)
if not end_offset then -- empty line
return idx
end
if self.use_xtext then
local line = self.vertical_string_list[ln]
self:_shapeLine(line)
--- @todo Probably some specific/inverted work if line.xglyphs.para_is_rtl
if line.xglyphs then -- non-empty line
for i, xglyph in ipairs(line.xglyphs) do
if xglyph.is_cluster_start then -- ignore non-start cluster glyphs
if x < xglyph.x1 then
if xglyph.cluster_len <= 1 then
return xglyph.text_index
else
-- Find the most adequate charpos among those in the
-- cluster by splitting its width into equal parts
-- for each original char.
local dw = xglyph.w / xglyph.cluster_len
for n=1, xglyph.cluster_len do
if x < xglyph.x0 + n*dw then
if xglyph.is_rtl then
return xglyph.text_index + xglyph.cluster_len - n
else
return xglyph.text_index + n - 1
end
end
end
end
end
end
end
end
return end_offset + 1 -- should not happen
end
-- Only when not self.use_xtext:
local w = 0
local w_prev
while idx <= end_offset do
@@ -1248,6 +1586,35 @@ function TextBoxWidget:onHoldReleaseText(callback, ges)
self.hold_start_y = nil
self.hold_start_tv = nil
if self.use_xtext then
-- With xtext and fribidi, words may not be laid out in logical order,
-- so the left of a visual word may be its end in logical order,
-- and the right its start.
-- So, just find out charpos (text indice) of both points and
-- find word edges in the logical order text/charlist.
local sel_start_idx = self:getCharPosAtXY(x0, y0)
local sel_end_idx = self:getCharPosAtXY(x1, y1)
if not sel_start_idx or not sel_end_idx then
-- one or both hold points were out of text
return true
end
if sel_start_idx > sel_end_idx then -- re-order if needed
sel_start_idx, sel_end_idx = sel_end_idx, sel_start_idx
end
-- Delegate word boundaries search to xtext.cpp, which can
-- use libunibreak's wordbreak features.
-- (50 is the nb of chars backward and ahead of selection indices
-- to consider when looking for word boundaries)
local selected_text = self._xtext:getSelectedWords(sel_start_idx, sel_end_idx, 50)
logger.dbg("onHoldReleaseText (duration:", hold_duration, ") :",
sel_start_idx, ">", sel_end_idx, "=", selected_text)
callback(selected_text, hold_duration)
return true
end
-- Only when not self.use_xtext:
-- similar code to find start or end is in _findWordEdge() helper
local sel_start_idx = self:_findWordEdge(x0, y0, FIND_START)
local sel_end_idx = self:_findWordEdge(x1, y1, FIND_END)

34
spec/unit/textboxwidget_spec.lua
View File

@@ -10,8 +10,39 @@ describe("TextBoxWidget module", function()
local tw = TextBoxWidget:new{
dimen = {x = 0, y = 0},
face = Font:getFace("cfont", 25),
text = 'YOOOOOOOOOOOOOOOO\nFoo.\nBar.',
text = 'YOOOOOOOOOOOOOOOO\nFoo.\nBar.\nFoo welcomes Bar into the fun.',
}
local pos={x=110,y=4}
tw:onHoldStartText(nil, {pos=pos})
tw:onHoldReleaseText(function(w)
assert.is.same(w, 'YOOOOOOOOOOOOOOOO')
end, {pos=pos})
pos={x=0,y=50}
tw:onHoldStartText(nil, {pos=pos})
tw:onHoldReleaseText(function(w)
assert.is.same(w, 'Foo')
end, {pos=pos})
pos={x=20,y=80}
tw:onHoldStartText(nil, {pos=pos})
tw:onHoldReleaseText(function(w)
assert.is.same(w, 'Bar')
end, {pos=pos})
tw:onHoldStartText(nil, {pos={x=50, y=100}})
tw:onHoldReleaseText(function(w)
assert.is.same(w, 'welcomes Bar into')
end, {pos={x=240, y=100}})
tw:onHoldStartText(nil, {pos={x=20, y=80}})
tw:onHoldReleaseText(function(w)
assert.is.same(w, 'Bar.\nFoo welcomes Bar into')
end, {pos={x=240, y=100}})
--[[
-- No more used, not implemented when use_xtext=true
tw:onHoldWord(function(w)
assert.is.same(w, 'YOOOOOOOOOOOOOOOO')
end, {pos={x=110,y=4}})
@@ -21,5 +52,6 @@ describe("TextBoxWidget module", function()
tw:onHoldWord(function(w)
assert.is.same(w, 'Bar')
end, {pos={x=20,y=80}})
]]--
end)
end)