TweetFollow Us on Twitter

Mouse in MacApp
Volume Number:6
Issue Number:12
Column Tag:Jörg's Folder

Related Info: Event Manager

MacApp-Tracking the Mouse

By Jörg Langowski, MacTutor Editorial Board

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

As promised, I will show you this month how to add code that handles mouse tracking to our last example. In the code as it was given in V6#11, we had no explicit mouse tracking routine defined; in that case MacApp uses the default routine, which simply draws the rectangle defined by the mouse starting point and the current mouse position. For dragging an object, this default behavior is quite inconvenient, because you don’t see the exact outline of the object being dragged and can’t position it exactly where you want it.

We would like dragged objects to behave like they do in MacDraw, where an outline of the object follows the mouse. How can one implement this?

All the changes we have do to are to the TDragger class. Specifically, we need to define a TrackFeedback method in this class. This method is called by MacApp’s TApplication.TrackMouse routine while it tracks the mouse. You may draw some shape here, which is then ‘dragged around’ with the mouse: TrackMouse will set the pen to patXOR mode before any calls to the feedback routine. When you move the mouse, the shape is first redrawn at the old position (erasing it that way), then drawn at the new position. All this is handled automatically by TrackMouse; you only need to provide the drawing routine.

So all we would have to do is write a TrackFeedback method that draws the shape at the current mouse position, maybe like this:

/* 1 */

pascal void TDragger::TrackFeedback(VPoint *anchorPoint,
 VPoint *nextPoint, Boolean turnItOn, Boolean mouseDidMove)
{
 Point  delta;

 if (mouseDidMove) {
 delta = fTextView->ViewToQDPt(nextPoint);
 SubPt(fTextView->ViewToQDPt(previousPoint), &delta);
 OffsetRect(&fBox->fLocation,delta.h,delta.v);
 fBox->DrawShape();
 }
}

In the call to the routine, anchorPoint and nextPoint are the starting point of the mouse drag and the current mouse position. mouseDidMove is true when the mouse actually did move since the last call to this routine; and turnItOn is a variable that controls whether feedback should be turned on or off; we don’t use it. To draw the shape at the new mouse position, we calculate the difference between the two coordinates (SubPt) and offset the shape rectangle accordingly; then we draw the shape.

This method should work without problems when you add it to last month’s example (try it, and don’t forget to include the method in the class definition in the header file). Since we change the location rectangle of fBox as we go, we may even simplify the code that changes oldLocation and newLocation at the end of the TDragger.TrackMouse routine; fBox->fLocation is already at its final value when the mouse is released.

However, I would like to show you a different way to do the feedback which can later be used in a much more general way, for instance if we want to drag an outline of a group of different shapes, change the aspect of the shape being dragged around, etc. The principle is taken from an example in the excellent book Programming with MacApp by David Wilson, Larry Rosenstein, and Dan Shafer (Addison-Wesley). We call the routines that we want to use for drawing the shape(s) to be dragged only once, when the mouse is first clicked or at its first movement. At that point, we create a picture, calling all the drawing routines, and store its handle in an instance variable. The TrackFeedback routine will then take this picture handle and call DrawPicture with it.

Creation of the picture, and destruction when we’re done with the dragging, is handled by the TrackMouse routine. When this routine is called, one parameter indicated what track phase we are in: whether the mouse button was just pressed (trackPress), is being held down (trackMove), or has just been released (trackRelease).

The track phase tells us what to do (see listing): when we are in trackPress, we create the picture and save its handle; when we are in trackMove, we offset the picture’s bounds rectangle by the distance the mouse has traveled; finally, in trackRelease, we change the shape’s coordinates to the mouse position and dispose of the picture. If we find out that the shape has not been moved at all out of its old position, we return gNoChanges.

Note that the mouse tracking routine does not do any drawing at all; drawing the dragged shape is done by the TrackFeedback routine, and the final draw of the shape at its new position is of course done when the window is updated automatically. Another point to remember is that you have to set the pen state to PenNormal and patXor when you create the picture (see listing). The current pen state is part of the picture information, so when the picture is created, that pen state will be remembered. The pen state in the TrackMouse routine in the trackPress phase is not the one we want; if you don’t set it to patXor yourself, it will be patCopy (I guess) when the picture is drawn by the feedback routine. That means you will create copies of your shape all over the screen when you drag it. Try it out.

