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 http://cirrus.sprl.umich.edu/waste/. In a perfect world the code looks something like the following.

class TText : public CAbstractText
    // Abstract text supplies all the other methods
 {
 private:
 TPrivateText  *fInternalText;
 public:
 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
 FocusToDraw();
 fInternalText->Activate(true);
 }
 else
 {
 FocusToDraw();
 fInternalText->Activate(false);
 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;
 fInternalText=newText;
 }
 }

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

void TText::Update(RgnHandle updateRgn)
 {
 
 if (RectInRgn(&fBoundingBox, updateRgn))
 {
 FocusToDraw();
 Frame();
 fInternalText->Update(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)
 {
 MoveTo(fPenStart.h,fPenStart.v);
 HLock(fText);   
 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);
 
 WEGetSelection(&oldStart,&oldEnd,fMacWE);
 
 if ((oldEnd-oldStart)<kMaxString) // not too long
 {
 WESetSelection(0,kMaxString,fMacWE);
 
 mode = doFont + doFace + doSize + doColor;
 
 alignment=WEGetAlignment(fMacWE);
 
    // one style
 if ((WEContinuousStyle(&mode, &aStyle, fMacWE)) &&
    // one line
 (WEOffsetToLine(kMaxString, fMacWE)==0) &&  
    // no fancy alignment
 ((alignment== weFlushLeft)
 || (alignment== weFlushDefault))  
 )
 canDo=true;
 
 WESetSelection(oldStart,oldEnd,fMacWE);
 }
else
 return canDo    
 }

Point TStyledText::GetPenStart()
 {
 Point penStart;
 short lineAscent,lineDescent;
 LongRect destRect;
 
 WEGetDestRect(&destRect,fMacWE);  
 
 penStart.h=destRect.left;
 
 _WECalcHeights(0, 1, &lineAscent, &lineDescent, fMacWE);
 
 penStart.v= destRect.top+lineAscent;
 
 return
 penStart
 }

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.

 
AAPL
$108.00
Apple Inc.
+1.02
MSFT
$46.95
Microsoft Corpora
+0.90
GOOG
$559.08
Google Inc.
+8.77

MacTech Search:
Community Search:

Software Updates via MacUpdate

Vitamin-R 2.20b1 - Personal productivity...
Vitamin-R creates the optimal conditions for your brain to work at its best by structuring your work into short bursts of distraction-free, highly focused activity alternating with opportunities for... Read more
Dropbox 2.10.44 - Cloud synchronization...
Dropbox is an application that creates a special Finder folder that automatically syncs online and between your computers. It allows you to both backup files and keep them up-to-date between systems... Read more
Sandvox 2.9.2 - Easily build eye-catchin...
Sandvox is for Mac users who want to create a professional looking website quickly and easily. With Sandvox, you don't need to be a Web genius to build a stylish, feature-rich, standards-compliant... Read more
Cocktail 8.0.1 - General maintenance and...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
LibreOffice 4.3.3.2 - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
VMware Fusion 7.0.1 - Run Windows apps a...
VMware Fusion allows you to create a Virtual Machine on your Mac and run Windows (including Windows 8.1) and Windows software on your Mac. Run your favorite Windows applications alongside Mac... Read more
OneNote 15.3.2 - Free digital notebook f...
OneNote is your very own digital notebook. With OneNote, you can capture that flash of genius, that moment of inspiration, or that list of errands that's too important to forget. Whether you're at... Read more
Audio Hijack Pro 2.11.4 - Record and enh...
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 with Audio Hijack... Read more
Iridient Developer 3.0.0 beta 3 - Powerf...
Iridient Developer (was RAW Developer) is a powerful image conversion application designed specifically for OS X. Iridient Developer gives advanced photographers total control over every aspect of... Read more
TextWrangler 4.5.11 - Free general purpo...
TextWrangler is the powerful general purpose text editor, and Unix and server administrator's tool. Oh, and also, like the best things in life, it's free. TextWrangler is the "little brother" to... Read more

