whats new ¦  programming tips ¦  indy articles ¦  intraweb articles ¦  informations ¦  links ¦  interviews
 misc ¦  tutorials ¦  Add&Win Game

Tips (1548)

Database (90)
Files (137)
Forms (107)
Graphic (116)
IDE (21)
Indy (5)
Internet / LAN (131)
IntraWeb (0)
Math (76)
Misc (127)
Multimedia (45)
Objects/
ActiveX (51)

OpenTools API (3)
Printing (35)
Strings (83)
System (268)
VCL (243)

Top15

Tips sort by
component


Search Tip

Add new Tip

Add&Win Game

Advertising

20 Visitors Online


 
...Draw a line without using the LineTo function?
Autor: Peter Bone
Homepage: http://www.geocities.com/peter_bone_uk
[ Print tip ]  

Tip Rating (26):  
     


{
  Enables you do draw a line if for some reason you
  cannot use the delphi LineTo procedure.
  For example, for drawing higher resolution lines
  or drawing lines in 2D arrays.
}

procedure DrawLine(APoint1, APoint2: TPoint; ACanvas: TCanvas);
var
  
Lpixel, LMaxAxisLength: integer;
  LRatio: Real;
begin
  
LMaxAxisLength := Max(abs(APoint1.X - APoint2.X), abs(APoint1.Y - APoint2.Y));
  for Lpixel := 0 to LMaxAxisLength do 
  begin
    
LRatio := Lpixel / LMaxAxisLength;
    ACanvas.Pixels[APoint1.X + Round((APoint2.X - APoint1.X) * LRatio),
      APoint1.Y + Round((APoint2.Y - APoint1.Y) * LRatio)] :=
      ACanvas.Pen.Color;
  end;
end;

// Draw a double resolution line
procedure DrawLineDouble(APoint1, APoint2: TPoint; ACanvas: TCanvas);
var
  
Lpixel, LMaxAxisLength: integer;
  LRatio: Real;
  LPoint: TPoint;
begin
  
LMaxAxisLength := max(abs(APoint1.X - APoint2.X), abs(APoint1.Y - APoint2.Y));
  for Lpixel := 0 to LMaxAxisLength do 
  begin
    
LRatio := Lpixel / LMaxAxisLength;
    LPoint.X := APoint1.X + Round((APoint2.X - APoint1.X) * LRatio);
    LPoint.Y := APoint1.Y + Round((APoint2.Y - APoint1.Y) * LRatio);
    with ACAnvas do 
    begin
      
Pixels[LPoint.X * 2, LPoint.Y * 2] := clBlack;
      Pixels[(LPoint.X * 2) + 1, LPoint.Y * 2] := clBlack;
      Pixels[LPoint.X * 2, (LPoint.Y * 2) + 1] := clBlack;
      Pixels[(LPoint.X * 2) + 1, (LPoint.Y * 2) + 1] := clBlack;
    end;
  end;
end;

 

Rate this tip:

poor
very good


Copyright © by SwissDelphiCenter.ch
All trademarks are the sole property of their respective owners