TweetFollow Us on Twitter

PowerPlant
Volume Number:11
Issue Number:9
Column Tag:Getting Started

PowerPlant

By Dave Mark, MacTech Magazine Regular Contributing Author

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

This month, we’re going to take a look at PowerPlant, the framework included on every CodeWarrior CD. If you own Symantec C++, take heart: we’ll get to the TCL in a future column. In the meantime, follow along anyway. Who knows, you might find yourself making the switch to PowerPlant someday.

This Month’s Program

I don’t know about you but, after four month’s straight of menus, I’m ready for something else. So instead of talking about PowerPlant and menu handling (we’ll do that in a future column), this month’s program will introduce PowerPlant’s messaging system.

As you design your PowerPlant programs, you’ll work with objects called broadcasters and listeners. A broadcaster sends a message and a listener receives that message. In this month’s program, we’ll create a window containing a button. Each time the button is clicked, it will send a message to any objects registered as listeners to it. Basically, this means that the broadcasting objects’ BroadcastMessage() member function calls the listening object’s ListenToMessage() member function.

This mechanism is simpler than it sounds. As we build our project, just remember that the button is a broadcaster, and that the class CDashboardApp will be the listener.

If you have the CW6 documentation, you might want to read the section named LBroadcaster & LListener in the PowerPlant manual (chapter 8, page 93).

As is usually the case when working with a framework, we’ll take an existing PowerPlant example and modify it to suit our needs.

• Duplicate the folder “CodeWarrior6:Metrowerks PowerPlant:More PowerPlant Examples:Dashboard Starter”.

If you run one of the projects in this folder (either Dashboard68K.µ or DashboardPPC.µ), you’ll see the window shown in Figure 1. To quit the program, select Quit from the File menu. As you can see, Quit is the only item in the File menu. In a future column, we’ll add some menus and items to a PowerPlant program. For now, let’s add a button to the Dashboard window.

Figure 1. The Dashboard Starter window, before our modifications.

Editing Dashboard.PPob

CodeWarrior comes with a ResEdit-like program, named Contructor, that lets you create and edit PowerPlant-specific resources. The resource we’re interested in in this column is the PPob resource. A PPob resource is like a combination of a DLOG and DITL, but for any PowerPlant view including windows and dialogs. We’ll use Constructor to add a button to the Dashboard window.

CodeWarrior 6 ships with two different versions of Constructor. Though both will do the job, Constructor 2.0a16 is far newer than Constructor 1.0.1 and seems pretty stable for an alpha release. The screen shots and instructions in this column were all based on 2.0a16. You’ll find both versions in the CodeWarrior 6 folder, inside the Metrowerks PowerPlant subfolder.

• Launch Constructor 2.0a16 and open the file Dashboard.PPob (it’s in the same folder as the two Dashboard project files).

As you can see by the Constructor window shown in Figure 2, the file Dashboard.PPob already contains a resource. This PPob resource represents the main Dashboard window. It has a resource ID of 200 and represents an object belonging to the class LWindow.

Figure 2. The Constructor window listing the view resources in Dashboard.PPob.

Our next step is to edit this PPob resource.

• Double-click on the LWindow PPob with an id of 200.

When you double-click on PPob 200, a PPob editing window will appear (see Figure 3) showing the object view hierarchy defined by this PPob. Right now, the PPob consists of a single window.

Figure 3. A Constructor window showing PPob 200.

If you click on the window view and select Pane Information... from the Pane menu (or just double-click on the window view), a pane info window will appear (see Figure 4) allowing you to edit the selected view. In this case, the selected view describes a document window with a zoom box, no close box, positioned automatically in the Alert position on the main screen, etc. Feel free to edit this view if you like. To test your changes, quit Constructor, saving your changes, then use CodeWarrior to rerun the project.

Figure 4. The Pane Info window describing the Dashboard window.

Figure 5. The items you can place in a window using Constructor.

