Question

VC++,谁帮我改成用不同颜色的线画线？

CPen penRed;//声明画笔对象,并创建宽度为3的红色实线画笔
penRed.CreatePen(PS_SOLID,1,RGB(255,0,0));
//使用新的画笔,保存原来的画笔以便恢复;
CPen *pOldPen;
pOldPen=pDC->SelectObject(&penRed);
for(t=0; t<=360;t=t++)
{//画出了李萨如图像部分
x=x0-a1*sin(w1*t*PI/180+u1);
y=y0-a2*sin(w2*t*PI/180+u2);
//这里最好用黑色的点把起始点给标志出来
if(t==0)
pDC-> MoveTo(x,y); //确定起始位置，从x0,y0开始
pDC-> LineTo(x,y);
pDC-> MoveTo(x,y);
}
最好能把起点用黑颜色或者一种颜色表示
画好了的用一种颜色，比如红色
正在画的用另外一种颜色，比如蓝色
谢谢
我追加给分，
画过的线颜色不一样也可以，只要能看出不一样和正在划线就可以

Answer 1

你问的是MFC吧？我没学过，但我想道理差不多，你应该参考一下API绘图的技巧。其实这是个小动画！
以下程序，使用Windows GDI函数随机画直线，当前直线的起点是前一条直线的终点。一开始的起点使用白色表示，为了明显，我特意把它画得大一点。画过的直线使用红色表示。正在画的直线使用蓝色表示。
特别注意：为了让你看得更清楚，我特意延时1秒，换句话说，当你点击窗口右上角的“X”关闭按钮时，要等一段时间（不会太长！）窗口才会关闭，注意！

下面是源程序，要想尝试请创建Win32 Application工程测试。

// INCLUDES ///////////////////////////////////////////////
#define WIN32_LEAN_AND_MEAN // 跟 MFC 说Bye-Bye

#include <windows.h>
#include <windowsx.h>
#include <stdlib.h>
#include <time.h>

// defines for windows
#define WINDOW_CLASS_NAME "WINCLASS1"

#define START_X 50
#define START_Y 50

// 全局变量 ////////////////////////////////////////////////
HWND main_window_handle = NULL;
HINSTANCE hinstance_app = NULL;
HDC hdc;
HPEN hpen;
int line_x = 0,line_y = 0;
int line_x1 = 0,line_y1 = 0;
char buffer[80];

// 窗口过程 //////////////////////////////////////////////
LRESULT CALLBACK WindowProc(HWND hwnd,
UINT msg,
WPARAM wparam,
LPARAM lparam)
{

PAINTSTRUCT ps;
HDC hdc;

switch(msg)
{
case WM_CREATE:
{

return(0);
} break;

case WM_PAINT:
{

hdc = BeginPaint(hwnd,&ps);

EndPaint(hwnd,&ps);

return(0);
} break;

case WM_DESTROY:
{

PostQuitMessage(0);

return(0);
} break;

default:break;

}

return (DefWindowProc(hwnd, msg, wparam, lparam));

} // end WinProc

///////////////////////////////////////////////////////////

int mypcluna_Main(void *parms = NULL, int num_parms = 0)
{

hdc=GetDC(main_window_handle);

if(hpen)
DeleteObject(hpen);

hpen=CreatePen(PS_SOLID,1,RGB(255,0,0));
SelectObject(hdc,hpen);

MoveToEx(hdc,line_x,line_y,NULL);
LineTo(hdc,line_x1,line_y1);

DeleteObject(hpen);

hpen=CreatePen(PS_SOLID,1,RGB(0,0,255));
SelectObject(hdc,hpen);

line_x = line_x1;
line_y = line_y1;
MoveToEx(hdc,line_x,line_y,NULL);

line_x1 = rand()%640;
line_y1 = rand()%480;

LineTo(hdc,line_x1,line_y1);

SetPixel(hdc,START_X,START_Y,RGB(255,255,255));
SetPixel(hdc,START_X-1,START_Y-1,RGB(255,255,255));
SetPixel(hdc,START_X-1,START_Y+1,RGB(255,255,255));
SetPixel(hdc,START_X+1,START_Y-1,RGB(255,255,255));
SetPixel(hdc,START_X+1,START_Y+1,RGB(255,255,255));
SetPixel(hdc,START_X,START_Y+1,RGB(255,255,255));
SetPixel(hdc,START_X,START_Y-1,RGB(255,255,255));
SetPixel(hdc,START_X-1,START_Y,RGB(255,255,255));
SetPixel(hdc,START_X+1,START_Y,RGB(255,255,255));

ReleaseDC(main_window_handle,hdc);

Sleep(1000);

return(1);

}

////////////////////////////////////////////////////////////

int mypcluna_Init(void *parms = NULL, int num_parms = 0)
{
line_x = START_X;
line_y = START_Y;
line_x1 = line_x;
line_y1 = line_y;

srand( (unsigned)time( NULL ) );

return(1);

}

/////////////////////////////////////////////////////////////

int mypcluna_Shutdown(void *parms = NULL, int num_parms = 0)
{
if(hpen)
DeleteObject(hpen);

return(1);

}

// WINMAIN ////////////////////////////////////////////////
int WINAPI WinMain( HINSTANCE hinstance,
HINSTANCE hprevinstance,
LPSTR lpcmdline,
int ncmdshow)
{

WNDCLASSEX winclass;
HWND hwnd;
MSG msg;

winclass.cbSize = sizeof(WNDCLASSEX);
winclass.style = CS_DBLCLKS | CS_OWNDC |
CS_HREDRAW | CS_VREDRAW;
winclass.lpfnWndProc = WindowProc;
winclass.cbClsExtra = 0;
winclass.cbWndExtra = 0;
winclass.hInstance = hinstance;
winclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
winclass.hCursor = LoadCursor(NULL, IDC_ARROW);
winclass.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
winclass.lpszMenuName = NULL;
winclass.lpszClassName = WINDOW_CLASS_NAME;
winclass.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

hinstance_app = hinstance;

if (!RegisterClassEx(&winclass))
return(0);

if (!(hwnd = CreateWindowEx(NULL,
WINDOW_CLASS_NAME,
"T3D Game Console Version 1.0",
WS_OVERLAPPEDWINDOW | WS_VISIBLE,
0,0,
640,480,
NULL,
NULL,
hinstance,
NULL)))
return(0);

main_window_handle = hwnd;

mypcluna_Init();

while(TRUE)
{

if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))
{

if (msg.message == WM_QUIT)
break;

TranslateMessage(&msg);

DispatchMessage(&msg);
}

mypcluna_Main();

}

mypcluna_Shutdown();

return(msg.wParam);

} // end WinMain

///////////////////////////////////////////////////////////

Answer 2

你要画个李萨如图像，那不直接就画出来了，什么叫正在画的，你上面代码又没有延时，说“已经画”和“正在画的”有意义吗？

换颜色就换种画笔就行了。
画点SetPixel
要突出某个点可以画个小圆