Convertor PNG to TGA

[BIT]

Hello, why is the image not being converted correctly?

Code: Pascal  [Select][+][-]

1. unit ImageConverter;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   LCLIntf, Classes, SysUtils, Graphics;
9.  
10. procedure ConvertToTGA(const PNGFileName: string; TGAFileName: string);
11.  
12. implementation
13.  
14. type
15.   TGAHeader = packed record
16.     IDLength: byte;
17.     ColorMapType: byte;
18.     ImageType: byte;
19.  
20.     colorMapIndex: word;
21.     colorMapLength: word;
22.     colorMapDepth: byte;
23.  
24.     offsetX: word;
25.     offsetY: word;
26.     Width: word;
27.     Height: word;
28.     pixelDepth: byte;
29.  
30.     origin: byte;
31.   end;
32.  
33.  
34. procedure ConvertToTGA(const PNGFileName: string; TGAFileName: string);
35. var
36.   PNGImage: TPortableNetworkGraphic;
37.   TGAFile: file of byte;
38.   TGAHead: TGAHeader;
39.   Col: TColor;
40.   X, Y: integer;
41.   A, B, G, R: byte;
42. begin
43.   PNGImage := TPortableNetworkGraphic.Create;
44.   try
45.     PNGImage.LoadFromFile(PNGFileName);
46.     AssignFile(TGAFile, TGAFileName);
47.     Rewrite(TGAFile);
48.  
49.     FillChar(TGAHead, SizeOf(TGAHead), 0);
50.     TGAHead.ImageType := 2;
51.     TGAHead.Width := PNGImage.Width;
52.     TGAHead.Height := PNGImage.Height;
53.     TGAHead.pixelDepth := 32;
54.     BlockWrite(TGAFile, TGAHead, SizeOf(TGAHead));
55.  
56.     for Y := PNGImage.Height - 1 downto 0 do
57.     begin
58.       for X := 0 to PNGImage.Width - 1 do
59.       begin
60.  
61.         Col := PNGImage.Canvas.Pixels[X, Y];
62.  
63.         A := byte(Col);
64.         B := GetBValue(Col);
65.         G := GetGValue(Col);
66.         R := GetRValue(Col);
67.  
68.         BlockWrite(TGAFile, B, SizeOf(byte));
69.         BlockWrite(TGAFile, G, SizeOf(byte));
70.         BlockWrite(TGAFile, R, SizeOf(byte));
71.         BlockWrite(TGAFile, A, SizeOf(byte));
72.       end;
73.     end;
74.  
75.   finally
76.     PNGImage.Free;
77.     CloseFile(TGAFile);
78.   end;
79. end;
80.  
81.  
82. end.

Use

Code: Pascal  [Select][+][-]

1.  
2. ImageConverter.ConvertToTGA('original.png', 'output.tga');  
3.  

images:
1: original PNG
2: output TGA

[circular]

The A value is not retrieved correctly.

The Pixels property returns a TColor so in principle it doesn't contain the alpha value. Instead you could try the Colors property that returns an TFPColor. The channels are stored as Word values so one need to shift them (shr 8) to get the byte value.

[BIT]

The A value is not retrieved correctly.

The Pixels property returns a TColor so in principle it doesn't contain the alpha value. Instead you could try the Colors property that returns an TFPColor. The channels are stored as Word values so one need to shift them (shr 8) to get the byte value.

Can I have a complete example? Otherwise I don't understand how to do it)

[circular]

I imagine it would be something like:

Code: Pascal  [Select][+][-]

1. var Col: TFPColor;
2. ...
3.         Col := PNGImage.Canvas.Colors[X, Y];
4.  
5.         A := Col.alpha shr 8;
6.         B := Col.blue shr 8;
7.         G := Col.green shr 8;
8.         R := Col.red shr 8;

[BIT]

I imagine it would be something like:

Code: Pascal  [Select][+][-]

1. var Col: TFPColor;
2. ...
3.         Col := PNGImage.Canvas.Colors[X, Y];
4.  
5.         A := Col.alpha shr 8;
6.         B := Col.blue shr 8;
7.         G := Col.green shr 8;
8.         R := Col.red shr 8;

it didn't help((

[circular]

The LCL sometimes doesn't handle alpha channel.

You can instead use BGRABitmap package.

Code: Pascal  [Select][+][-]

1. uses BGRABitmap;
2.  
3. procedure ConvertToTGA(const PNGFileName: string; TGAFileName: string);
4. var bmp: TBGRABitmap;
5. begin
6.   bmp.LoadFromFile(PNGFileName);
7.   bmp.SaveToFile(TGAFileName); // TGA is already implemented
8.   // or you can access bmp.Colors property
9. end;

[BIT]

The LCL sometimes doesn't handle alpha channel.

You can instead use BGRABitmap package.

