TweetFollow Us on Twitter

Finder Strings
Volume Number:9
Issue Number:4
Column Tag:Fun Hacks

Related Info: Finder Interface

Rändóm fiNdEr sgnirtS

A cute extension to help you with April Fools Day

By By Mike Scanlin, MacTech Magazine Regular Contributing Author

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

Recently at a friend’s house I saw a clock that ticks backwards. The whole thing looks like a normal clock would when viewed in a mirror. I thought to myself “Not very useful, is it? Kind of difficult to figure out what time it is. What if everything was backwards: newspapers, controls on my car, file names in the Finder... <click> Hey! Cool idea for an April Fool’s INIT.” And, so, here we are.

RandomFinderStrings is an INIT (Extension) that causes one of several effects to happen to each string drawn by the Finder: (1) the case of the letters is forced to be upper, lower, reversed or random, (2) the letters in the string are rearranged back-to-front, (3) all vowels get an accent mark or (4) all vowels are removed. The effect that happens to each string is random. The framework of the code has been set up to make it easy to add your own effects if you can think of a cool way to tweak a Str255 (maybe you could do a conversion to Pig Latin or something) or, you can just use the code as it appears here. You can have some fun if you give this INIT an unsuspecting name like “Easy Access” and put it on a [former?] friend’s Mac.

HOW DOES IT WORK?

The first part of the INIT code creates space for the patch and effects code in the system heap (about 800 bytes) and moves a copy of the code there. Then it installs a head patch on DrawString. The patched DrawString will first check if CurApName == “\pFinder” and that the Option key is not down. If both conditions are true then it will randomly change a copy of the string before calling the real DrawString to draw the string. Note that comment about the Option key. If you really need to see the true strings once this INIT is installed, and you can’t afford to remove it and reboot, you can hold down the Option key and cause the screen to refresh (with a screen saver)-everything will redraw normally (but if you let go of the option key then things begin to get drawn tweaked again).

WHAT DOES IT LOOK LIKE?

Here are some screen shots that show some of the effects this INIT is capable of. Figure 1 shows the System Folder when ACCENTED_VOWELS is on, figure 2 shows the About This Macintosh box when BACKWARDS_LETTERS is on and, figure 3 shows the File menu when DO_CASE_CHANGES is on (the NO_VOWELS option isn’t shown here). You can mix and match these effects until you reach the level of annoyance you desire but you will have to recompile each time you change which effects are on/off. You turn them off by setting their #defined values to 0 and you turn them on by setting their #defined values to 1. If ALWAYS_TWEAK_STRING is off (i.e. zero) then not every string drawn by the Finder will be modified (because of the -1 case in the main switch statement).

Figure 1

Figure 2

Figure 3

Except for maybe the trap patching, this code is pretty easy to understand. The actual effects that tweak the copy of the string are rather simple. One thing to note might be the politically correct way to check if the Option key is down at a time when we don’t have an EventRecord: We make a dummy event record and call OSEventAvail with a mask of zero. This is a much better method than using GetKeys.

Because this is an INIT, the Think C Project Type should be “Code Resource” and the File Type should be “INIT”. You can use whatever you want for the Creator and ID (I used “Twen” with an ID of 55). Have fun.

/*************************************************
 * RandomFinderStrings.c
 *
 * This INIT installs a patch on DrawString that will tweak 
 * strings drawn by the Finder. If CurApName != “/pFinder” 
 * or if the option key is down then a normal DrawString 
 * takes place. If we are in the Finder then a modified 
 * version of the string is drawn: the upper/lower case of 
 * the letters might be changed, the string might be flipped 
 * backwards, all the vowels might get accent marks, etc.
 *
 * You can add to the list of effects by adding an item to 
 * the Effects enum and the main switch statement in 
 * MyDrawString. If your effects need globals, put them in 
 * the PatchGlobals struct and initialize them in main.
 *
 * In Think C, set the Project Type to Code Resource, the 
 * File Type to INIT, the Creator to anything, the Type to 
 * INIT, the ID to something like 55 (55 will work but it
 * doesn’t have to be 55), turn Custom Header ON and Attrs 
 * to 20 (purgeable) and Multi Segment OFF.
 *
 * Mike Scanlin. 24 Jan 1993.
 ***********************************************
 * defines
 ************************************************/
#define _DrawString         0xA884

enum Effects {
    UpperCase = 0,
    LowerCase,
    ReverseCase,
    RandomCase,
    BackwardsLetters,
    AccentedVowels,
    NoVowels,
    PigLatin,
    NumEffects /* must be last */
};

/* Turn these all on for maximum randomness */
#define DO_CASE_CHANGES     1
#define BACKWARDS_LETTERS   1
#define ACCENTED_VOWELS     1
#define NO_VOWELS           1
#define PIG_LATIN           0