With the PPob 200 window in front, you should notice a palette window listing all the items you can place in a PPob view. The palette, shown in Figure 5, works just like ResEdit’s DITL palette. To add an item to a view, drag the item off the palette into the PPob window.

Here’s where we’ll add the button to the window.

• Drag an LStdButton off of the palette into the window view in the PPob 200 window.

• Double-click on the button that appears and edit the info window to match the one shown in Figure 6.

Figure 6. The info window for the LStdButton we added to our window view.

There are three important changes to make in the LStdButton info window. First, change the Pane ID: field to read 1000 (be sure the Text ID checkbox is unchecked before you change the ID). The Pane ID serves to identify the button pane from all the other panes in the PPob resource. By convention, number your panes starting at 1000 and moving upwards from there. For example, if you added three items to the Dashboard window represented by PPob 200, you’d set their Pane IDs to 1000, 1001, and 1002.

The second change to make to the LStdButton info window is to fill in the Button Title: field. Since we want our button to beep, the word Beep will make a fine button title.

The third change is to the Value Message: field. This field contains the message that will get sent when the button is clicked. The message is an integer constant that will be passed as a parameter to any objects registered as listeners to the broadcasting button. Again, by convention, we’ll number our messages starting at 1000.

That’s it. Save your changes and quit Constructor.

Dashboard68K.µ or DashboardPPC.µ

If you haven’t already, open up one of the Dashboard projects (either Dashboard68K.µ or DashboardPPC.µ). Since we want to add a button to our window, we’ll need to add the files that contain the PowerPlant classes that implement push buttons: LControl.cp and LStdControl.cp.

• In the project window, click on the triangle to the left of the group named Pane. When we add the two files, we want to add them to this group.

• Add the files LControl.cp and LStdControl.cp to the project. You’ll find them in the folder “CodeWarrior 6:Metrowerks C/C++:PowerPlant Libraries:Pane Classes”

CDashboardApp.h

• Open the file CDashboardApp.h.

• Add this line after the #include of <LApplication.h>:

#include <LListener.h>

• Change the first line of the CDashboardApp class to look like this:

class CDashboardApp : public LApplication, public LListener {

To convert the CDashboardApp class into a listener, we have to make sure it is derived from the class LListener. Deriving a class from more than one class is perfectly acceptable in C++ and is known as multiple inheritence.

Another step in making the CDashboardApp class a listener is to add a member function named ListenToMessage(). ListenToMessage() will get called when any broadcaster it is listening to broadcasts a message.

• Add this line after the definition of the member function FindCommandStatus():

 virtual void    ListenToMessage(MessageT inMessage, void *ioParam);

• Close CDashboardApp.h and save your changes.

CDashboardApp.cp

Here’s where all the action is. Take some time to look through the file and read all the comments (don’t worry, the file isn’t that long). Notice that main() defines a CDashboardApp object and then calls the member function Run() which was inherited from the LApplication class.

• Add this line after all the other #include files:

#include <LStdControl.h>

Notice that even though we added the files LStdControl.cp and LControl.cp to the project, we don’t include the file <LControl.h>. <LControl.h> is included by <LStdControl.h>.

• In the constructor, find the call of the static function URegister::RegisterClass() and add this line right below it:

 URegistrar::RegisterClass(LStdButton::class_ID,
 LStdButton::CreateStdButtonStream);

This line tells PowerPlant which function to call (LStdButton::CreateStdButtonStream()) when an object of type LStdButton is created based on a PPob resource. Before we came along, this program only needed to register the LWindow class. Since we added an LStdButton object to the PPob resource, we’ll need to register that class as well.

• Also in the constructor, just before the call of mDisplayWindow->Show(), add these lines:

 LStdButton *theButton =
 (LStdButton *)mDisplayWindow->FindPaneByID( 1000 );
 theButton->AddListener( this );

The first line searches the window mDisplayWindow for the pane with the id 1000. Now you know why we entered the number 1000 in the LStdButton’s Pane ID: field.

