Graphics 32 and Tbitmap32

[clintonb]

I have had an issue with the Tbitmap32.  To fix the problem i made a smaller program that just tried to load from a file and then save it//display it but i just keep getting a black background.

I made an even simpler application that creates a bitmap; draws on the canvas and then tries to assign and save it.  Eveything that is returned is a black background.  I tried a suggestion calling test.changed and then test.canvas.changed

test:=Tbitmap32.create(TLCLBackend);

     test.beginupdate;
     test.setsize(300,300);

     test.Canvas.moveto(0,0);
     test.canvas.Pen.Color:=clred;
     test.canvas.pen.width:=5;
     test.canvas.lineto(100,100);
     test.canvas.Brush.Color:=clred;
     test.canvas.Brush.Style:=bssolid;
     test.canvas.FillRect(0,0,100,100);
     test.endupdate;
     test.Canvas.Changed;

     image1.bitmap.assign(test);
     test.savetofile('/home/[username]/Desktop/Blank image.bmp');
     

Im using 64 bit linux and im using the latest library from the online packagemanager but no matter what i try i cannot get anything other that a black background.  Is there something i am missing or is there a very basic application that demonstrates the proper usage for this library?

[RAW]

You draw something (Bitmap32) and then want to show the result with an standard canvas TIMAGE ????
Use TImage32 from the lib!

[clintonb]

I might be misunderstanding what you are saying but image1 is a Timage32 that was just pasted onto the form.  The bottom line still ends with the image being a blank black canvas which shows in the file that it saves as well.

[wp]

It's been a very long time since I did a Delphi project with Graphics32. As its name says, Graphics 32 is a 32-bit library, this means the every color consists of 3 bytes for red, green and blue as well as one more byte for the alpha channel where 0 means complete transparency and $FF complete opaqueness.

You fill the Graphics32 canvas with the color clRed which is defined in unit graphics as $000000FF - the two 0s after the $ are the alpha channel - complete transparency. You should use the color declarations defined in unit GR32, I just looked: there is a clRed32 where the alpha channel is $FF.

[RAW]

Don't draw on/with the standard canvas if you need transparent pixels, the example shows nothing that can't be done with a normal bitmap. Use the GR32 routines... and the TImage in GR32 looks like this "Image321"... There's no Pen.Color in GR32 (BMP32.PenColor:= ...). There is no clRed only clTrRed32 or clRed32...  You are using the wrong canvas! 

[RAW]

This works for me ... 

Code: Pascal  [Select][+][-]

1. unit Unit1;
2. {$mode objfpc}{$H+}
3. interface
4. uses
5.   Classes,SysUtils,Forms,Controls,Graphics,GR32,ExtCtrls,StdCtrls;
6. type
7.   TForm1 = class(TForm)
8.     Button1: TButton;
9.     procedure Button1Click(Sender: TObject);
10.   private
11.  
12.   public
13.  
14.   end;
15. var
16.   Form1: TForm1;
17. implementation
18. {$R *.lfm}
19.  
20. procedure TForm1.Button1Click(Sender: TObject);
21. var
22.  BMP32: TBitmap32;
23.  IMG: TImage;
24. begin
25.   BMP32:= TBitmap32.Create(300,300);
26.   Try
27.    BMP32.FillRect(0,0,300,300,clRed32);
28.    BMP32.SaveToFile('BMP32.bmp');
29.    IMG:= TImage.Create(Self);
30.    IMG.Picture.Assign(BMP32);
31.    IMG.Parent:= Self;
32.   Finally
33.    BMP32.Free;
34.   End;
35. end;
36.  
37. end.

[clintonb]

Don't draw on/with the standard canvas if you need transparent pixels, the example shows nothing that can't be done with a normal bitmap. Use the GR32 routines... and the TImage in GR32 looks like this "Image321"... There's no Pen.Color in GR32 (BMP32.PenColor:= ...). There is no clRed only clTrRed32 or clRed32...  You are using the wrong canvas! 

And that good people is conclusive prrof that i am absolutely useless after 8pm.  Thanks mate