TweetFollow Us on Twitter

Micro-draw
Volume Number:6
Issue Number:7
Column Tag:Jörg's Folder

C++ micro-Draw

By Jörg Langowski, MacTutor Editorial Board

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

C++ micro-Draw

We’re going to expand on the Object Lists demo from V6#2 this month. You’ll probably have noted quite a few deficiencies to that example - it would be nice to be able to draw not only three objects at fixed places within the window, but create some kind of ‘micro-Draw’ utility where you could place as many ovals and rectangles where you like in the window, and also change their aspect.

This example, over the months, will (hopefully) evolve into a useful Draw utility. The first step towards that is to add some code which will allow us to move objects around in the window, change their drawing pattern, delete them etc. At the end of this example you will see that there are still many things left to do - we will add them in the course of the following columns. You should have copies of the preceding example code ready at hand, because we don’t want to reprint everything from scratch each time. The listing at the end gives only the changes that were made compared to the code in V6#2.

Cleaning up the lists

The first thing that we have to take care of is the removal of objects and lists when a document is closed. This was not done in the original example. When a window is closed, the document destructor is called:

//1

TListDoc::~TListDoc(void)
{delete fObjList;
 HideWindow(fDocWindow);  }

and thus, the associated object list will be deleted. However, the objects in it still float around in the heap, since they have been created with new and have not been deleted explicitly! Therefore, we have to define a destructor for the object list as well, in which each object in the list is deleted:

//2

TObjList::~TObjList(void)
{
 TObjLink* temp;
 while (fHeader != nil) 
 {
 temp = fHeader->GetNext();
 delete fHeader->GetmyObj();
 delete fHeader;
 fHeader = temp;
 }
 fNumObjs = 0;
}

This code will clean up properly after us when we close a window.

Creating and Deleting Objects

The next feature that we’d like to add is to be able to position objects by clicking in the window. We can select from the menu what type of object we want; the cursor will then change to a cross, and the object will be placed in the window at the point where we clicked.

To do this, we first define a new routine, ClickInWindow() (see listing); this function waits for a mouse down event and returns the location of the mouse click in the current port’s local coordinates. This routine is called by the menu selection handlers (DoMenuCommand) at the appropriate selections. The center of the object’s bounds rectangle is then set to the position of the mouse click, and the window redrawn. We have not added any means to change the size of an object yet; take this as an exercise, or wait until we give an example in this column.

To erase an object from the window, we simply click on it after the menu selection “Erase”. For implementing this behavior, we define the method FindObj(Point theLoc) which finds the object corresponding to a mouse click at a certain point in the window. This routine returns a pointer to a TDisplObj; to remove the object which we clicked at, we simply write

// 3

fCurListDoc->fObjList->
 RemoveObj(fCurListDoc->fObjList->FindObj(theLoc));

A good example how compact some operations can be expressed in C++.

Changing draw patterns of objects is easy, too; I have added three menu selections that allow to draw objects in either black, gray or white. Again, we find the object that was clicked at, and then set the draw pattern to a new value. For this, we need to define a new instance variable fObjPat in TDisplObj which holds the drawing pattern, and the new method SetObjPat(Pattern pat) which sets this pattern. Caution: a pattern can’t be simply assigned to another pattern variable as in

//4

Pattern myPat = yourPat;

because Pattern is an array, it is defined as unsigned char[8]. We have to write a little loop to do the job (see listing).

Moving objects around

The last method that we add to our example this time is one that allows us to drag an object around in the window. We define a method DragObj(Point *theLoc, Rect theRect) which is called right after the mouse has been clicked at theLoc and an object has been found there. We also need to define a method that allows us to set the bounds rectangle of the object, so it can actually be moved.

DragObj will first create a new region that corresponds to the outline of the object to be dragged. It will then call the Window Manager routine DragGrayRgn to move this outline around the window. The limit and slop rectangles for the dragging routine are set to the port rectangle of the document window, passed through the parameter theRect to DragObj. This means that we cannot exceed the window’s boundaries when we drag the object.

DragGrayRgn waits until the mouse button is released and then returns a longint that contains the distances moved in the vertical and horizontal directions in its high and low words. This information is used to change the value of theLoc. When DragObj returns, theLoc will contain the new mouse coordinates. The main routine then resets the center of the object’s bounds rectangle to this position. The window is redrawn, and the object will have moved.

