TweetFollow Us on Twitter

Bedrock Intro
Volume Number:9
Issue Number:7
Column Tag:New Technologies

Introducing Bedrock

No it’s not Fred Flintstone, but it is at least as important as Fred is to developers!

By Patrick Rigney, Director of Core Technology, Symantec Corporation

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks. These Bedrock samples and headers are not listed here.

Over the past decade, a number of Graphical User Interfaces (GUIs) have become popular in desktop and workstation computing. On PCs the most notable GUIs are Apple’s Macintosh System Software and Microsoft’s Windows.

As the demand for GUI-based applications has increased, so has their complexity. Users demand powerful functionality, access to the latest operating system and hardware features, and What You See Is What You Get (WYSIWYG) editing. For developers, the GUIs’ Application Program Interfaces (APIs) present a broad range of functionality, a substantial portion of which must be learned to build such complex applications. Applications that were once small and manageable by one or a small number of engineers now require a larger team. Software developers are searching for solutions to these problems.

ENTER BEDROCK

Bedrock is a library of C++ classes and tools that provide a toolkit and an object-oriented application framework. An application framework is a skeleton application that contains functionality common to most applications. The developer builds an application on top of this framework.

Bedrock’s mission is to reduce the time and effort spent on many complex yet common cross-platform issues, and to provide simpler interfaces to system features (such as the Clipboard and AppleEvents), allowing more time to be spent on quality, maintainability, or additional features that make the application stand out.

Many of Bedrock’s classes are designed to hide implementation details of the target platform from the application. In effect, Bedrock acts a translator between the application and the Macintosh and Windows systems, taking high-level requests and invoking the appropriate forms for each platform. While Bedrock hides these issues, it still allows the developer free access to them when necessary. Application code written on top of Bedrock can coexist with code written directly to the platform.

Bedrock also provides classes and methods for features specific to individual platforms. This points out another major goal of Bedrock: to provide simplified interfaces to complex system functionality. Without these, Bedrock would be reduced to a “least common denominator” solution.

A LAYER- AND COMPONENT-BASED DESIGN

The Bedrock design allows the developer to use pieces that best suit the application’s needs. Conceptually, Bedrock’s classes are segregated into four layers, each of which contains various components. A component is an abstraction that contains one or more C++ classes and provides a related set of capabilities.

The architecture is layered to organize the information flow between layers. The components of an upper layer request services from and depend upon the lower layers, but components in the lower layers do not call components in the layers above them. Figure 1 shows a sampling of the major components in their parent layers.

Figure 1. Bedrock Layers

This layer-and-component architecture actually makes Bedrock appear and function like many small class libraries, rather than one large one. The relationships between layers and components are more formal and distinct, as opposed to the Microsoft Foundation Classes (MFC) and Apple’s MacApp, in which most classes are derived from a single root class. This makes the framework easier to learn, and more scalable.

THE APPLICATION FRAMEWORK LAYER

When using Bedrock, much of the programming time is devoted to building on top of classes in the Application Framework layer. This layer contains the Application, Document, Clipboard, and Chore components, which are highly interdependent. For example, if the developer changes the way the document component works, this application component will likely also need to be changed.

The Application

Bedrock’s Application component provides the structure of functionality common to most GUI applications, including support for application-level menu items in the File, Edit, and Help menus, the Apple menu on the Macintosh platform, and managing undo/redo of tasks. The Application component depends on the GUI Layer of Bedrock to dispatch events and provide the user interface, and on the Document component to control windows and the user’s access to data.

The Document

The application framework model of Bedrock has been strongly influenced by the Macintosh and Windows document architectures. The document is responsible for directing the interaction between the data and the user’s view of that data. It supports document-level commands in the File, Edit, and Help menus, printing, undoing of commands, and multiple open documents.

Clipboard and Scrap

The Bedrock clipboard is closely tied to the document. The document creates a scrap object, which is copied to the clipboard. The scrap object knows what formats it can translate to and from, and knows how to install a view in the Clipboard window to view the current contents of the clipboard.

Bedrock supplies some common scrap objects, including a text object, a Macintosh PICT object, and a Windows MetaFile object. This functionality is extended by providing a scrap object that knows how to deal with new data types.

Chores

Chores are tasks that are performed at various times in the application. Bedrock provides an implementation for the following kinds of chores:

• Timer chores-executed at a regular intervals, specified at creation time.

• Idle chores-performed whenever the application is not performing any other tasks.

