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.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

TotalFinder 1.12.2 - Adds tabs, hotkeys,...
TotalFinder is a universally acclaimed navigational companion for your Mac. Enhance your Mac's Finder with features so smart and convenient, you won't believe you ever lived without them. Features... Read more
Duet 2.3.0.3 - Use your iPad as an exter...
Duet is the first app that allows you to use your iDevice as an extra display for your Mac using the Lightning or 30-pin cable. Note: This app requires a $9.99 iOS companion app. Version 2.3.0.3:... Read more
FileMaker Pro Advanced 18.0.3 - Powerful...
FileMaker Pro Advanced is the tool you use to create a custom app. You also use FileMaker Pro Advanced to access your app on a computer. Start by importing data from a spreadsheet or using a built-in... Read more
OsiriX Lite 10.0.6 - 3D medical image pr...
OsiriX Lite is an image processing software dedicated to DICOM images (".dcm" / ".DCM" extension) produced by medical equipment (MRI, CT, PET, PET-CT, ...) and confocal microscopy (LSM and BioRAD-PIC... Read more
Ableton Live 10.1.5 - Record music using...
Ableton Live lets you create and record music on your Mac. Use digital instruments, pre-recorded sounds, and sampled loops to arrange, produce, and perform your music like never before. Ableton Live... Read more
Burn 2.7.8 - Easily burn data, audio, vi...
Burn... There are a lot of ways to approach burning discs. Burn keeps it simple, but still offers a lot of advanced options. Create data discs with advanced data settings like, file permissions, the... Read more
Malwarebytes 4.0.30.3073 - 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
Acorn 6.5.3 - Bitmap image editor.
Acorn is a new image editor built with one goal in mind - simplicity. Fast, easy, and fluid, Acorn provides the options you'll need without any overhead. Acorn feels right, and won't drain your bank... Read more
Fantastical 2.5.13 - Create calendar eve...
Fantastical is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event... Read more
A Better Finder Rename 11.05 - File, pho...
A Better Finder Rename is the most complete renaming solution available on the market today. That's why, since 1996, tens of thousands of hobbyists, professionals and businesses depend on A Better... Read more

Latest Forum Discussions

See All

Eternal Warfare is a new idle clicker fo...
Idle games are a popular genre on mobile, they might not be to everyone's taste but they're made with such regularity and receive a lot of downloads, so it's hard to argue it's not big business. Eternal Warfare is set to join the sea of idle games... | Read more »
New heroes and balance updates set to ar...
It feels like Hearthstone: Battlegrounds only launched yesterday, and already the auto batter addition to Blizzard's megahit card game is set to receive new heroes and balance updates. [Read more] | Read more »
Pre-register for Hello Kitty AR: Kawaii...
Hello Kitty — the cute cat that launched a multi-billion-pound franchise — has been brought to life… sort of. Sanrio has teamed up with the Bublar Group to create a new mobile game that uses AR tech to turn the real world into Hello Kitty’s... | Read more »
Gorgeous and tranquil puzzler Spring Fal...
One-man indie studio SPARSE//GameDev has now launched its tranquil puzzler, Spring Falls. It's described as "a peaceful puzzle game about water, erosion, and watching things grow". [Read more] | Read more »
Black Desert Mobile gets an official rel...
Pearl Abyss has just announced that its highly-anticipated MMO, Black Desert Mobile, will launch globally for iOS and Android on December 11th. [Read more] | Read more »
Another Eden receives new a episode, cha...
Another Eden, WFS' popular RPG, has received another update that brings new story content to the game alongside a few new heroes to discover. [Read more] | Read more »
Overdox guide - Tips and tricks for begi...
Overdox is a clever battle royale that changes things up by adding MOBA mechanics and melee combat to the mix. This new hybrid game can be quite a bit to take in at first, so we’ve put together a list of tips to help you get a leg up on the... | Read more »
Roterra Extreme - Great Escape is a pers...
Roterra Extreme – Great Escape has been described by developers Dig-It Games as a mini-sequel to their acclaimed title Roterra: Flip the Fairytale. It continues that game's tradition of messing with which way is up, tasking you with solving... | Read more »
Hearthstone: Battlegrounds open beta lau...
Remember earlier this year when auto battlers were the latest hotness? We had Auto Chess, DOTA Underlords, Chess Rush, and more all gunning for our attention. They all had their own reasons to play, but, at least from where I'm standing, most... | Read more »
The House of Da Vinci 2 gets a new gamep...
The House of Da Vinci launched all the way back in 2017. Now, developer Blue Brain Games is gearing up to deliver a second dose of The Room-inspired puzzling. Some fresh details have now emerged, alongside the game's first official trailer. [Read... | Read more »

