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Windows and Views in the Haiku app_server

BodyLate last year, we decided to rewrite an important part of the Haiku app_server. Why was that? Let's start out with what the app_server is supposed to do: At the heart, it manages multiple applications simultaneously using the display device as a shared resource. Two of the important system objects through which this is organized are Windows and Views. Through views, the applications can draw information onto the screen, while a window is merely some sort of container for views.

The Attack Of The Warriors, Part 2: IO-Warrior24 - 16 Bit Multipurpose I/O Ports

BodyThe code discussed in this article can be found here. The IO-Warrior24 device from Code Mercenaries is equipped with 16 general purpose I/O (input/output) pins. When enabling the so-called special mode functions, more or less pins are reassigned to serve a special purpose. You can select between: I2C, IIC: a two-wire serial Inter-IC-Bus allowing connection to RAMs, EEPROMs, ADCs,DACs and a lot more. LCD: parallel communication with alphanumerics Liquid-Christal-Display units SPI: a four-wire serial Serial-Peripheral-Interface-Bus similar to I2C LED-Matrix: a serial communication bus to control LEDs in a multiplexed matrix configuration RC5IR: Infrared Remote control according to the RC5 code We'll now examine this impressive manifold of functions step-by-step.

Dependency Hell

BodyI suspect most readers have heard of this in reference to various Linux distributions. This describes the situation where package A requires package B that then requires package A, directly or indirectly, and you end up requiring a whole group of packages that seem to be entirely unrelated to installing package A, that include a lot of functionality of B. Well, that's just a higher level abstraction of what I will discuss in this article.

The Attack Of The Warriors, Part 1

The code discussed in this article can be found here.

The warrior family MouseWarrior, KeyWarrior, JoyWarrior and IO-Warrior of the German company Code Mercenaries (www.codemercs.com) enables you to communicate with your PC via USB in a manifold way to various external devices. All members of the family are full USB V1.1/2.0 compliant, low speed devices using the HID 1.1 (Human Interface Device) device class. If you are missing the GeekPort - it's back again.

Let's start with a really simple device, the JoyWarrior24 A8-8 USB joystick controller.

Managing Your Replicants: XShelfInspector and XContainer

BodyThe source discussed in this article can be found here. The original BeOS distribution from Be. Inc. contains two applications to help you manage your replicants: ShelfInspector and Container. Both can be found in the .../sample-code/application_kit/ folder. It's a good idea to read Be's original readme.txt concerning ShelfInspector. Both enhanced applications -- XShelfInspector and XContainer -- are working closely together like the original ones; however, some improvements have been added so one can use them more comfortably.

TransRepliShow: Dragging Replicants Transparently

BodyThis article follows up on Dr. Reh's previous newsletter article, RepliShow: A Replicable Image Viewer. The code discussed is available here for your convenience. Just remember Seth Flaxman's RepliShow: While dragging the replicant you only see the border lines of an empty rectangle - not very Be-like. However, only a few lines of code are necessary to obtain a rectangle containing the dragged image and looking transparently. Because the dragging action is managed by the BDragger class we need to do some subclassing.

Painter and How AGG Works

This article is intended to give an overview of the Anti-Grain Geometry 2D engine by Maxim Shemanarev. This C++ graphics engine is currently the back-end of the Haiku Painter class used by the app_server as its implementation of BView style drawing. By introducing some of the concepts of AGG and how they are used within Painter, I'm hoping to make it easier for others to join the development of Painter and finding ways of improving its efficiency, adding features and/or finding means of adding hardware acceleration.

RepliShow: A Replicable Image Viewer

BodyThe original version of RepliShow was written by Seth Flaxman, and has been modified by Dr. Hartmut Reh. The source discussed in this article can be found here. Today we'll be constructing a rather primitive application that displays images and is replicable. It will demonstrate two things: BeOS replicant technology and the Translation Kit. Replicant technology is a standard part of BeOS, although it has not been widely used by many applications.

Replicants - More application than an application

Yep. I remember when Be first announced Replicants. They were going to be the next ActiveX. I wonder what ever happened to them. The sad truth is that absolutely nothing happened to Replicants. Almost no one ever used them. No great mountains of applications ever came out for them. I was chatting with some people the other day on IRC and we wondered about this. Needing to write an article and not sure what to write, that commiseration came back to mind.

Against Directories

Body: Let me start out by saying that I am not "against" directories. It is more like "rethinking" directories. We have been talking on the Glass Elevator list about queries and how to make them more useful for some time now. There is a pretty broad consensus that we should try to bring more use of queries into R2 and beyond, that we should help the end user to use them far more than R5 does.