• Urgent chores-performed immediately, whenever they are assigned.

Chores can be used in limited circumstances to simulate multi-threading.

Actions

Actions are typically created in response to events, such as choosing the “Cut” command from the Edit menu. They provide basic protocol and interfaces for managing changes to the document’s data. The application object can track the last action committed and will direct it to undo in response to a user’s “Undo” command.

A mouse action is created in response to a mouse button press. The mouse action object continues to exist, providing such functions as visual feedback, until the user releases the button.

An action informs the application whether it is undoable and should be tracked, because some actions are normally not considered undoable (e.g. saving a file or resizing a window).

THE GUI LAYER

Besides the all-important concept of the Application Framework layer, Bedrock provides a layer to handle the GUI. The components in this layer include Event Handling, Menus, Views, Windows, Controls, Cursors, Carets, Icons, and Drag/Drop.

Event Handling

A characteristic of modern event-driven systems is that users can choose to take any of several actions at any one time. These actions, which are typically menu choices, button selections, and keystrokes, result in the generation of operating system events. Procedural applications typically trap the event and take action on it based upon a switch statement somewhere in the event dispatching loop.

System events trigger the creation of a Bedrock event object, which is dispatched to an event-handling object. Every event-handling object has a supervisor, which is also an event handler. The supervisor is specified when the event handler is instantiated. If an event handler does not wish to handle an event, it passes it on to its supervisor.

Behaviors are objects that can be associated with an event-handling object at runtime. They may be associated with a particular instance of an object, or an entire class of objects. When an event is dispatched to an event handler, Bedrock first looks to see if an instance or class behavior can handle the event, before looking at the static event handling methods. This mechanism provides a way to add or change event responses at runtime. For example, a behavior can be added to a button that allows it to be dragged when clicked, as opposed to the normal “execute command” behavior associated with buttons.

The highest-level event handler in Bedrock is the application object, which supervises the application desktop and the event handlers for dialogs.

Views

Every object that can appear on the screen (with the exception of some menu objects) is drawn within a view. As the highest level visible object, views have the following properties:

• Are contained in a visual hierarchy,

• Can be hidden, shown, resized and clipped,

• Can be enabled or disabled,

• Can receive the focus, and it can receive mouse clicks and keyboard events,

• Can change background color,

• Can change cursor shape as the mouse passes over it,

• Have a local coordinate system.

Every view has an enclosure, which is another view that usually encompasses every visual point of the enclosed view. An enclosure always owns all of its enclosed views. This enclosure relationship results in a runtime hierarchy referred to as the visual hierarchy. The application desktop is at the top of this hierarchy, and typically encloses one or more windows. In turn, the windows enclose one or more views. Bedrock uses this hierarchy to dispatch mouse events to views and to handle activation/deactivation of views.

A scroller is a special class of view that can be used when the visual representation of data is larger than the allotted visual area. The scroller knows how to scroll its enclosed subviews in response to the user’s actions; conversely, these subviews do not need to know how to scroll. Scrollers are typically associated with scrollbars, and manage all interaction with them. Scrollers also manage scrolling via autoscrolling (that is, dragging the mouse) and the keyboard (for example, Home, End, Page Up, and Page Down keys).

Canvases

Bedrock renders views on a canvas. There are four major canvases in Bedrock: window, printer, metafile, and bitmap. Each implements a common rendering interface, allowing a view to be drawn on either a window or a printer by merely switching the target canvas and telling the view to draw itself.

Each canvas also implements specific behavior for its type. For example, windows can be tiled, cascaded, iconized, and obscured by other windows. Bitmaps and metafiles can be in-memory or disk-based.

Controls

Controls in Bedrock are views that encapsulate the platform’s native controls, so the buttons look like Macintosh buttons on the Macintosh and Windows buttons under Windows.

Bedrock provides scroll bars, buttons, checkboxes (including tri-state checkboxes), radio buttons, push buttons, group boxes, static text controls, edit controls, and list boxes.

Dialogs

Dialogs consist of a dialog box, a director, and one or more subviews (typically controls). The appearance of a dialog conforms to the GUI standards for the platform. Bedrock supports Modal and Modeless dialogs on both platforms, and Application Modal dialogs on Windows.

A director acts as the mediator between controls. For example, a director may enable the “Open” button on a dialog in response to a file name selection in a list box. In addition, directors handle keyboard navigation and default button presses.