Latest Forum Discussions

See All

Monster Flash Review
Monster Flash Review By Jordan Minor on October 31st, 2014 Our Rating: :: ALONE IN THE DARKUniversal App - Designed for iPhone and iPad Solid shooting and a surprising amount of spooky tension make Monster Flash a great portable... | Read more »
Retry Review
Retry Review By Rob Thomas on October 31st, 2014 Our Rating: :: SOARING HIGHUniversal App - Designed for iPhone and iPad Flappy who? Let Retry wash all those bad bird-related memories away on a cool retro-flavored flight… right... | Read more »
Dementia: Book of the Dead Review
Dementia: Book of the Dead Review By Lee Hamlet on October 31st, 2014 Our Rating: :: A TOUGH READUniversal App - Designed for iPhone and iPad A witch hunter is sent after a demonic book in the spooky but short-lived Dementia: Book... | Read more »
Card Dungeon, the Semi-Board Game Roguel...
Card Dungeon, the Semi-Board Game Roguelike, Has Been Renovated Posted by Jessica Fisher on October 31st, 2014 [ permalink ] | Read more »
Logitech Protection + Power iPhone5/5S C...
Made by: Logitech Price: $99.99 Hardware/iOS Integration Rating: 3 out of 5 stars Usability Rating: 0.5 out of 5 stars Reuse Value Rating: 0.75 out of 5 stars Build Quality Rating: 0.75 out of 5 stars Overall Rating: 1.25 out of 5 stars | Read more »
This Is Not a Test Goes Free, Permanentl...
This Is Not a Test Goes Free, Permanently Posted by Jessica Fisher on October 31st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Swap Heroes Review
Swap Heroes Review By Campbell Bird on October 31st, 2014 Our Rating: :: STRATEGIC SWAPPINGUniversal App - Designed for iPhone and iPad Rotate a cast of heroes to fend of waves of monsters in this difficult, puzzle rpg.   | Read more »
Night Sky Pro™ (Reference)
Night Sky Pro™ 3.0.1 Device: iOS Universal Category: Reference Price: $2.99, Version: 3.0.1 (iTunes) Description: Night Sky Pro™Wonder No More™ Night Sky Pro™ is the ultimate stargazing experience. From the creators of the original... | Read more »
Audio Defence : Zombie Arena (Games)
Audio Defence : Zombie Arena 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: A zombie shooter audio game. Made from gut-wrenching 3D binaural sound, for a new kind of weird immersion. You... | Read more »
RPG Asdivine Hearts (Games)
RPG Asdivine Hearts 1.1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.1.0 (iTunes) Description: SPECIAL PRICE50% OFF (USD 7.99 -> USD 3.99)!!! Travel alongside four companions and a cat in the adventure of a... | Read more »

Price Scanner via MacPrices.net

Apple now offering refurbished 2014 13-inch R...
The Apple Store is now offering Apple Certified Refurbished 2014 13″ Retina MacBook Pros for up to $270 off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
Apple Regains Momentum As Windows Stutters An...
The latest smartphone sales data from Kantar Worldpanel ComTech, for the three months to March 2014, shows Apple performing strongly in the first quarter of the year, with sales bouncing back in... Read more
Worldwide Smartphone Shipments Increase 25.2%...
New smartphone releases and an increased emphasis on emerging markets drove global smartphone shipments above 300 million units for the second consecutive quarter, according to preliminary data from... Read more
Apple now offering refurbished 2014 15-inch M...
The Apple Store is now offering Apple Certified Refurbished 2014 15″ Retina MacBook Pros for up to $400 off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
Apple drops prices on refurbished 2013 Retina...
The Apple Store has dropped prices on 2013 Apple Certified Refurbished 13″ and 15″ Retina MacBook Pros, with Retina models now available starting at $999. Apple’s one-year warranty is standard, and... Read more
New 2.8GHz Mac mini on sale for $949, save $5...
Abt Electronics has the new 2.8GHz Mac mini in stock and on sale for $949.05 including free shipping. Their price is $50 off MSRP, and it’s the lowest price available for this model from any reseller... Read more
Sale! 3.7GHz Quad Core Mac Pro available for...
 B&H Photo has the 3.7GHz Quad Core Mac Pro on sale for $2649 including free shipping plus NY sales tax only. Their price is $350 off MSRP, and it’s the lowest price for this model from any... Read more
Mujjo Steps Up The Game With Refined Touchscr...
Netherlands based Mujjo have just launched their Refined Touchscreen Gloves, stepping up their game. The gloves feature a updated elegant design that takes these knitted gloves to the next level. A... Read more
Sale! Preorder the new 27-inch 5K iMac for $2...
 Abt Electronics has the new 27″ 3.5GHz 5K iMac on sale and available for preorder for $2374.05 including free shipping. Their price is $125 off MSRP, and it’s the lowest price available for this... Read more
Simplex Solutions Inc. Brings Secure Web Surf...
New York based Simplex Solutions Inc. has announced the release and immediate availability of Private Browser 1.0, its revolutionary new secure web browser developed for iPhone, iPad and iPod touch... Read more

Jobs Board

Position Opening at *Apple* - Apple (United...
**Job Summary** Every day, business customers come to the Apple Store to discover what powerful, easy-to-use Apple products can do for them. As a Business Leader, Read more
Sr. Manager, *Apple* Deployment Programs fo...
**Job Summary** Apple is seeking candidates for a new position on the Education Content and Technology team. iPad and Mac is in the hands of millions of teachers and Read more
*Apple* Solutions Consultant (ASC) - Apple I...
…important role that the ASC serves is that of providing an excellent Apple Customer Experience. Responsibilities include: * Promoting Apple products and solutions Read more
*Apple* Solutions Consultant (ASC) - Apple I...
…important role that the ASC serves is that of providing an excellent Apple Customer Experience. Responsibilities include: * Promoting Apple products and solutions Read more
*Apple* Solutions Consultant (ASC) - Apple I...
…important role that the ASC serves is that of providing an excellent Apple Customer Experience. Responsibilities include: * Promoting Apple products and solutions Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.