mirror of
https://github.com/koreader/koreader
synced 2024-11-13 19:11:25 +00:00
177 lines
5.3 KiB
Lua
177 lines
5.3 KiB
Lua
local Font = require("ui/font")
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local Screen = require("ui/screen")
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local Cache = require("cache")
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local CacheItem = require("cacheitem")
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local DEBUG = require("dbg")
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--[[
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TODO: all these functions should probably be methods on Face objects
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]]--
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local RenderText = {}
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local GlyphCache = Cache:new{
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max_memsize = 512*1024,
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current_memsize = 0,
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cache = {},
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-- this will hold the LRU order of the cache
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cache_order = {}
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}
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-- iterator over UTF8 encoded characters in a string
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local function utf8Chars(input)
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local function read_next_glyph(input, pos)
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if string.len(input) < pos then return nil end
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local value = string.byte(input, pos)
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if bit.band(value, 0x80) == 0 then
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-- TODO: check valid ranges
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return pos+1, value, string.sub(input, pos, pos)
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elseif bit.band(value, 0xC0) == 0x80 -- invalid, continuation
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or bit.band(value, 0xF8) == 0xF8 -- 5-or-more byte sequence, illegal due to RFC3629
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then
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return pos+1, 0xFFFD, "\xFF\xFD"
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else
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local glyph, bytes_left
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if bit.band(value, 0xE0) == 0xC0 then
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glyph = bit.band(value, 0x1F)
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bytes_left = 1
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elseif bit.band(value, 0xF0) == 0xE0 then
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glyph = bit.band(value, 0x0F)
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bytes_left = 2
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elseif bit.band(value, 0xF8) == 0xF0 then
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glyph = bit.band(value, 0x07)
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bytes_left = 3
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else
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return pos+1, 0xFFFD, "\xFF\xFD"
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end
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if string.len(input) < (pos + bytes_left - 1) then
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return pos+1, 0xFFFD, "\xFF\xFD"
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end
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for i = pos+1, pos + bytes_left do
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value = string.byte(input, i)
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if bit.band(value, 0xC0) == 0x80 then
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glyph = bit.bor(bit.lshift(glyph, 6), bit.band(value, 0x3F))
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else
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return i+1, 0xFFFD, "\xFF\xFD"
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end
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end
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-- TODO: check for valid ranges here!
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return pos+bytes_left+1, glyph, string.sub(input, pos, pos+bytes_left)
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end
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end
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return read_next_glyph, input, 1
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end
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function RenderText:getGlyph(face, charcode, bgcolor, fgcolor)
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if bgcolor == nil then bgcolor = 0.0 end
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if fgcolor == nil then fgcolor = 1.0 end
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local hash = "glyph|"..face.hash.."|"..charcode.."|"..bgcolor.."|"..fgcolor
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local glyph = GlyphCache:check(hash)
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if glyph then
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-- cache hit
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return glyph[1]
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end
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local rendered_glyph = face.ftface:renderGlyph(charcode, bgcolor, fgcolor)
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if face.ftface:checkGlyph(charcode) == 0 then
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for index, font in pairs(Font.fallbacks) do
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-- rescale face size by DPI since it will be scaled in getFace again
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local fb_face = Font:getFace(font, Screen:rescaleByDPI(face.size))
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if fb_face.ftface:checkGlyph(charcode) ~= 0 then
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rendered_glyph = fb_face.ftface:renderGlyph(charcode, bgcolor, fgcolor)
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--DEBUG("fallback to font", font)
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break
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end
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end
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end
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if not rendered_glyph then
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DEBUG("error rendering glyph (charcode=", charcode, ") for face", face)
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return
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end
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glyph = CacheItem:new{rendered_glyph}
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glyph.size = glyph[1].bb:getWidth() * glyph[1].bb:getHeight() / 2 + 32
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GlyphCache:insert(hash, glyph)
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return rendered_glyph
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end
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function RenderText:getSubTextByWidth(text, face, width, kerning)
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local pen_x = 0
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local prevcharcode = 0
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local char_list = {}
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for _, charcode, uchar in utf8Chars(text) do
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if pen_x < width then
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local glyph = self:getGlyph(face, charcode)
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if kerning and prevcharcode then
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local kern = face.ftface:getKerning(prevcharcode, charcode)
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pen_x = pen_x + kern
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end
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pen_x = pen_x + glyph.ax
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if pen_x <= width then
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prevcharcode = charcode
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table.insert(char_list, uchar)
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else
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break
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end
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end
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end
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return table.concat(char_list)
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end
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function RenderText:sizeUtf8Text(x, width, face, text, kerning)
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if not text then
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DEBUG("sizeUtf8Text called without text");
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return
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end
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-- may still need more adaptive pen placement when kerning,
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-- see: http://freetype.org/freetype2/docs/glyphs/glyphs-4.html
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local pen_x = 0
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local pen_y_top = 0
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local pen_y_bottom = 0
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local prevcharcode = 0
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for _, charcode, uchar in utf8Chars(text) do
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if pen_x < (width - x) then
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local glyph = self:getGlyph(face, charcode)
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if kerning and (prevcharcode ~= 0) then
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pen_x = pen_x + (face.ftface):getKerning(prevcharcode, charcode)
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end
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pen_x = pen_x + glyph.ax
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pen_y_top = math.max(pen_y_top, glyph.t)
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pen_y_bottom = math.max(pen_y_bottom, glyph.bb:getHeight() - glyph.t)
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--DEBUG("ax:"..glyph.ax.." t:"..glyph.t.." r:"..glyph.r.." h:"..glyph.bb:getHeight().." w:"..glyph.bb:getWidth().." yt:"..pen_y_top.." yb:"..pen_y_bottom)
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prevcharcode = charcode
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end -- if pen_x < (width - x)
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end
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return { x = pen_x, y_top = pen_y_top, y_bottom = pen_y_bottom}
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end
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function RenderText:renderUtf8Text(buffer, x, y, face, text, kerning, bgcolor, fgcolor)
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if not text then
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DEBUG("renderUtf8Text called without text");
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return 0
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end
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-- may still need more adaptive pen placement when kerning,
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-- see: http://freetype.org/freetype2/docs/glyphs/glyphs-4.html
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local pen_x = 0
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local prevcharcode = 0
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local buffer_width = buffer:getWidth()
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for _, charcode, uchar in utf8Chars(text) do
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if pen_x < buffer_width then
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local glyph = self:getGlyph(face, charcode, bgcolor, fgcolor)
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if kerning and (prevcharcode ~= 0) then
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pen_x = pen_x + face.ftface:getKerning(prevcharcode, charcode)
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end
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buffer:addblitFrom(
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glyph.bb,
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x + pen_x + glyph.l, y - glyph.t,
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0, 0,
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glyph.bb:getWidth(), glyph.bb:getHeight(), 1)
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pen_x = pen_x + glyph.ax
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prevcharcode = charcode
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end -- if pen_x < buffer_width
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end
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return pen_x
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end
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return RenderText
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