TweetFollow Us on Twitter

Regions with CLR
Volume Number:2
Issue Number:2
Column Tag:Basic School

Basic Does Regions (with CLR!)

By Dave Kelly, General Dynamics Corp., MacTutor Editorial Board

Hello! This month we will explore the Macintosh Quickdraw routines with a trip into the world of regions. This may be a review for some of you that program in other languages such as Pascal or C as this subject has been covered quite well in past issues of MacTutor (See Vol. 1 No. 3 "Quickdraw does Regions" or Vol 1 No. 4 "Ports O' Call in Quickdraw"). Until recently it has been impossible to meaningfully talk about regions from MSBASIC. Wth the Clear Lake Research (CLR) Libraries available it is now possible to give BASIC equal time with the other languages when referring to Quickdraw. Quickdraw routines are called from BASIC in much the same method used in Pascal or other languages. In fact, we recommend that you review the Pascal columns referred to above as they have information which may pertain to any language, not just Pascal. The same is true for this column when discussing calls to Quickdraw or other routines used by all languages.

Fig. 1 Screen dump of our regions program

First a bit of a review for those that are not familiar with Quickdraw regions and associated calls. We have available to us via the CLR Libraries [Note: These libraries are available from the MacTutor mail order store for $50 for both the libraries and the speech routines. -Ed.], over 20 statements involving regions. These are found listed with their functions on page 14 of the CLR manual or you may refer to Chapter 4 of Macintosh™ Revealed, Volume One by Chernicoff and published by Hayden Press. Instead of going into a detailed study of Quickdraw I refer you to the previous issues of MacTutor mentioned above. (Back issues are available through the MacTutor Store).

A few things to remember when working with Quickdraw: The horizontal coordinates increase from left to right and the vertical coordinates increase from top to bottom. You may want to think of a region as an area on the screen with a set of points inside the region and a set of points outside. A point in the region cannot be both inside and outside the region. It should also be noted that a graphic point is located to the 'right' and 'below' its corresponding mathematical coordinate.

The Region/Clip Demo program (note: requires CLR Libraries) will set up a region and by using the GetClip and SetClip statements (CLR) we can specify the region which we want the text (or graphics) to be drawn to. In this way, only drawing that occurs within the region will show up on the screen. Any drawing outside the region will not show up. This could be useful when you want to draw in a particular part of the screen without disturbing the contents of another part of the screen. The demo program first opens up the appropriate library:

LIBRARY"ToolLib"

Remember to include the disk volume name if necessary. I would advise you to use the Statement Mover program to move the libraries that you use over to the BASIC program file so they will always follow the program no matter what disk you put it on.

Next we set up some of the array variables used by the program and associated library routines. If the variable is undeclared the libraries cannot work. Also be sure to dimension the arrays properly. For example, if the pattern%() array below were dimensioned to 0 instead of three, the routine SetRect would go ahead and try to store 4 variables, but would only be able to find one. The results could be unpredictable. Save your work before running your program in case there might be any misteaks (ha, ha). The SetRect command sets the left, top, right, and bottom coordinates of the array equal to the indicated values respectively.

DIM R%(3),OvalR%(3),fontinfo%(3),pattern%(3)
x1%=50:y1%=20:x2%=450:y2%=200
SetRect R%(0),x1%,y1%,x2%,y2%
SetRect pattern%(0),&HAA,&HAA,&HAA,&HAA
SetRect pattern%(0),&HAA,&HAA,&HAA,&HAA

The window is opened and the background is set to the background pattern defined in the pattern%() array. The screen is cleared so that the background pattern will be redrawn. The pattern%() array is cleared with SetRect and the background pattern cleared so that subsequent CLS statements will clear the screen to white. Note that the CLS command only clears within the clipping region. When a BASIC window is opened up the clipping region defaults to the window size.

WINDOW 1,"",(2,30)-(508,275),4
CALL BACKPAT (VARPTR(pattern%(0)))
CLS
SetRect pattern%(0),0,0,0,0
CALL BACKPAT(VARPTR(pattern%(0)))

Another CLR Library statement allows us to determine the size of the currently selected font. The program sets the TEXTSIZE to 9 and then calls the getfontinfo routine. The font info is returned in the array fontinfo%(). The variable fontinfo%(0) returns the ascent, fontinfo%(1) returns the descent, fontinfo%(2) returns the maximum character width, and fontinfo%(3) returns the vertical distance between the descent line and the ascent line below it. The program needed to know the total spacing for each line of text which is given by the sum of the ascent, descent, and the vertical distance between the descent line and the ascent line below it. Note that a call to getfontinfo would be useful for programs trying to determine the number of lines of text to print per page (or screen) when using various sizes and styles of fonts.

