TweetFollow Us on Twitter

Transmuting Text

Volume Number: 13 (1997)
Issue Number: 4
Column Tag: Programming Techniques

Transmuting Text

By Martin Frické, Tucson, Arizona

Seemlessly exchanging text labels and editable text objects

One common problem with diagrams and intricate dialogs is that there are often many separate editable text items that have a small storage overhead relative to their own data content. For example, the user may want to label the four corners of a square; each label editable and most labels, but perhaps not all, consist of only a few characters in one style. A problem arises in that the data-structures to support style and styled-editing are reasonably substantial.

For example, the Mac TERec is 96 bytes large compared with one byte to represent the single character that is actually on one of the corners of the drawn square. If a single body of text is large, the supporting style data-structures are insignificant, but with a multiplicity of small labels in a diagram, the content can easily get swamped by the support - as much as 200k can be used for one page of symbols. On the other hand, if the program considers a label to be just a string of characters, the label can be stored frugally and drawn easily, but it would not be as easily editable.

Many commercial programs do not fare terribly well with this problem (no names, no pack drill). There are a few standard techniques. Several painting programs use once-only editing. A new label is editable, but the moment that new label is de-activated, the text in it is converted into a bit-map and merged into the background. Therefore, this label cannot be recovered back into text and edited again. Other programs use a string to represent an individual small text item, then they float editable text over the top of the single active item. This can work, but conceptually it is pretty unattractive and often aligning the floater and the background string can be awkward.

The Transmuting Approach

We are obviously going to use objects as far as we can. What is required most often are string objects for the individual small text items. However, at most there will be one editable text, so this will be an editable text object, and any of the string objects can assume this role. What is needed are transmuting objects.

There are to be many string objects, and at most, one of these may be transmuted back and forth to an editable text object as required. The time to transmute is clearly on activation and de-activation, since there is only one editable text at a time (the active one). The only other property required of the objects is the ability to draw themselves, especially when inactive, as might occur during an update. Care must be taken over the drawing, because the pen may have to produce and match exactly the same result when drawing either version of a transmuted object.

Transmutation here amounts to replacing one object with another - perhaps creating one and deleting the other. You would not want to do this with an object that is referred to by other parts of the program, for that might leave dangling references. Caution suggests hiding the transmuted object within a public object - all public references will then be to the public object.

It may be that the editing by the user makes what formerly was a simple label into complex styled text (maybe akin to the opening page of a King James Bible), in which case, the text is not transmuted back to a string on de-activation. Another decision concerns a default style for the labels - each label can have its own, or there could be a global style. The choice is left to the designing programmer.

A Code Example

The code uses Marco Piovanelli's WASTE styled-text engine In a perfect world the code looks something like the following.

class TText : public CAbstractText
    // Abstract text supplies all the other methods
 TPrivateText  *fInternalText;
 void   ActivateText (Boolean OnOff);
 void   Compact();
 void   UnCompact();
 virtual void    Update(RgnHandle updateRgn);

void TText::ActivateText (Boolean OnOff)
 if (OnOff)
 UnCompact();    // transmutes from a string, if needed
 Compact(); // attempts to transmute into a string

void TText::Compact()
 Handle itsText;
 TInternalText *newText;
 Point itsPenStart;
 if (fInternalText->CanCompact())  {
 itsText= fInternalText->GetText();
 itsPenStart= fInternalText->GetPenStart();
 newText= new TString(itsText,itsPenStart);
 delete fInternalText;

void TText::UnCompact()
 Handle itsText;
 TInternalText *newText;
 if (fInternalText->CanExpand())   {
 itsText= fInternalText->GetText();
 newText= new TStyledText(itsText);
 delete fInternalText;

void TText::Update(RgnHandle updateRgn)
 if (RectInRgn(&fBoundingBox, updateRgn))

class TInternalText  // important fields and methods only
 virtual void    ActivateText (Boolean OnOff) {;};
 virtual Boolean CanCompact() {return false};
 virtual Boolean CanExpand() {return false};
 virtual Handle  GetText();
 virtual Point   GetPenStart(){return PointOf(0,0)};
 virtual void    SetPenStart(Point aStart){;};
 virtual void    Update(RgnHandle updateRgn);

class TString  : public TInternalText
    // important fields and methods only          
 Handle fText;
 Point fPenStart;

