TweetFollow Us on Twitter

Scrolling Windows PP
Volume Number:11
Issue Number:12
Column Tag:Getting Started

PowerPlant and Scrolling Windows

By Dave Mark, MacTech Magazine Regular Contributing Author

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

Due to popular demand, this month’s column returns to the land of CodeWarrior and PowerPlant. Assuming it’s okay with all of you, I’d like to spend the next few months really getting to know PowerPlant, instead of hopping back and forth between PowerPlant, TCL, and Sprocket. Any dissenting opinions? Let me know! As always, look on page 2 of the magazine to find out how to get in touch with us.

I want to take a moment and thank Greg Dow, the creator of PowerPlant, for all his help. Greg has never been too busy to answer my questions, and spent a lot of time making sure I got it right. If you see Greg at MacWorld or at WWDC, thank him and buy him an Espresso!

Create the PictScroller Project

This month’s program will create windows that look like the one shown in Figure 1. Notice that the window is divided into two areas. The top area contains two buttons. The left button beeps when you click on it. The right button is disabled (we’ll change that in next month’s column). The lower portion of the window contains a PICT, and the scroll bars allow you to scroll the PICT up and down, left and right. The close box, zoom box, and size box each work as expected. The PICT is not scaled, and “sticks” to the upper left corner of the scrolling region. Perhaps the coolest thing about this program is that dragging the thumb forces the window to update dynamically. In other words, the window is constantly redrawn as you drag the thumb, unlike a normal Macintosh window which updates only after the scrollbar’s thumb is released.

Figure 1: A PictScroller window

Let’s get to work.

• Create a folder named PictScroller ƒ on your hard drive, anywhere outside of the CW7 folder.

• Lauch CodeWarrior IDE 1.3. You’ll find it inside the CodeWarrior 7 folder, inside the Metrowerks CodeWarrior subfolder.

• Create a new project file named PictScroller.µ - be sure you use one of the two PowerPlant stationery files when you create the project. Select either PowerPlant 68K.µ or PowerPlant PPC.µ from the Project Stationery popup menu.

• In the project window that appears, double-click on the file name <PP Starter Source>.cp.

This file is located in the stationery folder. Since we’ll eventually modify this file and we don’t want our changes reflected in the project stationery, we’ll save a copy of this file in our working folder.

• Select Save As... from the File menu and save the file as PictScroller.cp in your PictScroller ƒ folder.

Notice that the file name actually changed in the project window, showing that your copy of the file has replaced the stationery file in the project. Our next step is to change the name of the include file associated with this .cp file.

• Towards the top of the file PictScroller.cp, you’ll find an include file named <PP Starter Header>.h. Open this file by selecting the file name and typing AppleD.

• Once the file <PP Starter Header>.h opens, select Save As... from the File menu and save it in your PictScroller ƒ folder under the name PictScroller.h.

• Close the file PictScroller.h.

• Back in PictScroller.cp, change the reference <PP Starter Header>.h in the #include to say PictScroller.h instead.

At this point, all of our source code is disconnected from the stationery files. There is one more stationery dependency left, however, and that is the file <PP Starter Resource>, the default constructor file.

• Back in the project window, double-click on the file named <PP Starter Resource>.rsrc. Though the file contains regular old resources, its creator is MWC2, the creator type associated with Constructor 2.0.

• In Constructor, select Save As... from the File menu, navigate back over to your PictScroller ƒ folder and save the file as PictScroller.rsrc.

• Go back to CodeWarrior and select the file <PP Starter Resource>.rsrc in the project window.

• Select Add Files... from the Project menu and add the file PictScroller.rsrc to the project.

• Once again, select <PP Starter Resource>.rsrc in the project window. This time, select Remove Files from the Project menu to remove the last stationery file from the project.

We have now made our own copy of the three files we’ll be modifying: PictScroller.rsrc, PictScroller.cp, and PictScroller.h. Before we make our changes, let’s take the default project for a spin.

• Select Run from the Project menu.

PowerPlant will now compile all of the source code files (the entire PowerPlant framework) in your project. This took about one minute and 15 seconds on a PowerMac 8100/100. Your mileage may vary.

It is interesting to note that the completely compiled project file takes up about 1.1 meg of hard drive space, as compared with the more than 10 meg consumed by last month’s TCL project. Obviously, Symantec stores a lot more project information than CodeWarrior. Still, a size factor of 10 to 1 is pretty significant. Hey, Rich Parker, do you know why this is?

• Once the project compiles and runs, select Quit from the File menu.

We are now ready to use Constructor to design our custom two-button scrolling window.

