draft commit, test implementation

ft.c

@@ -142,6 +142,8 @@ static int renderGlyph(lua_State *L) {
 	lua_setfield(L, -2, "t");
 	lua_pushinteger(L, (*face)->glyph->advance.x >> 6);
 	lua_setfield(L, -2, "ax");
+	lua_pushinteger(L, (*face)->glyph->advance.y >> 6);
+	lua_setfield(L, -2, "ay");
 
 	return 1;
 }
@@ -169,6 +171,25 @@ static int getKerning(lua_State *L) {
 	return 1;
 }
 
+static int getHeight(lua_State *L) {
+	FT_Face *face = (FT_Face*) luaL_checkudata(L, 1, "ft_face");
+
+	double pixels_height,pixels_ascender;
+	double em_size, y_scale;
+
+	/* compute floating point scale factors */
+	em_size = 1.0 * (*face)->units_per_EM;
+	y_scale = (*face)->size->metrics.y_ppem / em_size;
+
+	/* convert design distances to floating point pixels */
+	pixels_height = (*face)->height * y_scale;
+	pixels_ascender = (*face)->ascender * y_scale;
+
+	lua_pushnumber(L, pixels_height);
+	lua_pushnumber(L, pixels_ascender);
+	return 2;
+}
+
 static int doneFace(lua_State *L) {
 	FT_Face *face = (FT_Face*) luaL_checkudata(L, 1, "ft_face");
 	if(*face != NULL) {
@@ -185,6 +206,7 @@ static const struct luaL_reg ft_face_meth[] = {
 	{"renderGlyph", renderGlyph},
 	{"hasKerning", hasKerning},
 	{"getKerning", getKerning},
+	{"getHeight", getHeight},
 	{"done", doneFace},
 	{"__gc", doneFace},
 	{NULL, NULL}

rendertext.lua

@@ -43,6 +43,35 @@ function clearglyphcache()
 	glyphcache = {}
 end
 
+function sizeUtf8Text(face, facehash, text, kerning)
+	if text == nil then
+		print("# 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 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, facehash, charcode)
+			if kerning and prevcharcode then
+				local kern = face:getKerning(prevcharcode, charcode)
+				pen_x = pen_x + kern
+				print("prev:"..string.char(prevcharcode+10).." curr:"..string.char(charcode).." kern:"..kern)
+				buffer:addblitFrom(glyph.bb, x + pen_x + glyph.l, y - glyph.t, 0, 0, glyph.bb:getWidth(), glyph.bb:getHeight())
+			else
+				print("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
+
 function renderUtf8Text(buffer, x, y, face, facehash, text, kerning)
 	if text == nil then
 		print("# renderUtf8Text called without text");
@@ -59,8 +88,10 @@ function renderUtf8Text(buffer, x, y, face, facehash, text, kerning)
 			if kerning and prevcharcode then
 				local kern = face:getKerning(prevcharcode, charcode)
 				pen_x = pen_x + kern
+				--print("prev:"..prevcharcode.." curr:"..charcode.." kern:"..kern)
 				buffer:addblitFrom(glyph.bb, x + pen_x + glyph.l, y - glyph.t, 0, 0, glyph.bb:getWidth(), glyph.bb:getHeight())
 			else
+				--print(" curr:"..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
@@ -69,4 +100,3 @@ function renderUtf8Text(buffer, x, y, face, facehash, text, kerning)
 	end
 	return pen_x
 end
-

rendertext_example.lua

@@ -6,19 +6,28 @@ fb = einkfb.open("/dev/fb0")
 width, height = fb:getSize()
 
 print("open")
-
-face = freetype.newBuiltinFace("sans", 64)
---face = freetype.newFace("test.ttf", 64)
+size = 50
+--face = freetype.newBuiltinFace("sans", 64)
+face = freetype.newFace("/usr/share/fonts/truetype/ttf-dejavu/DejaVuSans.ttf", size)
 print("got face")
 
 if face:hasKerning() then
 	print("has kerning")
 end
 
-fb.bb:paintRect(1,1,599,300,7);
-
-renderUtf8Text(fb.bb, 100, 100, face, "h", "AV T.T: gxyt!", true)
-renderUtf8Text(fb.bb, 100, 200, face, "h", "AV T.T: gxyt!", false)
+width, height = fb:getSize()
+fb.bb:paintRect(5,5,width-5,height-5,4);
+
+faceHeight, faceAscender = face:getHeight();
+print("face height:"..tostring(faceHeight).." - ascender:"..faceAscender)
+faceHeight = math.ceil(faceHeight)
+faceAscender = math.ceil(faceAscender)
+print("face height:"..tostring(faceHeight).." - ascender:"..faceAscender)
+
+posY = 5 + faceAscender
+renderUtf8Text(fb.bb, 5, posY, face, "h", "AV T.T: gxyt!", true)
+posY = posY + faceHeight
+renderUtf8Text(fb.bb, 5, posY, face, "h2", "AV T.T: gxyt!", false)
 
 fb:refresh()