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{
Free Pascal port of the OpenPTC C++ library.
Copyright (C) 2001-2003, 2006, 2007, 2009-2011 Nikolay Nikolov (nickysn@users.sourceforge.net)
Original C++ version by Glenn Fiedler (ptc@gaffer.org)
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version
with the following modification:
As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent modules,and
to copy and distribute the resulting executable under terms of your choice,
provided that you also meet, for each linked independent module, the terms
and conditions of the license of that module. An independent module is a
module which is not derived from or based on this library. If you modify
this library, you may extend this exception to your version of the library,
but you are not obligated to do so. If you do not wish to do so, delete this
exception statement from your version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
}
{$INLINE ON}
class function TPTCClipper.Clip(AArea, AClip: IPTCArea): IPTCArea;
var
left, top, right, bottom: Integer;
clip_left, clip_top, clip_right, clip_bottom: Integer;
begin
{ get in coordinates }
left := AArea.Left;
top := AArea.Top;
right := AArea.Right;
bottom := AArea.Bottom;
{ get clip coordinates }
clip_left := AClip.Left;
clip_top := AClip.Top;
clip_right := AClip.Right;
clip_bottom := AClip.Bottom;
{ clip left }
if left < clip_left then
left := clip_left;
if left > clip_right then
left := clip_right;
{ clip top }
if top < clip_top then
top := clip_top;
if top > clip_bottom then
top := clip_bottom;
{ clip right }
if right < clip_left then
right := clip_left;
if right > clip_right then
right := clip_right;
{ clip bottom }
if bottom < clip_top then
bottom := clip_top;
if bottom > clip_bottom then
bottom := clip_bottom;
Result := TPTCArea.Create(Left, Top, Right, Bottom);
end;
{ clip floating point area against a floating point clip area }
procedure TPTCClipper_clip(var left, top, right, bottom: Real;
clip_left, clip_top, clip_right, clip_bottom: Real); Inline;
begin
{ clip left }
if left < clip_left then
left := clip_left;
if left > clip_right then
left := clip_right;
{ clip top }
if top < clip_top then
top := clip_top;
if top > clip_bottom then
top := clip_bottom;
{ clip right }
if right < clip_left then
right := clip_left;
if right > clip_right then
right := clip_right;
{ clip bottom }
if bottom < clip_top then
bottom := clip_top;
if bottom > clip_bottom then
bottom := clip_bottom;
end;
{ clip floating point area against clip area }
procedure TPTCClipper_clip(var left, top, right, bottom: Real; const _clip: IPTCArea); Inline;
var
clip_left, clip_top, clip_right, clip_bottom: Real;
begin
{ get floating point clip area }
clip_left := _clip.left;
clip_top := _clip.top;
clip_right := _clip.right;
clip_bottom := _clip.bottom;
{ clip floating point area against floating point clip area }
TPTCClipper_clip(left, top, right, bottom, clip_left, clip_top, clip_right, clip_bottom);
end;
{ snap a floating point area to integer coordinates }
procedure TPTCClipper_round(var left, top, right, bottom: Real); Inline;
begin
left := Round(left);
top := Round(top);
right := Round(right);
bottom := Round(bottom);
end;
class procedure TPTCClipper.Clip(ASource, AClipSource: IPTCArea;
out AClippedSource: IPTCArea;
ADestination, AClipDestination: IPTCArea;
out AClippedDestination: IPTCArea);
var
source_left, source_top, source_right, source_bottom: Real;
clipped_source_left, clipped_source_top, clipped_source_right,
clipped_source_bottom: Real;
source_delta_left, source_delta_top, source_delta_right,
source_delta_bottom: Real;
source_to_destination_x, source_to_destination_y: Real;
destination_left, destination_top, destination_right,
destination_bottom: Real;
adjusted_destination_left, adjusted_destination_top,
adjusted_destination_right, adjusted_destination_bottom: Real;
clipped_destination_left, clipped_destination_top,
clipped_destination_right, clipped_destination_bottom: Real;
destination_delta_left, destination_delta_top, destination_delta_right,
destination_delta_bottom: Real;
destination_to_source_x, destination_to_source_y: Real;
adjusted_source_left, adjusted_source_top, adjusted_source_right,
adjusted_source_bottom: Real;
begin
{ expand source area to floating point }
source_left := ASource.Left;
source_top := ASource.Top;
source_right := ASource.Right;
