Getting Color of certain pixel on screen

[dietmar]

Hi,

I want
a) to determine the current background color value of a form
b) to determine the color (RGB, TColor) of a certain point on the screen.

Can you help?

Thx
Dietmar

[winni]

Hi!

Code: Pascal  [Select][+][-]

1. var
2.   ScreenDC: HDC;
3.   RGB, BGcol : TColor;
4.  
5. begin
6.     // a)
7.    BGcol := Form1.Color;
8.  
9.    // b) get color of pixel  10/20
10.   ScreenDC := GetDC(0);
11.   RGB := GetPixel(ScreenDC 10, 20);
12.  
13. end;

Winni

[440bx]

I want
a) to determine the current background color value of a form
b) to determine the color (RGB, TColor) of a certain point on the screen.

I can only tell you how to do it using the Windows API.  For a multiplatform answer, someone else will have to provide it.

for (a) use GetClassLongPtr using GCL_HBRBACKGROUND

for (b) use GetPixel

both of those functions are documented by MS.  Use Google to get to the detailed documentation.

HTH.

[wp]

The following code is taken from the mbColorLib package and is cross-platform:

Code: Pascal  [Select][+][-]

1. function ReadScreenColor(const X, Y: integer): TColor;
2. var
3.   ScreenDC: HDC;
4.   SaveBitmap: TBitmap;
5. begin
6.   SaveBitmap := TBitmap.Create;
7.   try
8.     SaveBitmap.SetSize(Screen.Width, Screen.Height);
9.     ScreenDC := GetDC(0);
10.     try
11.       SaveBitmap.LoadFromDevice(ScreenDC);
12.     finally
13.       ReleaseDC(0, ScreenDC);
14.     end;
15.     Result := SaveBitmap.Canvas.Pixels[X, Y];
16.   finally
17.     SaveBitmap.Free;
18.   end;
19. end;

[winni]

Hi!

Yes, that is the long version for a HowTo-Book.

I showed the short version above.

Winni

[dietmar]

Thank you all!

Dietmar

[wp]

I showed the short version above.

To my knowledge GetPixel is a function in the Windows unit. If it were cross-platform, it would be found in LCLIntf.