CALL TEXTSIZE(9)
getfontinfo fontinfo%(0)
fh%=fontinfo%(0)+fontinfo%(1)

Next the region handle variables are defined and the clipping region represented by the screen is stored away so it may be restored again later. If the OldReg! handle were not saved in this way, the last clipping region would be used the next time printing to the window. To define a new region, execute a NewRgn command. This allocates space for the new region and the region is initialized to the empty region. GetClip sets the region with the handle indicated (in this case OldReg! is the handle) to the current clip region.

handle!=0
OldReg!=0
NewRgn OldReg!
getclip OldReg!

We now define the region which we want to use as our clipping region. First we initialize the region with NewRgn with handle! . Next we may define the contents of the region. A series of graphics statements will make up the region we wish to create. We open the region with OpenRgn and follow it with whatever graphics commands we desire such as FRAMEOVAL, FRAMERECT, LINE, and others. Note that arcs cannot form part of the region definition. The end of the definition is indicated with the CloseRgn handle! statement where handle! is the handle! of the region being defined. Next the clipping region is set to the region with handle! with the statement Setclip handle! . All points either printed or drawn outside the region will not be shown. Only those points inside the region may be seen when printing is done inside the region.

NewRgn handle!
OpenRgn
    FRAMEOVAL VARPTR(R%(0))
CloseRgn handle!
Setclip handle!

The next several statements of the program print text in the region which has been set as the clipping region. Note that CLR has provided us with the Drawtext text$ statement to drawtext much faster than with the BASIC PRINT statement. To use drawtext you must move the quickdraw pen to the desired pixel position and issue the drawtext statement. It is harder to use that the BASIC printing statements but the speed difference makes it worth using when speed counts.

There are other statements which may be used with regions. One region may be subtracted from another with DiffRgn or use XorRgn or UnionRgn to combine regions. These and other commands will be left for future MacTutor columns. The program uses the framergn command to draw a border around the edge of the region. The current pensize is used for the border line.

CALL PENSIZE (2,2)
framergn handle!

Now for a word of caution: If your program should crash for some reason before your region is disposed of, you should be prepared to manually type in the disposeRgn statement and appropriate handle or handles for the regions used. Remember to dispose of all regions before quiting your program as the space for the regions has been allocated and will not be returned unless the regions have been disposed of. Otherwise, you may find yourself wondering why you are running out of room on the heap. The statement is:

disposergn handle!

A few words on the CLR Libraries clipping statements: The CLR Libraries manual mentions a statement named ClipRect which is supposed to set the clipping region to a rectangle. The ClipRect routine is not included on my ToolLib file. No need to panic yet, however, because the same command can be reconstructed with a combination of region calls and clipping calls. One solution is to use the following sequence to do a ClipRect (set the clipping region to a rectangle):

DIM rect%(3)
handle!=0
SetRect rect%(0),x1%,y1%,x2%,y2%
NewRgn handle!
OpenRgn
    FRAMERECT ( VARPTR(Rect%(0))
CloseRgn handle!
Setclip handle!

You may also use SetRectRgn or RectRgn to set a region equal to a rectangle. The statement syntax is:

SetRectRgn hand!,left%,top%,right%,bottom%

The region with handle hand! is set equal to the rectangle with coordinates left%,top%,right%, and bottom%.

RectRgn hand!, rect%(0)

The region specified by the handle hand! is set equal to the rectangle rect%. A region is not created by this, but must have been previously defined with NewRgn.

You may use either of these two statements in place of the OpenRgn and CloseRgn sequence above as desired.

Use GetClip to set a region to the current clipping region and SetClip to set the clipping region to a different region. You may want to use SetClip to switch back and forth between different clipping regions.

Have any interesting programs you have created after experimenting with clipping regions? Feel free to share them with others by sending them in to MacTutor.

