edit slider

can be used in:
x-fader dialog, for pos
row dialog? for val
master dialog, for all except damping?

line width: DC pen optimization

Don't re-select the DC pen when it's already selected: the GetStockObject and SelectObject calls are considerably more expensive than the test that avoids them.

Benchmark comparing wide-line version to original (default patch, total time spent in Draw function, 1000 calls) reveals that the wide-line version takes 0.06% longer:

old way:
1.3425
1.3459
1.3457
1.3393
1.3419
1.3411
1.3449
AVG = 1.3430

new way:
1.3433
1.3453
1.3428
1.3405
1.3467
1.3431
1.3456
AVG = 1.3439

#include "benchmark.h"
#define MAXSAMPS 1000
double  samp[MAXSAMPS];
int samps;
bool done;
void  CWhorldView::Draw(HDC dc)
{
Benchmark b;

...

if (samps < MAXSAMPS) {
    samp[samps++] = b.Elapsed();
} else {
    if (!done) {
        FILE *fp = fopen("test.txt", "w");
        double  sum = 0;
        for (int i = 0; i < samps; i++) {
            fprintf(fp, "%f\n", samp[i]);
            sum += samp[i];
        }
        fclose(fp);
        done = 1;
        CString s;
        s.Format("%f", sum);
        AfxMessageBox(s);
    }
}

another test, using Pinwheel but with # sides set to 20 and no LFO, 2500 samples

new 21.6328
old 21.5634
0.32% slower

again:
new 21.6226
old 21.5317
0.42% slower

line width

creating a 1-pixel wide CPen and selecting it takes 85 micros (avg)
best case is around 8 micros, worst case is 850 to nearly 1000 (!)

m_Pen.DeleteObject();
m_Pen.CreatePen(PS_SOLID, 1, rp.Color);
SelectObject(dc, m_Pen);

setting DC pen color and selecting DC pen takes 2 micros (avg)
best case is 1 micro, worst case is 5

CPen way is anywhere from 2 to 1000 times slower
it's worth it to branch if you plan on doing a lot of 1-pixel wide lines

lotus cross

lotus cross looks cool with these master settings:
speed 458
zoom 54
damping 51
tempo 20

Alt (menu) key

BOOL CMainFrame::PreTranslateMessage(MSG* pMsg) 
{
    // in full screen mode, ignore the Menu key, so we don't go modal
    if (pMsg->message == WM_SYSKEYDOWN && pMsg->wParam == VK_MENU && m_IsFullScreen)
        return(TRUE);
    return CFrameWnd::PreTranslateMessage(pMsg);
}

zoom

zoom can position origin off-canvas, resulting in no rings

in SetNormOrigin, must clamp:

    m_Origin.x = CLAMP(round(m_Size.cx * m_st.NormOrg.x), m_Canvas.left, m_Canvas.right - 1);
    m_Origin.y = CLAMP(round(m_Size.cy * m_st.NormOrg.y), m_Canvas.top, m_Canvas.bottom - 1);

Optimizing message order in a message map is useless

MFC caches the most frequently used messages anyway, to avoid repeated table searching.

mouse damping

Zone rings does damping from the timer hook: It repeatedly computes the difference between the origin and the mouse cursor, multiplies the difference by a normalized damping factor, and adds the result to the origin. The damping factor ranges from 0..1, 0 = maximum damping, 1 = no damping. At damping = 1, the result is always equal to the entire distance between origin and cursor, so the origin jumps immediately to the cursor position. At damping = 0, the origin would never move at all. Maybe the damping factor is kept above zero to prevent this.