Wm_paint

[anantwakode]

Hi,

Thanks for looking in to this !

I have my paint function,In Which I am calling Draw Method of Objects

OnPaint(CDC *pDC)
{

For(int i=0;i<Count;i++)
{
  CShape *temp=GetShape(i);
  temp->Draw(pDC);
}

}

and
CShape as well as Derived classes implemented Draw() method.

CMyRect::Draw(CDC *pDC)
{
  //Some Code
  //
  pDC->Rectangle(...);

}

CMyDate::Draw(CDC *pDC)
{
  //Some Code
  pDC->.......

}

I want to ignore the draw code if it does'nt lies in invalidate region.

CMyDate::Draw(CDC *pDC)
{
  if(InvalidateRgn Overlaps this object Rect)
 {
   //Some Code
  pDC->.......
 }
 else
 {
    //Ignore 
 }
}

How to do this ? Is there any API for getting invalidate region.
How to get Update Rect Inside Paint() ? as its get cleared after beginpaint call !
Thanks !
-Anant

[g_gili]

Hi anantwakode,

Did you have a look at

BOOL GetUpdateRect(
   LPRECT lpRect,
   BOOL bErase = FALSE 
);

Best Regards,
Gili

[anantwakode]

Hi,

Thanks g_gili !

I tried to get Update Rect by using GeUpdateRect(), but as I am calling it in OnPaint() its get Cleared as OnPaint is get Called after beginpaint().

now I am using getClipBox(). and its working fine.. !

is there any better way ? is there any advantage of using Rgn instead of Rect.

actually getClipbox() returns invalidate rect.

which is fine but problem is if suppose
I have object at pos 10,10 and 200,200 which are continously updated.
then it returns CRect(10,10,200,200),

and if I have Static object at 50,50 which is not overlapped by these two object still Draw() gets called for the object.

I think using Rgn I mean , InvalidateRgn() or something like can provide better solution ! Or is there any better solution ?

what do you think ?

Thanks
-Anant

[MikeAThon]

In OnDraw, you also need to check whether the object being drawn lies within the invalidated rectangle. Use IntersectRect, and in addition, define a method in your CShape class that returns the bounding rectangle for the shape.

The Scribble tutorial uses this approach. See the three steps at "Using a Hint For Effective Repainting" at http://msdn2.microsoft.com/en-us/lib...88(VS.60).aspx

GetClipRgn will retrieve an application-defined clipping region. This approach will work only if you are also willing to create your own clipping regions using the SetClipRgn function.

Mike

[anantwakode]

Thanks Mike !

-Anant