TweetFollow Us on Twitter

Using Controls
Volume Number:1
Issue Number:4
Column Tag:Forth Forum

Using Controls

By Jörg Langowski

In this month’s column I want to introduce to you some concepts of control handling on the Macintosh under MacForth. Controls, as you might have guessed by now, are a very basic concept of the Macintosh user interface: a major part of mouse input to an application is done through controls.

The four main types of controls that show up to you when you work with an application are buttons, check boxes, radio buttons and dials, and these are the ones that we will be talking about this time.

All control handling routines are built into the toolbox ROM. Therefore, one can call them - in principle - from any programming environment as toolbox traps. MacForth, of course, makes this job a little easier by providing a large number of predefined routines. Interestingly enough, most of these routines are already present in Version 1.1, even though the manual says that 1.1 does not support controls. I suppose this was a typo. They wanted to say that it does not document controls. Well, the Inside Macintosh manual does that very extensively and as you will see, it is not hard to transfer those concepts into Forth.

Let’s first look at the definitions of the four control types, as they are given in IM:

Buttons are the little rounded rectangles that have a text inside. When you click a button with the mouse, you tell the application to perform some action as shown in the example below.

“Yes” and “No” are buttons and you may choose either one.

Check boxes show the state of a parameter that can be on or off, and can be clicked on/off with the mouse:

Radio buttons are sets of buttons, only one of which may be on. They are used to set and display parameters that can assume discrete values or states, such as integer numbers:

Dials, the scroll bar being the most familiar example, are used to set and display a parameter that can change continuously (or quasi-continuously, such as the position in a text file).

Generating a control in your active window is very simple, it requires only one toolbox call. Just putting a control into a window like that, however, is useless. You can click and point at it as long as you wish, it won’t do anything unless you tell it what to do. Clicking a control only generates an event that your program has to recognize. For instance, if a radio button is clicked you have to make sure that the corresponding parameter is set on and all others that belong to the same group of radio buttons are turned off. If the page region in a scroll bar is clicked you have to tell the system what to do, change the parameter value and show the scroll bar with its new value.

But then, there is not much more to do. The Control Manager will auto- matically determine if you clicked a control and which one, and will also ‘track’ the control, that is, display it changing while you perform some action on it with the mouse. It will also, if appropriate, inactivate a control, which is then displayed in a different way and any actions on it are ignored (like the scroll bars in the Finder windows if all the icons fit into the window).

Let’s assume we want to generate a window that contains the following controls:

• a scroll bar that can be changed through a range from 0 to 300

• a check box that is used to turn the scroll bar on and off.

An example program that does these functions is given below, and most of it should be self-explanatory. The Toolbox function NewControl that creates a new control in a window, however, has to be explained in a little more detail.

It expects 10 parameters on the stack, from bottom to top:

- 4 bytes for the function result ControlHandle

- WindowPtr, the pointer to the window that the new control belongs to

- boundsRect, the address of a rectangle that gives the control’s size and location in the window’s local coordinates

- title, a pointer to the control’s title

- visible, a boolean value (16 bit); if TRUE, the control is actually drawn inside the window, otherwise, it’s invisible

- value, a 16-bit integer, the control’s initial value

- min, 16-bit integer, the control’s minimum value

- max, 16-bit integer, the control’s maximum value

- procID, 16-bit integer, a number that defines the type of control:

- 0 - simple button, 1 - check box, 2 - radio button, 16 - scroll bar.

- refCon, 32-bit integer, a number that you may use as a unique reference number; it is not used by the Control Manager at all.

This set of parameters is rather impressive, and you can immediately see that none of the standard toolbox trap defining words in MacForth can be used to call this function. First, only function calls with at most one parameter are supported, for the others you have to include space for the result on the stack and use the MT defining word. Second, there are five 16-bit parameters between 32-bit ones, and Forth normally pushes 32-bit items on the stack.

MacForth 2.0 has the word ADD.CONTROL built in, which is called with the stack set up like above, only the integers are all 32-bit. ADD.CONTROL then converts visible, value, min, max, and procID to 16 bits and calls NewControl, which creates the control. However, if you have MacForth 1.1, you can define your own ADD.CONTROL by using the 16-bit push PUSHW that was defined in the last MacTech. The example below contains the definitions of PUSHW and ADD.CONTROL.