There is still a small bug in the dragging code; when you drag outside the limit rectangle, the object will disappear. I encourage you to find the reason for this; the bug will be resolved in the next column.

Wish list

We’re on our way to create a ‘MacTutorDraw’ application; but we still have a long way to go, of course. Things that should be added in the future are:

• scrap handling, so that copy, cut and paste are implemented;

• replacement of the selection menu by a palette window;

• changing the size and order of objects;

• implementing more objects, such as lines, arcs, polygons and text boxes;

• code for saving/restoring/printing documents.

Don’t expect all this to happen in the next column, though...

More on Forth

At the end, I would like to tell the remaining Forth enthusiasts that there is very good news regarding object-oriented extensions to Forth. I have now seen three different ways to implement NEON-compatible systems, two of which use fast subroutine-threaded code. I’ll give you news very soon. Until then, happy hacking.

Listing: Changes to the V6#2 example code

void TDocListApp::AdjustMenus(void)
{
 WindowPtrfrontmost;
 MenuHandle menu;
 Boolean undo,cutCopyClear,paste;

 TListDoc* fCurListDoc = (TListDoc*) fCurDoc;

 frontmost = FrontWindow();

 menu = GetMHandle(mFile);
 if ( fDocList->NumDocs() < kMaxOpenDocuments )
   EnableItem(menu, iNew);// New is enabled when we can open more documents 

 else DisableItem(menu, iNew);
 if ( frontmost != (WindowPtr) nil )
   EnableItem(menu, iClose);
 // Close is enabled when there is a window to close 
 else DisableItem(menu, iClose);

 undo = false; cutCopyClear = false; paste = false;
 
 if ( fCurListDoc == nil )
   {  // all editing is enabled for DA windows 
 undo = true;  cutCopyClear = true;
 paste = true;  }
   
 menu = GetMHandle(mEdit);
 if ( undo )EnableItem(menu, iUndo);
 else   DisableItem(menu, iUndo);
 
 if ( cutCopyClear )
   {  EnableItem(menu, iCut);
 EnableItem(menu, iCopy);
 EnableItem(menu, iClear);} 
 else
   {  DisableItem(menu, iCut);
 DisableItem(menu, iCopy);
 DisableItem(menu, iClear); }
   
 if ( paste )  EnableItem(menu, iPaste);
 else   DisableItem(menu, iPaste);
 
 menu = GetMHandle(myMenu);
 EnableItem(menu, item1);
 EnableItem(menu, item2);
 EnableItem(menu, item3);
 EnableItem(menu, item5);
 EnableItem(menu, item7);
 EnableItem(menu, item8);
 EnableItem(menu, item9);
 EnableItem(menu, item11);
} // AdjustMenus

Point ClickInWindow()
{
 EventRecordtheEvent;
 Point  theLoc;
 Booleanev;
 
 CursHandle hCurs;
 hCurs = GetCursor(crossCursor);
 SetCursor(*hCurs);
 while (!(Button())) {} ;
 ev = WaitNextEvent(mDownMask,&theEvent,0,0);
 theLoc = theEvent.where;
 GlobalToLocal(&theLoc);
 return theLoc;
}

void TDocListApp::DoMenuCommand(short menuID, short menuItem)
{
 short  itemHit;
 Str255 daName;
 short  daRefNum;
 WindowPtrwindow;
 Rect   brect;
 Point  theLoc;
 TDisplObj*theObj;
 
 TListDoc* fCurListDoc = (TListDoc*) fCurDoc;

