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);
}

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Things 3.1.3 - Elegant personal task man...
Things is a task management solution that helps to organize your tasks in an elegant and intuitive way. Things combines powerful features with simplicity through the use of tags and its intelligent... Read more
BetterTouchTool 2.292 - Customize Multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Bookends 12.8.3 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Bookends uses the cloud to sync reference libraries on all the Macs you use.... Read more
Mellel 3.5.5 - The word processor for sc...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
Mellel 3.5.5 - The word processor for sc...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
Bookends 12.8.3 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Bookends uses the cloud to sync reference libraries on all the Macs you use.... Read more
Carbon Copy Cloner 4.1.18 - Easy-to-use...
Carbon Copy Cloner backups are better than ordinary backups. Suppose the unthinkable happens while you're under deadline to finish a project: your Mac is unresponsive and all you hear is an ominous,... Read more
Hopper Disassembler 4.2.14- - Binary dis...
Hopper Disassembler is a binary disassembler, decompiler, and debugger for 32- and 64-bit executables. It will let you disassemble any binary you want, and provide you all the information about its... Read more
BetterTouchTool 2.291 - Customize Multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Sound Studio 4.8.11 - Robust audio recor...
Sound Studio lets you easily record and professionally edit audio on your Mac. Easily rip vinyls and digitize cassette tapes, or record lectures and voice memos. Prepare for live shows with live... Read more

You can now apply to be Clash of Clans...
Earlier this month, word got out that the Builder, the trusty handiman who tirelessly built every single building inevery singleClash of Clansbase had called it quits. Sick of seeing his work destroyed endless, the Builder has set out for our world... | Read more »
Meshi Quest beginner's guide - how...
Meshi Quest is Square Enix's newest free-to-play release, and it's a real charmer. You start off as the head of a sushi restaurant, upgrading your food and equipment as you serve visitors heaping helpings of your delicious meals. As you progress,... | Read more »
BUST-A-MOVE JOURNEY (Games)
BUST-A-MOVE JOURNEY 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: BUST-A-MOVE Features:- Shoot bubbles and match 3 or more bubbles of the same color to make them pop!- Complete your... | Read more »
The best card combos in Clash Royale
Clash Royale is all about building a deck of units that synergise well. To help you get off to a flying start, we've put together a list of unit combinations that are incredibly effective. Looking for some choice 2v2 combos? Check out our guide. [... | Read more »
The best 2v2 card combos in Clash Royale
2v2 is making it's grand return toClash Royalequite soon. 2v2 has quickly become one of the game's most popular gameplay modes, though they still have yet to make it a permanent fixture in the game. 2v2 is exciting and adds some new flavor to... | Read more »
The best games we played this week - Aug...
Another busy week has come to a close. We played a lot of excellent games this week and now it's time to look back and reflect on some our favorites. Here are our picks for the week of August 18. [Read more] | Read more »
War Wings beginner's guide - how to...
War Wings is the newest project from well-established game maker Miniclip. It's a World War II aerial dogfighting game with loads of different airplane models to unlock and battle. The game offers plenty of single player and multiplayer action. We... | Read more »
How to win every 2v2 battle in Clash Roy...
2v2 is coming back to Clash Royale in a big way. Although it's only been available for temporary periods of time, 2v2 has seen a hugely positive fan response, with players clamoring for more team-based gameplay. Soon we'll get yet another taste of... | Read more »
Roll to Win with Game of Dice’s new upda...
Joycity’s hit Game of Dice gets a big new update this week, introducing new maps, mechanics, and even costumes. The update sets players loose on an exciting new map, The Cursed Tower, that allows folks to use special Runes mid-match. If you feel... | Read more »
Bottom of the 9th (Games)
Bottom of the 9th 1.0.1 Device: iOS iPhone Category: Games Price: $4.99, Version: 1.0.1 (iTunes) Description: Play the most exciting moment of baseball in this fast-paced dice and card game! | Read more »

Price Scanner via MacPrices.net

Free Instant Translator 2.0 App For iOS Relea...
Mobile application development company, Neoappz has announced the release and immediate availability of Instant Translator 2.0 for iOS devices. Instant Translator is a user-friendly application which... Read more
2017 15-inch MacBook Pros on sale for $200 of...
Amazon has 2017 15″ MacBook Pros on sale for $200 off MSRP. Shipping is free: – 15″ 2.8GHz MacBook Pro Space Gray: $2199.99, $200 off MSRP – 15″ 2.8GHz MacBook Pro Silver: $2296, $103 off MSRP – 15″... Read more
Apple’s 2017 Back to School Promotion: Free B...
Purchase a new Mac using Apple’s Education discount, and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free. As part... Read more
Clearance 2016 12-inch Retina MacBooks, Apple...
Apple has Certified Refurbished 2016 12″ Retina MacBooks available starting at $1019. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The following... Read more
15-inch 2.2GHz Retina MacBook Pro, Apple refu...
Apple has Certified Refurbished 2015 15″ 2.2GHz Retina MacBook Pros available for $1699. That’s $300 off MSRP, and it’s the lowest price available for a 15″ MacBook Pro. An Apple one-year warranty is... Read more
Apple refurbished Mac minis available startin...
Apple has Certified Refurbished Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: – 1.4GHz Mac mini: $419 $80 off MSRP – 2.6GHz Mac... Read more
Apple refurbished iPad Pros available startin...
Apple has Certified Refurbished 2016 12″ WiFi iPad Pros available starting at $589. An Apple one-year warranty is included with each model, and shipping is free: – 32GB 12″ iPad Pro WiFi: $589... Read more
Weekend sale: 13-inch MacBook Pros for up to...
Amazon has new 2017 13″ MacBook Pros on sale today for up to $200 off MSRP, each including free shipping: – 13″ 3.1GHz/256GB Space Gray MacBook Pro (MPXV2LL/A): $1599.99 $200 off MSRP – 13″ 3.1GHz/... Read more
Back To School With The Edge Desk All-in-one...
Back to school is just around the corner, and the ergonomically correct Edge Desk all-in-one portable kneeling desk is ideal for students living in dorms and small apartments, Edge Desk features:... Read more
Norton Core Secure Wi-Fi Router Now Available...
First introduced at the 2017 Consumer Electronics Show (CES), Norton Core, a secure, high-performance Wi-Fi router, fundamentally changed the concept of Wi-Fi routers by making security the primary... Read more

Jobs Board

*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
Development Operations and Site Reliability E...
Development Operations and Site Reliability Engineer, Apple Payment Gateway Job Number: 57572631 Santa Clara Valley, California, United States Posted: Jul. 27, 2017 Read more
Frameworks Engineering Manager, *Apple* Wat...
Frameworks Engineering Manager, Apple Watch Job Number: 41632321 Santa Clara Valley, California, United States Posted: Jun. 15, 2017 Weekly Hours: 40.00 Job Summary Read more
*Apple* Solutions Consultant - Apple Inc. (U...
…about helping others on a team while also delighting customers? As an Apple Solutions Consultant (ASC), you will discover customers needs and help connect them Read more
*Apple* Solutions Consultant - Apple Inc. (U...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.