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
$519.01
Apple Inc.
+1.05
MSFT
$40.40
Microsoft Corpora
+0.65
GOOG
$556.54
Google Inc.
+20.10

MacTech Search:
Community Search:

Software Updates via MacUpdate

PDFpenPro 6.2 - Advanced PDF toolkit for...
PDFpenPro allows users to edit PDF's easily. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Create... Read more
PDFpen 6.2 - Edit and annotate PDFs with...
PDFpen allows users to easily edit PDF's. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Features... Read more
Monolingual 1.5.9 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... 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
Starcraft II: Wings of Liberty 1.1.1.180...
Download the patch by launching the Starcraft II game and downloading it through the Battle.net connection within the app. Starcraft II: Wings of Liberty is a strategy game played in real-time. You... Read more
Sibelius 7.5.0 - Music notation solution...
Sibelius is the world's best-selling music notation software for Mac. It is as intuitive to use as a pen, yet so powerful that it does most things in less than the blink of an eye. The demo includes... Read more
Typinator 5.9 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
MYStuff Pro 2.0.16 - Create inventories...
MYStuff Pro is the most flexible way to create detail-rich inventories for your home or small business. Add items to MYStuff by dragging and dropping existing information, uploading new images, or... Read more
TurboTax 2013.r17.002 - Manage your 2013...
TurboTax guides you through your tax return step by step, does all the calculations, and checks your return for errors and overlooked deductions. It lets you file your return electronically to get... Read more
TrailRunner 3.8.769 - Route planning for...
Note: While the software is classified as freeware, it is actually donationware. Please consider making a donation to help support development. TrailRunner is the perfect companion for runners,... Read more

Latest Forum Discussions

See All

Unpossible (Games)
Unpossible 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: **Important** Requires at least iPad 2, iPhone 4S, iPod Touch (5th gen), or newer. | Read more »
Hitman GO (Games)
Hitman GO 1.2 Device: iOS Universal Category: Games Price: $4.99, Version: 1.2 (iTunes) Description: Get your daily fix of Agent 47 with this elegant, strategy-based Hitman game! | Read more »
The Seventh Sign: Hodappy Bird Released...
The Seventh Sign: Hodappy Bird Released on the App Store Posted by Jeff Scott on April 16th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Rogue Heroes (Games)
Rogue Heroes 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Rogue Heroes is awesome fast-paced 2D action-platforming roguelike game with RPG elements. - explore the depth of procedurally... | Read more »
Fourcast Review
Fourcast Review By Jennifer Allen on April 16th, 2014 Our Rating: :: VIDEO POTENTIALiPhone App - Designed for the iPhone, compatible with the iPad Fourcast is a great idea for combining video clips, but it does lack a number of... | Read more »
Hearthstone: Heroes of Warcraft is Avail...
Hearthstone: Heroes of Warcraft is Available on the U.S. App Store Right Now – Gogogogo! Posted by Rob Rich on April 16th, 2014 [ permalink ] | Read more »
Grammar Pop HD Review
Grammar Pop HD Review By Jennifer Allen on April 16th, 2014 Our Rating: :: FUN LEARNINGiPad Only App - Designed for the iPad Learning the different parts of speech isn’t always fun, but Grammar Pop HD makes it much more... | Read more »
Groundskeeper2 Review
Groundskeeper2 Review By Nadia Oxford on April 16th, 2014 Our Rating: :: SLICE THOSE ALIEN SLIMEUniversal App - Designed for iPhone and iPad Putting aside some minor control issues, Groundskeeper2 is a fun and furious action/... | Read more »
Pinnacle Studio for iPhone (Photography...
Pinnacle Studio for iPhone 5.0 Device: iOS iPhone Category: Photography Price: $9.99, Version: 5.0 (iTunes) Description: | Read more »
Season 3 of Zombies, Run! Starts Right N...
Season 3 of Zombies, Run! | Read more »

Price Scanner via MacPrices.net

Microsoft Blinks – Drops Microsoft Office 365...
Microsoft has dropped the annual subscription fee for Microsoft Office 365 Personal – which is needed in order to create and edit documents in Microsoft Office for iPad. However, Apple’s iOS and OS X... Read more
New AVG Vault Apps for iOS and Android Help K...
AVG Technologies N.V. an online security company for 177 million active users, has announced the launch of its latest mobile application, AVG Vault. The free app introduces an innovative user... Read more
Free Local Carrot iPhone App Helps Find Fresh...
I love fresh vegetables. I’m not a vegan, although I was for several years in the 1980s, but fresh vegetables and other whole foods are still my dietary mainstays as a matter of taste rather than... Read more
Apple refurbished iPad Airs available startin...
Apple is now offering Certified Refurbished iPad Airs for up to $140 off MSRP. Apple’s one-year warranty is included with each model, and shipping is free. The following Airs are available today: -... Read more
21-inch 2.7GHz iMac on sale for $1179, save $...
B&H Photo has the 21″ 2.7GHz iMac on sale for $1179 including free shipping plus NY sales tax only. Their price is $120 off MSRP. Add an iMac to your shopping cart, and B&H will offer an... Read more
Download our app, iTracx, for iOS and Android
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
Education discounts shave up to $300 off the...
Purchase a new Mac at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free, and all... Read more
Save $50 on Mac mini Server
B&H Photo has the 2012 Mac mini Server on sale for $949 including free shipping plus NY sales tax only. Their price is $50 off MSRP. Read more
PhatWare’s “Ultimate Writing App For iOS” Ren...
PhatWare Corp. has announced it has renamed its new WritePro word processing app for iPhone and iPad: WritePad Pro. The decision to change the app’s name to leverages the strong brand awareness and... Read more
Full Resolution Photo Editor Tint Mint 1.0 Re...
California based independent developer, Jeffrey Sun, creator of the iOS app Modern Editor, has released Tint Mint, a new photography app for editing enthusiasts. The app costs a dollar, and it packs... Read more

Jobs Board

*Apple* Retail - Manager - Holyoke - Apple I...
Job Summary Keeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you’re a master of them all. In the store’s fast-paced, Read more
*Apple* Retail - Manager - Apple (United Sta...
Job SummaryKeeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you're a master of them all. In the store's fast-paced, dynamic Read more
*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* Retail - Market Leader - Cincinnati...
…challenges of developing individuals, building teams, and affecting growth across Apple Stores. You demonstrate successful leadership ability - focusing on excellence Read more
*Apple* Retail - Manager - SoHo - Apple (Uni...
Job SummaryKeeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you're a master of them all. In the store's fast-paced, dynamic Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.