使用GDI绘制抛物线,双曲线。放大缩小和移动。
时间: 2023-06-13 19:08:38 浏览: 178
以下是使用GDI绘制抛物线和双曲线的示例代码,包括放大、缩小和移动功能:
```c++
#include <windows.h>
#include <cmath>
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Parabola and Hyperbola");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = szAppName;
if (!RegisterClass(&wndclass))
{
MessageBox(NULL, TEXT("This program requires Windows NT!"),
szAppName, MB_ICONERROR);
return 0;
}
hwnd = CreateWindow(szAppName, TEXT("Parabola and Hyperbola"),
WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN | WS_CLIPSIBLINGS,
CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInstance, NULL);
ShowWindow(hwnd, iCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static int cxClient, cyClient;
static int xCenter, yCenter;
static double scaleX = 1.0, scaleY = 1.0;
static double xMove = 0.0, yMove = 0.0;
static POINT ptPrev;
static bool bDragging = false;
switch (message)
{
case WM_SIZE:
cxClient = LOWORD(lParam);
cyClient = HIWORD(lParam);
xCenter = cxClient / 2;
yCenter = cyClient / 2;
return 0;
case WM_KEYDOWN:
switch (wParam)
{
case VK_ADD:
scaleX *= 1.1;
scaleY *= 1.1;
InvalidateRect(hwnd, NULL, TRUE);
return 0;
case VK_SUBTRACT:
scaleX /= 1.1;
scaleY /= 1.1;
InvalidateRect(hwnd, NULL, TRUE);
return 0;
case VK_LEFT:
xMove -= 10.0 / scaleX;
InvalidateRect(hwnd, NULL, TRUE);
return 0;
case VK_RIGHT:
xMove += 10.0 / scaleX;
InvalidateRect(hwnd, NULL, TRUE);
return 0;
case VK_UP:
yMove -= 10.0 / scaleY;
InvalidateRect(hwnd, NULL, TRUE);
return 0;
case VK_DOWN:
yMove += 10.0 / scaleY;
InvalidateRect(hwnd, NULL, TRUE);
return 0;
}
return 0;
case WM_LBUTTONDOWN:
SetCapture(hwnd);
ptPrev.x = LOWORD(lParam);
ptPrev.y = HIWORD(lParam);
bDragging = true;
return 0;
case WM_MOUSEMOVE:
if (bDragging)
{
xMove += (LOWORD(lParam) - ptPrev.x) / scaleX;
yMove += (HIWORD(lParam) - ptPrev.y) / scaleY;
InvalidateRect(hwnd, NULL, TRUE);
ptPrev.x = LOWORD(lParam);
ptPrev.y = HIWORD(lParam);
}
return 0;
case WM_LBUTTONUP:
ReleaseCapture();
bDragging = false;
return 0;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
// set up coordinate transformation
SetMapMode(hdc, MM_ANISOTROPIC);
SetViewportOrgEx(hdc, xCenter, yCenter, NULL);
SetWindowExtEx(hdc, cxClient, -cyClient, NULL);
SetViewportExtEx(hdc, (int)(cxClient / scaleX), (int)(cyClient / scaleY), NULL);
SetWindowOrgEx(hdc, (int)(-xMove * scaleX), (int)(yMove * scaleY), NULL);
// draw parabola
MoveToEx(hdc, -1000, (int)(1000 * 1000), NULL);
for (int x = -1000; x <= 1000; x++)
{
int y = (int)(-x * x / 1000.0);
LineTo(hdc, x, y);
}
// draw hyperbola
MoveToEx(hdc, -1000, 0, NULL);
for (int x = -1000; x <= -1; x++)
{
int y = (int)(1000 * sqrt(1.0 + x * x / 1000.0));
LineTo(hdc, x, y);
}
for (int x = 1; x <= 1000; x++)
{
int y = (int)(-1000 * sqrt(1.0 + x * x / 1000.0));
LineTo(hdc, x, y);
}
EndPaint(hwnd, &ps);
return 0;
}
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}
```
在上述代码中,我们使用 `SetMapMode` 和 `SetViewportOrgEx` 等 GDI 函数设置了坐标系的变换,使得我们可以方便地实现放大、缩小和移动功能。抛物线和双曲线的绘制都是通过 `LineTo` 函数实现的,具体细节可以参考代码注释。
阅读全文