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%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2008-2009. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%% @doc egd_font
%%
-module(egd_font).
-export([load/1, size/1, glyph/2]).
-include("egd.hrl").
%% Font represenatation in ets table
%% egd_font_table
%%
%% Information:
%% {Key, Description, Size}
%% Key :: {Font :: atom(), information}
%% Description :: any(), Description header from font file
%% Size :: {W :: integer(), H :: integer()}
%%
%% Glyphs:
%% {Key, Translation LSs} where
%% Key :: {Font :: atom(), Code :: integer()}, Code = glyph char code
%% Translation :: {
%% W :: integer(), % BBx width
%% H :: integer(), % BBx height
%% X0 :: integer(), % X start
%% Y0 :: integer(), % Y start
%% Xm :: integer(), % Glyph X move when drawing
%% }
%% LSs :: [[{Xl :: integer(), Xr :: integer()}]]
%% The first list is height (top to bottom), the inner list is the list
%% of line spans for the glyphs horizontal pixels.
%%
%%==========================================================================
%%
%% Interface functions
%%
%%==========================================================================
size(Font) ->
[{_Key, _Description, Size}] = ets:lookup(egd_font_table,{Font,information}),
Size.
glyph(Font, Code) ->
[{_Key, Translation, LSs}] = ets:lookup(egd_font_table,{Font,Code}),
{Translation, LSs}.
load(Filename) ->
{ok, Bin} = file:read_file(Filename),
Font = erlang:binary_to_term(Bin),
load_font_header(Font).
%%==========================================================================
%%
%% Internal functions
%%
%%==========================================================================
%% ETS handler functions
initialize_table() ->
ets:new(egd_font_table, [named_table, ordered_set, public]).
glyph_insert(Font, Code, Translation, LSs) ->
Element = {{Font, Code}, Translation, LSs},
ets:insert(egd_font_table, Element).
font_insert(Font, Description, Dimensions) ->
Element = {{Font, information}, Description, Dimensions},
ets:insert(egd_font_table, Element).
%% Font loader functions
is_font_loaded(Font) ->
try
case ets:lookup(egd_font_table, {Font, information}) of
[] -> false;
_ -> true
end
catch
error:_ ->
initialize_table(),
false
end.
load_font_header({_Type, _Version, Font}) ->
load_font_body(Font).
load_font_body({Key,Desc,W,H,Glyphs,Bitmaps}) ->
case is_font_loaded(Key) of
true -> Key;
false ->
% insert dimensions
font_insert(Key, Desc, {W,H}),
parse_glyphs(Glyphs, Bitmaps, Key),
Key
end.
parse_glyphs([], _ , _Key) -> ok;
parse_glyphs([Glyph|Glyphs], Bs, Key) ->
{Code, Translation, LSs} = parse_glyph(Glyph, Bs),
glyph_insert(Key, Code, Translation, LSs),
parse_glyphs(Glyphs, Bs, Key).
parse_glyph({Code,W,H,X0,Y0,Xm,Offset}, Bitmasks) ->
BytesPerLine = ((W+7) div 8),
NumBytes = BytesPerLine*H,
<<_:Offset/binary,Bitmask:NumBytes/binary,_/binary>> = Bitmasks,
LSs = render_glyph(W,H,X0,Y0,Xm,Bitmask),
{Code, {W,H,X0,Y0,Xm}, LSs}.
render_glyph(W, H, X0, Y0, Xm, Bitmask) ->
render_glyph(W,{0,H},X0,Y0,Xm,Bitmask, []).
render_glyph(_W, {H,H}, _X0, _Y0, _Xm, _Bitmask, Out) -> Out;
render_glyph(W, {Hi,H}, X0, Y0,Xm, Bitmask , LSs) ->
N = ((W+7) div 8),
O = N*Hi,
<<_:O/binary, Submask/binary>> = Bitmask,
LS = render_glyph_horizontal(
Submask, % line glyph bitmask
{down, W - 1}, % loop state
W - 1, % Width
[]), % Linespans
render_glyph(W,{Hi+1,H},X0,Y0,Xm, Bitmask, [LS|LSs]).
render_glyph_horizontal(Value, {Pr, Px}, 0, Spans) ->
Cr = bit_spin(Value, 0),
case {Pr,Cr} of
{up , up } -> % closure of interval since its last
[{0, Px}|Spans];
{up , down} -> % closure of interval
[{1, Px}|Spans];
{down, up } -> % beginning of interval
[{0, 0}|Spans];
{down, down} -> % no change in interval
Spans
end;
render_glyph_horizontal(Value, {Pr, Px}, Cx, Spans) ->
Cr = bit_spin(Value, Cx),
case {Pr,Cr} of
{up , up } -> % no change in interval
render_glyph_horizontal(Value, {Cr, Px}, Cx - 1, Spans);
{up , down} -> % closure of interval
render_glyph_horizontal(Value, {Cr, Cx}, Cx - 1, [{Cx+1,Px}|Spans]);
{down, up } -> % beginning of interval
render_glyph_horizontal(Value, {Cr, Cx}, Cx - 1, Spans);
{down, down} -> % no change in interval
render_glyph_horizontal(Value, {Cr, Px}, Cx - 1, Spans)
end.
bit_spin(Value, Cx) ->
<<_:Cx, Bit:1, _/bits>> = Value,
case Bit of
1 -> up;
0 -> down
end.
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