GDI-贝塞尔曲线的例子

最新推荐文章于 2023-11-29 22:06:43 发布

原创最新推荐文章于 2023-11-29 22:06:43 发布 · 823 阅读

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CC 4.0 BY-SA版权

本文介绍了如何使用Windows API和数学函数实现贝塞尔曲线绘制，并通过窗口事件处理用户输入来调整曲线形状。通过事件监听和绘图函数，实现了响应鼠标点击和移动操作来实时更新和显示曲线，为用户提供直观的图形艺术创作体验。

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#include <Windows.h>
#include <math.h>

#define NUM 1000
#define TWOPI (2*3.14159)

void DrawBezier(HDC hdc, POINT apt[])
{
PolyBezier(hdc,apt,4);
MoveToEx(hdc,apt[0].x,apt[0].y,NULL);
LineTo(hdc,apt[1].x,apt[1].y);

MoveToEx(hdc,apt[2].x,apt[2].y,NULL);
LineTo(hdc,apt[3].x,apt[3].y);
};

LRESULT CALLBACK WindowProc(
HWND hwnd,      // handle to window
UINT uMsg,      // message identifier
WPARAM wParam, // first message parameter
LPARAM lParam   // second message parameter
)
{
int cxClient,cyClient;
HDC hdc;

PAINTSTRUCT ps;
static POINT apt[4];

switch(uMsg)
{
case WM_CHAR:
  {
   return 0;
  }break;
case WM_LBUTTONDOWN:
case WM_RBUTTONDOWN:
case WM_MOUSEMOVE:
  {
   if(wParam &MK_LBUTTON || wParam &MK_RBUTTON)
   {
    hdc = GetDC(hwnd);
    SelectObject(hdc,GetStockObject(WHITE_PEN));
    DrawBezier(hdc,apt);

    if(wParam & MK_LBUTTON)
    {
     apt[1].x = LOWORD(lParam);
     apt[1].y = HIWORD(lParam);
    }
    if(wParam & MK_RBUTTON)
    {
     apt[2].x = LOWORD(lParam);
     apt[2].y = HIWORD(lParam);
    }
    SelectObject(hdc,GetStockObject(BLACK_PEN));
    DrawBezier(hdc,apt);
    ReleaseDC(hwnd,hdc);

   }
  }break;
case WM_PAINT:
  {
   //hdc = BeginPaint(hwnd,&ps);
   /*
   MoveToEx(hdc,0,cyClient/2,NULL);

   LineTo(hdc,cxClient,cyClient/2);
   for(i = 0;i<NUM;i++)
   {
    apt[i].x = i*cxClient/NUM;
    apt[i].y = (int)(cyClient /2*(1 - sin(TWOPI*i/NUM)));
   }
   Polyline(hdc,apt,NUM);
   */
   //Rectangle(hdc,cxClient/8,cyClient/8,7*cxClient/8,7*cyClient/8);
   //MoveToEx(hdc,0,0,NULL);
   //LineTo(hdc,cxClient,cyClient);
   //Ellipse(hdc,cxClient/8,cyClient/8,7*cxClient/8,7*cyClient/8);
   //Ellipse(hdc,cxClient/8,cxClient/8,cxClient,cyClient);
   //EndPaint(hwnd,&ps);

InvalidateRect(hwnd,NULL,TRUE);

hdc = BeginPaint(hwnd,&ps);

DrawBezier(hdc,apt);

EndPaint(hwnd,&ps);

  }break;
case WM_SIZE:
  {
   cxClient = LOWORD(lParam);
   cyClient = HIWORD(lParam);

apt[0].x = cxClient/4;
apt[0].y = cyClient/2;

apt[1].x = cxClient/2;
apt[1].y = cyClient/4;

apt[2].x = cxClient/2;
apt[2].y = 3*cyClient/4;

apt[3].x = 3*cxClient/4;
apt[3].y = cyClient/2;

  }break;
case WM_DESTROY:
  PostQuitMessage(0);
default:
  return DefWindowProc(hwnd,uMsg,wParam,lParam);
}

return 0;
}

int WINAPI WinMain(
HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nShowCmd )
{
//配置属性
WNDCLASS wndclass;

wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
//窗体背景
wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
//鼠标样式
wndclass.hCursor = LoadCursor(NULL,IDC_HAND);
//窗体图标
wndclass.hIcon = LoadIcon(NULL,IDI_WARNING);
//窗体句柄
wndclass.hInstance = hInstance;
//消息处理
wndclass.lpfnWndProc = WindowProc;

wndclass.lpszClassName = "Magic";

wndclass.lpszMenuName = NULL;

wndclass.style = CS_VREDRAW|CS_HREDRAW;

RegisterClass(&wndclass);

HWND hwnd = CreateWindow("Magic","图片艺术",WS_OVERLAPPEDWINDOW,
0,0,600,400,NULL,NULL,hInstance,NULL);

ShowWindow(hwnd,SW_SHOWNORMAL);

UpdateWindow(hwnd);

MSG msg;

BOOL flag = 0;

while((flag = GetMessage(&msg,NULL,0,0))!=0)
{
  if(flag ==-1)
  {

  }
  else
  {
   TranslateMessage(&msg);
   DispatchMessage(&msg);
  }
}

return msg.wParam;
}