Bedrock provides the following dialogs:

• Color Selection

• Open File

• Save File

• Confirm File-Close

• Confirm File-Revert

• Font Selection

• Printer Setup

• Print Job Initiate

• Print Job Progress/Status

Menus

Bedrock allows the developer to create multiple menu bars, and alternate between them by sending messages to the desktop.

Bedrock supports pull-down , pop-up , bitmap and custom-drawn menus. Each menu can have other menus added to it, or removed from it, as well as have individual menu items added. Menus and menu items can also be enabled and disabled (with appropriate highlighting changes occurring automatically).

Text Editing

Bedrock supplies basic text-editing capabilities. This component is useful mainly in the context of controls containing editable text.

Cursors, Carets, and Icons

Every view has a cursor associated with it. The cursor associated with the view will be displayed whenever the mouse is positioned over a visible region of the view. The application can create any number of cursors, but only one may be associated with a view at a given time.

A caret (usually marked with an I-beam cursor) marks the current insertion point in text. Bedrock provides the caret in its default text-editing services, and provides methods for setting the caret in a text view.

Icons are one of the significant characteristics of a GUI. Bedrock provides support for loading icons from resources and displaying them in a view.

Drag-and-Drop Support

Drag-and-Drop is the ability to drag “objects” (data) between locations. A good example of this is in the Macintosh Finder, which allows the user to delete a file by dragging its icon to the Trash.

Bedrock fully supports the Drag-and-Drop feature, both within an application (between views) and between applications, on both platforms.

THE OPERATING SYSTEM LAYER

Bedrock provides basic components that help hide the underlying operating system from the application. At this layer, the application will normally be using the services that Bedrock provides, with little subclassing or overriding.

Components in this layer include Graphics Support, System Configuration, Memory Management, Files, and Resources.

Graphics support

Bedrock supports platform-independent drawing with the following primitives: Line, Polyline, Rectangle, Rounded Rectangle, Region, Ellipse, Chord, Pie, Arc, Bitmap, Picture (Macintosh PICT and Windows MetaFile), Icon, and Text.

Bedrock also provides a logical coordinate system that supports translation and scaling. By default, Bedrock’s coordinate system defines the origin as the top left corner of the view. The coordinate system can easily be changed as necessary. to accommodate, for example, Cartesian coordinates with the origin at the bottom left. In addition, it is possible to independently transform and scale the x and y axes.

System Configuration

The system configuration abstraction provides information about the system upon which the Bedrock application is being run. Thus, the application can request system-wide (as opposed to application-specific) attributes and actions, such as current directory, screen resolution, or (on the Macintosh) hardware configuration flags (Macintosh Gestalt information).

Memory Management

Bedrock provides a general-purpose allocation scheme that shields the developer from the details of managing memory across platforms. Bedrock’s allocator requests large blocks from the system and suballocates them on demand to the application. When freed by the application, adjacent free blocks are coalesced in to larger blocks.

Bedrock objects are pointer-based. Handle-based objects are not supported.

Files

The Bedrock file components provide platform-independent file I/O and uniform handling of errors. The FileAccess component is extensible to allow network- or memory-based random access to data.

Resources

Most applications use resources to store small pieces of code or data that can be changed without recompiling the application. For example, all strings used by an application can be stored in resources for easy localization.

Bedrock supplies tools to improve the portability of resources. The Bedrock Resource Compiler (BEDRC) takes resources defined in Bedrock resource statements and compiles them into the native resources of the platform. The Bedrock Resource Language syntax is an extension of Apple’s Rez language, adding type declaration (typedef statements) and complex type creation (struct, class, union). The syntax is C++ compatible, and the compiler supports the ANSI C preprocessor directives, allowing it to read and derive type information directly from C++ header files. The developer can then use these new types in resources.

Bedrock’s resource mechanism allows the application to instantiate objects by name from a resource definition. For example, a view hierarchy may be defined in a Bedrock resource, and later be instantiated by name from the resource file. By modifying the resource file, users can modify the view hierarchy without recompiling the application.

THE FOUNDATION LAYER

Bedrock’s Foundation Layer provides basic services to the higher layers, or directly to application code. The components at this level are largely independent of one another. The Foundation Layer components, in turn, depend only upon the facilities of the C++ language. These components include Streams, Sinks, Strings, Collections, Exceptions, and International support.

Streams and Sinks

Streams provide a generalized interface for reading and writing data, including protocol for higher-level entities (integers, floats, strings, and so on), and thus provide platform- and device-independence for all kinds of I/O. Streams are generally heterogeneous; that is, they operate on many types of data.