source_bottom := ASource.Bottom;
{ setup clipped source area }
clipped_source_left := source_left;
clipped_source_top := source_top;
clipped_source_right := source_right;
clipped_source_bottom := source_bottom;
{ perform clipping on floating point source area }
TPTCClipper_clip(clipped_source_left, clipped_source_top, clipped_source_right,
clipped_source_bottom, AClipSource);
{ check for early source area clipping exit }
if (clipped_source_left = clipped_source_right) or
(clipped_source_top = clipped_source_bottom) then
begin
{ clipped area is zero }
AClippedSource := TPTCArea.Create(0, 0, 0, 0);
AClippedDestination := AClippedSource;
exit;
end;
{ calculate deltas in source clip }
source_delta_left := clipped_source_left - source_left;
source_delta_top := clipped_source_top - source_top;
source_delta_right := clipped_source_right - source_right;
source_delta_bottom := clipped_source_bottom - source_bottom;
{ calculate ratio of source area to destination area }
source_to_destination_x := ADestination.Width / ASource.Width;
source_to_destination_y := ADestination.Height / ASource.Height;
{ expand destination area to floating point }
destination_left := ADestination.Left;
destination_top := ADestination.Top;
destination_right := ADestination.Right;
destination_bottom := ADestination.Bottom;
{ calculate adjusted destination area }
adjusted_destination_left := destination_left + source_delta_left * source_to_destination_x;
adjusted_destination_top := destination_top + source_delta_top * source_to_destination_y;
adjusted_destination_right := destination_right + source_delta_right * source_to_destination_x;
adjusted_destination_bottom := destination_bottom + source_delta_bottom * source_to_destination_y;
{ setup clipped destination area }
clipped_destination_left := adjusted_destination_left;
clipped_destination_top := adjusted_destination_top;
clipped_destination_right := adjusted_destination_right;
clipped_destination_bottom := adjusted_destination_bottom;
{ perform clipping on floating point destination area }
TPTCClipper_clip(clipped_destination_left, clipped_destination_top,
clipped_destination_right, clipped_destination_bottom, AClipDestination);
{ check for early destination area clipping exit }
if (clipped_destination_left = clipped_destination_right) or
(clipped_destination_top = clipped_destination_bottom) then
begin
{ clipped area is zero }
AClippedSource := TPTCArea.Create(0, 0, 0, 0);
AClippedDestination := AClippedSource;
exit;
end;
{ calculate deltas in destination clip }
destination_delta_left := clipped_destination_left - adjusted_destination_left;
destination_delta_top := clipped_destination_top - adjusted_destination_top;
destination_delta_right := clipped_destination_right - adjusted_destination_right;
destination_delta_bottom := clipped_destination_bottom - adjusted_destination_bottom;
{ calculate ratio of destination area to source area }
destination_to_source_x := 1 / source_to_destination_x;
destination_to_source_y := 1 / source_to_destination_y;
{ calculate adjusted source area }
adjusted_source_left := clipped_source_left + destination_delta_left * destination_to_source_x;
adjusted_source_top := clipped_source_top + destination_delta_top * destination_to_source_y;
adjusted_source_right := clipped_source_right + destination_delta_right * destination_to_source_x;
adjusted_source_bottom := clipped_source_bottom + destination_delta_bottom * destination_to_source_y;
{ assign adjusted source to clipped source }
clipped_source_left := adjusted_source_left;
clipped_source_top := adjusted_source_top;
clipped_source_right := adjusted_source_right;
clipped_source_bottom := adjusted_source_bottom;
{ round clipped areas to integer coordinates }
TPTCClipper_round(clipped_source_left, clipped_source_top,
clipped_source_right, clipped_source_bottom);
TPTCClipper_round(clipped_destination_left, clipped_destination_top,
clipped_destination_right, clipped_destination_bottom);
{ construct clipped area rectangles from rounded floating point areas }
AClippedSource := TPTCArea.Create(Trunc(clipped_source_left),
Trunc(clipped_source_top),
Trunc(clipped_source_right),
Trunc(clipped_source_bottom));
AClippedDestination := TPTCArea.Create(Trunc(clipped_destination_left),
Trunc(clipped_destination_top),
Trunc(clipped_destination_right),
Trunc(clipped_destination_bottom));
end;
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