• Go back to Constructor. The file PictScroller.rsrc should still be open.

Figure 2 shows the PictScroller.rsrc Constructor window before we start messing with it. Constructor handles three different resource types. Views, by far the most popular type, are what we’ll be working with. Views are Constructor interface elements designed to act as containers for other Constructor elements. You’ll frequently encounter the terms view and pane. All visual Constructor elements are panes. Views are panes that can contain other panes. Don’t get too hung up on the terminology. It really isn’t important.

Figure 2: The PictScroller.rsrc window, before we make our changes

Text traits allow you to embed TextEdit style information inside a resource, rather than specifying it programmatically using QuickDraw calls. Think of text traits as a poor person’s style sheet.

Custom types allow you to create your own custom views, as opposed to the views that are built into Constructor.

The project stationery came with a single view, an LWindow with a resource ID of 1 and a name of <replace me>. This View resource will act as the template for our two-button scrolling window. Let’s start changing it.

• Make sure the LWindow view is selected, then select Resource Info from the Edit menu.

A resource info window will appear (Figure 3). We’ll change the resource name to something a little more meaningful.

Figure 3: The resource info window for the LWindow view

• Change the Resource Name: to PictScroller.

• Close the resource info window.

• Now double-click on the LWindow view. A view editing window will appear (Figure 4).

You should recognize this as the window that appeared when you ran your program before. Notice that this view consists of 2 panes, one representing the window and one representing a static text string that appears in the window.

Figure 4: The “before” picture of our LWindow view

• Click on the static text string and press the Delete key to delete the static text pane from the LWindow view.

• Double-click on the window pane (the one with the number 1 in the upper right corner). A pane info window will appear (Figure 5).

• Click on the Size Box, Resizable, and Zoom Box checkboxes (so all five checkboxes in that area are checked).

• Select Stagger on Main Screen from the Auto Position: popup menu.

• Change the Window Title: to PictScroller.

• Close the info window.

Figure 5: The pane info window for the PictScroller window,
after all the changes were made

• Click on the Tools palette window and drag an LStdButton from the palette into the PictScroller view.

• Double-click on the button that appears. A pane info window for the button will appear (Figure 6).

Figure 6: The pane info for the Beep button,
after all the changes were made

The Binding to Superview: checkboxes let you specify how this pane binds to its enclosure. For example, if we check the Top checkbox, the button will stick to the top of the enclosing view. If the enclosing view is resized, the button won’t move. If the Bottom checkbox were checked instead, the button would move when the enclosing view is resized, sticking a fixed number of pixels from the bottom. Note that if the Top and Bottom checkboxes were both checked, if the enclosing view was resized, the button would scale!

Since the top of our enclosing pane won’t scroll, not checking any of the checkboxes is equivalent to checking both Top and Left.

• Change the Pane ID: to 1000. We can use this ID to retireve a pointer to the button object. We’ll do this in the code later on.

• Change the Button Title: to Beep.

• Change the Value Message: to 1000. As pointed out in the last PowerPlant column, the Text Message check box lets you use 4-letter codes (like 'beep') instead of integers (like 1000).

• Change the Location: fields as follows. Left = 20, Top = 8, Width = 80, and Height = 20.

• Close the button’s info window.

Now let’s do the second button.

• Drag out a second LStdButton from the Tools palette.

• Double-click on the button. The button’s info window will appear.

• In the Binding to Superview: window, click on the Right checkbox. This makes the button stick to the right side of the window when the window is resized.

• Change the Location: fields as follows. Left = 200, Top = 8, Width = 80, and Height = 20.

• Change the Button Title: to Dialog.

• Uncheck the Enabled check box (so the button is dimmed). Note that there is a bug in Constructor: disabled buttons appear with no title text. No big deal. The title appears in grey when you run the program.

• Change the Pane ID to 1001.

• Change the Value Message to 1001. We won’t be tying any code to this button till next month.

• Close the button’s info window.

Now let’s create the scrolling pane that will contain the PICT.

• Drag an LActiveScroller from the palette to the LWindow view window. An LActiveScroller updates dynamically in response to thumb drags. An LScroller updates once the thumb is released.

• Double-click on the LActiveScroller. The LActiveScroller’s info window will appear.

• Change the Location: fields as follows. Left = -1, Top = 36, Width = 302, and Height = 165. Try some different values and you’ll see why I chose these.

• Check all four of the Binding to Superview: checkboxes. We do this so that the pane will stay the same size as the window, even when it resizes. Note that this will not affect the PICT resource that we embed in this view. In other words, just because this view scales doesn’t mean that embedded panes scale.

• Set the Pane ID: to 1002.

