(SOLVED) Convert PNG transparency in white color
lazarus / 39-Graphics

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AsleyCruz · 2020-03-24 18:26

Hi coders,

I have an PNG file with transparency in a TImage. I save it in JPG
format but the transparency has black background.
Is there a function to convert the transparency in white color?

Many thanks a lot.

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winni · 2020-03-24 19:14

Hi!

Why do you want to do that??

JPG has no transparency, it is a lossy format and with high
compression it has a lousy quality.

Anyway:

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 Uses ....
BGRAbitmap, BGRAdefaultBitmap; .... var BGRA: TBGRAbitmap; beginBGRA
:= TBGRAbitmap.create (Image1.Picture.Bitmap);BGRA.ReplaceColor
(BGRAPixelTransparent, clWhite);BGRA.Draw
(Image1.Canvas,0,0);BGRA.Free;.....
Winni

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lucamar · 2020-03-24 19:24

One other, maybe more simple, way (without resorting to 3rd party
libs) would be to create a white TBitmap of the proper dimensions,
draw the PNG over it and convert that to JPEG.

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AsleyCruz · 2020-03-24 19:45

Quote from: winni on March 24, 2020, 08:14:23 pmHi!

Why do you want to do that??

JPG has no transparency, it is a lossy format and with high
compression it has a lousy quality.

Anyway:

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 .....
Winni

Many thanks winni but I dont know what I am doing wrong.
Please see attached image. Tested in a blank document.

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winni · 2020-03-24 20:32

Hi!

Sorry - I forgot in the uses

BGRAbitmapTypes;

That's the whole secret.

Winni

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AsleyCruz · 2020-03-24 22:49

Quote from: winni on March 24, 2020, 09:32:29 pmHi!

Sorry - I forgot in the uses

BGRAbitmapTypes;

That's the whole secret.

Winni

Thanks Winni, it works and replaces transparent color of any BMP image
only.
Unable to replace transparent color on PNG files.

Thanks

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lainz · 2020-03-24 23:05

Create a white bgrabitmap of the same size of the image. Then draw on
top of it your transparent image.

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AsleyCruz · 2020-03-24 23:24

Quote from: lainz on March 25, 2020, 12:05:19 amCreate a white
bgrabitmap of the same size of the image. Then draw on top of it your
transparent image.

Hi Lainz

What I tried, it replace all red background :/
Any idea to drop the PNG file?

Thanks a lot

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 BGRA :=
TBGRABitmap.Create(256,256,clred);

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lainz · 2020-03-24 23:49

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 var 
bgBitmap, bgImage: TBGRABitmap; bgImage :=
TBGRABitmap.Create('image.png'); bgBitmap :=
TBGRABitmap.Create(bgImage.Width, bgImage.Height,
BGRAWhite); bgBitmap.PutImage(0,0,bgImage, dmDrawWithTransparency); bg
Image.Free; bgBitmap.SaveToFile('image.jpg'); bgBitmap.Free;

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AsleyCruz · 2020-03-25 00:25

Quote from: lainz on March 25, 2020, 12:49:15 amCode: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var 
bgBitmap, bgImage: TBGRABitmap; bgImage :=
TBGRABitmap.Create('image.png'); bgBitmap :=
TBGRABitmap.Create(bgImage.Width, bgImage.Height,
BGRAWhite); bgBitmap.PutImage(0,0,bgImage, dmDrawWithTransparency); bg
Image.Free; bgBitmap.SaveToFile('image.jpg'); bgBitmap.Free;
Oye, tu componente es excelente, lástima no conocer bien sus
capacidades.
Apenas en 2 proyectos míos lo he usado, pocas líneas y grandes
resultados.
Mil gracias bro.

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lainz · 2020-03-25 01:46

Isn't mine. The author is circular
I only contribute in bgracontrols