Command.mouseDragBegin Event

# Import fusion360utils folder, which includes event_utils.py.
from ...lib import fusion360utils as futil

# Global variable used to maintain a reference to all event handlers.
local_handlers = []

# "command_var" is a variable referencing a Command object.
# "command_mouseDragBegin" is the event handler function.
futil.add_handler(command_var.mouseDragBegin, command_mouseDragBegin, local_handlers=local_handlers)

# Event handler for the mouseDragBegin event.
def command_mouseDragBegin(args: adsk.core.MouseEventArgs):
    # Code to react to the event.
    app.log('In command_mouseDragBegin event handler.')

# Global variable used to maintain a reference to all event handlers.
handlers = []

# "command_var" is a variable referencing a Command object.
# "MyMouseDragBeginHandler" is the name of the class that handles the event.
onMouseDragBegin = MyMouseDragBeginHandler()
command_var.mouseDragBegin.add(onMouseDragBegin)
handlers.append(onMouseDragBegin)

# Event handler for the mouseDragBegin event.
class MyMouseDragBeginHandler(adsk.core.MouseEventHandler):
    def __init__(self):
        super().__init__()
    def notify(self, args: adsk.core.MouseEventArgs):
        # Code to react to the event.
        app.log('In MyMouseDragBeginHandler event handler.')

#include <Core/UserInterface/Command.h>
#include <Core/UserInterface/MouseEvent.h>
#include <Core/UserInterface/MouseEventHandler.h>
#include <Core/UserInterface/MouseEventArgs.h>

// Event handler for the mouseDragBegin event.
class MyMouseDragBeginEventHandler : public adsk::core::MouseEventHandler
{
public:
    void notify(const Ptr<MouseEventArgs>& eventArgs) override
    {
        // Code to react to the event.
        ui->messageBox("In MyMouseDragBeginEventHandler event handler.");
    }
} _mouseDragBegin;

// "command_var" is a variable referencing a Command object.
// Connect the handler function to the event.
Ptr<MouseEvent> mouseDragBeginEvent = command_var->mouseDragBegin();
if (!mouseDragBeginEvent)
    return;

bool isOk = mouseDragBeginEvent->add(&_mouseDragBegin);
if (!isOk)
    return;