The second line registers the current object (the CDashboardApp object, known here as this) as a listener of the button we just found.

• At the end of the file, add the member function CDashboardApp::ListenToMessage():

// ----------------------------------------------------------
// • ListenToMessage
// ----------------------------------------------------------
// Respond to message 1000 broadcast by pushbutton

void
CDashboardApp::ListenToMessage(MessageT inMessage, void *ioParam)
{
 if ( inMessage == 1000 )
 SysBeep( 20 );
}

This function will get called whenever the button is clicked. The message 1000 will be passed in as the parameter inMessage.

Figure 7. The Dashboard window. This time it has a button in it.

Running the Program

That’s about it. Save your changes and run the program. The usual Dashboard window will appear, but this time with a button smack-dab in the middle of it. Press the button and, guess what, your Mac will beep at you.

Till Next Month

Obviously, this month’s program gives you only a brief glimpse into the PowerPlant framework. On the other hand, it’s a pretty solid glimpse. Try your hand at adding some other panes to the Dashboard window containment hierarchy. Start by adding a second button with its own pane ID and its own message ID. Next, try to add some other controls.

What part of PowerPlant would you like to learn about next? Should I get into other control types? How about (shudder) menus? Send email. I’ll be waiting to hear from you. See you next month...

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Whitethorn Games combines two completely...
If you have ever gone fishing then you know that it is a lesson in patience, sitting around waiting for a bite that may never come. Well, that's because you have been doing it wrong, since as Whitehorn Games now demonstrates in new release Skate... | Read more »
Call of Duty Warzone is a Waiting Simula...
It's always fun when a splashy multiplayer game comes to mobile because they are few and far between, so I was excited to see the notification about Call of Duty: Warzone Mobile (finally) launching last week and wanted to try it out. As someone who... | Read more »
Albion Online introduces some massive ne...
Sandbox Interactive has announced an upcoming update to its flagship MMORPG Albion Online, containing massive updates to its existing guild Vs guild systems. Someone clearly rewatched the Helms Deep battle in Lord of the Rings and spent the next... | Read more »
Chucklefish announces launch date of the...
Chucklefish, the indie London-based team we probably all know from developing Terraria or their stint publishing Stardew Valley, has revealed the mobile release date for roguelike deck-builder Wildfrost. Developed by Gaziter and Deadpan Games, the... | Read more »
Netmarble opens pre-registration for act...
It has been close to three years since Netmarble announced they would be adapting the smash series Solo Leveling into a video game, and at last, they have announced the opening of pre-orders for Solo Leveling: Arise. [Read more] | Read more »
PUBG Mobile celebrates sixth anniversary...
For the past six years, PUBG Mobile has been one of the most popular shooters you can play in the palm of your hand, and Krafton is celebrating this milestone and many years of ups by teaming up with hit music man JVKE to create a special song for... | Read more »
ASTRA: Knights of Veda refuse to pump th...
In perhaps the most recent example of being incredibly eager, ASTRA: Knights of Veda has dropped its second collaboration with South Korean boyband Seventeen, named so as it consists of exactly thirteen members and a video collaboration with Lee... | Read more »
Collect all your cats and caterpillars a...
If you are growing tired of trying to build a town with your phone by using it as a tiny, ineffectual shover then fear no longer, as Independent Arts Software has announced the upcoming release of Construction Simulator 4, from the critically... | Read more »
Backbone complete its lineup of 2nd Gene...
With all the ports of big AAA games that have been coming to mobile, it is becoming more convenient than ever to own a good controller, and to help with this Backbone has announced the completion of their 2nd generation product lineup with their... | Read more »
Zenless Zone Zero opens entries for its...
miHoYo, aka HoYoverse, has become such a big name in mobile gaming that it's hard to believe that arguably their flagship title, Genshin Impact, is only three and a half years old. Now, they continue the road to the next title in their world, with... | Read more »