#define ALWAYS_TWEAK_STRING 1

#if ALWAYS_TWEAK_STRING && !(DO_CASE_CHANGES || \
    BACKWARDS_LETTERS || ACCENTED_VOWELS || NO_VOWELS)
    not!
    /* Generate a compile time error if you set up an 
     * impossible situation. You need to have at least one 
     * effect enabled if ALWAYS_TWEAK_STRING is enabled. */
#endif

/*************************************************
 * typedefs
 ************************************************/
typedef pascal void (*DSProcPtr)(Str255 *theStringPtr);

typedef struct PatchGlobals {
    DSProcPtr       pgOldDS;
} PatchGlobals, *PatchGlobalsPtr;

/*************************************************
 * prototypes
 ************************************************/
void main(void);
void StartPatchCode(void);
pascal void MyDrawString(Str255 *theStringPtr);
short abs(short n);
void EndPatchCode(void);

/******************** main ***********************
 * Gets some memory in the system heap and installs the 
 * DrawString patch (as well as allocating and initializing 
 * the patch globals).  This is the only routine that gets 
 * executed at startup time (by the INIT mechanism).
 *
 * The block of memory that main allocates will
 * look like this when main has finished:
 *
 *                   +--------------------+
 *                   |    PatchGlobals    |
 *                   +--------------------+
 *                   |  StartPatchCode()  |
 *   DS trap addr -> +--------------------+
 *                   |   MyDrawString()   |
 *                   +--------------------+
 *                   |       abs()        |
 *                   +--------------------+
 *                   |   EndPatchCode()   |
 *                   +--------------------+
 ************************************************/
void main()
{
    Ptr             patchPtr;
    PatchGlobalsPtr pgPtr;
    long            codeSize, offset;
        
    /* try and get some memory in the system heap
     * for code and globals */
    codeSize = (long) EndPatchCode -
        (long) StartPatchCode;
    patchPtr = NewPtrSys(codeSize +
        sizeof(PatchGlobals));
    if (!patchPtr)
        return; /* out of memory-abort patching */
    
    /* initialize the patch globals at the
     * beginning of the block */
    pgPtr = (PatchGlobalsPtr) patchPtr;
    pgPtr->pgOldDS = (DSProcPtr)
        GetTrapAddress(_DrawString);
    
    /* move the code into place after the globals */
    BlockMove(StartPatchCode, patchPtr +
        sizeof(PatchGlobals), codeSize);
    
    /* set the patches */
    patchPtr += sizeof(PatchGlobals);
    offset = (long) MyDrawString -
        (long) StartPatchCode;
    SetTrapAddress((long) patchPtr + offset,
        _DrawString);
}

/***************** StartPatchCode ****************
 * Dummy proc to mark the beginning of the code 
 * for the patches. Make sure all of your patch
 * code is between here and EndPatchCode.
 ************************************************/
void StartPatchCode()
{
}

/*********************** MyDrawString **********************
 * Head patch on DrawString that randomly tweaks the string 
 * to be drawn if the current application is the Finder and 
 * the Option key is not down.
***********************************************************/
pascal void MyDrawString(Str255 *theStringPtr)
{
    Str255          copyOfString;
    EventRecord     theEvent;
    PatchGlobalsPtr pgPtr;
    Byte            *p, *inputPtr;
    short           rand;
    Byte            i, ch;
        
    /* if we’re not in the Finder then exit */
    if (*(char *) &CurApName != 6 ||
      *(long *) ((Ptr) &CurApName + 1) != ‘Find’ ||
      *(short *) ((Ptr) &CurApName + 5) != ‘er’ )
        goto DontDoAnything;
    
    /* if the option key is down then exit */
    OSEventAvail(0, &theEvent);
    if (theEvent.modifiers & optionKey)
        goto DontDoAnything;
    
    /* we’re in the Finder so do something to a
     * copy of the string (unless it’s zero-length) */
    if (i = *(Byte *) theStringPtr) {
        p = (Byte *) &copyOfString;
        BlockMove(theStringPtr, p++, i + 1);