Final words

This was a short Christmas column; next time will be longer, because we’ll add code for different shapes and for dragging a selection of shapes. Also, it might be that my test copy of MacFortran II comes in until then, so that we can finally see those comprehensive benchmarks. Absoft, I want my M F Two...

Listing 1: Changes to the V6#9 example to support track feedback

// Dragging support with custom mouse track feedback
// © JL/MT 10/90
pascal void 
 TDragger::IDragger(TBox *itsBox, 
 TTEDocument *itsDocument, TTextView *itsView)
{
 TScroller *aScroller;

 aScroller = itsView->GetScroller(true);
 ICommand(cDragBox, itsDocument, itsView, aScroller);
 fTEDocument = itsDocument;
 fTextView = itsView;
 fBox = itsBox;
 oldLocation = fBox->fLocation;
 newLocation = fBox->fLocation;
}

pascal struct TCommand 
 *TDragger::TrackMouse(TrackPhase aTrackPhase,
 VPoint *anchorPoint, VPoint *previousPoint, 
 VPoint *nextPoint, Boolean mouseDidMove)
{
 Point  delta;
 Rect   r;
 RgnHandleoldClip;
 PenState oldState;
 
 if (aTrackPhase == trackPress) {
 r = fBox->fLocation;
 oldClip = MakeNewRgn();  // MacApp routine
 
// get the old environment for later restore
 GetClip(oldClip);
 GetPenState(&oldState);
// and open a new picture
 fFeedbackPicture = OpenPicture(&r);
 FailNIL(fFeedbackPicture); // be safe
 ClipRect(&r);
// the following lines ARE necessary since the picture 
// remembers the pen state that was in effect when this 
// routine was called.
// Since we are in trackPress, the pen has NOT yet been 
// set to patXOR. Comment out the next two lines, 
// you’ll see interesting effects -- JL
 PenNormal();
 PenMode(patXor);
// draw the shape
 fBox->DrawShape();
 ClosePicture();
 fPictureBounds = r;

// restore old environment
 SetClip(oldClip);
 DisposeRgn(oldClip);
 SetPenState(&oldState);
 
 if (EmptyRect(&(*fFeedbackPicture)->picFrame)) {
 KillPicture(fFeedbackPicture);
 fFeedbackPicture = nil;
 FailNIL(fFeedbackPicture);
 }
 }

 if ((aTrackPhase == trackMove) && mouseDidMove) {
 delta = fTextView->ViewToQDPt(nextPoint);
 SubPt(fTextView->ViewToQDPt(previousPoint), &delta);
// we don’t actually move the shape here, only its picture.
// the move is done in the last phase
 OffsetRect(&fPictureBounds,delta.h,delta.v);
 }

 if ((aTrackPhase == trackRelease) && mouseDidMove) {
 if (fFeedbackPicture != nil)  {
// being paranoid: normally we should never get here if the 
// picture couldn’t be created, but who knows
 KillPicture(fFeedbackPicture);
 fFeedbackPicture = nil; }

 delta = fTextView->ViewToQDPt(nextPoint);
 SubPt(fTextView->ViewToQDPt(anchorPoint), &delta);
 newLocation = oldLocation;
 if ((delta.h == 0) && (delta.v == 0))
 { return gNoChanges;}
// if we get here, something has been changed. 
// move the shape to its new location
 OffsetRect(&newLocation,delta.h,delta.v);
 fBox->fLocation = newLocation;    
 }
 return this;
}

pascal void 
 TDragger::TrackFeedback(VPoint *anchorPoint, 
 VPoint *nextPoint,
 Boolean turnItOn, Boolean mouseDidMove)
{
 Rect r;
 
 if (mouseDidMove && (fFeedbackPicture != nil)) {
 r = fPictureBounds;
 DrawPicture(fFeedbackPicture,&r); // that’s all!! 
 }
}

pascal void TDragger::DoIt()
{
 fTextView->InvalidRect(&newLocation);
 fTextView->InvalidRect(&oldLocation);
}