Price Scanner via MacPrices.net

B&H has Apple’s 13-inch M2 MacBook Airs o...
B&H Photo has 13″ MacBook Airs with M2 CPUs and 256GB of storage in stock and on sale for up to $150 off Apple’s new MSRP, starting at only $849. Free 1-2 day delivery is available to most US... Read more
M2 Mac minis on sale for $100-$200 off MSRP,...
B&H Photo has Apple’s M2-powered Mac minis back in stock and on sale today for $100-$200 off MSRP. Free 1-2 day shipping is available for most US addresses: – Mac mini M2/256GB SSD: $499, save $... Read more
Mac Studios with M2 Max and M2 Ultra CPUs on...
B&H Photo has standard-configuration Mac Studios with Apple’s M2 Max & Ultra CPUs in stock today and on Easter sale for $200 off MSRP. Their prices are the lowest available for these models... Read more
Deal Alert! B&H Photo has Apple’s 14-inch...
B&H Photo has new Gray and Black 14″ M3, M3 Pro, and M3 Max MacBook Pros on sale for $200-$300 off MSRP, starting at only $1399. B&H offers free 1-2 day delivery to most US addresses: – 14″ 8... Read more
Department Of Justice Sets Sights On Apple In...
NEWS – The ball has finally dropped on the big Apple. The ball (metaphorically speaking) — an antitrust lawsuit filed in the U.S. on March 21 by the Department of Justice (DOJ) — came down following... Read more
New 13-inch M3 MacBook Air on sale for $999,...
Amazon has Apple’s new 13″ M3 MacBook Air on sale for $100 off MSRP for the first time, now just $999 shipped. Shipping is free: – 13″ MacBook Air (8GB RAM/256GB SSD/Space Gray): $999 $100 off MSRP... Read more
Amazon has Apple’s 9th-generation WiFi iPads...
Amazon has Apple’s 9th generation 10.2″ WiFi iPads on sale for $80-$100 off MSRP, starting only $249. Their prices are the lowest available for new iPads anywhere: – 10″ 64GB WiFi iPad (Space Gray or... Read more
Discounted 14-inch M3 MacBook Pros with 16GB...
Apple retailer Expercom has 14″ MacBook Pros with M3 CPUs and 16GB of standard memory discounted by up to $120 off Apple’s MSRP: – 14″ M3 MacBook Pro (16GB RAM/256GB SSD): $1691.06 $108 off MSRP – 14... Read more
Clearance 15-inch M2 MacBook Airs on sale for...
B&H Photo has Apple’s 15″ MacBook Airs with M2 CPUs (8GB RAM/256GB SSD) in stock today and on clearance sale for $999 in all four colors. Free 1-2 delivery is available to most US addresses.... Read more
Clearance 13-inch M1 MacBook Airs drop to onl...
B&H has Apple’s base 13″ M1 MacBook Air (Space Gray, Silver, & Gold) in stock and on clearance sale today for $300 off MSRP, only $699. Free 1-2 day shipping is available to most addresses in... Read more

Jobs Board

Senior Product Associate - *Apple* Pay (AME...
…is seeking a Senior Associate of Digital Product Management to support our Apple Pay product team. Labs drives innovation at American Express by originating, Read more
Medical Assistant - Surgical Oncology- *Apple...
Medical Assistant - Surgical Oncology- Apple Hill Location: WellSpan Medical Group, York, PA Schedule: Full Time Sign-On Bonus Eligible Remote/Hybrid Regular Apply Read more
Omnichannel Associate - *Apple* Blossom Mal...
Omnichannel Associate - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Read more
Cashier - *Apple* Blossom Mall - JCPenney (...
Cashier - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Blossom Mall Read more
Operations Associate - *Apple* Blossom Mall...
Operations Associate - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.