'Region/Clip Demo
'by Dave Kelly
'MacTutor ©1986

LIBRARY"ToolLib"
DIM R%(3),OvalR%(3),fontinfo%(3),pattern%(3)
x1%=50:y1%=20:x2%=450:y2%=200
SetRect R%(0),x1%,y1%,x2%,y2%
SetRect pattern%(0),&HAA,&HAA,&HAA,&HAA
WINDOW 1,"",(2,30)-(508,275),4
CALL BACKPAT (VARPTR(pattern%(0)))
CLS
SetRect pattern%(0),0,0,0,0
CALL BACKPAT(VARPTR(pattern%(0)))
CALL TEXTSIZE(9)
getfontinfo fontinfo%(0)
fh%=fontinfo%(0)+fontinfo%(1)
handle!=0
OldReg!=0
NewRgn OldReg!
getclip OldReg!
NewRgn handle!
OpenRgn
    FRAMEOVAL VARPTR(R%(0))
CloseRgn handle!
Setclip handle!
CALL MOVETO(x1%,y1%)
FOR i=1 TO 18
    CALL MOVETO (x1%,y1%+i*fh%)
    FOR j=1 TO 6
        drawtext "Read Mac Tutor!  "
    NEXT j
NEXT i
CALL PENSIZE (2,2)
framergn handle!
disposergn handle!
dh%=50:dy%=25
x1%=x1%+dh%:y1%=y1%+dy%
x2%=x2%-dh%:y2%=y2%-dy%
SetRect R%(0),x1%,y1%,x2%,y2%

NewRgn handle!
OpenRgn
    FRAMEOVAL VARPTR(R%(0))
CloseRgn handle!

Setclip handle!
CLS
CALL MOVETO(x1%,y1%)
FOR i=1 TO 18
    CALL MOVETO (x1%,y1%+i*fh%)
    FOR j= 1 TO 6
        drawtext "It's Grrrreat!  "
    NEXT j
NEXT i
framergn handle!
disposergn handle!
Setclip OldReg!
disposergn OldReg!
LIBRARY CLOSE
END
 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Audio Hijack 3.7.3 - Record and enhance...
Audio Hijack (was Audio Hijack Pro) drastically changes the way you use audio on your computer, giving you the freedom to listen to audio when you want and how you want. Record and enhance any audio... Read more
CleanMyMac X 4.6.15 - Delete files that...
CleanMyMac makes space for the things you love. Sporting a range of ingenious new features, CleanMyMac lets you safely and intelligently scan and clean your entire system, delete large, unused files... Read more
Suitcase Fusion 21.2.1 - Font management...
Suitcase Fusion is the creative professional's font manager. Every professional font manager should deliver the basics: spectacular previews, powerful search tools, and efficient font organization.... Read more
Civilization VI 1.3.6 - Next iteration o...
Civilization® VI is the award-winning experience. Expand your empire across the map, advance your culture, and compete against history’s greatest leaders to build a civilization that will stand the... Read more
Dashlane 6.2042.0 - Password manager and...
Dashlane is an award-winning service that revolutionizes the online experience by replacing the drudgery of everyday transactional processes with convenient, automated simplicity - in other words,... Read more
Airfoil 5.9.2 - Send audio from any app...
Airfoil allows you to send any audio to AirPort Express units, Apple TVs, and even other Macs and PCs, all in sync! It's your audio - everywhere. With Airfoil you can take audio from any... Read more
VirtualBox 6.1.16 - x86 virtualization s...
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers... Read more
Xcode 12.1 - Integrated development envi...
Xcode includes everything developers need to create great applications for Mac, iPhone, iPad, and Apple Watch. Xcode provides developers a unified workflow for user interface design, coding, testing... Read more
FileZilla 3.51.0 - Fast and reliable FTP...
FileZilla (ported from Windows) is a fast and reliable FTP client and server with lots of useful features and an intuitive interface. Version 3.51.0: Bugfixes and minor changes: Fixed import of... Read more
KeyCue 9.8 - Displays all menu shortcut...
KeyCue has always been a handy tool for learning and remembering keyboard shortcuts. With a simple keystroke or click, KeyCue displays a table with all available keyboard shortcuts, system-wide... Read more

Latest Forum Discussions

See All

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 »
Genshin Impact Guide - Gacha Strategy: W...
If you're playing Genshin Impact without spending money, you'll always need to be looking for ways to optimize your play to maximize rewards without getting stuck in a position where you're tempted to spend. The most obvious trap here is the game'... | Read more »
Genshin Impact Adventurer's Guide
Hello and well met, fellow adventurers of Teyvat! Check out our all-in-one resource for all things Genshin Impact. We'll be sure to add more as we keep playing the game, so be sure to come back here to check for updates! [Read more] | Read more »
Genshin Impact Currency Guide - What...
Genshin Impact is great fun, but make no mistake: this is a gacha game. It is designed specifically to suck away time and money from you, and one of the ways the game does this is by offering a drip-feed of currencies you will feel compelled to... | Read more »
XCOM 2 Collection on iOS now available f...
The XCOM 2 Collection, which was recently announced to be coming to iOS in November, is now available to pre-order on the App Store. [Read more] | Read more »
Presidents Run has returned for the 2020...
IKIN's popular endless runner Presidents Run has returned to iOS and Android just in time for the 2020 election season. It will see players choosing their favourite candidate and guiding them on a literal run for presidency to gather as many votes... | Read more »
New update for Cookies Must Die adds new...
A new update for Rebel Twins’ platformer shooter Cookies Must Die is coming out this week. The update adds quite a bit to the game, including new levels and characters to play around with. [Read more] | Read more »
Genshin Impact Guide - How to Beat Pyro...
The end game of Genshin Impact largely revolves around spending resin to take on world bosses and clear domain challenges. These fights grant amazing rewards like rare artifacts and ascension materials for weapons and adventurers, but obviously... | Read more »

