Re: [Dev-C++] Whoops - drawing in Windows

[Per W. <pw...@ia...>]

There isn't a right or wrong between lists or bitmaps. The question is
what problems to solve.

Just fix repaint of window:
Simple bitmap will make perfect redraw in constant time, using constant
amount of memory.

Support undo, rescaling etc:
If all paint operations are stored in a list (or vector, ...) it the
amount of needed memory and needed redraw time will increase with the
complexity of the drawing. However, the additional bonus is easy support
for undo - just remove last entry from the list and redraw. Also, if all
coordinates are stored as a percentage of the window size, it is possible
to resize the window, and at repaint getting the image stretched
correspondingly, without any strange jaggies introduced by the resize of a
bitmap.

/Per W

On Thu, 24 Oct 2002, Daniel Glenfield wrote:

> I'm sure the linked list is the right way to do it, I just can't remember 
> the specifics.
> 
> 
> 
> 
> 
> 
> >From: "Vlada Djurovic" <dj...@im...>
> >To: "Daniel Glenfield" 
> ><sp...@ho...>,<dev...@li...>
> >Subject: Re: [Dev-C++] Whoops - drawing in Windows
> >Date: Thu, 24 Oct 2002 14:02:32 +0200
> >
> >
> >----- Original Message -----
> >From: "Daniel Glenfield" <sp...@ho...>
> >To: <dj...@im...>; <dev...@li...>
> >Sent: Thursday, October 24, 2002 11:59 AM
> >Subject: Re: [Dev-C++] Whoops - drawing in Windows
> >
> >
> > > Nope maybe not, serialising is for saving and restoring.
> > >
> > > I think you have to store the info in to an array, but looking at this 
> >old
> > > code I cannot remember what exactly you have to do. I worked on the
> >Scribble
> > > tutorial that comes with VC++ - have a look on MSDN for it.
> > >
> > >
> >I tried to store all the info in a linked list, but I think I did something
> >wrong because the program just froze when I tried to draw something. Then I
> >thought it would be easier to store the drawing in a compatible memory
> >bitmap and then just copy it back in the client area when it needs to be
> >redrawn, but this also didn't work because the program froze again. That's
> >why I was asking if anyone can give me some guidelines about how to do this
> >(the bitmap way).
> >As for the tutorials, I read the book "Teach yourself VC++ in 21 days" 
> >which
> >also has some stuff about this, but although I think I did everything the
> >way it's done in VC++- it doesn't work.
> >
> >Regards, Vlada
> > >
> > > >From: "Vlada Djurovic" <dj...@im...>
> > > >To: "'DevC++ help'" <dev...@li...>
> > > >Subject: [Dev-C++] drawing in Windows
> > > >Date: Thu, 24 Oct 2002 10:32:16 +0200
> > > >
> > > >Hi, everybody
> > > >Here's my problem: I'm trying to write a simple drawing app (just for
> > > >exercise) and so far its been going OK. I can draw lines in client area
> >in
> > > >different colors, but when ever I minimize or maximize the window, or
> > > >something similar happenes, all the content of the window is gone. I
> >tried
> > > >to use a memory DC an bitmap to save the contents in, and BitBlt it 
> >back
> >in
> > > >response to WM_PAINT message, but the program just "froze". Can anybody
> > > >give me a hint how to do it? Here's the code used for drawing lines
> >without
> > > >any restoring parts:
> > > >
> > > >         case WM_MOUSEMOVE:
> > > >         {
> > > >             switch(iTool)           /* iTool is used for dtetrmining
> >which
> > > >drawing tool is selected(line, rect etc.)*/
> > > >             {
> > > >                 case 0:
> > > >                 {
> > > >                    if(wParam==MK_LBUTTON)    /*if line is selected
> > > >(itool=0) and left button presed*/
> > > >                    {
> > > >                          HDC hDC=GetDC(hwnd);
> > > >
> > > >                        HPEN
> >hPen=CreatePen(PS_SOLID,iCurWidth,crCurColor);
> > > >                        HPEN hOldPen=(HPEN)SelectObject(hDC,hPen);
> > > >                        CLine* pLine=new
> > > >CLine(ptPrevPos,MAKEPOINTS(lParam),iCurWidth,crCurColor); /*create new
> >line
> > > >object*/
> > > >                        pLine->DrawLine(hDC);
> > > >                        ptPrevPos=MAKEPOINTS(lParam);
> > > >                        SelectObject(hDC,hOldPen);
> > > >                        DeleteDC(hDC);
> > > >                    }
> > > >                 }
> > > >                 break;
> > > >                 case 1: /* nothing here yet*/
> > > >                 break;
> > > >             }
> > > >         }
> > >
> > >
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