• Set the Scrolling View ID: to 1003. Note that this is the ID of the view we want scrolled inside this view. We’ll create view 1003 next.

• Close the LActiveScroller’s info window.

Now we’ll create the pane that will hold the PICT resource.

• Drag an LPicture from the palette inside the LActiveScroller.

Due to a bug in Constructor, you won’t be able to drag the LPicture so it is embedded inside the LActiveScroller. Luckily, there is a different way to make this happen.

• Select Show Hierarchy from the Display menu. The hierarchy window will appear, listing all the views inside the LWindow view.

• In the hierarchy window, click on the LPicture icon and drag it to the right and slightly up. The little black triangle that appears as you drag should point to the lower right corner of the LActiveScroller icon and the line that appears should be below LActiveScroller. Figure 7 shows a before and after picture of the hierarchy change.

Figure 7: The first picture is before
and the second picture is after the hierarchy change,
moving the LPicture within the LActiveScroller

• Close the hierarchy window.

Now we’ll set the LPicture info.

• Double-click on the LPicture. The LPicture’s info window will appear.

• Change the Location: fields as follows. Left = 1, Top = 1, Width = 285, and Height = 148.

• Set the Pane ID: to 1003.

• Set the PICT Resource ID: to 128.

• Check all four of the Binding to Superview: checkboxes. Once you get your program working, try unchecking a few of these to see what happens.

• Check the Reconcile Overhang checkbox. This keeps white space from appearing when you grow the window down. It is usually checked for PICTs, unchecked for text.

• Set the Scroll Unit: values to 1 and 1. This specifies the scrolling resolution.

• Leave the Image Size: values at 0 and 0. This tells Constructor to use the FrameRect of the PICT as the bounding rectangle. Try setting these values as the width and height used in the Location: fields. Combine this with your Binding to Superview experimentation for maximal effect.

• Leave the Scroll Position: values at 0 and 0. These are the initial values of the scroll bars. 0 and 0 will start the PICT off unscrolled.

• Close the LPicture info window.

At this point, the LPicture will be grey. That’s because we haven’t created a PICT resource with an ID of 128. We’ll do that next.

• Quit Constructor, saving your changes when prompted to.

• Go into Resorcerer or ResEdit and open the file PictScroller.rsrc.

• Open up your Scrapbook and copy a picture into the clipboard.

• Back in Resorcerer/ResEdit, paste the picture, creating a new PICT resource.

• Change the PICT resource ID to 128.

• Quit Resorcerer/ResEdit, saving your changes.

• Go back into Constructor, open PictScroller.rsrc and verify that your picture made it into the LPicture (Figure 8).

• Quit Constructor.

Figure 8: The final version of the PictScroller view in Constructor

Modifying the Source Code

Now that we have our Constructor view completely defined, we’ll make a few small code changes to bring it to life. Since our stationery-based program already has the ability to generate a new window tied to the LWindow view with a resource ID of 1, all we have to do is register the LActiveScroller class (you’ll see why in a minute), turn the CPPStarterApp class into an LListener, then add a function that listens for the message generated by the Beep button (and beep when we get that message).

• Back in CodeWarrior, open the file PictScroller.h.

• Change the declaration of the CPPStarterApp class so it is derived from both the LApplication and LListener class. Take a look at the new listing of PictScroller.h that follows the next few commands.

• Add the #include of the file LListener.h.

• Finally, add a new, public member function named ListenToMessage() to the class declaration.

• Close PictScroller.h.

Here’s the new version of PictScroller.h:

// ====================
// <PP Starter Header>.h         ©1994-1995 Metrowerks Inc.
// All rights reserved.
// ====================

#pragma once

#include <LApplication.h>
#include <LListener.h>

class CPPStarterApp : 
 public LApplication, public LListener {

public:

    // constructor registers all PPobs
 CPPStarterApp();
    // stub destructor
 virtual ~CPPStarterApp();
 
    // this overriding function performs application functions
 virtual Boolean ObeyCommand
 (CommandT inCommand, void* ioParam);
 
    // this overriding function returns the status of menu items
 virtual void FindCommandStatus
 (CommandT inCommand,
 Boolean &outEnabled, Boolean &outUsesMark,
 Char16 &outMark, Str255 outName);
 
 virtual void ListenToMessage
 (MessageT inMessage,
 void *ioParam);

protected:

    // overriding startup functions
 virtual voidStartUp();
};

We covered the LListener class 3 columns ago, in our first PowerPlant program. As a reminder, a class that is derived from LListener can receive messages sent to it by other classes. In this case, we’re going to tie a CPPStarterApp object to the Beep button by passing a CPPStarterApp pointer to the Beep button object’s AddListener() member function. Check back to the previous PowerPlant column for more detail. And if you still don’t get it, don’t worry. We’ll do more message listening in future PowerPlant columns.

