我正在编写一个 GDI 应用程序（黑色背景和星空动画）。我需要窗口拖动代码方面的帮助。它可以完美地拖动，但是通过选择窗口的上部（标题）及其附近的区域来拖动它，窗口会丢失。我不知道我做错了什么。我尝试做其他事情，但动画停止了一秒钟然后继续，我不希望这样。
#include <Windows.h>
#include <iostream>
#include <windowsx.h>
#define IDB_EXIT 102
PAINTSTRUCT ps;
HDC hdc;
RECT starfield_rc;
int WIDTH = 350;
int HEIGHT = 400;
const int numStars = 50;
const int starSpeed = 1;
struct Star
{
int x, y;
int speed;
};
const int NUM_STARS = 100;
Star stars[NUM_STARS];
HDC hdcMem;
HBITMAP hbmMem;
HBITMAP hbmOld;
void starfield(HDC hdc, int x, int y, RECT *rc)
{
int width = 335;
rc->left = x;
rc->top = y;
rc->right = width;
rc->bottom = 249;
HDC hdcMem = CreateCompatibleDC(hdc);
HBITMAP hbmMem = CreateCompatibleBitmap(hdc, width, 215);
HBITMAP hbmOld = (HBITMAP)SelectObject(hdcMem, hbmMem);
HBRUSH brush = CreateSolidBrush(RGB(0, 0, 0));
FillRect(hdcMem, rc, brush);
DeleteObject(brush);
for (int i = 0; i < NUM_STARS; i++)
{
SetPixel(hdcMem, stars[i].x, stars[i].y, RGB(255, 255, 255));
stars[i].x = (stars[i].x + stars[i].speed) % width;
}
BitBlt(hdc, x, y, width, 215, hdcMem, 0, 0, SRCCOPY);
SelectObject(hdcMem, hbmOld);
DeleteObject(hbmMem);
DeleteDC(hdcMem);
}
// main function
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lparam);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int nCmdShow)
{
for (int i = 0; i < NUM_STARS; i++)
{
stars[i].x = rand() % 340;
stars[i].y = rand() % 249;
stars[i].speed = rand() % 3 + 1;
}
TCHAR appname[] = TEXT("Template");
WNDCLASS wndclass;
MSG msg;
HWND hwnd;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wndclass.hInstance = hInstance;
wndclass.lpfnWndProc = WndProc;
wndclass.lpszClassName = appname;
wndclass.lpszMenuName = NULL;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
// check this window class is registered or not
if (!RegisterClass(&wndclass))
{
MessageBox(NULL, TEXT("Window class is not registered"), TEXT("Error...."), MB_ICONERROR);
return 0;
}
hwnd = CreateWindowEx(WS_EX_LAYERED | WS_EX_COMPOSITED,
appname, // window name
appname, // window text
WS_VISIBLE | WS_SYSMENU | WS_POPUP, // set POPUP window style for no border & controls
100, // window position x
100, // window position y
WIDTH, // width
HEIGHT, // height
NULL,
NULL,
hInstance,
NULL);
// show & update created window
SetTimer(hwnd, 1, 10, NULL); // Set a timer to trigger every 100ms
ShowWindow(hwnd, nCmdShow);
// get message from queue
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
bool isSizingOrMoving = false;
// WndProc function
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
HINSTANCE hIns;
HWND exit_button, gen_button, title, license;
LRESULT move = NULL;
static int xClick;
static int yClick;
switch (message)
{
case WM_CREATE:
{
exit_button = CreateWindow(TEXT("BUTTON"), NULL, WS_CHILD | WS_VISIBLE | BS_BITMAP,
250, 360, 70, 30, hwnd, (HMENU)100, hIns, 0);
HBITMAP exitImg = (HBITMAP)LoadImageA(GetModuleHandleA(nullptr), (LPCSTR)MAKEINTRESOURCE(IDB_EXIT), IMAGE_BITMAP, 0, 0, NULL);
title = CreateWindow(TEXT("STATIC"), TEXT("Hello"), WS_CHILD | WS_VISIBLE, 150, 5, 120, 20, hwnd, 0, hIns, 0);
SendMessageW(exit_button, BM_SETIMAGE, IMAGE_BITMAP, (LPARAM)exitImg);
}
break;
case WM_PAINT:
{
PAINTSTRUCT ps;
hdc = BeginPaint(hwnd, &ps);
starfield(hdc, 6, 31, &starfield_rc);
EndPaint(hwnd, &ps);
break;
}
case WM_TIMER:
InvalidateRect(hwnd, &starfield_rc, FALSE);
break;
case WM_COMMAND:
switch (wParam)
{
case 100:
PostQuitMessage(EXIT_SUCCESS);
return 0;
}
break;
case WM_CTLCOLORSTATIC:
{
hdc = (HDC)wParam;
return (LRESULT)CreateSolidBrush(RGB(0, 0, 0)); // black and white
break;
}
case WM_CTLCOLOREDIT:
{
hdc = (HDC)wParam;
return (LRESULT)CreateSolidBrush(RGB(0, 0, 0)); // black and white
break;
}
case WM_LBUTTONDOWN:
// Get the click position
xClick = LOWORD(lParam);
yClick = HIWORD(lParam);
if (xClick < 0 && yClick < 0)
{
return 1;
}
// Restrict mouse input to current window
SetCapture(hwnd);
return 1;
case WM_LBUTTONUP:
{
// Window no longer requires all mouse input
ReleaseCapture();
return 1;
}
case WM_MOUSEMOVE:
{
if (GetCapture() == hwnd) // Check if this window has mouse input
{
// Get the window's screen coordinates
RECT rcWindow;
GetWindowRect(hwnd, &rcWindow);
// Get the current mouse coordinates
int xMouse = LOWORD(lParam);
int yMouse = HIWORD(lParam);
// Calculate the new window coordinates
int xWindow = rcWindow.left + xMouse - xClick;
int yWindow = rcWindow.top + yMouse - yClick;
// Set the window's new screen position (don't resize or change z-order)
SetWindowPos(hwnd, NULL, xWindow, yWindow, 0, 0,
SWP_NOSIZE | SWP_NOZORDER);
}
break;
}
case WM_DESTROY:
PostQuitMessage(EXIT_SUCCESS);
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}
这里的许多问题（使用统一变量、边缘情况等）是，在
WM_MOUSEMOVESetWindowPosDefaultWndProc // Get the current mouse coordinates
int xMouse = GET_X_LPARAM(lParam);
int yMouse = GET_Y_LPARAM(lParam);
请勿使用 LOWORD 或 HIWORD 宏来提取 x- 和 y- 光标位置的坐标，因为这些宏返回 在具有多个显示器的系统上结果不正确。系统具有 多个显示器可以具有负 x 和 y 坐标，并且 LOWORD HIWORD 将坐标视为无符号量。
具有虚拟桌面的现代 Windows 也是多屏幕的，因此如果您尝试在任务栏附近“跨”屏幕边框，可能会遇到窗口“跳”出屏幕的问题。
另外，至少检查一下是否成功（您不需要将其传递给）：
if (SetWindowPos(hwnd, NULL, xWindow, yWindow, 0, 0,
SWP_NOSIZE | SWP_NOZORDER)) {
return 0; // MUST return zero of WM_MOUSEMOVE is processed
}