[vtkusers] Question on display changed(or changeable) imagedata

[wang minyou]

Hello everyone,

I came across some problem on imagedata.
I use BMPReader to readin a picture, change several pixels in it and then 
display it. I may do many different changes and wish they could be 
displayed in turn. For example, I want to add a circle in the image and the 
circle can change with the position of center or the scalar of radius. I 
use the function as follow:
bmpReader->GetOutput()->SetScalarComponentFromFloat(outx[i],outy[i],0,0,255.0);

Now the circle can be dispaly, but when the position of center or the 
scalar of radius changes, the origin circle still exists, added with a new 
circle. That means the last steps of operation on imagedata and current 
step of operation are all presented on the window. 

Someone have better idea of doing such work? Please help me!
Thank you all very much!

Codes related: 
void CSegmentationView::OnRChange(WPARAM wRaram,LPARAM lParam)
{
int centerx=pInfoDlg->nCenterX;
int centery=pInfoDlg->nCenterY;
int radius=pInfoDlg->nRadius;
int wide=pInfoDlg->nWide;
int height=pInfoDlg->nHeight;

int size=(int)(radius*2*3.14159);
double* t=new double[size];
int* datax=new int[size];
int* datay=new int[size];
for(int i=0;i<size;i++)
{
	t[i]=(2*3.14159/size)*i;
	datax[i]=centerx+(int)(radius*cos(t[i]));
	datay[i]=centery+(int)(radius*sin(t[i]));
	if(datax[i]<0)
		datax[i]=0;
	else if(datax[i]>=wide)
		datax[i]=wide-1;
	if(datay[i]<0)
		datay[i]=0;
	else if(datay[i]>=height)
		datay[i]=height-1;
}

for(i=0;i<size;i++)
{
	
bmpReader->GetOutput()->SetScalarComponentFromFloat(datax[i],datay[i],0,0,255.0);

           
bmpReader->GetOutput()->SetScalarComponentFromFloat(datax[i],datay[i],0,1,0.0);

           
bmpReader->GetOutput()->SetScalarComponentFromFloat(datax[i],datay[i],0,2,0.0);

}

imageActor2->SetInput(bmpReader->GetOutput());
pRender2->AddProp(imageActor2);

pRenWin->Render();
}

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