How to draw lines in a Dialog Box using MFC

[pradeepkrao]

Hi,

How to draw lines or any other on a Dialog Box.

I want to draw lines when I move my mouse...

How can I do it.. I am Using VC++ 6.0.


I have already tried using .. But no good..

Help me out....

void CPaintBDlg::OnLButtonDown(UINT nFlags, CPoint point) 
{
static CPoint p;	
CPaintDC dc(this);
	
CPen * myPen = new CPen(PS_SOLID,2,RGB(255,0,0));
	
dc.SelectObject(myPen);

dc.MoveTo(p.x,p.y);
dc.LineTo(point.x,point.y);
p.x=point.x;
p.y=point.y;
delete myPen;	

CDialog::OnLButtonDown(nFlags, point);
}

[CornedBee]

Should the line be persistent (i.e. should they remain after redrawing)?

[pradeepkrao]

Persistent.... Not required...

Can I use double buffering to make it persistent...

Any way as of now I just wana draw on a Dialog Box Created using VB 6.0 MFC..

[CornedBee]

using VB 6.0 MFC..

Watch your typing. Most typos are harmless, but some can be confusing.

Anyway, double-buffering a dialog is probably a bad idea - too much code for too little gain. Easier to create a CLine class and store a list of them. Then go through the list and draw each.

As for the other thing, usual line drawing algorithm looks like this:

// MouseDown event:
{
  SetCapture();
  m_bIsDragging = true;
  m_ptStart = m_ptEnd = clickedPoint;
  DrawTempLine(m_ptStart, m_ptEnd);
}

// MouseMove event:
{
  if(m_bIsDragging) {
    EraseTempLine(m_ptStart, m_ptEnd);
    m_ptEnd = mousePos;
    DrawTempLine(m_ptrStart, m_ptEnd);
  }
}

// MouseUp event:
{
  if(m_bIsDragging) {
    EraseTempLine(m_ptStart, m_ptEnd);
    m_ptEnd = clickedPoint;
    DrawFinalLine(m_ptStart, m_ptEnd);
    AddLineToStore(m_ptStart, m_ptEnd);
    ReleaseCapture();
    m_bIsDragging = false;
  }
}

// Paint event:
{
  for each line in store {
    DrawFinalLine(line);
  }
}

[pradeepkrao]

hi,

I dont wana draw in paint method.. I wana draw in the Mouse move event..

As far as drawing lines are concerned I agree that double buffering is not a good idea.. But when it comes to bmp's then there is no better way... wat do ya say..?..

[CornedBee]

Uhhh...


You mean drawing bitmaps?

Double buffering is always a bad idea when it's about a whole dialog.

[pradeepkrao]

Cornedbee...

how to draw bmp in a dialogbox..

I think that I can load the bmp to hdc...

But when I do that nothing appears..

even when I dram line nothing appeares..

It appeares only if i put it under the OnPaint method.. Which I dont wana do...

Is there a simple method like say.. I press Button 1 and few lines are drawn then I press second button and few circles or rectangles are drawn.. similarly BMP's..

[CornedBee]

It seems like the dialog prefers to draw itself.

[pradeepkrao]

Whatever you think..

But do let me know...

For a moment I thought that doing all this in a Dialog box dint sound good..
I thought why not on a Window.. (CreateWindow())....

There I will have no problem in drawing..

Let me know....what would be better..

[CornedBee]

Not sure, what pros has a dialog? Do you have many controls?

[CornedBee]

What about adding a child window to your dialog and drawing in there?

[pradeepkrao]

Hello Cornedbee....

Well I just want to dram some things on a window.. ...
No Dialog tree or plant .. Just draw

(VB was lot better for these stuffs...)...

Any way.. I wana draw .....

I just need some simple examples ..

I am familar with Windows Programming and I am moving towards MFC... (Project Requirement.. you see..)..

But the examples given in the book are completely different than what i see in the IDE.. ...

[CornedBee]

Then use a normal window. A dialog is not intended for drawing.

And I don't believe that VB is better for pure drawing.

[pradeepkrao]

...

May be VB is not better.. But it is indeed Simpler....

For mere drawing lines.. If I have to break my Head in VC++.. in VB its just drag and drop Lines..

Any way Thanks for your reply..

....

I will post my other questions.. here.. when i go to the other chapters...