TryAgain:

        switch (abs(Random()) % NumEffects) {
        
#if DO_CASE_CHANGES
        case UpperCase:
            /* force all letters to upper case */
            do {
                if (*p >= ‘a’ && *p <= ‘z’)
                    *p -= ‘a’ - ‘A’;
                p++;
            } while (-i);
            break;
            
        case LowerCase:
            /* force all letters to lower case */
            do {
                if (*p >= ‘A’ && *p <= ‘Z’)
                    *p += ‘a’ - ‘A’;
                p++;
            } while (-i);
            break;
            
        case ReverseCase:
            /* flip the upper/lower case of each letter */
            do {
                if (*p >= ‘a’ && *p <= ‘z’)
                    *p -= ‘a’ - ‘A’;
                else if (*p >= ‘A’ && *p <= ‘Z’)
                    *p += ‘a’ - ‘A’;
                p++;
            } while (-i);
            break;
            
        case RandomCase:
            /* randomly set the case of each letter */
            do {
                /* force to lower case */
                if (*p >= ‘A’ && *p <= ‘Z’)
                    *p += ‘a’ - ‘A’;
                /* make half of them upper case */
                if (*p >= ‘a’ && *p <= ‘z’ && Random() < 0)
                    *p -= ‘a’ - ‘A’;
                p++;
            } while (-i);
            break;
#endif

#if BACKWARDS_LETTERS
        case BackwardsLetters:
            /* flip the string front to back */
            inputPtr = (Byte *) theStringPtr + i;
            do {
                *p++ = *inputPtr;
                inputPtr-;
            } while (-i);
            break;
#endif

#if ACCENTED_VOWELS
        case AccentedVowels:
            /* put an accent mark over each vowel */
            do {
                rand = abs(Random());
                switch (*p) {
                case ‘A’:
                    switch (rand & (4-1)) {
                    case 0: *p = 0x80; break;
                    case 1: *p = 0x81; break;
                    case 2: *p = 0xCB; break;
                    case 3: *p = 0xCC; break;
                    }
                    break;
                case ‘E’:
                    *p = 0x83;
                    break;
                case ‘O’:
                    if (Random() < 0)
                        *p = 0x85;
                    else
                        *p = 0xCD;
                    break;
                case ‘U’:
                    *p = 0x86;
                    break;
                case ‘a’:
                    *p = 0x87 + (rand % 6);
                    break;
                case ‘e’:
                    *p = 0x8E + (rand & (4-1));
                    break;
                case ‘i’:
                    *p = 0x92 + (rand & (4-1));
                    break;
                case ‘o’:
                    *p = 0x97 + (rand % 5);
                    break;
                case ‘u’:
                    *p = 0x9C + (rand & (4-1));
                    break;
                default:
                    break;
                }
                p++;
            } while (-i);
            break;
#endif

#if NO_VOWELS
        case NoVowels:
            /* remove all vowels */
            inputPtr = (Byte *) theStringPtr + 1;
            do {
                ch = *inputPtr;
                if (ch >= ‘A’ && ch <= ‘Z’)
                    ch += ‘a’ - ‘A’;
                if (ch == ‘a’ || ch == ‘e’ || ch == ‘i’
                  || ch == ‘o’ || ch == ‘u’)
                    copyOfString[0]-;
                else
                    *p++ = *inputPtr;
                inputPtr++;
            } while (-i);
            /* make sure the string length is at least 1 */
            if (copyOfString[0] == 0) {
                copyOfString[0] = 1;
                copyOfString[1] = 
 *((Byte *) theStringPtr + 1);
            }
            break;
#endif

#if PIG_LATIN
        case PigLatin:
            /* not implemented */
            break;
#endif

        case -1:                    
        default:
#if ALWAYS_TWEAK_STRING
            goto TryAgain;
#endif
            break;
        }
        
        theStringPtr = &copyOfString;
    }

DontDoAnything:
    
    /* find our globals */
    pgPtr = (PatchGlobalsPtr) ((long) StartPatchCode -
        sizeof(PatchGlobals));

    /* call the real DrawString */
    (*pgPtr->pgOldDS)(theStringPtr);
}

/********************* abs **********************
 * Return the absolute value of n.
 ************************************************/
short
abs(short n)
{
    if (n < 0)
        return (-n);
    return (n);
}


/******************* EndPatchCode ********************
 * Dummy proc to mark the end of the code for
 * the patches. Make sure all of your patch code
 * is between here and StartPatchCode.
 ************************************************/
void EndPatchCode()
{
}