Code: Pascal  [Select][+][-]

1. uses BGRABitmap;
2.  
3. procedure ConvertToTGA(const PNGFileName: string; TGAFileName: string);
4. var bmp: TBGRABitmap;
5. begin
6.   bmp.LoadFromFile(PNGFileName);
7.   bmp.SaveToFile(TGAFileName); // TGA is already implemented
8.   // or you can access bmp.Colors property
9. end;

I've tried all the libraries, they don't suit me, the maximum suitable tga format for my purposes is the code in the first post.
But there's a problem with transparency, I don't know how to solve it((

[AlexTP]

If there is smthing that BGRABitmap does wrong with TGA, you can post the bugreport (with the full demo project) to the GitHub
https://github.com/bgrabitmap/bgrabitmap/issues

[circular]

Well @BIT, as indicated in my commentary, there is also a Colors property in TBGRABitmap. So your example can be adapted like this:

Code: Pascal  [Select][+][-]

1. unit ImageConverter;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.  Classes, SysUtils, BGRABitmap, FPImage;
9.  
10. procedure ConvertToTGA(const PNGFileName: string; TGAFileName: string);
11.  
12. implementation
13.  
14. type
15.   TGAHeader = packed record
16.     IDLength: byte;
17.     ColorMapType: byte;
18.     ImageType: byte;
19.  
20.     colorMapIndex: word;
21.     colorMapLength: word;
22.     colorMapDepth: byte;
23.  
24.     offsetX: word;
25.     offsetY: word;
26.     Width: word;
27.     Height: word;
28.     pixelDepth: byte;
29.  
30.     origin: byte;
31.   end;
32.  
33.  
34. procedure ConvertToTGA(const PNGFileName: string; TGAFileName: string);
35. var
36.   PNGImage: TBGRABitmap;
37.   TGAFile: file of byte;
38.   TGAHead: TGAHeader;
39.   Col: TFPColor;
40.   X, Y: integer;
41.   A, B, G, R: byte;
42. begin
43.   PNGImage := TBGRABitmap.Create(PNGFileName);
44.   AssignFile(TGAFile, TGAFileName);
45.   Rewrite(TGAFile);
46.   try
47.     FillChar(TGAHead, SizeOf(TGAHead), 0);
48.     TGAHead.ImageType := 2;
49.     TGAHead.Width := PNGImage.Width;
50.     TGAHead.Height := PNGImage.Height;
51.     TGAHead.pixelDepth := 32;
52.     BlockWrite(TGAFile, TGAHead, SizeOf(TGAHead));
53.  
54.     for Y := PNGImage.Height - 1 downto 0 do
55.     begin
56.       for X := 0 to PNGImage.Width - 1 do
57.       begin
58.  
59.         Col := PNGImage.Colors[X, Y];
60.  
61.         A := Col.alpha shr 8;
62.         B := Col.blue shr 8;
63.         G := Col.green shr 8;
64.         R := Col.red shr 8;
65.  
66.         BlockWrite(TGAFile, B, SizeOf(byte));
67.         BlockWrite(TGAFile, G, SizeOf(byte));
68.         BlockWrite(TGAFile, R, SizeOf(byte));
69.         BlockWrite(TGAFile, A, SizeOf(byte));
70.       end;
71.     end;
72.  
73.   finally
74.     PNGImage.Free;
75.     CloseFile(TGAFile);
76.   end;
77. end;
78.  
79. end.

[BIT]

Well @BIT, as indicated in my commentary, there is also a Colors property in TBGRABitmap. So your example can be adapted like this:

Code: Pascal  [Select][+][-]

1. unit ImageConverter;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.  Classes, SysUtils, BGRABitmap, FPImage;
9.  
10. procedure ConvertToTGA(const PNGFileName: string; TGAFileName: string);
11.  
12. implementation
13.  
14. type
15.   TGAHeader = packed record
16.     IDLength: byte;
17.     ColorMapType: byte;
18.     ImageType: byte;
19.  
20.     colorMapIndex: word;
21.     colorMapLength: word;
22.     colorMapDepth: byte;
23.  
24.     offsetX: word;
25.     offsetY: word;
26.     Width: word;
27.     Height: word;
28.     pixelDepth: byte;
29.  
30.     origin: byte;
31.   end;
32.  
33.  
34. procedure ConvertToTGA(const PNGFileName: string; TGAFileName: string);
35. var
36.   PNGImage: TBGRABitmap;
37.   TGAFile: file of byte;
38.   TGAHead: TGAHeader;
39.   Col: TFPColor;
40.   X, Y: integer;
41.   A, B, G, R: byte;
42. begin
43.   PNGImage := TBGRABitmap.Create(PNGFileName);
44.   AssignFile(TGAFile, TGAFileName);
45.   Rewrite(TGAFile);
46.   try
47.     FillChar(TGAHead, SizeOf(TGAHead), 0);
48.     TGAHead.ImageType := 2;
49.     TGAHead.Width := PNGImage.Width;
50.     TGAHead.Height := PNGImage.Height;
51.     TGAHead.pixelDepth := 32;
52.     BlockWrite(TGAFile, TGAHead, SizeOf(TGAHead));
53.  
54.     for Y := PNGImage.Height - 1 downto 0 do
55.     begin
56.       for X := 0 to PNGImage.Width - 1 do
57.       begin
58.  
59.         Col := PNGImage.Colors[X, Y];
60.  
61.         A := Col.alpha shr 8;
62.         B := Col.blue shr 8;
63.         G := Col.green shr 8;
64.         R := Col.red shr 8;
65.  
66.         BlockWrite(TGAFile, B, SizeOf(byte));
67.         BlockWrite(TGAFile, G, SizeOf(byte));
68.         BlockWrite(TGAFile, R, SizeOf(byte));
69.         BlockWrite(TGAFile, A, SizeOf(byte));
70.       end;
71.     end;
72.  
73.   finally
74.     PNGImage.Free;
75.     CloseFile(TGAFile);
76.   end;
77. end;
78.  
79. end.

Thank you this code is working!
Now the tga file is loaded into the UnrealEd editor