The scroll bar that we define is horizontal. The up button and page-up regions of a horizontal bar are on the left side, but the bar is incremented to the right (an inconsistency in the Control Manager). Therefore the program decrements the control’s value when the up button is clicked and increments it on the down button.

The only other control in the example is a check box that turns the scroll bar on and off. I have not included simple buttons or radio buttons; you may want to try them out on your own by setting procID to different values. Remember, if you define a set of radio buttons, your program has to keep track of which one is on and turn the others off. There is no way how the Control Manager could know which buttons belong to the same group.

( Demo program for using the Control Manager from Mac Forth )
( © 1985  MacTutor by J. Langowski  )

( pushw, new.control ) hex
: pushw s0 @ >R sp@ 2- s0 ! sp! r> s0 ! drop ;
A954 mt (new.control)
: add.control
  >r ( refCon )   >r ( procID )  >r ( max )   >r ( min )   >r ( value 
)
  pushw  ( visible ) r> pushw  ( value )
  r> pushw  ( min )  r> pushw ( max ) r> pushw  ( procID )  r> ( refCon 
)
 (new.control)  ;

( test window for new.control )              ( JL Jan 1985 )
decimal  new.window my.window  50 100 200 450 my.window w.bounds
close.box size.box + my.window w.attributes   my.window add.window
50 50 75 300 rect my.scroll
( set up scroll bar )
0 my.window my.scroll 
“  “ ( no title )
 -1  ( visible=true )
100  ( value )
0    ( min )
300  ( max )
16   ( procID for scroll bar )
here ( to get a unique ref # )
add.control 
constant my.control in.heap ( so that handle is released when FORGETting 
)

( on/off box for test window )
25 50 40 200 rect button.a.rect ( check box )
0 my.window button.a.rect “  Scroll Bar Off” -1 0 0 1 1 ( check box ) 

here add.control
constant my.button in.heap   my.window show.controls
80 50 95 150 rect text.rect  ( for output )

( control tracking )
( track control, given a control handle and mouse position, tracks a 
control )
: my.track this.control @ @mouse track.control ;

( get.control, given a control handle, gets the value of that control 
)
: show.value my.control get.control text.rect erase.rect
             0 textfont  50 90 move.to .” Value:” . .”    “  ;

( set.control, given a control handle and an integer, sets the control 
to 
  that integer value )

( scroll bar )
: do.thumb  my.track drop get.window show.controls show.value ;
: inc.scroll this.control @ dup get.control 1+ set.control show.value 
;
: dec.scroll this.control @ dup get.control 1- set.control show.value 
;
: inc10.scroll this.control @ dup get.control 10 + set.control show.value 
;
: dec10.scroll this.control @ dup get.control 10 - set.control show.value 
;

( scroll bar )
: do.scroll.bar  case in.thumb of  do.thumb   endof
           up.button of dec.scroll endof  down.button of inc.scroll endof
           page.up of dec10.scroll endof  page.down of inc10.scroll endof
                 endcase  ;


( check box )
( hilite.control, given control handle and integer value, sets the control
 active if value=0 and inactive if value=255 ) 
: do.button drop my.track if this.control @ dup get.control 1 swap -
                         my.control over 255 * hilite.control set.control 
then
     get.window show.controls ;

( control actions )
: do.controls swap  case my.control of  do.scroll.bar endof
                         my.button  of  do.button endof
                    endcase ;