 window = FrontWindow();
 switch ( menuID )
   {  case mApple:
 switch ( menuItem )
   {  case iAbout: // About box
 itemHit = Alert(rAboutAlert, nil);
 break;
 default: // DAs etc.
 GetItem(GetMHandle(mApple), menuItem, daName);
 daRefNum = OpenDeskAcc(daName);
 break; }
 break;
 case mFile:
 switch ( menuItem )
   {  case iNew: DoNew(); break;
 case iClose:
 if (fCurListDoc != nil)
   {  fDocList->RemoveDoc
 (fCurListDoc);
 delete fCurListDoc; }
 else CloseDeskAcc(((WindowPeek)
 fWhichWindow)->windowKind);
 break;
 case iQuit:Terminate();  break; }
 break;
 case mEdit:
 // call SystemEdit for DA editing & MultiFinder 
 if ( !SystemEdit(menuItem-1) )
   {  switch ( menuItem )
   {  case iCut: break;
 case iCopy: break;
 case iPaste: break;
 case iClear: break; }
   }
 break;
 case myMenu:
 if (fCurListDoc != nil) 
 { switch ( menuItem )
   { case item1: // TRoundRect
 theLoc=ClickInWindow();
 SetRect(&brect,theLoc.h-40,
 theLoc.v-20, theLoc.h+40, theLoc.v+20);
 fCurListDoc->fObjList->AddObj(
 new TRoundRect(brect));
 break;
 case item2: // TOval
 theLoc=ClickInWindow();
 SetRect(&brect,theLoc.h-40,
 theLoc.v-20, theLoc.h+40, theLoc.v+20);
 fCurListDoc->fObjList->AddObj(
 new TOval(brect));
 break;
 case item3:  // TRect
 theLoc=ClickInWindow();
 SetRect(&brect,theLoc.h-40,
 theLoc.v-20, theLoc.h+40,
 theLoc.v+20);
 fCurListDoc->fObjList->AddObj(
 new TRect(brect));
 break;
 case item5: // Erase
 theLoc=ClickInWindow();
 fCurListDoc->fObjList->RemoveObj(
 fCurListDoc->fObjList->FindObj(theLoc));
 break;
 case item7: // White
 theLoc=ClickInWindow();
 theObj = fCurListDoc->fObjList->
 FindObj(theLoc);
 if (theObj != nil) 
 theObj->SetObjPat(qd.white);
 break;
 case item8: // Gray
 theLoc=ClickInWindow();
 theObj = fCurListDoc->fObjList->
 FindObj(theLoc);
 if (theObj != nil) 
 theObj->SetObjPat(qd.gray);
 break;
 case item9: // Black
 theLoc=ClickInWindow();
 theObj = fCurListDoc->fObjList->
 FindObj(theLoc);
 if (theObj != nil) 
 theObj->SetObjPat(qd.black);
 break;
 case item11: // Move
 theLoc=ClickInWindow();
 theObj = fCurListDoc->fObjList->
 FindObj(theLoc);
 if (theObj != nil)
 { theObj->DragObj(
 &theLoc,window->portRect);
 SetRect(&brect,theLoc.h-40, 
 theLoc.v-20, theLoc.h+40, 
 theLoc.v+20);
 theObj->SetBoundRect(brect);
 }
 break;
 }
 InvalRect(&(window->portRect));
 fCurListDoc->DoUpdate();
 InitCursor();
 }
 break;
   }
 HiliteMenu(0);
} // DoMenuCommand

// List document class
class TListDoc : public TDocument {
 
  protected:
 void DrawWindow(void);

  public:
 TObjList*fObjList;// list of objects to be drawn
 TListDoc(short resID);
 ~TListDoc(void);
 
 // methods from TDocument we override
 void DoUpdate(void);
};

const int kMinDocDim = 40;

// create and delete the document window

TListDoc::TListDoc(short resID) : (resID)
{
 fObjList = new TObjList();
 ShowWindow(fDocWindow);  
}

void TListDoc::DrawWindow(void)
{TObjLink* temp;
 
 SetPort(fDocWindow);
 EraseRect(&fDocWindow->portRect);
 if (fObjList->NumObjs() != 0)
 for (temp = fObjList->Header(); 
 temp != nil; temp = temp->GetNext())
   temp->GetmyObj()->Draw(
 temp->GetmyObj()->GetObjPat());
} // DrawWindow

class TDisplObj {
  private:
 Boolean HiLiteState;// true : highlighted
  protected:
 TDisplObj(Rect r);
 Rect fBoundRect;
 Pattern fObjPat;
  public:
 virtual void Draw(Pattern) 
 {DebugStr(“\pCall to TDisplObj::Draw”);}
 virtual void Erase()     
 {DebugStr(“\pCall to TDisplObj::Erase”);}
 virtual void DoContent()   
 {DebugStr(“\pCall to TDisplObj::DoContent”);}
 virtual void DoIdle() { /* do nothing by default*/ }
 Rect GetBoundRect() {return fBoundRect;}
 void SetBoundRect(Rect theRect) 
 {fBoundRect = theRect;}
 Pattern GetObjPat() {return fObjPat;}
 void SetObjPat(Pattern pat); 
 void DragObj(Point*, Rect); 
};

class TObjList {
 TObjLink*fHeader;
 int    fNumObjs;
public:
 TObjList(void);  ~TObjList(void);
 
 inline TObjLink* Header() { return fHeader; }
 inline int NumObjs() { return fNumObjs; }

 void   AddObj(TDisplObj* obj);
 void   RemoveObj(TDisplObj* obj);
 TDisplObj* FindObj(Point theLoc);
};