Our next step is to make changes to the file PictScroller.cp.

• Open the file PictScroller.cp.

• Add this line below the #include of LEditField.h:

 
#include <LActiveScroller.h>

• Scroll down to the constructor CPPStarterApp::CPPStarterApp(), and add this line at the end of the function:

 URegistrar::RegisterClass
 (LActiveScroller::class_ID,
 LActiveScroller::CreateActiveScrollerStream);

As we discussed in the previous PowerPlant column, we need to register all the PowerPlant classes we’ll be using. Before we added this line, the only thing the constructor did was call RegisterAllPPClasses(), which registers a bunch of classes. Unfortunately, this does not include the LActiveScroller class. No big deal. We just registered it ourselves.

To see which classes are registered automatically, open the file PPobClasses.cp and check out the function RegisterAllPPClasses() (at the very bottom of the file). To get there quickly, once you’ve compiled your source, option-double-click on the constructor call RegisterAllPPClasses().

I copied the RegisterClass() call above directly from the bottom of PPobClasses.cp. Note that we could have avoided this step if we had used an LScroller instead of an LActiveScroller. LScrollers are part of the mainstream. LActiveScrollers are part of the iconoclastic fringe, the bad seeds, the outcasts...

OK, OK, back to the code. Our next step is to add a listener function that beeps when it gets the right message.

• Add this function to the bottom of PictScroller.cp:

// ---------
// • ListenToMessage
// ---------
// Constructor

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

Our final step: add the listener to the Beep button.

• Find the function CPPStarterApp::ObeyCommand(). It is about 3/4 of the way through the file.

• In the switch statement, find the case for cmd_New.

• Insert these lines after the call to CreateWindow() and before the call theWindow->Show():

 LStandardButton *theButton =
 (LStandardButton *)theWindow->FindPaneByID( 1000 );
 theButton->AddListener( this );

Here’s what the entire case looks like:

 case cmd_New:
    // EXAMPLE, create a new window
 LWindow*theWindow;
 theWindow = LWindow::CreateWindow
 (window_Sample, this);
 LStdButton *theButton =
 (LStdButton *)theWindow->FindPaneByID( 1000 );
 theButton->AddListener( this );
 theWindow->Show();
 break;

Run the Sucker

That’s it. Now go take this puppy for a ride. When it runs, a window like the one shown in Figure 1 will appear by default. Look through the code and see if you can figure out why. Select New from the File menu and more windows will appear. If your PICT was large enough, you’ll be able to scroll it. Try dragging a scrollbar’s thumb. Is that cool or what? The window updates automatically, as you move the thumb. Interestingly, the CodeWarrior source code windows do the same thing. Gee, do you think the CodeWarrior editor was written in PowerPlant? Very cool.

When you resize the window, notice that the right, disabled button sticks to the right side of the window. If you make the window small enough, the buttons will run into each other. Go back into Constructor and figure out how to set the minimum height and width for the window. Here’s a clue: To get at the LWindow info window, open the LWindow view, then double-click on the title bar of the window shown in the overview window (the window shown in Figure 8).

Finally, notice that the Beep button beeps and that the Dialog button is disabled and that its title was drawn in grey.

Till Next Month...

Next month, we’ll add another view to our program. Right now, I’m thinking about a modeless dialog, but who knows? See you then...