( event loop for test window )
: my.action show.value if begin do.events
                          case mouse.down of  @mouse.dn get.window
                             find.control ?dup if do.controls then endof
                          endcase again
  else .” My Window Deactivated” then ;

my.window on.activate my.action

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Alfred 4.2 - Quick launcher for apps and...
Alfred is an award-winning productivity application for OS X. Alfred saves you time when you search for files online or on your Mac. Be more productive with hotkeys, keywords, and file actions at... Read more
MenuMeters 2.0.8 - CPU, memory, disk, an...
MenuMeters is a set of CPU, memory, disk, and network monitoring tools for Mac OS X. Although there are numerous other programs which do the same thing, none had quite the feature set I was looking... Read more
ClipGrab 3.8.15 - Download videos from Y...
ClipGrab is a free downloader and converter for YouTube, Vimeo, Facebook and many other online video sites. It converts downloaded videos to MPEG4, MP3 or other formats in just one easy step Version... Read more
Malwarebytes 4.6.11.3824 - Adware remova...
Malwarebytes (was AdwareMedic) helps you get your Mac experience back. Malwarebytes scans for and removes code that degrades system performance or attacks your system. Making your Mac once again your... Read more
Safari Technology Preview 14.1 - The new...
Safari Technology Preview contains the most recent additions and improvements to WebKit and the latest advances in Safari web technologies. And once installed, you will receive notifications of... Read more
Mactracker 7.9.7 - Database of all Mac m...
Mactracker provides detailed information on every Mac computer ever made, including items such as processor speed, memory, optical drives, graphic cards, supported OS X versions, and expansion... Read more
Tor Browser 10.0.2 - Anonymize Web brows...
The Tor Browser Bundle is an easy-to-use portable package of Tor, Vidalia, Torbutton, and a Firefox fork preconfigured to work together out of the box. It contains a modified copy of Firefox that... Read more
iTubeDownloader 6.5.24 - Easily download...
iTubeDownloader is a powerful-yet-simple YouTube downloader for the masses. Because it contains a proprietary browser, you can browse YouTube like you normally would. When you see something you want... Read more
TeamViewer 15.11.6 - Establish remote co...
TeamViewer gives you remote control of any computer or Mac over the Internet within seconds, or can be used for online meetings. Find out why more than 200 million users trust TeamViewer! Free for... Read more
ffWorks 2.1.18 - Convert multimedia file...
ffWorks, focused on simplicity, brings a fresh approach to the use of FFmpeg, allowing you to create ultra-high-quality movies without the need to write a single line of code on the command-line.... Read more

Latest Forum Discussions

See All

Genshin Impact Progression Guide - Mid-G...
Once you get up to around Adventure Rank 25, Genshin Impact starts to turn into a different thing. What was once a story-driven affair evolves into something more like a traditional MMO. | Read more »
Pixboy, the hit retro-themed platformer,...
Following its successful debut on PC and Nintendo Switch last summer, retro-themed platformer Pixboy has made the lead to mobile devices. The award-winning indie hit, which was developed by a two-person team at Oaky Games, has drawn comparisons to... | Read more »
Raziel: Dungeon Arena's newest char...
Raziel: Dungeon Arena's October update offers a little bit more than usual Halloween-themed outfits you often get this time of year, though those are here too. But beyond that, there is a new character, mercenary system and much more. In need of... | Read more »
Genshin Impact - Marvelous Merchant Even...
We're month since Genshin Impact's initial release, and we're already here at our second event. The Marvelous Merchant event has already been underway for two days and we have just the info you need to complete this silly scavenger hunt each day... | Read more »
Crash Bandicoot: On The Run! spins onto...
There’s a Crash Bandicoot endless runner coming to mobile sometime next spring. [Read more] | Read more »
Mulled 2 is a refreshingly simple ball-p...
Some of the greatest mobile games are actually the simplest ones, and it’s this philosophy that Mulled 2 was built on. Out now for iOS and Android, the puzzle sequel takes the accessible mechanics of its predecessor and builds on them with enticing... | Read more »
Physics-based tower defense game Goblin...
Indie developer Arif Games has released Goblin Raiders on iOS and Android. [Read more] | Read more »
PUBG Mobile has provided yet another upd...
PUBG Mobile has been making a point of publicly mentioning all of their ongoing efforts to vanquish cheating from the popular battle royale. Today two teams within the company have provided updates on their progress. [Read more] | Read more »
Zombieland: AFK Survival is celebrating...
Zombieland: AFK Survival is currently celebrating its one-year anniversary. If you don't quite recognise the name that's because it initially launched as Zombieland: Double Tapper. Anyway, the game is celebrating turning one with two Halloween-... | Read more »
Distract Yourself With These Great Mobil...
There’s a lot going on right now, and I don’t really feel like trying to write some kind of pithy intro for it. All I’ll say is lots of people have been coming together and helping each other in small ways, and I’m choosing to focus on that as I... | Read more »

