```
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
HPEN hPen;
HPEN hPenOld;
hPen = CreatePen(PS_SOLID, 3, RGB(255, 0, 0));
hPenOld = (HPEN)SelectObject(hdc, hPen);
// MoveToEx(hdc, 20, 10, NULL);
// LineTo(hdc, 200, 100);
SelectObject(hdc, hPenOld);
// DeleteObject(hPen);
// TODO: 在此處添加使用 hdc 的任何繪圖代碼...
//
double slope = 0.7;// 0.65;// 0.6123;// 0.6;// 0.75;// 當斜率大于1的時候,繪圖要反轉,即以y和 DeltaY為循環變量!
//1.75;// 0.75;// deltY/deltX=1.45 即斜率(y2-y1)/(x2-x1)=1.75
int x100 = 1000;// 100;
int x500 = 5000;// 500;
int y100 = 1000;// 100;
int y400 = 4000;// 400;
MoveToEx(hdc, 50, 10, NULL);
Ellipse(hdc, 1, 1, x100 / 100, y100 / 100);// , x500 / 10, y400 / 10);//這是光源 // 15, 15, 130, 130);
Rectangle(hdc, x100/10, y100/10, x500/10, y400/10);
INT64 maxY; maxY = 2 ^ 63 - 1;
INT64 x1 = 100; double dx1 = (double)x1;
INT64 x2 = x1; double dx2 = (double)x2;
INT64 y1 = 100; double dy1 = (double)y1;
INT64 y2 = y1; double dy2 = (double)y2;
int flagx = 1; int flagy = 1; int flagy0 = 0;// -1;
//flagy0比較晦澀難懂, 有時精密計算的結果是 y2多次等于邊界 y400等,當是第一次的時候 就反轉
//
//for (INT64 ii = 100; ii < 99999; ++ii) {//for110
for (INT64 ii = 100; ii < 999999; ++ii) {//for110 //for (INT64 ii = 100; ii < 9999999; ++ii) {//for110
//x1 = ixi;// / 10; //精密到 0.1
//dx1 = (double)x1;
aboutFlag:
int needDrawflag = 0;
//x1 = (int)dx1;
if (x100 >= (x1/1) ) { //if (100 == (x1/10) ) {
flagx = 1; needDrawflag = 1;
}
if (x500 <= (x1/1)) {//if (x500 == (x1/10)) {
flagx = -1; needDrawflag = 1;
}
y1 = (int)dy1;//把y的坐標找出來變成整數
if (y100 >= y1) {//if (y100 == y1) {
flagy = 1; needDrawflag = 1;
}
//if (0==flagy0 && y400 == (int)(y1/1) ) { //if (y400 == (int)(y1/10) || (4000==(int)y1 ) ) {
if ( y400 <= (int)y1) { //(int)(y1 / 1)) {
flagy = -1; flagy0 = 2; needDrawflag = 1;
}
if (100 == x1 && 100 == y1) { flagx = 1; flagy = 1; needDrawflag = 1;
} //這個點特殊,這是光源,或笛卡爾坐標原點
//aboutFlag-End;
if (1 == needDrawflag) { needDrawflag = 0;
//about 顏色
hPen = CreatePen(PS_SOLID, 1, RGB(55, 200, 0));
hPenOld = (HPEN)SelectObject(hdc, hPen);
//MoveToEx(hdc, 20, 10, NULL);
// LineTo(hdc, 200, 100);
// SelectObject(hdc, hPenOld);
//about 顏色-End
LineTo(hdc, x1/10,y1/10);
SelectObject(hdc, hPenOld);
}
label_Y_as_aVar:
x2 = x1 + (flagx) * 1;
dx2 = dx1 + (flagx) * 1;
INT64 deltaX = labs(long(x2 - x1));
dy2 = (flagy)*deltaX*slope + dy1;
// SetPixel(hdc, (x2/10), (int)(dy2/10), RGB(1, 200, 0));
//
labelEnd990:
x1 = x2;
dx1 = dx2;
if (y1 != y2) { flagy0 = 0; }//此舉回復反轉開關
y1 = y2;
dy1 = dy2;
}//for110
//
//
EndPaint(hWnd, &ps);
}//case WM_PAINT:
break;
case WM_DESTROY:
```
運行結果
（左上角小圓象征光源）
用時：不到1秒，(0.1秒？）
當：
for (INT64 ii = 100; ii < 2999999; ++ii) {// 6個九9 時：for110 //999999
7個九：
徹底被“著色”
并且用時不到一秒鐘
測試筆記本電腦：
macbookPro2011(I7CPU，8G內存）