Streams read from and write to sinks. A sink is a “device” that can be a source or destination for a stream of bytes. Sinks provide only a byte-oriented, untyped interface. Bedrock provides file sinks and memory block (resizable and nonresizable) sinks. Sinks may be extended to construct, for example, serial interface sinks and network interface sinks.

Strings

A string is a run of text, composed of characters. Strings always use characters as the units of transfer, so type-safety is guaranteed and access is fast and efficient. Bedrock stores characters in Unicode format, and provides ways to export characters to other character systems such as ASCII.

International Support

Bedrock provides support for localization through resources (as discussed earlier), writing systems, and locales.

A writing system encompasses all the information a Bedrock application needs to edit, display, store, and retrieve text strings. It depends on the locale abstraction to supply basic information such as date format, thousands separator, and so on.

Together, the writing system and the locale track and implement script properties, sort orders, word-breaking and boundary behavior, mapping and translation tables, and formatting for times, dates, and numbers.

Data Structures and Collections

Bedrock’s collections are a subset of the Rational C++ Booch Components, consisting of Collection, Ordered Collection, Map (a dictionary of domain/range pairs), Queue, Stack, and Tree.

Tools and iterators are used to act on a collection. Bedrock includes tools for searching and sorting collections.

Collections, tools and iterators are implemented using C++ templates, and can therefore store and operate on any data type, rather than just objects.

Exception Handling

The components in each layer detect errors that the application must handle. In those cases where the library does not know how to handle an error, it can throw an exception object. The application can catch this object and respond.

Bedrock’s exception handling is based on that described in The C++ Programming Language and The Annotated C++ Reference Manual (ARM). The Bedrock Exception Library (BEL) is included to emulate this mechanism on compilers that do not support ARM Exception Handling. BEL’s syntax is slightly different from the ARM syntax, but is designed to easily translate to that syntax. When using a compiler that supports C++ exceptions, one can remove the BEL emulation.

BROAD RANGE OF FUNCTIONALITY

Bedrock’s varied components provide a broad range of functionality to the application developer. Complexity in the framework is reduced by layering the components, which helps organize their interactions. Within the layers, each component acts as a class library in itself, making the entire system easier to learn and use.

By combining this architecture with the general benefits of object oriented programming, Bedrock provides cross-platform capabilities and simplifies the interface to system features (both cross-platform and platform-specific). The developer using Bedrock can more quickly deliver high-quality applications on both the Macintosh and Windows.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Little Snitch 3.5.3 - Alerts you about o...
Little Snitch gives you control over your private outgoing data. Track background activity As soon as your computer connects to the Internet, applications often have permission to send any... Read more
Cocktail 8.4 - General maintenance and o...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
PDFKey Pro 4.3 - Edit and print password...
PDFKey Pro can unlock PDF documents protected for printing and copying when you've forgotten your password. It can now also protect your PDF files with a password to prevent unauthorized access and/... Read more
Kodi 15.0.beta1 - Powerful media center...
Kodi (was XBMC) is an award-winning free and open-source (GPL) software media player and entertainment hub that can be installed on Linux, OS X, Windows, iOS, and Android, featuring a 10-foot user... Read more
DiskCatalogMaker 6.4.12 - Catalog your d...
DiskCatalogMaker is a simple disk management tool which catalogs disks. Simple, light-weight, and fast. Finder-like intuitive look and feel. Super-fast search algorithm. Can compress catalog data... Read more
Macs Fan Control 1.3.0.0 - Monitor and c...
Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more
Lyn 1.5.11 - Lightweight image browser a...
Lyn is a lightweight and fast image browser and viewer designed for photographers, graphic artists and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it... Read more
NeoOffice 2014.11 - Mac-tailored, OpenOf...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
LaunchBar 6.4 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more
Remotix 3.1.4 - Access all your computer...
Remotix is a fast and powerful application to easily access multiple Macs (and PCs) from your own Mac. Features Complete Apple Screen Sharing support - including Mac OS X login, clipboard... Read more

