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Simple Way to Make Transparent Dialog

, 5 Aug 2013 CPOL
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Enable user to make a dialog transparent without making its child control transparent

Introduction

This is my first tip. I am writing a simple block of code to make a dialog transparent. I have seen many articles which make a dialog completely transparent with its child control too.

This tip uses a simple trick to make a transparent dialog without making its child controls transparent.

Using the Code

The idea behind making a transparent dialog is:

We can set the opacity and transparency color key of a layered window.

I used SetLayeredWindowAttributes with LWA_COLORKEY to replace a color with transparency, in order to achieve a transparent background.

The code that makes dialog is:

  1. Set the background color of the dialog which is not used in the application. I selected a color (e.g., RGB(1,11,21)) that is not present anywhere except in the dialog background.
  2. Set that color transparent using SetLayeredWindowAttributes with the LWA_COLORKEY flag.
SetBackgroundColor(RGB(1,11,21));
LONG ExtendedStyle = GetWindowLong(GetSafeHwnd(),GWL_EXSTYLE );
SetWindowLong(GetSafeHwnd(),GWL_EXSTYLE,ExtendedStyle | WS_EX_LAYERED );
::SetLayeredWindowAttributes(GetSafeHwnd(),RGB(1,11,21),0,LWA_COLORKEY);

Paste the above code in the OnInitDialog() function of your dialog class. Use Visual Studio 2010 and derive your dialog class from the CDialogEx class.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Gautam Agrawal (Programing Expert)
Software Developer Retina Software Pvt Ltd
India India
No Biography provided

Comments and Discussions

 
GeneralMy vote of 2 PinmemberGOLDENPrinciple11-Sep-13 6:39 

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