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koreader/frontend/ui/rendertext.lua
Qingping Hou e3b567b2b1 fix kerning for Utf8Text family methods from tigran123
refer to master pullrequest #386 and #383, related
commits are (all in master(kpv) tree):
cb25029ddd
c7b4cf71f8
379cba7b68
2012-10-09 16:08:34 -04:00

108 lines
3.2 KiB
Lua

require "cache"
--[[
TODO: all these functions should probably be methods on Face objects
]]--
function getGlyph(face, charcode)
local hash = "glyph|"..face.hash.."|"..charcode
local glyph = Cache:check(hash)
if glyph then
-- cache hit
return glyph[1]
end
local rendered_glyph = face.ftface:renderGlyph(charcode)
if not rendered_glyph then
DEBUG("error rendering glyph (charcode=", charcode, ") for face", face)
return
end
glyph = CacheItem:new{rendered_glyph}
glyph.size = glyph[1].bb:getWidth() * glyph[1].bb:getHeight() / 2 + 32
Cache:insert(hash, glyph)
return glyph[1]
end
function getSubTextByWidth(text, face, width, kerning)
local pen_x = 0
local prevcharcode = 0
local char_list = {}
for uchar in string.gfind(text, "([%z\1-\127\194-\244][\128-\191]*)") do
if pen_x < width then
local charcode = util.utf8charcode(uchar)
local glyph = getGlyph(face, charcode)
if kerning and prevcharcode then
local kern = face.ftface:getKerning(prevcharcode, charcode)
pen_x = pen_x + kern
end
pen_x = pen_x + glyph.ax
if pen_x <= width then
prevcharcode = charcode
table.insert(char_list, uchar)
else
break
end
end
end
return table.concat(char_list)
end
function sizeUtf8Text(x, width, face, text, kerning)
if not text then
DEBUG("sizeUtf8Text called without text");
return
end
-- may still need more adaptive pen placement when kerning,
-- see: http://freetype.org/freetype2/docs/glyphs/glyphs-4.html
local pen_x = 0
local pen_y_top = 0
local pen_y_bottom = 0
local prevcharcode = 0
for uchar in string.gfind(text, "([%z\1-\127\194-\244][\128-\191]*)") do
if pen_x < (width - x) then
local charcode = util.utf8charcode(uchar)
local glyph = getGlyph(face, charcode)
if kerning and (prevcharcode ~= 0) then
pen_x = pen_x + face.ftface:getKerning(prevcharcode, charcode)
end
pen_x = pen_x + glyph.ax
pen_y_top = math.max(pen_y_top, glyph.t)
pen_y_bottom = math.max(pen_y_bottom, glyph.bb:getHeight() - glyph.t)
--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)
prevcharcode = charcode
end -- if pen_x < (width - x)
end -- for uchar
return { x = pen_x, y_top = pen_y_top, y_bottom = pen_y_bottom}
end
function renderUtf8Text(buffer, x, y, face, text, kerning)
if not text then
DEBUG("renderUtf8Text called without text");
return 0
end
-- may still need more adaptive pen placement when kerning,
-- see: http://freetype.org/freetype2/docs/glyphs/glyphs-4.html
local pen_x = 0
local prevcharcode = 0
local buffer_width = buffer:getWidth()
for uchar in string.gfind(text, "([%z\1-\127\194-\244][\128-\191]*)") do
if pen_x < buffer_width then
local charcode = util.utf8charcode(uchar)
local glyph = getGlyph(face, charcode)
if kerning and (prevcharcode ~= 0) then
pen_x = pen_x + face.ftface:getKerning(prevcharcode, charcode)
end
buffer:addblitFrom(
glyph.bb,
x + pen_x + glyph.l, y - glyph.t,
0, 0,
glyph.bb:getWidth(), glyph.bb:getHeight())
pen_x = pen_x + glyph.ax
prevcharcode = charcode
end -- if pen_x < buffer_width
end -- for uchar
return pen_x
end