TObjList::~TObjList(void)
{
 TObjLink* temp;
 while (fHeader != nil) 
 {
 temp = fHeader->GetNext();
 delete fHeader->GetmyObj();
 delete fHeader;
 fHeader = temp;
 }
 fNumObjs = 0;
}

TDisplObj* TObjList::FindObj(Point theLoc)
{
 TObjLink* temp;
 Rect theRect;

 for (temp = fHeader; temp != nil; 
 temp = temp->GetNext())
 { theRect = temp->GetmyObj()->GetBoundRect();
 if (PtInRect(theLoc,&theRect))
   return (temp->GetmyObj());
 }
 return nil;
}

TDisplObj::TDisplObj(Rect r)  
 { fBoundRect = r; SetObjPat(qd.gray); }

void TDisplObj::SetObjPat(Pattern pat)  
 { for (int i=0; i<8; i++) fObjPat[i] = pat[i]; }

void TDisplObj::DragObj(Point *theLoc, Rect theRect)  
{
 RgnHandle theRgn = NewRgn();
 OpenRgn();
 this->Draw(fObjPat);
 CloseRgn(theRgn);
 
 long res=DragGrayRgn(theRgn,*theLoc, &theRect,&theRect,0,0);
 if (res != 0x8000)
 { theLoc->v += HiWord(res);
 theLoc->h += LoWord(res);
 }
 DisposeRgn(theRgn);
}

 
AAPL
$118.93
Apple Inc.
-0.07
MSFT
$47.81
Microsoft Corpora
+0.06
GOOG
$541.83
Google Inc.
+1.46

MacTech Search:
Community Search:

Software Updates via MacUpdate

Adobe Photoshop Elements 13.0 - Consumer...
Adobe Photoshop Elements 12--the #1 selling consumer photo editing software--helps you edit pictures with powerful, easy-to-use options and share them via print, the web, Facebook, and more.Version... Read more
Skype 7.2.0.412 - Voice-over-internet ph...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
HoudahSpot 3.9.6 - Advanced file search...
HoudahSpot is a powerful file search tool built upon MacOS X Spotlight. Spotlight unleashed Create detailed queries to locate the exact file you need Narrow down searches. Zero in on files Save... Read more
RapidWeaver 6.0.3 - Create template-base...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
iPhoto Library Manager 4.1.10 - Manage m...
iPhoto Library Manager lets you organize your photos into multiple iPhoto libraries. Separate your high school and college photos from your latest summer vacation pictures. Or keep some photo... Read more
iExplorer 3.5.1.9 - View and transfer al...
iExplorer is an iPhone browser for Mac lets you view the files on your iOS device. By using a drag and drop interface, you can quickly copy files and folders between your Mac and your iPhone or... Read more
MacUpdate Desktop 6.0.3 - Discover and i...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
SteerMouse 4.2.2 - Powerful third-party...
SteerMouse is an advanced driver for USB and Bluetooth mice. It also supports Apple Mighty Mouse very well. SteerMouse can assign various functions to buttons that Apple's software does not allow,... Read more
iMazing 1.1 - Complete iOS device manage...
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
PopChar X 7.0 - Floating window shows av...
PopChar X helps you get the most out of your font collection. With its crystal-clear interface, PopChar X provides a frustration-free way to access any font's special characters. Expanded... Read more

