[SOLVED] BGRABitmap Rotate
lazarus / 39-Graphics

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Handoko · 2020-08-08 15:23

I want to rotate the icon on its center and draw it on the center of
the form. But I can't make it work correctly. How to fix it?

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
Unit1; {$mode objfpc}{$H+} interface uses  Classes, SysUtils, Forms,
Controls, ExtCtrls,  BGRABitmap, BGRABitmapTypes,
BGRATransform; type   { TForm1 }   TForm1 = class(TForm)    Timer1:
TTimer;    procedure FormCreate(Sender: TObject);    procedure
Timer1Timer(Sender: TObject);  end; var  Form1:
TForm1; implementation {$R *.lfm} { TForm1 } var  Image: TBGRABitmap; 
Tick:  Integer; procedure TForm1.Timer1Timer(Sender: TObject);var 
Temp:   TBGRABitmap;  Affine: TBGRAAffineBitmapTransform;begin 
Inc(Tick);  Temp := TBGRABitmap.Create(ClientWidth, ClientHeight,
BGRAWhite);  Affine := TBGRAAffineBitmapTransform.Create(Image); 
Affine.Translate(-Image.Width div 2, -Image.Height div 2); 
Affine.RotateDeg(Tick);  Temp.FillPolyAntialias([PointF(0, 0),
PointF(ClientWidth, 0),    PointF(ClientWidth, ClientHeight),
PointF(0, ClientHeight)], Affine);  Affine.Free;  Temp.Draw(Canvas,
ClientWidth div 2, ClientHeight div 2);  Temp.Free;end; procedure
TForm1.FormCreate(Sender: TObject);begin  Image :=
TBGRABitmap.Create('project1.ico');end; end.Requirement: BGRABitmap
package

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circular · 2020-08-08 15:49

You need to add a Translate after the Rotate to restore the center
position.
Code: [Select]  Temp := TBGRABitmap.Create(ClientWidth, ClientHeight,
BGRAWhite);
  Affine := TBGRAAffineBitmapTransform.Create(Image);
  Affine.Translate(-Image.Width div 2, -Image.Height div 2);
  Affine.RotateDeg(Tick);
  Affine.Translate(Image.Width div 2, Image.Height div 2);
  Temp.Fill(Affine);
  Affine.Free;
  Temp.Draw(Canvas, 0, 0);
  Temp.Free;

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Handoko · 2020-08-08 17:32

That works. But I keep using FillPolyAntialias because Fill(Affine)
will give black background.

Thanks circular.

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circular · 2020-08-08 19:53

Oh ok. You can add dmDrawWithTransparency parameter to Fill. It is in
principle slightly faster.

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Handoko · 2020-08-09 03:07

Yes, Temp.Fill(Affine, dmDrawWithTransparency); is what I need.

Thank you.

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circular · 2020-08-09 06:58

You're welcome