I need to implement mouse drag events which look something like this:
class MouseDragEvent
{
public:
uint m_btn;
uint m_x, m_y;
uint m_delta_x, m_delta_y;
};
I think I will need to check for WM_LBUTTONDOWN and WM_LBUTTONUP messages and manually find the change in x and y. Is there a drag message or a better way?
Start by detecting WM_LBUTTONDOWN. Record the starting coordinates where the mouse button was pressed. Check for WM_MOUSEMOVE, and when the mouse has moved outside the rectangle determined by GetSystemParameters(SM_CXDRAG) and GetSystemParameters(SM_CYDRAG) use SetCapture to capture the mouse. At this point continue responding to WM_MOUSEMOVE and check for WM_LBUTTONUP. You might want to change the mouse cursor at this point. Also check for WM_CAPTURECHANGED, which means the drag has been aborted. After the drag is complete call ReleaseCapture.
Edit: Most of this process can be automated with the DragDetect function. Call this function from the WM_LBUTTONDOWN handler.
There are drag-and-drop APIs in Windows (e.g. RegisterDragDrop), but concerned with the from- and to- windows (often in different applications), not the coordinates.
If you want to deal with delta-x and delta-y coordinated, then processing button down and button up messages is appropriate.
Did you try this:
http://www.codeproject.com/KB/miscctrl/rdragdropfiles.aspx
This may also be helpful:
http://msdn.microsoft.com/en-us/magazine/cc163915.aspx
Related
My question is:
How do i continuously get the mouse's position even when it isn't on any dialogs, in mfc?
It depends on your specific requirements. If you need to direct mouse input temporarily to a control you can call SetCapture. This will request the system to send all mouse messages to a specific window until you not longer need it by calling ReleaseCapture, or you lose it, when another window gains input focus. The latter is signaled through a WM_CAPTURECHANGED message.
If, on the other hand, you need continuous information about mouse positions you can install a timer (SetTimer) and call GetCursorPos.
You can always install a mouse hook. It's a bit overkill, but, it will give you what you want.
What is the most appropriate way of getting the mouse cursor position or button state on Windows (Windows 7 and above)? I previously used DirectInput, but I am not longer using it and do not wish to. I saw there is GetCursorPos, however, I do not see anything for getting mouse button states. I have read previously that just reading the window messages (such as WM_LBUTTONUP) was considered "slow" for real time applications, so I do not know of any other option.
If you want to poll/query the current cursor position, you can use GetCursorPos. To see the button states, use GetAsyncKeyState.
If you are implementing a message loop in a window, the notification you will get for a mouse movement is WM_MOUSEMOVE. You will be notified of mouse inputs through the notifications listed here.
WM_LBUTTONUP is as good as any window message, for windowed games is great because it is generated only when the mouse clicks the client area, so you can resize and move the window freely.
As an alternative to direct input, you can use raw inputs which take up some more code to initialize, but it's the best way to go with the mouse movement since WM_INPUT is generated when the physical mouse moves, not the cursor, so you can clip the cursor in the client area without worrying that the user may hit the side of the clip rect and the mouse movement messages won't be generated anymore.
link
How does one check if the mouse is over a certain HWND? I have tried using the WM_MOUSELEAVE and WM_MOUSEMOVE messages to keep track, but if you click a button and drag the mouse out of the button, it doesn't receive the WM_MOUSELEAVE until the mouse is released, which is too late, because:
When you click a button, the WM_COMMAND message is only sent if:
1. The mouse was originally depressed over the button
2. The mouse is over the button
3. The mouse is released over the button
I need to replicate this functionality.
To duplicate this functionality, just call SetCapture() so that mouse messages are sent to your window even if the mouse leaves it. You can read the current mouse position as it moves and determine if it is still over your window/button (I'm still not 100% sure what you are doing). And, when the mouse button is released, you can call ReleaseCapture() to restore where mouse messages are sent.
EDIT: Oh, and you can use the Windows API function WindowFromPoint() to determine which window the mouse is over.
This is built-in to Windows, it is called 'mouse capture', SetCapture(hWnd). It ensures you get mouse messages even though the mouse has moved outside of the window. You call it on the WM_LBUTTONDOWN message notification.
I want to allow a user to drag my Win32 window around only inside the working area of the desktop. In other words, they shouldn't be able to have any part of the window extend outside the monitor(s) nor should the window overlap the taskbar.
I'd like to do it in a way that does cause any stuttering. Handling WM_MOVE messages and calling MoveWindow() to reposition the window if it goes off works, but I don't like the flickering effect that's caused by MoveWindow().
I also tried handling WM_MOVING which prevents the need to call MoveWindow() by altering the destination rectangle before the move actually happens. This resolves the flickering problem, but another issue I run into is that the cursor some times gets aways from the window when a drag occurs allowing the user to drag the window around while the cursor is not even inside the window.