pascal void TDragger::RedoIt()  
{  
 fBox->fLocation = newLocation;
 DoIt(); 
}

pascal void TDragger::UndoIt()
{
 fBox->fLocation = oldLocation;
 DoIt(); 
}

#ifdef qDebug
pascal void TDragger::Fields(pascal void (*DoToField) 
 (StringPtr fieldName, Ptr fieldAddr, short fieldType, 
 void *link), void *link)
{
 DoToField(“\pTDragger”, nil, bClass, link);
 DoToField(“\pfTEDocument”, 
 (Ptr) &fTEDocument, bObject, link);
 DoToField(“\pfTextView”, 
 (Ptr) &fTextView, bObject, link);
 DoToField(“\pfBox”, (Ptr) &fBox, bObject, link);
 DoToField(“\poldLocation”, 
 (Ptr) &oldLocation, bRect, link);
 DoToField(“\pnewLocation”, 
 (Ptr) &newLocation, bRect, link);
 DoToField(“\pfFeedbackPicture”, 
 (Ptr) &fFeedbackPicture, bHandle, link);
 DoToField(“\pfPictureBounds”, 
 (Ptr) &fPictureBounds, bRect, link);
 inherited::Fields(DoToField, link);
}
#endif

 
AAPL
$97.67
Apple Inc.
+0.64
MSFT
$44.50
Microsoft Corpora
+0.10
GOOG
$589.02
Google Inc.
-4.33

MacTech Search:
Community Search:

Software Updates via MacUpdate

Vienna 3.0.0 RC 2 :be5265e: - RSS and At...
Vienna is a freeware and Open-Source RSS/Atom newsreader with article storage and management via a SQLite database, written in Objective-C and Cocoa, for the OS X operating system. It provides... Read more
VLC Media Player 2.1.5 - Popular multime...
VLC Media Player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, MP3, OGG, ...) as well as DVDs, VCDs, and various streaming protocols. It... Read more
Default Folder X 4.6.7 - Enhances Open a...
Default Folder X attaches a toolbar to the right side of the Open and Save dialogs in any OS X-native application. The toolbar gives you fast access to various folders and commands. You just click... Read more
TinkerTool 5.3 - Expanded preference set...
TinkerTool is an application that gives you access to additional preference settings Apple has built into Mac OS X. This allows to activate hidden features in the operating system and in some of the... Read more
Audio Hijack Pro 2.11.0 - 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
Intermission 1.1.1 - Pause and rewind li...
Intermission allows you to pause and rewind live audio from any application on your Mac. Intermission will buffer up to 3 hours of audio, allowing users to skip through any assortment of audio... Read more
Autopano Giga 3.6 - Stitch multiple imag...
Autopano Giga allows you to stitch 2, 20, or 2,000 images. Version 3.0 integrates impressive new features that will definitely make you adopt Autopano Pro or Autopano Giga: Choose between 9... Read more
Airfoil 4.8.7 - 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
Microsoft Remote Desktop 8.0.8 - Connect...
With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more
xACT 2.30 - Audio compression toolkit. (...
xACT stands for X Aaudio Compression Toolkit, an application that encodes and decodes FLAC, SHN, Monkey’s Audio, TTA, Wavpack, and Apple Lossless files. It also can encode these formats to MP3, AAC... Read more

