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//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.4 (Public License)
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Anti-Grain Geometry - Version 2.4 Release Milano 3 (AggPas 2.4 RM3)
// Pascal Port By: Milan Marusinec alias Milano
// milan@marusinec.sk
// http://www.aggpas.org
// Copyright (c) 2005-2006
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
// mcseemagg@yahoo.com
// http://www.antigrain.com
//
// [Pascal Port History] -----------------------------------------------------
//
// 30.01.2006-Milano: Unit port establishment
//
{ agg_gamma_spline.pas }
unit
agg_gamma_spline ;
INTERFACE
{$I agg_mode.inc }
uses
agg_basics ,
agg_bspline ,
agg_vertex_source ;
{ TYPES DEFINITION }
type
// Class-helper for calculation gamma-correction arrays. A gamma-correction
// array is an array of 256 unsigned chars that determine the actual values
// of Anti-Aliasing for each pixel coverage value from 0 to 255. If all the
// values in the array are equal to its index, i.e. 0,1,2,3,... there's
// no gamma-correction. Class agg::polyfill allows you to use custom
// gamma-correction arrays. You can calculate it using any approach, and
// class gamma_spline allows you to calculate almost any reasonable shape
// of the gamma-curve with using only 4 values - kx1, ky1, kx2, ky2.
//
// kx2
// +----------------------------------+
// | | | . |
// | | | . | ky2
// | | . ------|
// | | . |
// | | . |
// |----------------.|----------------|
// | . | |
// | . | |
// |-------. | |
// ky1 | . | | |
// | . | | |
// +----------------------------------+
// kx1
//
// Each value can be in range [0...2]. Value 1.0 means one quarter of the
// bounding rectangle. Function values() calculates the curve by these
// 4 values. After calling it one can get the gamma-array with call gamma().
// Class also supports the vertex source interface, i.e rewind() and
// vertex(). It's made for convinience and used in class gamma_ctrl.
// Before calling rewind/vertex one must set the bounding box
// box() using pixel coordinates.
gamma_spline = object(vertex_source )
m_gamma : array[0..255 ] of char;
m_x ,
m_y : array[0..3 ] of double;
m_x1 ,
m_y1 ,
m_x2 ,
m_y2 ,
m_cur_x : double;
m_spline : bspline;
constructor Construct;
destructor Destruct; virtual;
procedure values(kx1 ,ky1 ,kx2 ,ky2 : double ); overload;
procedure values(kx1 ,ky1 ,kx2 ,ky2 : double_ptr ); overload;
function gamma : char_ptr;
function _y (x : double ) : double;
procedure box(x1 ,y1 ,x2 ,y2 : double );
procedure rewind(path_id : unsigned ); virtual;
function vertex(x ,y : double_ptr ) : unsigned; virtual;
end;
{ GLOBAL PROCEDURES }
IMPLEMENTATION
{ LOCAL VARIABLES & CONSTANTS }
{ UNIT IMPLEMENTATION }
{ CONSTRUCT }
constructor gamma_spline.Construct;
begin
m_spline.Construct;
m_x1:=0;
m_y1:=0;
m_x2:=10;
m_y2:=10;
m_cur_x:=0.0;
values(1.0 ,1.0 ,1.0 ,1.0 );
end;
{ DESTRUCT }
destructor gamma_spline.Destruct;
begin
m_spline.Destruct;
end;
{ VALUES }
procedure gamma_spline.values(kx1 ,ky1 ,kx2 ,ky2 : double );
var
i : int;
begin
if kx1 < 0.001 then
kx1:=0.001;
if kx1 > 1.999 then
kx1:=1.999;
if ky1 < 0.001 then
ky1:=0.001;
if ky1 > 1.999 then
ky1:=1.999;
if kx2 < 0.001 then
kx2:=0.001;
if kx2 > 1.999 then
kx2:=1.999;
if ky2 < 0.001 then
ky2:=0.001;
if ky2 > 1.999 then
ky2:=1.999;
m_x[0 ]:=0.0;
m_y[0 ]:=0.0;
m_x[1 ]:=kx1 * 0.25;
m_y[1 ]:=ky1 * 0.25;
m_x[2 ]:=1.0 - kx2 * 0.25;
m_y[2 ]:=1.0 - ky2 * 0.25;
m_x[3 ]:=1.0;
m_y[3 ]:=1.0;
m_spline.init(4 ,@m_x ,@m_y );
for i:=0 to 255 do
m_gamma[i ]:=char(trunc(_y(i / 255.0 ) * 255.0 ) );
end;
{ VALUES }
procedure gamma_spline.values(kx1 ,ky1 ,kx2 ,ky2 : double_ptr );
begin
kx1^:=m_x[1 ] * 4.0;
ky1^:=m_y[1 ] * 4.0;
kx2^:=(1.0 - m_x[2 ] ) * 4.0;
ky2^:=(1.0 - m_y[2 ] ) * 4.0;
end;
{ GAMMA }
function gamma_spline.gamma;
begin
result:=@m_gamma[0 ];
end;
{ _Y }
function gamma_spline._y;
var
val : double;
begin
if x < 0.0 then
x:=0.0;
if x > 1.0 then
x:=1.0;
val:=m_spline.get(x );
if val < 0.0 then
val:=0.0;
if val > 1.0 then
val:=1.0;
result:=val;
end;
{ BOX }
procedure gamma_spline.box;
begin
m_x1:=x1;
m_y1:=y1;
m_x2:=x2;
m_y2:=y2;
end;
{ REWIND }
procedure gamma_spline.rewind;
begin
m_cur_x:=0.0;
end;
{ VERTEX }
function gamma_spline.vertex;
begin
if m_cur_x = 0.0 then
begin
x^:=m_x1;
y^:=m_y1;
m_cur_x:=m_cur_x + (1.0 / (m_x2 - m_x1 ) );
result :=path_cmd_move_to;
exit;
end;
if m_cur_x > 1.0 then
begin
result:=path_cmd_stop;
exit;
end;
x^:=m_x1 + m_cur_x * (m_x2 - m_x1 );
y^:=m_y1 + _y(m_cur_x ) * (m_y2 - m_y1 );
m_cur_x:=m_cur_x + (1.0 / (m_x2 - m_x1 ) );
result :=path_cmd_line_to;
end;
END.
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