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

Vienna 3.0.6 :5eaf312: - RSS and Atom ne...
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
Kodi 15.1.rc1 - Powerful media center to...
Kodi (was XBMC) is an award-winning free and open-source (GPL) software media player and entertainment hub that can be installed on Linux, OS X, Windows, iOS, and Android, featuring a 10-foot user... Read more
Bookends 12.5.8 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Access the power of Bookends directly from Mellel, Nisus Writer Pro, or MS Word (... Read more
Chromium 44.0.2403.125 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 44.0.2403.125: This release contains a number... Read more
iMazing 1.2.2 - Complete iOS device mana...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more
Audio Hijack 3.2.0 - Record and enhance...
Audio Hijack (was 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... Read more
FontExplorer X Pro 5.0.1 - Font manageme...
FontExplorer X Pro is optimized for professional use; it's the solution that gives you the power you need to manage all your fonts. Now you can more easily manage, activate and organize your... Read more
Calcbot 1.0.2 - Intelligent calculator a...
Calcbot is an intelligent calculator and unit converter for the rest of us. Featuring an easy-to-read history tape, expression view, intuitive conversion, and much more! Features History Tape -... Read more
MTR 5.0.0.1 - The Mac's oldest and...
MTR (was MacTheRipper)--the Mac's oldest and smartest DVD-backup app--is now updated to version 5.001 MTR -- the complete toolbox, not a one-trick, point-and-click extractor. MTR is intended for... Read more
LibreOffice 4.4.5.2 - Free, open-source...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more

Card King: Dragon Wars - Tips, Tricks an...
[Read more] | Read more »
Pac-Man Championship Edition DX has brou...
Bandai Namco has released Pac-Man Championship Edition DX on iOS and Android, which features the classic arcade gameplay that we've all grown to love. Pac-Man Championship Edition DX can be enjoyed in much shorter bursts than the arcade versions... | Read more »
Cosmonautica (Games)
Cosmonautica 1.1 Device: iOS Universal Category: Games Price: $6.99, Version: 1.1 (iTunes) Description: Cast off! Are you ready for some hilarious adventures in outer space? | Read more »
Rescue humanity from a Demon horde in An...
Angel Stone is Fincon's follow up to the massively successful Hello Hero and is out now on iOS and Android. You play as a member of The Resistance, a group of mighty human warriors who have risen up in defiance of the Demon horde threatening to... | Read more »
Gallery Doctor (Photography)
Gallery Doctor 1.0 Device: iOS iPhone Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Free up valuable iCloud and iPhone storage with Gallery Doctor, the only iPhone cleaner that automatically identifies the... | Read more »
You Against Me (Games)
You Against Me 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: A simple game… You. Me. Claim, steal, lock, score, win! | Read more »
Yep, it's True - Angry Birds 2 is O...
The not exactly rumors were true and the birds are back. Angry Birds 2 has come to the App Store and the world will... well I suppose it'll still be the same, but now we have more bird-flinging options! [Read more] | Read more »
You Could Design Your Own Card for Chain...
If you've ever wanted to create your own item, weapon, trap, or even monster for Chainsaw Warrior: Lords of the Night, this is your chance. Auroch Digital is currently holding a contest so that fans can fight to the death (not really) to see which... | Read more »
Bitcoin Billionaire is Going Back in Tim...
If you thought you managed to buy everything there is to buy in Bitcoin Billionaire and make all the money, well you though wrong. Those of you who made it far enough might remember investing in time travel - and it looks like that investment is... | Read more »
Domino Drop (Games)
Domino Drop 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Domino Drop is a delightful new puzzle game with dominos and gravity!Learn how to play it in a minute, master it day by day.Your... | Read more »

Price Scanner via MacPrices.net

Back-to-School with Tablet and Smartphone Acc...
Belkin helps you prepare for the coming school year with a wide variety of the latest mobile and tablet accessories to outfit both grade school and college students. The line-up includes charging... Read more
11-inch MacBook Airs on sale for $100 off MSR...
Best Buy has 11-inch MacBook Airs on sale for $100 off MSRP. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary: - 11″ 1.6GHz... Read more
iPad Air 2 on sale for up to $100 off MSRP
Best Buy has iPad Air 2s on sale for up to $100 off MSRP on their online store for a limited time. Choose free shipping or free local store pickup (if available). Sale prices available for online... Read more
Sale! 13-inch MacBook Pros on sale for $100 o...
B&H Photo has 13″ MacBook Pros on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.5GHz/500GB MacBook Pro: $999.99 save $100 - 13″ 2.7GHz/128GB Retina... Read more
Sale! Save $100 on 13-inch MacBook Airs this...
B&H Photo has the 13″ 1.6GHz/128GB MacBook Air on sale for $899.99 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model.... Read more
Worldwide Tablet Market Decline Continues, Ap...
The worldwide tablet market declined -7.0% year-over-year in the second quarter of 2015 (2Q15) with shipments totaling 44.7 million units according to preliminary data from the International Data... Read more
TP-LINK TL-PA8030P KIT Powerline Featuring Ho...
Consumer and business networking products provider TP-LINK is now shipping its TL-PA8030P KIT AV1200 3-Port Gigabit Passthrough Powerline Starter Kit that expands your home’s network over its... Read more
Apple refurbished iPad Air 2s available for u...
The Apple Store has Apple Certified Refurbished iPad Air 2s available for up to $140 off the price of new models. Apple’s one-year warranty is included with each model, and shipping is free: - 128GB... Read more
Updated Apple iPad Price Trackers
We’ve updated our iPad Air Price Tracker and our iPad mini Price Tracker with the latest information on prices and availability from Apple and other resellers. Read more
Apple refurbished 2014 13-inch 128GB MacBook...
The Apple Store has Apple Certified Refurbished 2014 13″ MacBook Airs available starting at $759. An Apple one-year warranty is included with each MacBook, and shipping is free: - 13″ 1.4GHz/128GB... Read more

Jobs Board

*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
Infrastructure Engineer - *Apple* /Mac - Hil...
Infrastructure Engineer - Apple /Mac Job Code: 1608 # of openings: 1 Description Our fortune 500 client is looking to hire an experienced Infrastructure Engineer to join Read more
Executive Administrative Assistant, *Apple*...
…supporting presentation development for senior leadership. * User experience with Apple hardware and software is preferred. Additional Requirements The following list Read more
*Apple* Bus Company is now hirin - Apple Bus...
Apple Bus Company is now hiring school bus drivers in the Pettis County area. Class B CDL preferred. Free training provided. No nights or weekends required. Flexible Read more
*Apple* Certified Mac Technician - Updated 6...
…and friendly, hands-on technical support to customers troubleshooting and repairing Apple /Mac products with courtesy, speed and skill. Use your problem-solving skills Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.