AlphaForm is a Microsoft Windows Forms control that allows you to use any 32 bit alpha channel image as a custom window frame. The control allows you to layout a 32 bit image with an alpha channel in the Forms designer and arrange additional controls within user specified areas of the image. At runtime, the control will generate a per pixel alpha composited Form with the desktop. This control also supports:

• Changing of the image at runtime (skinning)
• Fade in or out with rate and ease in/ease out adjustment
• Support for running under variable DPI settings
• Form dragging either by dragging the image frame and optionally the background

AlphaForm was introduced as an article on CodeProject. This commercial release introduces several features and fixes not included in the CodeProject version. They include fade in/out functionality, expanded dragging options, better support for non-standard DPIs (common on notebook displays), and support for displaying the entire form as a contiguous image with controls on top (as opposed to cut out regions against a separate background).

Easy Drop Shadows

Simply add a drop shadow to your image in Photoshop or your favorite image editing program, and then use that image with AlphaForm. AlphaForm will take care of compositing the image with your desktop.

The Problem with Window Regions & Transparency Keys

Windows has long had the ability to specify a region or transparency key allowing you to define an arbitrary Window border. This is often used with a background image to define an image outline as a Window frame. There are a number of third-party components that simply construct a window region from a bitmap. However, this border is composited with the desktop as a one bit mask giving you a pixelated boundary. In fact, you can see this with Microsoft's own Media Player.

It is especially unattractive with curvilinear borders which really need antialiasing and per pixel compositing, and you can't have visual elements like drop shadows. Aside from the unsightliness, it's not easy to define the region and/or transparency key to achieve a complex image based Window frame. AlphaForm solves these problems allowing the window frame to be an alpha channel image with variable transparency and arbitrary shape.

Compatibility & Technical Info

• Windows XP & Vista
• .NET 2.0 or later (may be compileable under .NET 1.x but not supported)
• 64 bit XP and 64 bit Vista have not been tested and are not currently supported
• Written in C#
• Code is provided as a Visual Studio 2005 project

 

Copyright © 2007 Jeff Anderson
Last modified: 07/25/07