Price Scanner via MacPrices.net

Use our exclusive iPhone Price Trackers to fi...
Looking for a new Apple iPhone 12 or 12 Pro? Perhaps a deal on last year’s iPhone 11? Check out our iPhone Price Tracker here at MacPrices.net. We track new and clearance iPhone prices from Apple as... Read more
Weekend deal: $100 off 13″ MacBook Airs at Am...
Amazon has new 2020 13″ MacBook Airs on sale for $100 off Apple’s MSRP, starting at only $899. Their prices are the lowest available for new MacBooks from any Apple resellers. These are the same 13″... Read more
New 10.9″ 64GB Apple iPad Air on sale for $55...
Amazon has Apple’s new 2020 10.9″ 64GB WiFi iPad Air on sale today for $549.99 shipped. That’s $40 off MSRP. Pre-orders are available today at this discounted price, and Amazon states that the iPad... Read more
Get a clearance 2019 27″ 5K iMac for up to $5...
Apple has Certified Refurbished 2019 27″ 5K iMacs available starting at $1439 and up to $520 off their original MSRP. Apple’s one-year warranty is standard and shipping is free. The following... Read more
AT&T offers the Apple iPhone 11 for $10/m...
AT&T is offering Apple’s 64GB iPhone 11 for $10 per month, for customers opening a new line of service, no trade-in required. Discount is applied via monthly bill credits over a 30 month period.... Read more
Apple’s 2020 11″ iPad Pros on sale today for...
Apple reseller Expercom has new 2020 11″ Apple iPad Pros on sale for $50-$75 off MSRP, with prices starting at $749. These are the same iPad Pros sold by Apple in their retail and online stores: – 11... Read more
Did Apple Drop The Ball By Not Branding Its C...
EDITORIAL: 10.21.20 – In the branding game, your marketing strategy can either be a hit or a miss and the latter is the case for Apple when it missed out on an opportunity to brand its “SE” series of... Read more
27″ 6-core and 8-core iMacs on sale for up to...
Adorama has Apple’s 2020 27″ 6-core and 8-core iMacs on sale today for $50-$100 off MSRP, with prices starting at $1749. Shipping is free: – 27″ 3.1GHz 6-core iMac: $1749, save $50 – 27″ 3.3GHz 6-... Read more
Apple’s 16″ MacBook Pros are on sale for $300...
B&H Photo has 16″ MacBook Pros on sale today for $300-$350 off Apple’s MSRP, starting at $2099. Expedited shipping is free to many addresses in the US. Their prices are among the lowest available... Read more
Apple has 2020 13″ MacBook Airs available sta...
Apple has a full line of Certified Refurbished 2020 13″ MacBook Airs available starting at only $849 and up to $200 off the cost of new Airs. Each MacBook features a new outer case, comes with a... Read more

Jobs Board

Dental Receptionist - *Apple* Valley Clinic...
Dental Receptionist - Apple Valley Clinic + Job ID: 57314 + Department: Apple Valley Dental + City: Apple Valley, MN + Location: HP - Apple Valley Clinic Read more
*Apple* Mobility Specialist - Best Buy (Unit...
**788165BR** **Job Title:** Apple Mobility Specialist **Job Category:** Store Associates **Store Number or Department:** 001013-Virginia Commons-Store **Job 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 Oct 08, 2020 Requisition # 124800 Sign Up for Read more
*Apple* Mobility Specialist - Best Buy (Unit...
**784631BR** **Job Title:** Apple Mobility Specialist **Job Category:** Store Associates **Store Number or Department:** 000522-Baxter-Store **Job Description:** The Read more
Senior Data Engineer - *Apple* - Theorem, L...
Job Summary Apple is seeking an experienced, detail-minded data engineeringconsultant to join our worldwide business development and strategy team. If you are Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.