Latest Forum Discussions

See All

Mystery Case Files: Dire Grove, Sacred G...
Mystery Case Files: Dire Grove, Sacred Grove HD Review By Jennifer Allen on November 28th, 2014 Our Rating: iPad Only App - Designed for the iPad A decent new installment for the popular Mystery Case Files series.   | Read more »
Castaway Paradise – Tips, Tricks, and St...
Ahoy there, castaways: Were you curious about our own thoughts regarding this pristine shipwreck? Check out our Castaway Paradise review! Castaway Paradise is out for iOS, finally giving mobile gamers the opportunity to enjoy the idyllic lifestyle... | Read more »
Castaway Paradise VIP Subs are on Sale f...
Castaway Paradise VIP Subs are on Sale for a Limited Time, and a Special Holiday Update is Coming Soon Posted by Rob Rich on November 28th, 2014 [ | Read more »
Primitive Review
Primitive Review By Jordan Minor on November 28th, 2014 Our Rating: :: FOLK ARTUniversal App - Designed for iPhone and iPad True to its name, Primitive is about as straightforward as runners get.   | Read more »
7 tips to get ahead of the competition i...
7 tips to get ahead of the competition in Dynasty of Dungeons Posted by Simon Reed on November 28th, 2014 [ permalink ] Playcrab has launched their action-packed new dungeon crawler, Dynasty of Dungeons, today. | Read more »
Master of Tea Kung Fu Review
Master of Tea Kung Fu Review By Jordan Minor on November 28th, 2014 Our Rating: :: ONE DROP RULESUniversal App - Designed for iPhone and iPad Master of Tea Kung Fu is a creative and complex caffeinated brawler.   | Read more »
Monster Strike Review
Monster Strike Review By Campbell Bird on November 28th, 2014 Our Rating: :: BILLIARD STRATEGYUniversal App - Designed for iPhone and iPad Collect monsters and battle by flinging them across the battlefield in this strangely... | Read more »
Proun+ Review
Proun+ Review By Jennifer Allen on November 28th, 2014 Our Rating: :: TWITCHY RACINGUniversal App - Designed for iPhone and iPad Twitchy racing aplenty in Proun+, an enjoyably tricky title.   | Read more »
Lucha Amigos (Games)
Lucha Amigos 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Forget Ninja Turtles, and meet Wrestlers Turtles! Crazier, Spicier and…Bouncier! Sling carapaces of 7 Luchadores to knock all... | Read more »
Record of Agarest War Zero (Games)
Record of Agarest War Zero 1.0 Device: iOS Universal Category: Games Price: $7.99, Version: 1.0 (iTunes) Description: HyperDevbox Holiday Turkey Black Friday Special Pricing! To celebrate the opening of the holiday season HyperDevbox... | Read more »

Price Scanner via MacPrices.net

Up To 75% Off Infovole Text Apps Over Black F...
Infovole’s entire range of apps, including the Textkraft family of word processors for iPads and iPhones, is being offered at 50-75% off over the Black Friday and Cyber Monday weekend. The five-day... Read more
Black Friday: Up to $60 off Mac minis, NY tax...
 B&H Photo has new 2014 Mac minis on sale for up to $60 off MSRP as part of their Black Friday sale. Shipping is free, and B&H charges NY sales tax only: - 1.4GHz Mac mini: $449.99 $50 off... Read more
Black Friday: 27-inch 5K iMac for $2299, save...
 B&H Photo continues to offer Black Friday sale prices on the 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... Read more
Karalux Announces 24K Gold-Plated iPhone 6
Karalux, a Vietnam-based jewellery firm, has launched a unique 24 karat gold-plated iPhone 6 version with gold-cast monolithic dragon on its back panel. The real 24 karat gold plated enclosure doesn’... Read more
Black Friday: 13-inch 2.6GHz Retina MacBook P...
 B&H Photo has lowered their price for the 13″ 2.6GHz/128GB Retina MacBook Pro to $1159 for Black Friday. That’s $140 off MSRP, and it’s the lowest price for this model (except for Apple’s $1099... Read more
View all the Black Friday sales on our Mac Pr...
We’ve updated our Mac Price Trackers with the latest information on prices, bundles, and availability on systems from Apple’s authorized internet/catalog resellers. View Black Friday sale prices at a... Read more
Black Friday: 11-inch MacBook Air for $779, s...
 Best Buy has lowered their price for the 2014 11″ 1.4GHz/128GB MacBook Air to $779.99 for Black Friday. That’s $120 off MSRP. Choose free shipping or free local store pickup (if available). Sale... Read more
Apple Store Black Friday sale for 2014: $100...
BLACK FRIDAY The Apple Store has posted their Black Friday deals for 2014. Receive a $100 PRODUCT(RED) branded iTunes gift card with the purchase of select Macs, $50 with iPads, and $25 with iPods,... Read more
Black Friday: 15% off iTunes Gift Cards
Staples is offering 15% off $50 and $100 iTunes Gift Cards on their online store as part of their Black Friday sale. Click here for more information. Shipping is free. Best Buy is offering $100... Read more
BEVL Releases Dock Tailored for iPhone 6 and...
Seattle based BEVL has released their first product: an iPhone dock that is divergent in build quality, rock-solid function and visual simplicity to complement the iPhone. BEVL is now accepting... 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
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, 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
*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) - 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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.