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Author Topic: Transparent form  (Read 1680 times)

pcurtis

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Transparent form
« on: July 06, 2020, 11:48:50 pm »
Is it possible to make a form transparent, but keep the components solid?

Thanks in advance.
Windows 10 / Linux Mint 20
Laz 2.0.8
FPC 3.0.4

jamie

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Re: Transparent form
« Reply #1 on: July 07, 2020, 12:58:15 am »
Yes but there are two ways to do it, one that may work in all targets and one that works well that only works in Windows because of a couple API calls.

you need to be more specific on your requirements..
The only true wisdom is knowing you know nothing

RAW

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Re: Transparent form
« Reply #2 on: July 07, 2020, 02:26:28 am »
On Windows you can use
Code: Pascal  [Select][+][-]
  1. CreatePolygonRgn, SetWindowRgn
  but this way the result is 100% transparent not semi transparent. Or you use a second window in the background with
Code: Pascal  [Select][+][-]
  1. AlphaBlend:= True; AlphaBlendValue:= 128;

In other words 1. cut out everything you don't need from window 1 and then create window 2 behind window 1 fully semi transparent ...
Trial and error ..  :)

Windows 7 Pro (x64 Sp1) And Windows XP Pro (x86 Sp3) - LAZARUS 2.0.8 FPC 3.0.4 - TRUNK 2.1.0 FPC 3.3.1
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// There are 10 types of people in this world, those who understand mind control and ...

Davo

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Re: Transparent form
« Reply #3 on: July 07, 2020, 03:34:31 am »
Some time ago I received guidance in this Forum to the same question. It works for me - Windows only. The relevant code insert into the FormShow event handler is :

Code: Pascal  [Select][+][-]
  1.   {make the form transparent - works only with Windows operating systems}
  2.   SetWindowLong(Handle, GWL_EXSTYLE, GetWindowLong(Handle, GWL_EXSTYLE) or
  3.     WS_EX_LAYERED);
  4.   SetLayeredWindowAttributes(Handle, clWhite, 255, LWA_COLORKEY);
  5.  
« Last Edit: July 07, 2020, 03:40:50 am by Davo »

Handoko

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Re: Transparent form
« Reply #4 on: July 07, 2020, 04:28:25 am »
I remember there was a similar discussion, maybe helpful:
https://forum.lazarus.freepascal.org/index.php/topic,34038.msg222021.html

pcurtis

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Re: Transparent form
« Reply #5 on: July 07, 2020, 04:35:12 am »
@jamie - I use Win 10
@RAW - Any sample? (I'm not so advanced)
@Davo - I'm not quite sure what it does?
@Handoko - It's what I want but for "Any Component" not just TImage - Any ideas?

@All - Thanks for answering
« Last Edit: July 07, 2020, 07:11:14 am by pcurtis »
Windows 10 / Linux Mint 20
Laz 2.0.8
FPC 3.0.4

Davo

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Re: Transparent form
« Reply #6 on: July 07, 2020, 08:19:20 am »
After including the code segment in the Form's OnShow procedure, the form itself will be transparent but any shapes created on the form or any lines drawn using a PaintBox component added to the form will show as floating over any background that is visible behind the form.

You will need to include unit Windows in the Form's uses clause.

pcurtis

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Re: Transparent form
« Reply #7 on: July 07, 2020, 09:29:17 am »
Davo - It works. I just had to set the forms colour to clWhite.

Cheers.
Windows 10 / Linux Mint 20
Laz 2.0.8
FPC 3.0.4

pcurtis

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Re: Transparent form
« Reply #8 on: July 08, 2020, 12:17:40 pm »
@DAVO - I have a small problem.

The code you suggested work, but there is one small problem.

On the form I display images, but if the image contains clWhite that part of the image also becomes see through  :(

Any ideas?
Windows 10 / Linux Mint 20
Laz 2.0.8
FPC 3.0.4

jamie

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Re: Transparent form
« Reply #9 on: July 08, 2020, 12:42:32 pm »
Use a different mask color for the form like a value 1 for example
Change the form color to 1 and the attribute settings to 1 also..

 The other way is to shift all white pixels down by 1 before displaying them

Other ways takes more. Code.
The only true wisdom is knowing you know nothing

pcurtis

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Re: Transparent form
« Reply #10 on: July 08, 2020, 01:25:14 pm »
I haven't tried yet, but won't changing from clWhite to 1 just move the problem colour? I'm sure that the colour '1' also exists in the images.
Windows 10 / Linux Mint 20
Laz 2.0.8
FPC 3.0.4

pcurtis

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Re: Transparent form
« Reply #11 on: July 08, 2020, 11:17:55 pm »
Just as I thought. It just changes the problem colour  :(
Windows 10 / Linux Mint 20
Laz 2.0.8
FPC 3.0.4

RAW

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Re: Transparent form
« Reply #12 on: July 09, 2020, 05:08:36 am »
You can cut off everything you like from the form ...  :)

