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

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Arq 5.7.2 - Online backup to Google Driv...
Arq is super-easy online backup for Mac and Windows computers. Back up to your own cloud account (Amazon Cloud Drive, Google Drive, Dropbox, OneDrive, Google Cloud Storage, any S3-compatible server... Read more
Spotify 1.0.47.13. - Stream music, creat...
Spotify is a streaming music service that gives you on-demand access to millions of songs. Whether you like driving rock, silky R&B, or grandiose classical music, Spotify's massive catalogue puts... Read more
Together 3.7.3 - Store and organize all...
Together helps you organize your Mac, giving you the ability to store, edit and preview your files in a single clean, uncluttered interface. Features Smart storage. With simple drag-and-drop... Read more
Cocktail 10.2 - General maintenance and...
Cocktail is a general purpose utility for macOS that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Sierra Cache Cleaner 11.0.3 - Clear cach...
Sierra Cache Cleaner is an award-winning general purpose tool for macOS X. SCC makes system maintenance simple with an easy point-and-click interface to many macOS X functions. Novice and expert... Read more
NeoFinder 7.0.1 - Catalog your external...
NeoFinder (formerly CDFinder) rapidly organizes your data, either on external or internal disks, or any other volumes. It catalogs all your data, so you stay in control of your data archive or disk... Read more
Sketch 42 - Design app for UX/UI designe...
Sketch is an innovative and fresh look at vector drawing for the Mac. Its intentionally minimalist design is based upon a drawing space of unlimited size and layers, free of palettes, panels, menus,... Read more
Quicken 4.4.3 - Complete personal financ...
Quicken makes managing your money easier than ever. Whether paying bills, upgrading from Windows, enjoying more reliable downloads, or getting expert product help, Quicken's new and improved features... Read more
Apple Safari 10.0.3 - Apple's Web b...
Note: The direct download link is currently unavailable. It is available in the OS X 10.11.6 release, as well as in the Apple Security Updates. Apple Safari is Apple's web browser that comes with OS... Read more
Apple iTunes 12.5.5 - Play Apple Music a...
Apple iTunes lets you organize and stream Apple Music, download and watch video and listen to Podcasts. It can automatically download new music, app, and book purchases across all your devices and... Read more

Clash Royale gets some serious balance u...
| Read more »
Ironhide Game Studio prepares for a busy...
Kingdom Rush breathed fresh life into the tired tower defense genre way back in 2012. The game was a robust challenge that somehow managed to lift you up, rather than leaving you feeling crushed and hopeless. The rich array of unit types and... | Read more »
Collect pets and sling arrows in Arcane...
Mobile gaming is a crowded market, but regular updates are a good way to keep us attention-short players keen. The brand new content in Arcane Online is a prime example. Published by Japanese developer Gala, Arcane Online is a fantasy MMO that... | Read more »
Super Mario Run dashes onto Android in M...
Super Mario Run was one of the biggest mobile launches in 2016 before it was met with a lukewarm response by many. While the game itself plays a treat, it's pretty hard to swallow the steep price for the full game. With that said, Android users... | Read more »
WarFriends Beginner's Guide: How to...
Chillingo's new game, WarFriends, is finally available world wide, and so far it's a refreshing change from common mobile game trends. The game's a mix of tower defense, third person shooter, and collectible card game. There's a lot to unpack here... | Read more »
Super Gridland (Entertainment)
Super Gridland 1.0 Device: iOS Universal Category: Entertainment Price: $1.99, Version: 1.0 (iTunes) Description: Match. Build. Survive. "exquisitely tuned" - Rock Paper Shotgun No in-app purches, and no ads! | Read more »
Red's Kingdom (Games)
Red's Kingdom 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Mad King Mac has kidnapped your father and stolen your golden nut! Solve puzzles and battle goons as you explore and battle your... | Read more »
Turbo League Guide: How to tame the cont...
| Read more »
Fire Emblem: Heroes coming to Google Pla...
Nintendo gave us our first look at Fire Emblem: Heroes, the upcoming mobile Fire Emblem game the company hinted at last year. Revealed at the Fire Emblem Direct event held today, the game will condense the series' tactical RPG combat into bite-... | Read more »
ReSlice (Music)
ReSlice 1.0 Device: iOS Universal Category: Music Price: $9.99, Version: 1.0 (iTunes) Description: Audio Slice Machine Slice your audio samples with ReSlice and create flexible musical atoms which can be triggered by MIDI notes or... | Read more »

Price Scanner via MacPrices.net

HDRtist NX 1.0 For macOS Next Generation HDR...
Ohanaware Co., Ltd. have announced the immediate release of their latest High Dynamic Range Imaging software “HDRtist NX”. HDRtist NX is the third installment in the HDRtist series of applications... Read more
Built To Last Maverick Leather Laptop Messeng...
Wild West melds with modern in San Francisco designer-manufacturer of custom laptop sleeves, bags and cases WaterField Designs’ new Maverick Leather Laptop Messenger. This luxury laptop bag blends... Read more
Logitech Sets Company Record With 15 GOOD DES...
Logitech has announced that it has won 15 GOOD DESIGN 2016 awards. This marks the sixth consecutive year Logitech products have been recognized by the GOOD DESIGN awards, and the most award wins for... Read more
13-inch Touch Bar MacBook Pros in stock for $...
B&H Photo has the new 2016 13″ Touch Bar MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.9GHz/512GB Touch Bar... Read more
9-inch 32GB Space Gray iPad Pro on sale for $...
B&H Photo has the 9.7″ 32GB Space Gray Apple iPad Pro on sale for $549 for a limited time. Shipping is free, and B&H charges NY sales tax only. Read more
15-inch 2.2GHz Retina MacBook Pro on sale for...
Amazon has 2015 15″ 2.2GHz Retina MacBook Pros (MJLQ2LL/A) on sale for $1749.99 including free shipping. Apple charges $1999 for this model, so Amazon’s price is represents a $250 savings. Read more
Deal alert! 13-inch 2.0GHz MacBook Pros for $...
B&H Photo has the new 2016 13″ 2.0GHz non-Touch Bar MacBook Pros in stock today and on sale for $225 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro... Read more
Free LibreOffice Portable 5.2.4 Complete Offi...
PortableApps.com and The Document Foundation have announce the release of LibreOffice Portable 5.2.4. LibreOffice Portable is an Open Source full-featured office suite — including a word processor,... Read more
Apple Planning Three New Tablets For 2017 – D...
Digitimes’ Rebecca Kuo and Joseph Tsai say that unnamed insider sources report Apple having three new tablets in the pipeline for 2017 release: a 9.7-inch model with a friendly price range, a new mid... Read more
Roundup of 15-inch Touch Bar MacBook Pro sale...
B&H Photo has the new 2016 15″ Apple Touch Bar MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more

Jobs Board

*Apple* & PC Desktop Support Technician...
APPLE & PC DESKTOP SUPPORT TECHNICIAN JOB IN STAMFORD, CT! We have immediate job openings for several Desktop Support Technicians with one of our most well-known Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Manhattan, NY Introduction: We have immediate job openings for several Desktop Support Technicians with one of our most Read more
*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Stamford, CT We have immediate job openings for several Desktop Support Technicians with one of our most well-known Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.