Minigui学习---鼠标获取和坐标在不同区域转换
(1)设置鼠标的所在的Wnd：
函数定义（window.h文件中定义的）：
MG_EXPORT HWND GUIAPI GetCapture(void); //Retrives the handle to the window (if any) that has captured the mouse.return The handle to the window that has captured the mouse, 0 for no window captures the mouse.
Only one window at a time can capture the mouse; this window receives mouse input whether or not the cursor is within its borders.
MG_EXPORT HWND GUIAPI SetCapture(HWND hWnd);//Sets the mouse capture to the specified window. param hWnd The handle to the window.return The old capture window. Once a window has captured the mouse, all mouse input is directed to that window, regardless of whether the cursor is within the borders of that window. Only one window at a time can capture the mouse.
MG_EXPORT void GUIAPI ReleaseCapture(void); //Releases the mouse capture from a window and restores normal mouse input processing
例如：
printf("hjhe--hwnd=%x\n",hWnd);
printf("hjhe--getCapture=%x\n",GetCapture());
SetCapture(hWnd);
printf("hjhe--1 getCapture=%x\n",GetCapture());
返回值为：
hjhe--hwnd=8c04cc0
hjhe--getCapture=0
hjhe--1 getCapture=8c04cc0
（2）屏幕和窗口坐标转换
函数定义（window.h文件中定义的）：
/*
* \param hWnd The handle to the window.
* \param x The pointer to the x coordinate.
* \param y The pointer to the y coordinate.
*/
MG_EXPORT void GUIAPI ClientToScreen (HWND hWnd, int* x, int* y);//converts the client coordinates of the specified point (*x,*y) in the specified window hWnd to screen coordinates.
/**
* \param hWnd The handle to the window.
* \param x The pointer to the x coordinate.
* \param y The pointer to the y coordinate.
*/
MG_EXPORT void GUIAPI ScreenToClient (HWND hWnd, int* x, int* y);//converts the screen coordinates of the specified point (*x,*y) to client coordinates of the specified window hWnd
注意：Screen coordinates是包括标题栏、边框等在内的所有部分；而client coordinates仅是除去标题栏、边框的客户绘制区域；所以当我们在创建窗体的时候将窗口的style设置为none（即 CreateInfo.dwStyle = WS_VISIBLE | WS_NONE ），那么窗口将没有 标题栏和边框，所以这两个坐标是一致的；但是如果设置了标题栏和边框（即：CreateInfo.dwStyle = WS_VISIBLE | WS_BORDER |WS_CAPTION;），那么这两个坐标就是不一致的，他们之间的差值是：标题栏的高度和边框的宽度
注意：当处理过程接收到MSG_LBUTTONUP、MSG_MOUSEMOVE、MSG_LBUTTONDOWN、MSG_RBUTTONDOWN等消息时，通过int x = LOWORD (lParam); int y = HIWORD (lParam);解析到的坐标为client coordinates坐标值。
注意：通过GetWindowRect获取到的是client 区域的大小，而不是Screen区域大小；可以通过ClientToScreen函数将其转换为Screen区域大小。
例如：
RECT rcx;
GetWindowRect(hMainWnd, &rcx);
printf("hjhe--hMainWnd rcx.left=%d,rcx.top=%d,rcx.right=%d,rcx.bottom=%d\n",rcx.left,rcx.top,rcx.right,rcx.bottom);
GetWindowRect(hWnd, &rcx);
printf("hjhe--hWnd rcx.left=%d,rcx.top=%d,rcx.right=%d,rcx.bottom=%d\n",rcx.left,rcx.top,rcx.right,rcx.bottom);
ClientToScreen(hMainWnd, &rcx.left, &rcx.top);
ClientToScreen(hMainWnd, &rcx.right, &rcx.bottom);
printf("hjhe--rcx.left=%d,rcx.top=%d,rcx.right=%d,rcx.bottom=%d\n",rcx.left,rcx.top,rcx.right,rcx.bottom);
返回值为：
hjhe--hMainWnd rcx.left=0,rcx.top=0,rcx.right=240,rcx.bottom=320
hjhe--hWnd rcx.left=0,rcx.top=0,rcx.right=240,rcx.bottom=320
hjhe--rcx.left=2,rcx.top=23,rcx.right=242,rcx.bottom=343
从返回值可以看出，Screen区域比Client区域高13，宽2，即可知道标题栏目高为13，边框宽度为2。
例如：
int x = LOWORD (lParam);
int y = HIWORD (lParam);
printf("hjhe--2 x=%d,y=%d\n",x,y);
ClientToScreen (hWnd, &x, &y);
printf("hjhe--1 x=%d,y=%d\n",x,y);
ScreenToClient(hWnd, &x, &y);
printf("hjhe--x=%d,y=%d\n",x,y);
返回值为：
hjhe--2 x=176,y=58
hjhe--1 x=178,y=81
hjhe--x=176,y=58
从返回值中可以验证：Screen区域比Client区域高13。
（3）window坐标和屏幕坐标转换
函数定义（window.h文件中定义的）：
/**
*
* \param hWnd The handle to the window.
* \param x The pointer to the x coordinate.
* \param y The pointer to the y coordinate.
*/
MG_EXPORT void GUIAPI WindowToScreen (HWND hWnd, int* x, int* y);//converts the window coordinates of the specified point (*x,*y) in the specified window \a hWnd to the screen coordinates
/**
*
* \param hWnd The handle to the window.
* \param x The pointer to the x coordinate.
* \param y The pointer to the y coordinate.
*/
MG_EXPORT void GUIAPI ScreenToWindow (HWND hWnd, int* x, int* y);//converts the screen coordinates of the specified point (*x,*y) to the window coordinates of the specfied window \a hWnd