 Boolean  CanExpand() {return true};
 Handle GetText() {return fText};
 void   SetPenStart(Point aStart){fPenStart=aStart};
 void   Update(RgnHandle updateRgn);

class TStyledText: public TInternalText
    // important fields and methods only 
 void   ActivateText (Boolean OnOff);
 Boolean  CanCompact();
 virtual Point GetPenStart(){return PointOf(0,0)};
 Handle GetText();
 void   Update(RgnHandle updateRgn);

void TString::Update(RgnHandle updateRgn)
 DrawText( *fText, 0, GetHandleSize (fText) ); // Toolbox Routine           HUnlock( 
fText );

Boolean TStyledText::CanCompact()
 long oldStart,oldEnd,length;
 long kMaxString=999;
 SignedByte alignment;
 Boolean canDo=false;
 length= WEGetTextLength(fMacWE);
 if ((oldEnd-oldStart)<kMaxString) // not too long
 mode = doFont + doFace + doSize + doColor;
    // one style
 if ((WEContinuousStyle(&mode, &aStyle, fMacWE)) &&
    // one line
 (WEOffsetToLine(kMaxString, fMacWE)==0) &&  
    // no fancy alignment
 ((alignment== weFlushLeft)
 || (alignment== weFlushDefault))  
 return canDo    

Point TStyledText::GetPenStart()
 Point penStart;
 short lineAscent,lineDescent;
 LongRect destRect;
 _WECalcHeights(0, 1, &lineAscent, &lineDescent, fMacWE);

void TStyledText::Update(RgnHandle updateRgn)
 WEUpdate(updateRgn, fMacWE); // passed to the styled text engine

Unfortunately, the real world forced some modifications to this code. The Macintosh styled-text engine and the WASTE styled-text engine were not originally written as objects. They could have been given a wrapper to make them into objects, but normally they are used as Handles to records. This is not much different from Handles to objects. In the practical implementation the internal private text objects are not used. Instead, the fInternalText field is either just a Handle directly to a WASTE record or a handle to the raw text. Strictly speaking, the text transmutes a Handle based internal data structure rather than a Handle based internal object. However, it does work perfectly to produce results like the following sequence.

Figure 1. The top label is active editable text.

Figure 2. Some of the text is obscured (to demonstrate that the drawing routines mesh properly).

At this point, both labels are strings. The first several letters of the top label have been drawn by the text drawing routine.

Figure 3. Text is redrawn by string drawinf routine.

If we move the the obscuring window to one side (Figure 3) we notice that the half ‘e' and the ‘xt' in the top label are drawn perfectly by the string drawing routine and the mesh of half-a-text-draw and half-a-string-draw is exact.

Next, the document and the top label is activated and the ‘xt' changed to Chicago 18. This makes the label styled text, which will not transmute. The text is obscured again. Remove the obscuring window, and there is a perfect redraw of the top label (as styled text) and the bottom label (as a string). (See Figure 4.)

Figure 4. Obscured styled-text redrawn.

Similarly, the document and the bottom label can be activated, the bottom label made into styled text, and the obscuring sequence repeated.

A sceptic might say that the drawing routines here and the end results are visually indistinguishable from one another - how do we know that all this transmutation is actually happening? To see that the code was working properly, a single debugging SysBeep(5) is enclosed with the string drawing routine, and a double SysBeep(5) with the text drawing routine - you can hear the Updates.


