[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: images / alpha-blending

From: David Reitter
Subject: Re: images / alpha-blending
Date: Mon, 20 Feb 2006 11:44:23 +0000

On 19 Feb 2006, at 22:47, Richard M. Stallman wrote:

What is alpha-blending?  What does the feature do?

We don't want Emacs to support features that are limited to a non-free
system; that would betray the goal we are working for.

An "alpha layer" is a form of "graded transparency layer". With basic transparency, you define a bitmask where one bit corresponds to one pixel, indicating whether or not the background should be displayed in that pixel (rather than a pixel belonging to the actual image). An alpha layer assignes a value of higher resolution to each pixel. When the image is displayed, the background color for that pixel blends in with the image pixel. This produces smooth edges.

Supporting this is not merely a matter for the application (Emacs), but also for the graphics device and layers in between. So of course it wouldn't make sense to produce an alternative icon set if the images required something that isn't and won't be equally supported on the free platforms. Hence my question.

reply via email to

[Prev in Thread] Current Thread [Next in Thread]