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
$116.47
Apple Inc.
+0.16
MSFT
$47.98
Microsoft Corpora
-0.72
GOOG
$537.50
Google Inc.
+2.67

MacTech Search:
Community Search:

Software Updates via MacUpdate

Cobook 3.0.7 - Intelligent address book....
Cobook Contacts is an intuitive, engaging address book. Solve the problem of contact management with Cobook Contacts and its simple interface and powerful syncing and integration possibilities.... Read more
StatsBar 1.9 - Monitor system processes...
StatsBar gives you a comprehensive and detailed analysis of the following areas of your Mac: CPU usage Memory usage Disk usage Network and bandwidth usage Battery power and health (MacBooks only)... Read more
Cyberduck 4.6 - FTP and SFTP browser. (F...
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Evernote 6.0.1 - 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
calibre 2.11 - Complete e-library manage...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital... Read more
Herald 5.0.1 - Notification plugin for M...
Note: Versions 2.1.3 (for OS X 10.7), 3.0.6 (for OS X 10.8), and 4.0.8 (for OS X 10.9) are no longer supported by the developer. Herald is a notification plugin for Mail.app, Apple's Mac OS X email... Read more
Firetask 3.7 - Innovative task managemen...
Firetask uniquely combines the advantages of classical priority-and-due-date-based task management with GTD. Stay focused and on top of your commitments - Firetask's "Today" view shows all relevant... Read more
TechTool Pro 7.0.6 - Hard drive and syst...
TechTool Pro is now 7, and this is the most advanced version of the acclaimed Macintosh troubleshooting utility created in its 20-year history. Micromat has redeveloped TechTool Pro 7 to be fully 64... Read more
PhotoDesk 3.0.1 - Instagram client for p...
PhotoDesk lets you view, like, comment, and download Instagram pictures/videos! (NO Uploads! / Image Posting! Instagram forbids that! AND you *need* an *existing* Instagram account). But you can do... Read more

Latest Forum Discussions

See All

Ubisoft Gives Everyone Two New Ways to E...
Ubisoft Gives Everyone Two New Ways to Earn In-Game Stuff for Far Cry 4 Posted by Jessica Fisher on November 21st, 2014 [ permalink ] | Read more »
Golfinity – Tips, Tricks, Strategies, an...
Dig this: Would you like to know what we thought of being an infinite golfer? Check out our Golfinity review! Golfinity offers unlimited ways to test your skills at golf. Here are a few ways to make sure your score doesn’t get too high and your... | Read more »
Dark Hearts, The Sequel to Haunting Meli...
Dark Hearts, The Sequel to Haunting Melissa, is Available Now Posted by Jessica Fisher on November 21st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Meowza! Toyze Brings Talking Tom to Life...
Meowza! | Read more »
Square Enix Announces New Tactical RPG f...
Square Enix Announces New Tactical RPG for Mobile, Heavenstrike Rivals. Posted by Jessica Fisher on November 21st, 2014 [ permalink ] With their epic stories and gorgeous graphics, | Read more »
Quest for Revenge (Games)
Quest for Revenge 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: The great Kingdom of the west has fallen. The gods ignore the prayers of the desperate. A dark warlord has extinguished... | Read more »
Threadz is a New Writing Adventure for Y...
Threadz is a New Writing Adventure for You and Your Friends Posted by Jessica Fisher on November 21st, 2014 [ permalink ] In the tradition of round-robin storytelling, | Read more »
SteelSeries Stratus XL Hardware Review
Made by: SteelSeries Price: $59.99 Hardware/iOS Integration Rating: 4 out of 5 stars Usability Rating: 4.5 out of 5 stars Reuse Value Rating: 4.25 out of 5 stars Build Quality Rating: 4.5 out of 5 stars Overall Rating: 4.31 out of 5 stars | Read more »
ACDSee (Photography)
ACDSee 1.0.0 Device: iOS iPhone Category: Photography Price: $1.99, Version: 1.0.0 (iTunes) Description: Capture, perfect, and share your photos with ACDSee. The ACDSee iPhone app combines an innovative camera, a powerful photo... | Read more »
ProTube for YouTube (Entertainment)
ProTube for YouTube 2.0.2 Device: iOS Universal Category: Entertainment Price: $1.99, Version: 2.0.2 (iTunes) Description: ProTube is the ultimate, fully featured YouTube app. With it's highly polished design, ProTube offers ad-free... | Read more »

Price Scanner via MacPrices.net

CEA Study Finds More People Recycling Electro...
A new study by the Consumer Electronics Association (CEA) finds that electronics recycling receives the continued and growing support of consumers. According to the CEA,s Recycling and Reuse Study,... Read more
15″ 2.2GHz Retina MacBook Pro on sale for $17...
 B&H Photo has the 2014 15″ 2.2GHz Retina MacBook Pro on sale today for $1749. Shipping is free, and B&H charges NY sales tax only. B&H will also include free copies of Parallels Desktop... Read more
27-inch 3.5GHz 5K iMac in stock today and on...
 B&H Photo has the new 27″ 3.5GHz 5K iMac in stock today and on sale for $2299 including free shipping plus NY sales tax only. Their price is $200 off MSRP, and it’s the lowest price available... Read more
21-inch 1.4GHz iMac on sale for $979, save $1...
B&H Photo has the new 21″ 1.4GHz iMac on sale for $979.99 including free shipping plus NY sales tax only. Their price is $120 off MSRP. B&H will also include free copies of Parallels Desktop... Read more
13-inch 1.4GHz/256GB MacBook Air on sale for...
B&H Photo has lowered their price on the 13″ 1.4GHz/256GB MacBook Air to $1059.99 including free shipping plus NY sales tax only. Their price is $140 off MSRP, and it’s the lowest price for this... Read more
Save up to $400 with Apple refurbished 2014 1...
The Apple Store has restocked 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 shipping... Read more
New 13-inch 1.4GHz MacBook Air on sale for $8...
 Adorama has the 2014 13″ 1.4GHz/128GB MacBook Air on sale for $899.99 including free shipping plus NY & NJ tax only. Their price is $100 off MSRP. B&H Photo has the 13″ 1.4GHz/128GB MacBook... Read more
Apple Expected to Reverse Nine-Month Tablet S...
Apple and Samsung combined accounted for 62 percent of the nearly 36 million branded tablets shipped in 3Q 2014, according to early vendor shipment share estimates from market intelligence firm ABI... Read more
Stratos: 30 Percent of US Smartphone Owners t...
Stratos, Inc., creator of the Bluetooth Connected Card Platform, has announced results from its 2014 Holiday Mobile Payments Survey. The consumer survey found that nearly one out of three (30 percent... Read more
2014 1.4GHz Mac mini on sale for $449, save $...
 B&H Photo has lowered their price on the new 1.4GHz Mac mini to $449.99 including free shipping plus NY tax only. Their price is $50 off MSRP, and it’s the lowest price available for this new... 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
*Apple* Solutions Consultant (ASC)- Retail S...
**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
Project Manager, *Apple* Financial Services...
**Job Summary** Apple Financial Services (AFS) offers consumers, businesses and educational institutions ways to finance Apple purchases. We work with national and Read more
*Apple* Store Leader Program - College Gradu...
Job Description: Job Summary As an Apple Store Leader Program agent, you can continue your education as you major in the art of leadership at the Apple Store. You'll Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.