Latest Forum Discussions

See All

This Week at 148Apps: July 21-25, 2014
Another Week of Expert App Reviews   At 148Apps, we help you sort through the great ocean of apps to find the ones we think you’ll like and the ones you’ll need. Our top picks become Editor’s Choice, our stamp of approval for apps with that little... | Read more »
Reddme for iPhone - The Reddit Client (...
Reddme for iPhone - The Reddit Client 1.0 Device: iOS iPhone Category: News Price: $.99, Version: 1.0 (iTunes) Description: Reddme for iPhone is an iOS 7-optimized Reddit client that offers a refreshing new way to experience Reddit... | Read more »
Jacob Jones and the Bigfoot Mystery : Ep...
Jacob Jones and the Bigfoot Mystery : Episode 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Jacob Jones is back in Episode 2 of one of Apples 'Best of 2013' games and an App Store... | Read more »
New Trailer For Outcast Odyssey, A New K...
New Trailer For Outcast Odyssey, A New Kind of Card Battler Posted by Jennifer Allen on July 25th, 2014 [ permalink ] Out this Fall is a new kind of card battle game: Outcast Odyssey. | Read more »
Hay Day – Tip, Tricks, Strategies, and C...
Recently got into Supercell’s other huge hit, Hay Day and could do with some advice on what to do? We’ve got you covered with some helpful trips and tricks to bear in mind! Ticking Along One of the key things to keep in mind while building up that... | Read more »
Monster Head Review
Monster Head Review By Nadia Oxford on July 25th, 2014 Our Rating: :: FEEDING TIMEUniversal App - Designed for iPhone and iPad Racking up a high score with Monster Head is trickier than it first appears. The appeal wears out fairly... | Read more »
Garfield: Survival of the Fattest Coming...
Garfield: Survival of the Fattest Coming to iOS this Fall Posted by Jennifer Allen on July 25th, 2014 [ permalink ] Who loves lasagna? Me. Also everyone’s favorite grumpy fat cat, Garfield. | Read more »
Happy Flock Review
Happy Flock Review By Andrew Fisher on July 25th, 2014 Our Rating: :: HERD IT ALL BEFOREUniversal App - Designed for iPhone and iPad Underneath the gloss of Happy Flock’s visuals is a game of very little substance. It’s cute, but... | Read more »
Square Register Updates Adds Offline Pay...
Square Register Updates Adds Offline Payments Posted by Ellis Spice on July 25th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Looking For Group – Hearthstone’s Curse...
For the first time since its release (which has thankfully been a much shorter window for iPad players than their PC counterparts), Blizzard’s wildly successful Hearthstone: Heroes of Warcraft CCG is sporting some brand new content: the single... | Read more »

Price Scanner via MacPrices.net

Apple’s 2014 Back to School promotion: $100 g...
 Apple’s 2014 Back to School promotion includes a free $100 App Store Gift Card with the purchase of any new Mac (Mac mini excluded), or a $50 Gift Card with the purchase of an iPad or iPhone,... Read more
iMacs on sale for $150 off MSRP, $250 off for...
Best Buy has iMacs on sale for up to $160 off MSRP for a limited time. Choose free home shipping or free instant local store pickup (if available). Prices are valid for online orders only, in-store... Read more
Mac minis on sale for $100 off MSRP, starting...
Best Buy has Mac minis on sale for $100 off MSRP. Choose free shipping or free instant local store pickup. Prices are for online orders only, in-store prices may vary: 2.5GHz Mac mini: $499.99 2.3GHz... Read more
Global Tablet Market Grows 11% in Q2/14 Notwi...
Worldwide tablet sales grew 11.0 percent year over year in the second quarter of 2014, with shipments reaching 49.3 million units according to preliminary data from the International Data Corporation... Read more
New iPhone 6 Models to Have Staggered Release...
Digitimes’ Cage Chao and Steve Shen report that according to unnamed sources in Apple’s upstream iPhone supply chain, the new 5.5-inch iPhone will be released several months later than the new 4.7-... Read more
New iOS App Helps People Feel Good About thei...
Mobile shoppers looking for big savings at their favorite stores can turn to the Goodshop app, a new iOS app with the latest coupons and deals at more than 5,000 online stores. In addition to being a... Read more
Save on 5th generation refurbished iPod touch...
The Apple Store has Apple Certified Refurbished 5th generation iPod touches available starting at $149. Apple’s one-year warranty is included with each model, and shipping is free. Many, but not all... Read more
What Should Apple’s Next MacBook Priority Be;...
Stabley Times’ Phil Moore says that after expanding its iMac lineup with a new low end model, Apple’s next Mac hardware decision will be how it wants to approach expanding its MacBook lineup as well... Read more
ArtRage For iPhone Painting App Free During C...
ArtRage for iPhone is currently being offered for free (regularly $1.99) during Comic-Con San Diego #SDCC, July 24-27, in celebration of the upcoming ArtRage 4.5 and other 64-bit versions of the... Read more
With The Apple/IBM Alliance, Is The iPad Now...
Almost since the iPad was rolled out in 2010, and especially after Apple made a 128 GB storage configuration available in 2012, there’s been debate over whether the iPad is a serious tool for... Read more

Jobs Board

*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
WW Sales Program Manager, *Apple* Online St...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
Lead Software Engineer, *Apple* Online Stor...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
Manager, *Apple* Fullfillment Operation (AF...
…cross-functional teams to drive the highest level of program management quality for Apple . You will help plan launch strategy and demand generation programs with Read more
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.