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

How to build a successful civilisation i...
GodFinger 2 grants you godlike powers, leaving you to raise a civilization of followers. In the spirit of games like Black & White, the GodFinger games will see you building bigger and better villages, developing more advanced technology and... | Read more »
How to get all the crabs in Mr Crab 2
Mr. Crab 2 may look like a cutesy platformer for kids, but if you're the kind of person who likes to complete a game 100%, you'll soon realise that it's a tougher than a crustacean's shell. [Read more] | Read more »
How to be a star in Britney Spears: Amer...
If you've ever wanted to be a star, baby, then you've probably already checked out Britney Spears: American Dream and are happily making your way up the charts. But fame doesn't come easy, and everyone needs a helping hand sometimes. So we've got... | Read more »
AppSpy is hiring a part time Staff Write...
| Read more »
How to save lives in ER Surgery Simulato...
A serious earthquake has struck a nearby town in ER Surgery Simulator - Emergency Doctor, and it’s up to you to save the victims. [Read more] | Read more »
Tips and tricks to get a high score in G...
Ketchapp Games loves the endless runner genre. And its newest game, Gravity Switch, is no exception. Gravity Switch takes a fresh approach, though, as you move a block, suspended in zero gravity, safely through a maze of shifting pillars. If the... | Read more »
Tips and tricks to get a high score in S...
Smash Fu is a high-paced tile-tapping game that requires quick reflexes and some practice. You’ll have to smash bricks with the skill of a seasoned black belt to get a high score. To raise the stakes a bit, you’ll also have to avoid tapping any... | Read more »
How to keep the ball rolling in Dropple
If you're new to the minimalist puzzler Dropple, you may find yourself struggling to make it beyond the first couple of steps before your ball falls into the endless abyss below. [Read more] | Read more »
Game Craft releases new Legend of War ti...
Set for release at the end of this month, real time strategy title Legend of War seems sure to delight with a veritable feast of sweet features to get stuck into. Developed by Game Craft, the game is due for release through both the App Store and... | Read more »
How not to die in Traffic Rider
Traffic Rider, an Out Run-esque game in which your ride a motorcycle recklessly into trffic, might not seem particularly complicated. [Read more] | Read more »

Price Scanner via MacPrices.net

Apple refurbished iMacs available for up to $...
Apple has Certified Refurbished 2015 21″ & 27″ iMacs available for up to $350 off MSRP. Apple’s one-year warranty is standard, and shipping is free. The following models are available: - 21″ 3.... Read more
Textkraft Professional Becomes A Mobile Produ...
The new update 4.1 of Textkraft Professional for the iPad comes with many new and updated features that will be particularly of interest to self-publishers of e-books. Highlights include import and... Read more
SnipNotes 2.0 – Intelligent note-taking for i...
Indie software developer Felix Lisczyk has announced the release and immediate availability of SnipNotes 2.0, the next major version of his productivity app for iOS devices and Apple Watch.... Read more
Pitch Clock – The Entrepreneur’s Wingman Laun...
Grand Rapids, Michigan based Skunk Tank has announced the release and immediate availability of Pitch Clock – The Entrepreneur’s Wingman 1.1, the company’s new business app available exclusively on... Read more
13-inch 2.9GHz Retina MacBook Pro on sale for...
B&H Photo has the 13″ 2.9GHz Retina MacBook Pro (model #MF841LL/A) on sale for $1599 including free shipping plus NY tax only. Their price is $200 off MSRP. Amazon also has the 13″ 3.9GHz Retina... Read more
Apple price trackers, updated continuously
Scan our Apple Price Trackers for the latest information on sales, bundles, and availability on systems from Apple’s authorized internet/catalog resellers. We update the trackers continuously: - 15″... Read more
Clearance 12-inch Retina MacBooks available s...
B&H Photo has dropped prices on leftover 2015 12″ Retina MacBooks with models now available starting at $999. Shipping is free, and B&H charges NY tax only: - 12″ 1.1GHz Gray Retina MacBook... Read more
Check Apple prices on any device with the iTr...
MacPrices is proud to offer readers a free iOS app (iPhones, iPads, & iPod touch) and Android app (Google Play and Amazon App Store) called iTracx, which allows you to glance at today’s lowest... Read more
New 2016 13-inch 256GB MacBook Air on sale fo...
B&H Photo has the new 13″ 1.6GHz/256GB MacBook Air (model MMGG2LL/A) on sale for $1149 including free shipping plus NY sales tax only. Their price is $50 off MSRP. Amazon has the 13″ 1.6GHz/256GB... Read more
Apple refurbished iPad Air 2s available start...
Apple has Certified Refurbished iPad Air 2 available starting at $339. Apple’s one-year warranty is included with each model, and shipping is free: - 128GB Wi-Fi iPad Air 2: $499 - 64GB Wi-Fi iPad... Read more

Jobs Board

*Apple* Nissan Service Technicians - Apple A...
Apple Automotive is one of the fastest growing dealer...and it shows. Consider making the switch to the Apple Automotive Group today! At Apple Automotive , Read more
ISCS *Apple* ID Site Support Engineer - APP...
…position, we are looking for an individual who has experience supporting customers with Apple ID issues and enjoys this area of support. This person should be Read more
Automotive Sales Consultant - Apple Ford Linc...
…you. The best candidates are smart, technologically savvy and are customer focused. Apple Ford Lincoln Apple Valley is different, because: $30,000 annual salary Read more
*Apple* Support Technician II - Worldventure...
…global, fast growing member based travel company, is currently sourcing for an Apple Support Technician II to be based in our Plano headquarters. WorldVentures is Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.