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

OmniGraffle 6.3 - Create diagrams, flow...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more
PDFKey Pro 4.3.2 - Edit and print passwo...
PDFKey Pro can unlock PDF documents protected for printing and copying when you've forgotten your password. It can now also protect your PDF files with a password to prevent unauthorized access and/... Read more
Ableton Live 9.2.2 - Record music using...
Ableton Live lets you create and record music on your Mac. Use digital instruments, pre-recorded sounds, and sampled loops to arrange, produce, and perform your music like never before. Ableton Live... Read more
Macs Fan Control 1.3.1.0 - Monitor and c...
Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more
NetShade 6.3.1 - Browse privately using...
NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN servers spanning seven countries. NetShade masks your IP address as you... Read more
Dragon Dictate 4.0.7 - Premium voice-rec...
With Dragon Dictate speech recognition software, you can use your voice to create and edit text or interact with your favorite Mac applications. Far more than just speech-to-text, Dragon Dictate lets... Read more
Persecond 1.0.2 - Timelapse video made e...
Persecond is the easy, fun way to create a beautiful timelapse video. Import an image sequence from any camera, trim the length of your video, adjust the speed and playback direction, and you’re done... Read more
GIMP 2.8.14p2 - Powerful, free image edi...
GIMP is a multi-platform photo manipulation tool. GIMP is an acronym for GNU Image Manipulation Program. The GIMP is suitable for a variety of image manipulation tasks, including photo retouching,... Read more
Sandvox 2.10.2 - Easily build eye-catchi...
Sandvox is for Mac users who want to create a professional looking website quickly and easily. With Sandvox, you don't need to be a Web genius to build a stylish, feature-rich, standards-compliant... Read more
LibreOffice 5.0.1.2 - 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

ReBoard: Revolutionary Keyboard (Utilit...
ReBoard: Revolutionary Keyboard 1.0 Device: iOS Universal Category: Utilities Price: $1.99, Version: 1.0 (iTunes) Description: Do everything within the keyboard without switching apps! If you are in WhatsApp, how do you schedule a... | Read more »
Tiny Empire (Games)
Tiny Empire 1.1.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.1.3 (iTunes) Description: Launch cannonballs and blow tiny orcs into thousands of pieces in this intuitive fantasy-themed puzzle shooter! Embark on an... | Read more »
Astropad Mini (Productivity)
Astropad Mini 1.0 Device: iOS iPhone Category: Productivity Price: $4.99, Version: 1.0 (iTunes) Description: *** 50% off introductory price! ​*** Get the high-end experience of a Wacom tablet at a fraction of the price with Astropad... | Read more »
Emo Chorus (Music)
Emo Chorus 1.0.0 Device: iOS Universal Category: Music Price: $1.99, Version: 1.0.0 (iTunes) Description: Realistic Choir simulator ranging from simple Chorus emulation to full ensemble Choir with 128 members. ### introductory offer... | Read more »
Forest Spirit (Games)
Forest Spirit 1.0.5 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.5 (iTunes) Description: | Read more »
Ski Safari 2 (Games)
Ski Safari 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: The world's most fantastical, fun, family-friendly skiing game is back and better than ever! Play as Sven's sister Evana, share... | Read more »
Lara Croft GO (Games)
Lara Croft GO 1.0.47768 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.47768 (iTunes) Description: Lara Croft GO is a turn based puzzle-adventure set in a long-forgotten world. Explore the ruins of an ancient... | Read more »
Whispering Willows (Games)
Whispering Willows 1.23 Device: iOS Universal Category: Games Price: $4.99, Version: 1.23 (iTunes) Description: **LAUNCH SALE 50% OFF** - Whispering Willows is on sale for 50% off ($4.99) until September 9th. | Read more »
Calvino Noir (Games)
Calvino Noir 1.1 Device: iOS iPhone Category: Games Price: $3.99, Version: 1.1 (iTunes) Description: The film noir stealth game. Calvino Noir is the exploratory, sneaking adventure through the 1930s European criminal underworld.... | Read more »
Angel Sword (Games)
Angel Sword 1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.0 (iTunes) Description: Prepare to adventure in the most epic full scale multiplayer 3D RPG for mobile! Experience amazing detailed graphics in full HD.... | Read more »

Price Scanner via MacPrices.net

Apple offering refurbished 2015 13-inch Retin...
The Apple Store is offering Apple Certified Refurbished 2015 13″ Retina MacBook Pros for up to $270 (15%) off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
Apple refurbished 2015 MacBook Airs available...
The Apple Store has Apple Certified Refurbished 2015 11″ and 13″ MacBook Airs (the latest models), available for up to $180 off the cost of new models. An Apple one-year warranty is included with... Read more
21-inch iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ iMacs on sale for up to $120 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $999.99 $100 off - 21″ 2.7GHz iMac: $1199.99 $100 off - 21″ 2.9GHz iMac... Read more
5K iMacs on sale for up to $150 off MSRP, fre...
B&H Photo has the 27″ 3.3GHz 5K iMac on sale for $1899.99 including free shipping plus NY tax only. Their price is $100 off MSRP. They have the 27″ 3.5GHz 5K iMac on sale for $2149.99 $2199.99, $... Read more
1.4GHz Mac mini, refurbished, available for $...
The Apple Store has Apple Certified Refurbished 1.4GHz Mac minis available for $419. Apple’s one-year warranty is included, and shipping is free. Their price is $80 off MSRP, and it’s the lowest... 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
MacBook Airs on sale for $100 off MSRP
Best Buy has MacBook Airs on sale for $100 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary... Read more
Big Grips Lift Handle For iPad Air and iPad A...
KEM Ventures, Inc. which pioneered the extra-large, super-protective iPad case market with the introduction of Big Grips Frame and Stand in 2011, is launching Big Grips Lift featuring a new super-... Read more
Samsung Launches Galaxy Tab S2, Its Most Powe...
Samsung Electronics America, Inc. has announced the U.S. release of the Galaxy Tab S2, its thinnest, lightest, ultra-fast tablet. Blending form and function, elegant design and multitasking power,... Read more
Tablet Screen Sizes Expanding as iPad Pro App...
Larger screen sizes are gaining favor as the tablet transforms into a productivity device, with shipments growing 185 percent year-over-year in 2015. According to a new Strategy Analytics’ Tablet... 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
*Apple* Desktop Analyst - KDS Staffing (Unit...
…field and consistent professional recruiting achievement. Job Description: Title: Apple Desktop AnalystPosition Type: Full-time PermanentLocation: White Plains, NYHot Read more
*Apple* Systems Engineer (Mclean, VA and NYC...
Title: Apple Systems Engineer (Mclean, VA and NYC) Location: United States-New York-New York-200 Park Ave (22005) Other Locations: United States-Virginia-Vienna-Towers Read more
*Apple* Systems Engineer (Mclean, VA and NYC...
…Assist in providing strategic direction and technical leadership within the Apple portfolio, including desktops, laptops, and printing environment. This person will Read more
*Apple* Subject Matter Expert - Experis (Uni...
We are seeking an Apple Subject Matter Expert to assist in developing the architecture, support and services for integration of Apple devices into the company's Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.