No colorkey necessary ...
Code: Pascal  [Select][+][-]
  1. unit Unit1;
  2.  
  3. {$mode objfpc}{$H+}
  4. interface
  5.  
  6. uses
  7.   Windows, Classes, SysUtils, Forms, Controls, Graphics, StdCtrls;
  8.  
  9. type
  10.   TForm1 = class(TForm)
  11.     Memo1: TMemo;
  12.     Button1: TButton;
  13.     procedure FormCreate(Sender: TObject);
  14.     procedure Button1Click(Sender: TObject);
  15.     procedure Memo1MouseDown(Sender: TObject; Button: TMouseButton;
  16.       Shift: TShiftState; X, Y: integer);
  17.   private
  18.  
  19.   public
  20.  
  21.   end;
  22.  
  23. var
  24.   Form1: TForm1;
  25.  
  26. implementation
  27.  
  28. {$R *.lfm}
  29.  
  30. procedure CutWnd(hForm: HWND);
  31. var
  32.   arrPts: array[0..12] of TPoint;
  33.   RGN: HRGN;
  34. begin
  35.   // cut off everything outside the polygon !!!
  36.  
  37.   // Point 1
  38.   arrPts[0].X := 0;
  39.   arrPts[0].Y := 0;
  40.   // Point 2
  41.   arrPts[1].X := 0;
  42.   arrPts[1].Y := 100;
  43.   // Point 3
  44.   arrPts[2].X := 350;
  45.   arrPts[2].Y := 100;
  46.  
  47.   arrPts[3].X := 350;
  48.   arrPts[3].Y := 200;
  49.  
  50.   arrPts[4].X := 50;
  51.   arrPts[4].Y := 200;
  52.  
  53.   arrPts[5].X := 50;
  54.   arrPts[5].Y := 100;
  55.  
  56.   arrPts[6].X := 0;
  57.   arrPts[6].Y := 100;
  58.  
  59.   arrPts[7].X := 0;
  60.   arrPts[7].Y := 220;
  61.  
  62.   arrPts[8].X := 250;
  63.   arrPts[8].Y := 220;
  64.  
  65.   arrPts[9].X := 250;
  66.   arrPts[9].Y := 260;
  67.  
  68.   arrPts[10].X := 150;
  69.   arrPts[10].Y := 260;
  70.  
  71.   arrPts[11].X := 150;
  72.   arrPts[11].Y := 220;
  73.  
  74.   arrPts[12].X := 0;
  75.   arrPts[12].Y := 220;
  76.  
  77.   // setup window
  78.   RGN := CreatePolygonRgn(arrPts, 13, Winding);
  79.   SetWindowRgn(hForm, RGN, True);
  80. end;
  81.  
  82. procedure TForm1.FormCreate(Sender: TObject);
  83. begin
  84.   BorderStyle := bsNone;
  85.   Width := 400;
  86.   Height := 300;
  87.   Position := poDesktopCenter;
  88.   Color := clGray; // only to see the difference !
  89.   Memo1.SetBounds(50, 100, 300, 100);
  90.   Memo1.Text := 'Move Window With MemoOnMouseDown';
  91.   Button1.SetBounds(150, 220, 100, 40);
  92.   // cut form
  93.   CutWnd(Handle);
  94. end;
  95.  
  96. procedure TForm1.Button1Click(Sender: TObject);
  97. begin
  98.   // reset form
  99.   SetWindowRgn(Handle, 0, True);
  100. end;
  101.  
  102. procedure TForm1.Memo1MouseDown(Sender: TObject; Button: TMouseButton;
  103.   Shift: TShiftState; X, Y: integer);
  104. begin
  105.   // move window with mouse over memo
  106.   ReleaseCapture;
  107.   SendMessage(Handle, WM_SYSCOMMAND, $F012, 0);
  108. end;
  109.  
  110. end.
Windows 7 Pro (x64 Sp1) And Windows XP Pro (x86 Sp3) - LAZARUS 2.0.8 FPC 3.0.4 - TRUNK 2.1.0 FPC 3.3.1
// This is polarity (hell) and hell is reigned by lies, nothing but lies. Be careful what you believe ...
// There are 10 types of people in this world, those who understand mind control and ...

pcurtis

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Re: Transparent form
« Reply #13 on: July 09, 2020, 11:50:29 am »
@RAW Looks good - Thanks
Windows 10 / Linux Mint 20
Laz 2.0.8
FPC 3.0.4

Mr.Madguy

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Re: Transparent form
« Reply #14 on: July 09, 2020, 06:28:16 pm »
I had my screensaver-like flying triangle OpenGL program long time ago, but I've lost it's code and it's very complex, so I don't have time to recreate it in a nearest future.
DynamicData 3.0 is released!
Since now development is frozen - only optimization passes will be made at some point.
Lack of multiple inheritance turns it into abomination.

 

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