Community Search:
MacTech Search:

Software Updates via MacUpdate

Microsoft Office 2016 16.11 - Popular pr...
Microsoft Office 2016 - Unmistakably Office, designed for Mac. The new versions of Word, Excel, PowerPoint, Outlook, and OneNote provide the best of both worlds for Mac users - the familiar Office... Read more
Adobe Photoshop CC 2018 19.1.2 - Profess...
Photoshop CC 2018 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Photoshop customer). Adobe Photoshop CC 2018, the industry standard... Read more
Adobe Dreamweaver CC 2018 -...
Dreamweaver CC 2018 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Dreamweaver customer). Adobe Dreamweaver CC 2018 allows you to... Read more
Adobe Flash Player - Plug-in...
Adobe Flash Player is a cross-platform, browser-based application runtime that provides uncompromised viewing of expressive applications, content, and videos across browsers and operating systems.... Read more
Drive Genius 5.2.0 - $79.00
Drive Genius features a comprehensive Malware Scan. Automate your malware protection. Protect your investment from any threat. The Malware Scan is part of the automated DrivePulse utility. DrivePulse... Read more
MegaSeg 6.0.6 - Professional DJ and radi...
MegaSeg is a complete solution for pro audio/video DJ mixing, radio automation, and music scheduling with rock-solid performance and an easy-to-use design. Mix with visual waveforms and Magic... Read more
ffWorks 1.0.7 - Convert multimedia files...
ffWorks (was iFFmpeg), 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... Read more
Dash 4.1.5 - Instant search and offline...
Dash is an API documentation browser and code snippet manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
Evernote 7.0.3 - Create searchable notes...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
jAlbum Pro 15.3 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. You can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly... Read more

Latest Forum Discussions

See All

Around the Empire: What have you missed...
Oh hi nice reader, and thanks for popping in to check out our weekly round-up of all the stuff that you might have missed across the Steel Media network. Yeah, that's right, it's a big ol' network. Obviously 148Apps is the best, but there are some... | Read more »
All the best games on sale for iPhone an...
It might not have been the greatest week for new releases on the App Store, but don't let that get you down, because there are some truly incredible games on sale for iPhone and iPad right now. Seriously, you could buy anything on this list and I... | Read more »
Everything You Need to Know About The Fo...
In just over a week, Epic Games has made a flurry of announcements. First, they revealed that Fortnite—their ultra-popular PUBG competitor—is coming to mobile. This was followed by brief sign-up period for interested beta testers before sending out... | Read more »
The best games that came out for iPhone...
It's not been the best week for games on the App Store. There are a few decent ones here and there, but nothing that's really going to make you throw down what you're doing and run to the nearest WiFi hotspot in order to download it. That's not to... | Read more »
Death Coming (Games)
Death Coming Device: iOS Universal Category: Games Price: $1.99, Version: (iTunes) Description: --- Background Story ---You Died. Pure and simple, but death was not the end. You have become an agent of Death: a... | Read more »
Hints, tips, and tricks for Empires and...
Empires and Puzzles is a slick match-stuff RPG that mixes in a bunch of city-building aspects to keep things fresh. And it's currently the Game of the Day over on the App Store. So, if you're picking it up for the first time today, we thought it'd... | Read more »
What You Need to Know About Sam Barlow’s...
Sam Barlow’s follow up to Her Story is #WarGames, an interactive video series that reimagines the 1983 film WarGames in a more present day context. It’s not exactly a game, but it’s definitely still interesting. Here are the top things you should... | Read more »
Pixel Plex Guide - How to Build Better T...
Pixel Plex is the latest city builder that has come to the App Store, and it takes a pretty different tact than the ones that came before it. Instead of being in charge of your own city by yourself, you have to work together with other players to... | Read more »
Fortnite Will Be Better Than PUBG on Mob...
Before last week, if you asked me which game I prefer between Fortnite Battle Royale and PlayerUnknown’s Battlegrounds (PUBG), I’d choose the latter just about 100% of the time. Now that we know that both games are primed to hit our mobile screens... | Read more »
Siege of Dragonspear (Games)
Siege of Dragonspear 2.5.12 Device: iOS Universal Category: Games Price: $9.99, Version: 2.5.12 (iTunes) Description: Experience the Siege of Dragonspear, an epic Baldur’s Gate tale, filled with with intrigue, magic, and monsters.... | Read more »