How do I constrain my window without running into these issues?
Windows are, ultimately, positioned via the SetWindowPos API.
SetWindowPos starts by validating its parameters by sending the window being sized or moved a WM_WINDOWPOSCHANGING message, and then a WM_WINDOWPOSCHANGED message notifying the window proc of the changed size and/or position.
DefWindowProc handling of these messages is to, in turn, send WM_GETMINMAXINFO and then WM_SIZE or WM_MOVE messages.
Anyway, handle WM_WINDOWPOSCHANGING to filter both user, and code, based attempts to position a window out of bounds.
Keep in mind that users with multi-monitor setups may have a desktop that extends into negative x- and y-coordinates, or that is not rectangular. Also, some users use alternative window managers such as LiteStep, which implement virtual desktops by moving them off-screen; if you try to fight this, your application will break for these users.
You can do this by handling the WM_MOVING message and changing the RECT pointed to by the lParam.
lParam: Pointer to a RECT structure with the current position of the window, in screen coordinates. To change the position of the drag rectangle, an application must change the members of this structure.
you may also want to handle WM_ENTERSIZEMOVE to know when the window is beginning to move, and WM_EXITSIZEMOVE
WM_GETMINMAXINFO is what you seem to be looking for.
In my Win32 app, I don't get WM_MOUSELEAVE messages when I hold down the left mouse button and quickly move the mouse pointer out of the window. But If I, holding down the left mouse button, start from the inside of the window and move slowly past the window edge, it'll generate a WM_MOUSELEAVE.
If I don't hold the left mouse button, I get WM_MOUSELEAVE messages every time no matter how fast the mouse pointer moves off the window.
What's the difference? What can I do to handle both cases properly?
EDIT: If I left click and hold, move out of the window and then let go of the left mouse button I get the WM_MOUSELEAVE message. But it's way too late.
On Windows 7, I was trying to make an owner-drawn button. I subclassed the button in order to get more accurate mouseenter/mouseleave events, essentially. When doing this, I used TrackMouseEvent when I got a WM_MOUSEMOVE because this is only posted when the mouse is over the button. If not already set, I would then set a boolean to specify that the mouse is over the button as well as call TrackMouseEvent so that whenever the mouse left, I could unset my boolean. However, like you, I was not getting the WM_MOUSELEAVE when I pressed and held the left mouse button on the owner drawn button, then dragging the mouse out. Upon releasing the mouse outside of the button, I suddenly get the WM_MOUSELEAVE message - way too late.
I determined that the reason for this behavior was that the default button proc's handling for WM_LBUTTONDOWN calls SetCapture, and releases it later. The usage of SetCapture is what is breaking our reception of the WM_MOUSELEAVE event. However, as a side-effect of SetCapture being called, we will get WM_MOUSEMOVE events even if the control is not under the mouse. Thus, my workaround is duplicating the logic in WM_MOUSELEAVE in the WM_MOUSEMOVE handler to unset my boolean that indicates the mouse is over the button if I get a mousemove event that is outside of my button's area. If SetCapture isn't actually used inside WM_LBUTTONDOWN for the default button proc, then we'll already be getting our WM_MOUSELEAVE message and the code will still work... so this workaround works in both cases.
Your problem sounds like it is likely identical to mine, so hopefully this helps you.
WM_MOUSELEAVE is so that you can detect the mouse leaving your window when you don't have capture. When you have capture, you are responsible for detecting that yourself (if you care).
so It doesn't make any sense to SetCapture AND TrackMouseEvent at the same time, you would use one or the other.
Now, if it would be more convenient for you to see the WM_MOUSELEAVE messages while you have capture, it's a relatively simple matter to do that by yourself in your message pump.
You would just add code that looks something like this between the GetMessage() and the DispatchMessage() calls in your message pump.
GetMessage(pmsg, ...);
.....
if ((IS_WITHIN(pmsg->message, WM_MOUSEFIRST, WM_MOUSELAST) ||
IS_WITHIN(pmsg->message, WM_NCMOUSEMOVE, WM_NCMBUTTONDBLCLK)) &&
MyMouseLeaveDetection(pmsg, g_hwndNotifyMouseLeave))
{
MSG msg = *pmsg;
msg.message = WM_MOUSELEAVE;
msg.hwnd = g_hwndNotifyMouseLeave; // window that want's
msg.lParam = 0xFFFFFFFF;
g_hwndNotifyMouseLeave = NULL;
DispatchMessage (&msg);
}
.....
TranslateMessage(pmsg);
DispatchMessage(pmsg);
As waiting for a WM_MOUSELEAVE is unreliable, the best solution I've found is to directly look at the mouse position during a WM_MOUSEMOVE. I compare the mouse position against the client area and if the position is outside then I handle that as a mouse leave.
I also make sure to call SetCapture when the mouse position is within the client area and ReleaseCapture when it leaves.