Price Scanner via MacPrices.net

B&H offers $100 discounts on 4-Core and 6...
B&H Photo has new 4-Core and 6-Core Mac minis in stock and on sale today for $100 off Apple’s MSRP. Prices start at $699. Overnight shipping is free to many addresses in the US: – 3.6GHz Quad-... Read more
Save $200 today on a 2019 13″ MacBook Air wit...
Apple has a full line of Certified Refurbished 2019 13″ MacBook Airs available starting at only $929 and up to $200 off the cost of new Airs. Each MacBook features a new outer case, comes with a... Read more
New Verizon Pre-Black Friday 2019 deal: Buy o...
Buy one new Apple iPhone 11 model or 2018 iPhone XS model at Verizon and get a second one for free. One new line of service required. Offer is valid from November 21, 2019 to November 27, 2019. Here... Read more
AirPods with Wireless Charging Case on sale t...
Abt Electronics has 2019 AirPods with the Wireless Charging Case on sale today for $163 shipped. Their price is $36 off Apple’s MSRP, and it’s currently the cheapest price for these AirPods from any... Read more
Apple continues to offer 2017 13″ Dual-Core n...
Apple has Certified Refurbished 2017 13″ 2.3GHz Dual-Core non-Touch Bar MacBook Pros still available starting at $1019. An standard Apple one-year warranty is included with each model, outer cases... Read more
Save up to $120 on the new 16″ MacBook Pro at...
Apple’s resellers are starting to receive stock of new 16″ MacBook Pros, and the first set of sales & deals are now available: (1) Amazon 16″ MacBook Pros start on sale for $100-$116 off Apple’s... Read more
Apple Watch Series 3 models on sale at Amazon...
Amazon has Apple Watch Series 3 GPS models on sale for $30 off MSRP, starting at only $169. There prices are the lowest we’ve ever seen for these models from any Apple reseller. Choose Amazon as the... Read more
The ‘Mac Potpourri’ Mailbag: Edition #1- Info...
COMMENTARY: 11.20.19- Welcome to the inaugural edition of the “Mac Potpourri” Mailbag where we take a look at correspondence received from readers of this column from all over the world who write in... Read more
13″ 2.4GHz MacBook Pros available for up to $...
Apple has a full line of Certified Refurbished 2019 13″ 2.4GHz 4-Core Touch Bar MacBook Pros available starting at $1529 and up to $300 off MSRP. Apple’s one-year warranty is included, shipping is... Read more
New at T-Mobile: Switch to T-Mobile, and get...
T-Mobile is offering a free 64GB iPhone 8 for new customers who switch to T-Mobile and open a new line of service. Eligible trade-in required, and discount applied over a 24 month period. The fine... Read more

Jobs Board

Best Buy *Apple* Computing Master - Best Bu...
**747303BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Sales **Store NUmber or Department:** 001413-Cypress-Store **Job Description:** **What Read more
*Apple* Mobility Pro - Best Buy (United Stat...
**743221BR** **Job Title:** Apple Mobility Pro **Job Category:** Store Associates **Store NUmber or Department:** 000230-Greenwood-Store **Job Description:** At Best Read more
*Apple* Mobility Pro - Best Buy (United Stat...
**747338BR** **Job Title:** Apple Mobility Pro **Job Category:** Store Associates **Store NUmber or Department:** 000254-Superstition Springs-Store **Job Read more
Best Buy *Apple* Computing Master - Best Bu...
**745516BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Store Associates **Store NUmber or Department:** 001101-Manhattan-Store **Job Read more
Best Buy *Apple* Computing Master - Best Bu...
**746655BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Sales **Store NUmber or Department:** 002518-Atlantic Center-Store **Job Description:** Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.