Price Scanner via MacPrices.net

Apple now offering $8000 discount on maxed Ma...
Apple’s powerful Mac Pro can be fully optioned to a max of $53,399 by choosing a 2.5GHz 28-core Xeon W CPU, 1.5TB of memory, Two Radeon Pro Vega II Duo video cards with 2x32GB memory each, 8TB of... Read more
How to save $100-$200 on a new MacBook with A...
Are you a teacher, student, or staff member of any educational institution and need a new Apple MacBook? When you purchase a new MacBook using Apple’s Education discount, Apple will take $100-$200... Read more
Amazon offers Apple Watch Series 6 and SE dis...
Amazon is among the first Apple resellers to offer sale prices on new Apple Watch Series 6 and Apple Watch SE models with models available for up to $25 off Apple’s MSRP. These are the same Watches... Read more
3rd generation 12.9″ iPad Pros available toda...
Apple restocked select 3rd generation 12.9″ WiFi iPad Pros starting at only $699 and up to $380 off original MSRP. Each iPad comes with a standard Apple one-year warranty, outer cases are new, and... Read more
Upgrading To The iPhone 12 And Making The Swi...
FEATURE: 10.28.20 – The future of wireless technology is here but before you can jump onto the 5G bandwagon, you’ll need to upgrade to a compatible device like one of the new iPhones Apple... Read more
Gazelle drops prices on Apple’s iPhone 11 mod...
Gazelle is offering a range of discounted pre-owned unlocked Apple iPhone 11 models starting at $475, with some models seeing price reductions of up to $200. iPhones are offered in Fair, Good, and... Read more
B&H Photo has 2020 13″ Dual-Core MacBook...
B&H Photo has 2020 13″ Dual-Core MacBook Airs on sale today for $100 off Apple’s MSRP, only $899. Expedited shipping is free to many addresses in the US. These MacBook Airs are the same models... Read more
New promo at Verizon: New 64GB iPhone 11 Pro...
Verizon is offering the new 64GB iPhone 11 Pro Max for free for customers switching and opening a new line of service. Qualified trade-in required, worth up to $850 credited to your account over a 24... Read more
Apple has 2020 13″ 1.4GHz MacBook Pros in sto...
Apple has Certified Refurbished 2020 13″ 1.4GHz/256GB 4-Core Touch Bar MacBook Pros available for $1099, $200 off MSRP. Apple’s one-year warranty is included, shipping is free, and each MacBook has a... Read more
Amazon offers $50 discount on all new 2020 12...
Amazon has new 2020 Apple 12.9″ iPad Pros on sale today for $50 off MSRP, with prices starting at $949. Shipping is free. These are the same iPad Pros sold by Apple in their retail and online stores... Read more

Jobs Board

Licensed Dental Hygienist - *Apple* Valley...
Park Dental Apple Valley is seeking a compassionate, professional Dental Hygienist to join our team-oriented practice. Clinical Requirements Minnesota Licensure and Read more
Deskside Support Technician - *Apple* , Wind...
Deskside Support Technician - Apple , Windows **Ref No.:** 20-01859 **Location:** Northridge, California As part of a leading IT managed services specialist with more Read more
*Apple* Computing Specialist - Best Buy (Uni...
**789374BR** **Job Title:** Apple Computing Specialist **Job Category:** Store Associates **Store Number or Department:** 000896-Atlanta GA-Store **Job Read more
Geek Squad Advanced Repair *Apple* Professi...
**789256BR** **Job Title:** Geek Squad Advanced Repair Apple Professional **Job Category:** Store Associates **Store Number or Department:** 001135-Gulf Coast-Store Read more
Cub Foods - *Apple* Valley - Now Hiring Par...
Cub Foods - Apple Valley - Now Hiring Part Time! United States of America, Minnesota, Apple Valley Retail Post Date 1 day ago Requisition # 124800 Sign Up for Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.