Price Scanner via

Sunday Sales: $200 off 13″ Touch Bar MacBook...
Amazon has new 2017 13″ 3.1GHz Touch Bar MacBook Pros on sale this weekend for $200 off MSRP, each including free shipping: – 13″ 3.1GHz/256GB Space Gray MacBook Pro (MPXV2LL/A): $1599.99 $200 off... Read more
B&H drops prices on 15″ MacBook Pros up t...
B&H Photo has dropped prices on new 2017 15″ MacBook Pros, now up to $300 off MSRP and matching Adorama’s price drop yesterday. Shipping is free, and B&H charges sales tax for NY & NJ... Read more
Apple restocks Certified Refurbished 2017 13″...
Apple has restocked Certified Refurbished 2017 13″ 2.3GHz MacBook Pros for $200-$230 off MSRP. A standard Apple one-year warranty is included with each MacBook, models receive new outer cases, and... Read more
13″ Space Gray Touch Bar MacBook Pros on sale...
Adorama has new 2017 13″ Space Gray Touch Bar MacBook Pros on sale for $150 off MSRP. Shipping is free, and Adorama charges sales tax in NY & NJ only: – 13″ 3.1GHz/256GB Space Gray MacBook Pro (... Read more
Best deal of the year on 15″ Apple MacBook Pr...
Adorama has New 2017 15″ MacBook Pros on sale for up to $300 off MSRP. Shipping is free, and Adorama charges sales tax in NJ and NY only: – 15″ 2.8GHz Touch Bar MacBook Pro Space Gray (MPTR2LL/A): $... Read more
Save $100-$150+ on 13″ Touch Bar MacBook Pros...
B&H Photo has 13″ Touch Bar MacBook Pros on sale for $100-$150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13″ 3.1GHz/256GB Space Gray MacBook Pro... Read more
Current deals on 27″ Apple iMacs, models up t...
B&H Photo has 27″ iMacs on sale for up to $150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27″ 3.8GHz iMac (MNED2LL/A): $2149 $150 off MSRP – 27″ 3... Read more
Thursday Deal: 13″ 2.3GHz MacBook Pro for $11...
B&H Photo has the 13″ 2.3GHz/128GB Space Gray MacBook Pro on sale for $100 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13-inch 2.3GHz/128GB Space... Read more
How to save $100-$190 on 10″ & 12″ iPad P...
Apple is now offering Certified Refurbished 2017 10″ and 12″ iPad Pros for $100-$190 off MSRP, depending on the model. An Apple one-year warranty is included with each model, and shipping is free: –... Read more
Silver 12″ 1.3GHz MacBook on sale at B&H...
B&H Photo has the 2017 12″ 1.3GHz Silver MacBook on sale for $1399.99 including free shipping plus sales tax for NY & NJ residents only. Their price is $200 off MSRP, and it’s the lowest... Read more

Jobs Board

*Apple* Genius - Technical Customer Service...
Job Description:Job SummaryAs a Genius at the Apple Store, you maintain customers' trust in Apple as the skilled technical customer service expert, Read more
*Apple* Endpoint Administrator - Massachuset...
Reporting to the Director of Client Services (DCS), the Apple Endpoint Administrator serves as a member of the Client Services team, which provides technical support Read more
Franchise Operations Advisor- *APPLE* Exper...
UFG, Inc. Franchise Operations Advisor - MUST HAVE APPLE OR WINDOWS EXPERIENCE (Outside Sales / Business Development / Customer Service / Full Time) Top Five Reasons Read more
Engineering- Platform- *Apple* Enterprise P...
…& RESPONSIBILITIES You are responsible for creating and supporting our next-gen Apple Platform Installers from ground-up. We use Jamf Composer tool along with Read more
*Apple* OS X Server Administrator (Active Se...
Apple OS X Server Administrator \(Active Secret Clearance\) Description Come be a part of a top notch team, apply today\!\! Tuva TUVA provides turnkey solutions that Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.