Painting the array to a window takes too long

[Old Nick]

Hi,

I've written some code to display the output from a 64x64 camera array we've designed, the problem I'm having is that painting the array to a window takes too long (around a second or so!)

I'm using a function containing

hPenArray=CreatePen(PS_SOLID,0,RGB(g_RGB,0,0));
	hPenOld = SelectObject(hdc, hPenArray);
	lb.lbColor=RGB(g_RGB,0,0);
	lb.lbStyle = BS_SOLID;
	hBrush = CreateBrushIndirect(&lb);
	hBrushOld = SelectObject(hdc, hBrush);
	for (y=0;y<64;y++)
	{
		for (x=0;x<64;x++)
		Rectangle(hdc, g_X*150, (g_Y+1)*150, (g_X+1)*150, g_Y*150);
.
.
.

where g_RGB is the voltage output og the individual pixels.
This function is called after every pixel read and the window updated.

the painting is done in

void Cls_OnPaint(HWND hwnd)
{
        PAINTSTRUCT             ps;
		RECT					rectCl;

        BeginPaint(hwnd, &ps);
		SetMapMode(ps.hdc, MM_HIMETRIC);
		GetClientRect(hwnd, &rectCl);
		SetViewportOrgEx(ps.hdc, 0, rectCl.bottom, NULL);
		SetWindowOrgEx(ps.hdc, -500, -500, NULL);

		TextOut(ps.hdc, 0, 15000, g_pathName, strlen(g_pathName));
		TextOut(ps.hdc, 0, 14000, g_fileName, strlen(g_fileName));
		drawArray (hwnd, ps.hdc);
		drawGraph (hwnd, ps.hdc);

        EndPaint(hwnd, &ps);

}

this code is in Cls_OnCommand

for (row=0;row<64;row++)
				{
			//		cbDOut(boardNum,PortNumB,row); //send row address to camera
					
					for (col=0;col<64;col++)
					{
			//			UDStat = cbDOut(boardNum, PortNumA, col); //send column address to camera
						captureData(Chan0, &(DataArrayA[row][col]), photoNumber, row, col);
						captureData(Chan0, &(DataArrayB[row][col]), photoNumber, row, col);
						captureData(Chan0, &(DataArrayC[row][col]), photoNumber, row, col);
						captureData(Chan0, &(DataArrayD[row][col]), photoNumber, row, col);
						g_X=col;
						g_Y=row;
						InvalidateRect(hwnd, NULL, FALSE);
						UpdateWindow(hwnd);
					
						
					}

g_RGB is calculated elsewhere.

I've tried writing all the values to an array/buffer, then repainting the window after a complete frame grab (using a loop). Is there another way to display this 64x64 array to the screen which will be faster, or am I just stuck with this? I was hoping for 10 frames per sec, which I'm nowhere near.
I'm not a C expert, and am using prettymuch straight C to write this.

 

[Old Nick]

Re: Painting Windows

I've managed to rearrange my code, and re-introduce the buffer and I am now getting a reasonable speed of repaint.

However the drawing of the array flickers, I have used the following code to repaint the window,

InvalidateRect(hwnd, NULL, FALSE);
UpdateWindow(hwnd);

the FALSE, meaning that the background is not repainted which reduces the flicker a lot, but the array still flickers badly.

Anyone have any ideas how to remedy this? Or is this just unavoidable without using some more advanced graphics libraries?

Cheers,

Nick