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mirror of https://github.com/koreader/koreader synced 2024-11-04 12:00:25 +00:00
koreader/rendertext.lua
2012-04-20 18:29:08 +08:00

107 lines
3.5 KiB
Lua

glyphcache_max_memsize = 256*1024 -- 256kB glyphcache
glyphcache_current_memsize = 0
glyphcache = {}
glyphcache_max_age = 4096
function glyphCacheClaim(size)
if(size > glyphcache_max_memsize) then
error("too much memory claimed")
return false
end
while glyphcache_current_memsize + size > glyphcache_max_memsize do
for k, _ in pairs(glyphcache) do
if glyphcache[k].age > 0 then
glyphcache[k].age = glyphcache[k].age - 1
else
glyphcache_current_memsize = glyphcache_current_memsize - glyphcache[k].size
glyphcache[k].glyph.bb:free()
glyphcache[k] = nil
end
end
end
glyphcache_current_memsize = glyphcache_current_memsize + size
return true
end
function getGlyph(face, charcode)
local hash = glyphCacheHash(face.hash, charcode)
if glyphcache[hash] == nil then
local glyph = face.ftface:renderGlyph(charcode)
local size = glyph.bb:getWidth() * glyph.bb:getHeight() / 2 + 32
glyphCacheClaim(size);
glyphcache[hash] = {
age = glyphcache_max_age,
size = size,
g = glyph
}
else
glyphcache[hash].age = glyphcache_max_age
end
return glyphcache[hash].g
end
function glyphCacheHash(face, charcode)
return face..'_'..charcode;
end
function clearGlyphCache()
glyphcache = {}
end
function sizeUtf8Text(x, width, face, text, kerning)
if text == nil 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 then
local kern = face.ftface:getKerning(prevcharcode, charcode)
pen_x = pen_x + kern
--debug("prev:"..string.char(prevcharcode).." curr:"..string.char(charcode).." kern:"..kern)
else
--debug("curr:"..string.char(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
end
return { x = pen_x, y_top = pen_y_top, y_bottom = pen_y_bottom}
end
function renderUtf8Text(buffer, x, y, face, text, kerning)
if text == nil 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
for uchar in string.gfind(text, "([%z\1-\127\194-\244][\128-\191]*)") do
if pen_x < buffer:getWidth() 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
--debug("prev:"..string.char(prevcharcode).." curr:"..string.char(charcode).." pen_x:"..pen_x.." kern:"..kern)
buffer:addblitFrom(glyph.bb, x + pen_x + glyph.l, y - glyph.t, 0, 0, glyph.bb:getWidth(), glyph.bb:getHeight())
else
--debug(" curr:"..string.char(charcode))
buffer:blitFrom(glyph.bb, x + pen_x + glyph.l, y - glyph.t, 0, 0, glyph.bb:getWidth(), glyph.bb:getHeight())
end
pen_x = pen_x + glyph.ax
prevcharcode = charcode
end
end
return pen_x
end