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Multimedia » GDI+ » General     Intermediate

Per Pixel Alpha Blend in C#

By Rui Lopes

Demonstrates how to create per pixel alpha blending windows
C#.NET 1.0, Win2K, Visual Studio, Dev
Posted:11 Feb 2002
Updated:3 Jun 2004
Views:223,513
Bookmarked:111 times
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Popularity: 6.57 Rating: 4.10 out of 5
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Preview of the per pixel alpha blend effect

Preview of the per pixel alpha blend effect

Introduction

This is a port of my other article from C++/MFC to C#/Windows Forms. The concept of creating a per-pixel-alpha blending window remains the same, the GDI function UpdateLayeredWindow.

What changed

  • Image loading is handled by GDI+ classes (System.Drawing namespace).
  • No need to pre-multiply the rgb channels with the alpha channel.
  • No more support for PSP files. PNG file are the best choice.

Usage

To use this code you need to include PerPixelAlphaForm.cs file in your project, create a class that inherits from PerPixelAlphaForm, load a bitmap using System.DrawingImage.FromFile static method and then call the PerPixelAlphaForm.SetBitmap method.

The example source code is inside the main.cs file. In the source code you will also find the new ways of doing the old things, like, handling dropped files from windows explorer.

Installing & Building

  1. Download and extract the source code of this article;
  2. To build, run the build.bat file from command prompt;
  3. Now, run the bin\main.exe and enjoy!

Changelog

31 May 2004

  • Fix clipping problems by creating the form without borders.
  • Move PerPixelAlphaForm class to PerPixelAlphaForm.cs file.

12 Feb 2002

  • Initial version.

Do you have any question or comment? Contact me!

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

Rui Lopes


Member

Occupation: Web Developer
Location: Portugal Portugal

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 Msgs 1 to 25 of 86 (Total in Forum: 86) (Refresh)FirstPrevNext
GeneralAdd Controls PinmemberGottdrak9913:23 19 Nov '08  
GeneralRe: Add Controls Pinmembercolche20:52 25 Feb '09  
GeneralRe: Add Controls Pinmemberrbrender18:44 9 Mar '09  
GeneralRe: Add Controls PinmemberMarko Padjen14:39 31 Mar '09  
GeneralExactly what I was looking for. Thanks. Pinmembermlavenne12:36 18 Aug '08  
GeneralGreat but can I use the function also for a control? Pinmemberit-bergmann2:24 14 Feb '08  
GeneralRe: Great but can I use the function also for a control? PinmemberMember 42028005:49 19 May '09  
Generalcool Pinmemberradioman.lt@gmail.com23:20 12 Dec '07  
Generalwhy doing win32 with c#? Pinmemberbkaratte21:46 11 Dec '07  
GeneralRe: why doing win32 with c#? Pinmembertic8414:12 10 Jun '08  
GeneralVB.Net Pinmemberdawmail33323:47 24 Aug '07  
GeneralRe: VB.Net PinmemberDj Den4ik0:05 12 Feb '08  
GeneralGreat!!!!!!!!!!!!! Pinmembershp-coding8:44 9 Aug '07  
GeneralWay to add some controls Pinmemberihess5:17 30 Jul '07  
GeneralRe: Way to add some controls [modified] PinmemberSp3cial9:12 24 Aug '08  
GeneralHelp Pinmembergsampath21:15 28 May '07  
GeneralImage problem Pinmemberdarb213:57 20 Apr '07  
GeneralRe: Image problem PinmemberDaryl Fish15:58 15 Jan '08  
GeneralProblem when changing the form parent to desktop with dual-monitoring [modified] PinmemberPim-Pom2:59 7 Oct '06  
GeneralNice example, but... Pinmembermoebiusproject10:35 12 Sep '06  
GeneralRe: Nice example, but... PinmemberTung Nguyen18:37 15 Apr '07  
GeneralRe: Nice example, but... Pinmembertic8414:14 10 Jun '08  
GeneralProblem in design mode PinmemberCapt'N Stabbin'20:09 12 Jul '06  
GeneralRe: Problem in design mode PinmemberODaniell1:52 3 Aug '06  
GeneralRe: Problem in design mode PinmemberMember 42028005:50 19 May '09  

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Last Updated: 3 Jun 2004
Editor: Nishant Sivakumar
Copyright 2002 by Rui Lopes
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