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

VisualRuler - turns your iPhone into rul...
VisualRuler - turns your iPhone into ruler 1.0 Device: iOS iPhone Category: Utilities Price: $2.99, Version: 1.0 (iTunes) Description: Need to measure the size of the object but do not have a ruler? VisualRuler calculates the size of... | Read more »
Blyss (Games)
Blyss 2.0 Device: iOS Universal Category: Games Price: $1.99, Version: 2.0 (iTunes) Description: Travel through Beautiful mountains, serene valleys and harsh deserts solving Blyss' unique and self-evolving puzzles. The endless... | Read more »
Road Not Taken (Games)
Road Not Taken 1.0 Device: iOS iPhone Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: "It looks like a cute fairy tale, but this is a turn-based game that's thorny with challenge and packed with an incredible number... | Read more »
What is PokéVision -- and why doesn...
The biggest thing that Pokemon GO players want to know is where to find the Pokemon they don't already have. The crux of the game is catching 'em all, so tracking down elusive pocket monsters is generally task number one any time someone fires up... | Read more »
Win every gym battle in Pokemon GO
Let me know if this scenario sounds familiar. You've got a Pokemon GO gym battle within easy walking distance, and you've visited it many times. Maybe you've even dropped one of your Pokemon there to help defend the place and reap the benefits. [... | Read more »
Can PokeMatch help you find love with Po...
The unofficial Pokemon GO companion app space has exploded almost as fast as the game itself over the last few weeks. Aspiring app developers, many of them working solo, have given us apps that locate Pokemon, keep track of the server status, and... | Read more »
How to get started with Prisma
If there's one thing people like to do more than taking pictures with their smartphones, it's tinkering with those photos in some way. Numerous apps have sprung up over the last several years that allow you to use filters and special effects to... | Read more »
6 Pokemon GO updates you can expect, acc...
Pokemon GO had a scheduled appearance at this year's San Diego Comic-Con for a while, but it was only relatively close to the show that it was upgraded to a spot in Hall H. That's the biggest venue at SDCC, one usually reserved for the largest... | Read more »
How to evolve Eevee in Pokemon GO
By now, almost everyone should be hip to how to evolve Pokemon in Pokemon GO (and if not, there's a guide for that). Just gather enough candy of the appropriate type, feed them all to the Pokemon, and evolution happens. It's a miracle that would... | Read more »
CSR Racing 2: Guide to all game modes
It might not seem like there are all that many ways to go fast in a straight line, but CSR Racing 2 begs to differ. [Read more] | Read more »

Price Scanner via MacPrices.net

Bare Bones Software Releases Free TextWrangle...
Bare Bones Software has announced the release and immediate availability of TextWrangler 5.5, a significant update to its powerful, free, general purpose text editor for Mac OS X. TextWrangler is a... Read more
Apple’s 2016 Back to School promotion: Free B...
Purchase a new Mac or iPad using Apple’s Education Store and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free, and... Read more
Apple refurbished iPad Air 2s available start...
Apple has Certified Refurbished iPad Air 2 available starting at $339. Apple’s one-year warranty is included with each model, and shipping is free: - 128GB Wi-Fi iPad Air 2: $499 - 64GB Wi-Fi iPad... Read more
13-inch 2.5GHz MacBook Pro available for $964...
Overstock has the 13″ 2.5GHz MacBook Pro available for $964.21 including free shipping. Their price is $135 off MSRP. Read more
External Keyboard Innovations For iPad Pro (1...
I’m an input device aficionado. With non-touchscreen computers, which includes all Macs, the keyboard and mouse or trackpad are the tactile points of interface between user and machine, and the... Read more
GSK Rheumatoid Arthritis Study Leverages iPho...
Global healthcare products company GlaxoSmithKline (GSK) says that since 2014 they have begun transforming the way they conduct research, by leveraging state-of-the-art digital technologies — a... Read more
Clearance 12-inch Retina MacBooks, Apple refu...
Apple has Certified Refurbished 2015 12″ Retina MacBooks available starting at $929. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The following... Read more
13-inch Retina MacBook Pros on sale for up to...
B&H Photo has 13″ Retina MacBook Pros on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1199 $100 off MSRP - 13″ 2.7GHz/... Read more
13-inch 1.6GHz/128GB MacBook Air on sale for...
Amazon has the 13″ 1.6GHz/128GB MacBook Air on sale for $200 off MSRP for a limited time. Shipping is free: - 13″ 1.6GHz/128GB MacBook Air (sku MMGF2LL/A): $799.99 $200 off MSRP Their price is the... Read more
13-inch 1.6GHz/256GB MacBook Air on sale for...
Amazon has the 13″ 1.6GHz/256GB MacBook Air on sale for $200 off MSRP for a limited time. Shipping is free: - 13″ 1.6GHz/256GB MacBook Air (sku MMGG2LL/A): $999.99 $200 off MSRP Their price is the... Read more

Jobs Board

*Apple* Retail - Multiple Positions, Willow...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Evangelist - JAMF Software (United S...
The Apple Evangelist is responsible for building and cultivating strategic relationships with Apple 's small and mid-market business development field teams. This Read more
*Apple* Solutions Consultant - APPLE (United...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
*Apple* Professional Learning Specialist - A...
Job Summary The Apple Professional Learning Specialist is a full-time position for one year with Apple in the Phoenix, AZ area. This position requires a high Read more
*Apple* Picker - Apple Hill Orchard (United...
Apple Hill Orchard, Co. Rte. 21,Whitehall, NY 9/7/16-10/228/16. Pick fresh market or processing apples Productivity of 60 boxes and 80 boxes processing fruit per Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.