Battle of Gods: Ascension (Games)
Battle of Gods: Ascension 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: TURN-BASED TACTICAL COMBATFight tactical battles against the forces of Hades! In Battle of Gods: Ascension you play... | Read more »
Shadowmatic's Latest Update Adds a...
Shadowmatic's shadowy shadow-ness is getting a little shadowy-er thanks to a recent update that adds an Arcade Mode. [Read more] | Read more »
Sunrise Calendar and Slack Have Assimila...
Wunderlist is perhaps one of the most populat and beloved productivity apps on the App Store - and now it's gone and incorporated itself into other useful services like Sunrise Calendar and Slack. [Read more] | Read more »
Crossy Road Devs Hipster Whale are Bring...
Hipster Whale, the minds behind the rather popular (and rather great) Crossy Road, have teamed-up with Bandai Namco to create PAC-MAN 256: an absolutely bonkers looking maze runner chaser thing. | Read more »
Meet the New Spotify Music
Spotify Music  has a lot going on. They're introducing 3 new modes to serve all your musical needs, with the "Now" start page  gives you curated playlists based on your particular tastes. As you listen the app will learn more about your tastes and... | Read more »
What the Apple Watch Gets Right, and Wha...
| Read more »
Celebrate PAC-MAN's 35th Birthday W...
BANDAI NAMCO Entertainment America is celebrating PAC-MAN's 35th anniversary by releasing updates for PAC-MAN and PAC-MAN Lite for iOS. [Read more] | Read more »
Strike Wing Episode 2 has Landed on the...
Strike Wing: Raptor Rising is an exciting space combat simulator by Crescent Moon Games, which was recently updated to continue the story with Episode 2. [Read more] | Read more »
Kiqplan Expands its Interactive Coaching...
The makers of Fitbug have been hard at work on their Kiqplan lineup, and have added four new summer themed plans to help you get the most out of your workout. [Read more] | Read more »
Make a Photobook in Minutes with Pictyea...
What happens when you can't stop taking photos and have an urge to create a photobook? Pictyear saves the day. [Read more] | Read more »

Price Scanner via MacPrices.net

What Would the ideal Apple Productivity Platf...
For the past four years I’ve kept a foot in both the Mac and iPad camps respectively. my daily computing hours divided about 50/50 between the two devices with remarkable consistency. However, there’... Read more
New 13-inch 2.9GHz Retina MacBook Pro on sale...
B&H Photo has the 13″ 2.9GHz/512GB Retina MacBook Pro on sale for $1699.99 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price for this model from... Read more
12-inch MacBook stock status for Monday, May...
The new 12″ Retina MacBooks are still on backorder at The Apple Store with a 3-5 week waiting period. However, a few models are in stock today at Apple resellers. Stock is limited, so act now if you’... Read more
New 27-inch 3.3GHz 5K iMac in stock with free...
Adorama has the new 27″ 3.3GHz 5K iMac in stock today for $1999 including free shipping plus NY & NJ sales tax only. Adorama will include a free copy of Apple’s 3-year AppleCare Protection Plan. Read more
Memorial Day Weekend Sale: New 27-inch 3.3GHz...
Best Buy has the new 27″ 3.3GHz 5K iMac on sale for $1899.99 this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store prices may vary... Read more
OtterBox Maximizes Portability, Productivity...
From the kitchen recipe book to the boarsroom presentation, the OtterBox Agility Tablet System turns tablets into one of the most versatile pieces of handheld technology available. Available now, the... Read more
Launch of New Car App Gallery and Open Develo...
Automatic, a company on a mission to bring the power of the Internet into every car, has announced the launch of the Automatic App Gallery, an app store for nearly every car or truck on the road... Read more
Memorial Day Weekend Sale: 13-inch 1.6GHz Mac...
Best Buy has the new 13″ 1.6GHz/128GB MacBook Air on sale for $849 on their online store this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders... Read more
Memorial Day Weekend Sale: 27-inch 3.5GHz 5K...
Best Buy has the 27″ 3.5GHz 5K iMac on sale for $2099.99 this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store prices may vary.... Read more
Sale! 16GB iPad mini 3 for $349, save $50
B&H Photo has the 16GB iPad mini 3 WiFi on sale for $349 including free shipping plus NY sales tax only. Their price is $50 off MSRP, and it’s the lowest price available for this model. Read more

Jobs Board

Architect / Senior Software Engineer, *Apple...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
*Apple* Pay Support Readiness Project Manage...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
Hardware Design Validation Engineer - *Apple...
**Job Summary** The Apple Watch team is looking for a Hardware Design Validation Engineer. This person will be part of the Apple Watch hardware team with Read more
Sr. Payment Program Manager, *Apple* Pay -...
**Job Summary** Apple Pay is an exciting environment and a…devices in a simple, private and secure way. The Apple Pay Team is looking for an experienced Senior Read more
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.