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 Difference ImageEn #3.12 and #4.0		  New Topic  Reply to Topic
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Marius

Netherlands
21 Posts
Posted - Jul 19 2011 :  05:11:57  Show Profile  Reply
Hello Fabio/Nigel,

Nice to see you back in action Fabio, finally my favorite graphic toolbox is actively developed again!


1) We have just upgraded to imageen 4.0 and i'm get the following exception on the line "APng.TransparentColor := clWhite".
Exception: "Setting bit transparency color is not allowed for png images containing alpha value for each pixel (COLOR_RGBALPHA and COLOR_GRAYSCALEALPHA)". As soon as i put the 3.12 back this is working properly. I got this working again by modifying the bitmap and setting the transparant color (which wasn't alway's the case). Did something change in this corner or do i do something wrong?

2) The same code still goes wrong on making a couple of png's transparant. This ONLY happends with Rgb(255, 255, 000), i attached one of the images (other images with the same color are ok so i do expect its a imageen#4 issue). Is there something i do wrong in this code?

If you need more info or need the example project please ask (i dont want to post it here)


APng := TPngImage.Create;
AStream := TMemoryStream.Create;
ImageEn2 := TImageEn.Create(nil);
try
ImageEn2.IO.LoadFromFileBMP(AFilename);
ImageEn2.IO.Params.BMP_HandleTransparency := true;
ImageEn2.IO.Params.PNG_Background := TColor2TRGB(clWhite);

//Replace yellow with the newcolor
ANewColor := Rgb(255, 255, 000);
for x := 0 to ImageEn2.IEBitmap.Width do begin
for y := 0 to ImageEn2.IEBitmap.Height do begin
if ImageEn2.IEBitmap.Canvas.Pixels[x, y] = clYellow
then ImageEn2.IEBitmap.Canvas.Pixels[x, y] := ANewColor;
end;
end;
ImageEn2.Proc.Resample(20, 20, rfNearest); //Resize
ImageEn2.IO.SaveToStreamPng(AStream);

AStream.Position := 0;
APng.LoadFromStream(AStream);
APng.TransparentColor := clWhite;
ADatamodule.ImageList.AddPng(APng);
finally
ImageEn2.Free;
AStream.Free;
APng.Free;
end;


Greetings,
Marius

fab

1310 Posts
Posted - Jul 19 2011 :  07:47:21  Show Profile  Reply
Hi Marius,
what is the goal of your code?
I suppose:
1) load an image (that hasn't alpha channel, true?)
2) resample to a specified size (ie 20x20)
3) make some colors transparent and save as PNG

If the supposition is right I will send you the right code to do the task.

Please note that TPngImage is not an ImageEn class. However the exception is right, because you are trying to make a color transparent, while the PNG created by ImageEn already has an alpha channel (which use, your color or the embedded alpha channel?).
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Marius

Netherlands
21 Posts
Posted - Jul 19 2011 :  08:50:16  Show Profile  Reply
hello Fabrizio,

The code is part of a tool we use to generates resources files, in the end the imagelist contains about 300 images with different variations of colors. Your assumptions are almost correct, just a few minor corrections:

1) load an image (that hasn't alpha channel, true?) yes.
-> replace a specific marked color with another.
2) resample to a specified size (ie 20x20) yes.
3) make some colors transparent and save as PNG (yes, but only white should be transparent in this case)

My major problem is that in step 3 the image with the specific color Rgb(255, 255, 000) is not transparent while other are.


Greetings,
Marius
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fab

1310 Posts
Posted - Jul 19 2011 :  14:05:27  Show Profile  Reply
The "ImageEn" way is:


var
  oldColor, newColor, transpColor:TRGB;
  ...other variables
begin
  ImageEnView1.IO.LoadFromFile('20117195814_Analysis.bmp');

  // replace all pixels with "oldColor" with "newColor"
  oldColor := CreateRGB(255, 255, 0); // yellow
  newColor := CreateRGB(0, 0, 255);   // blue
  ImageEnView1.Proc.CastColorRange(oldColor, oldColor, newColor);

  // resample to 20x20
  ImageEnView1.Proc.Resample(20, 20, rfNearest);

  // make all pixels with "transpColor" transparent (alpha=0)
  transpColor := CreateRGB(255, 255, 255);  // white
  ImageEnView1.Proc.SetTransparentColors(transpColor, transpColor, 0);

  // now you can save the PNG and reload it
  ImageEnView1.IO.SaveToStreamPNG(AStream);
  AStream.Position := 0;
  APng.LoadFromStream(AStream);
  ADatamodule.ImageList.AddPng(APng);

end;


Note that CreateRGB is defined in "imageenproc" unit.

Hope this helps.
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