I have a Drag() method on form_MouseDown event. I also have a click event on the form. The problem is that if I click on the form, MouseDown event gets triggered and it never gets the chance to trigger click event.
What is the best way to solve this issue? I was thinking counting pixels if the form is actually dragged, but there has to be a better way. Any suggestions?
I was thinking counting pixels if the form is actually dragged, but there has to be a better way.
Nope, that's exactly how you have to do it.
This isn't just a software limitation; it's very much a practical one as well. If you think through the problem from a user's perspective, you'll immediately see the problem as well as the solution. Ask yourself, what is the difference between a click and a drag?
Both of them start with the mouse button going down over the object, but one of them ends with the mouse button going back up over the object in the same position and the other one ends with the mouse button going back up in a completely different position.
Since time machines haven't been perfected yet, you have no way of knowing this in advance.
So yes, you need to maintain some kind of a distance threshold, and if the pointer moves outside of that distance threshold while it is down over the object, then you consider it a drag. Otherwise, you consider it a click.
That distance threshold should not be 0. The user should not be required to hold the mouse completely still in order to initiate a click. A lot of users are sub-par mousers. They are very likely to twitch slightly when trying to click. If the threshold is 0, they'll end up doing a lot of inadvertent dragging when they try to click.
Of course, you don't actually have to worry about any of this or compute the drag threshold yourself. Instead, use the Windows default values, obtainable by calling the GetSystemMetrics function and specifying either SM_CXDRAG or SM_CYDRAG. (These might be exposed somewhere by the WinForms framework, but I don't think so. It's just as easy to P/Invoke them yourself.)
const int SM_CXDRAG = 68;
const int SM_CYDRAG = 69;
[DllImport("user32.dll")]
static extern int GetSystemMetrics(int index);
Point GetDragThreshold()
{
return new Point(GetSystemMetrics(SM_CXDRAG), GetSystemMetrics(SM_CYDRAG));
}
In the field of UX/UI, this sort of thing is called hysteresis or debouncing, by analogy to the use of these terms in physics and electronics.
I found this solution, although it is for a double-click and a mouse down events:
void pictureBox_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left && e.Clicks ==1)
{
PictureBox pb = (PictureBox)sender;
DoDragDrop((ImageData)pb.Tag, DragDropEffects.Copy);
}
}
source: http://code.rawlinson.us/2007/04/c-dragdrop-and-doubleclick.html
Unfortunatelly, at the point of time when "button-is-pressed" you don't know yet if the desired action is just a click or a drag-drop. You will find it out it later.
For a click, the determinant is "no movement" and "button up".
For a drag, the determinant is "movement" and "button up".
Hence, to disambiguate those interactions, you have to track not only the buttons, but also the movement. You do not need to track the overall movement, only the movement between button-down and button-up is interesting.
Those events are therefore a good place to start/stop the Mouse.Capture mechanisms (to dynamically present drag adorners and drop location hints), or, in simplier form - to store the origin and target of movement vector and check if the distance is > D (even if movement occurred, there should be some safe minimal distance within which the DRAG is canceleed. The mouse is "jaggy" sometimes, and people would really don't like your app to start dragging when they double click at the end of fast mouse pointer movement :) )
Related
[please see update at the end]
I'm an old stack overflow user (as most developers on, you know, Earth), but that's my first question here.
I'm trying to use an "air mouse" for gaming (pointing it to the screen), but as the mouse sensor is a gyroscope, there's some problems with off-screen movement that I'd like to try to fix by software.
With this gyro mouse, when the user moves its arm pointing outside the screen, the cursor stops at the screen limit, which is no problem. However, when he moves his arm back, no matter the distance from the screen, the cursor immediately moves on-screen. This causes a giant difference between the air mouse real position and the cursor.
This could be fixed with a simple control over the number of pixels, and direction, travelled off-screen, in conjunction with some event handling. If I could sum the number of "offscreen" pixels traveled in -X, +X, -Y and +Y, it would be possible to prevent/cancel the mouse move event - or set the cursor to its previous position, at the edge of the screen - until the control tells me that the physical mouse is pointing back to the screen. Just then I'd allow the cursor to move freely.
Maybe this isn't that usefull, but it's an interesting problem, and see this working would be fun as hell!
Currently, based on this great project, I can just state when the mouse is off-screen, but cannot control how far and in which direction it is moving, to properly implement what I'm trying. It seems to me that such kind of information would be too low-level for my current Windows knowledge.
So, to be clear: how can I, in C# (other languages accepted, but I'd have to learn a lot ;), get any kind of "delta position" information or direction of movement, when the cursor is at the limit of screen?
With all due respect, I'm not interested on using different kinds of controllers, as well as "you shouldn't do this" answers. I have this problem to solve, with these elements, and it would be great to make this work!
UPDATE:
Ok, here's my progress up to now.
In order to get raw mouse data and know about the mouse movement 'offscreen', I had to register my application, using some windows API functions, to receive WM_INPUT messages.
Based on a very old code I found, I was able to get mouse raw data and implement exactly what I wanted. Except for the fact that this code is based on a WdnProc callback, and so it only works when my application has the focus. And I need it to also work when the focus is elsewhere - after all, I'm trying to improve the pointing provided by a gyro mouse, for third party games.
It seems that I should use a hook (a good example here), but I have no idea how to hook for input messages. Tried to merge the code of the two links above, but the first one needs the message.LParam that is passed to the WdnProc - which seems to be unavailable when merely hooking mouse events.
Now I'm way out of my league to make some real progress. Any ideas?
One of the simplest solution to get cursor position and then detect its movement regardless where the cursor is to use win32 API from the user32.dll.
Here is a simple code which gets the cursor position in every 10ms using the timer in the C# Windows Form application and displays it as the title of the window.
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Drawing;
public partial class Form1 : Form
{
Timer timer = new Timer();
public Form1()
{
InitializeComponent();
timer.Interval = 10;
timer.Tick += Timer_Tick;
timer.Start();
}
private void Timer_Tick(object sender, EventArgs e)
{
// do here whatever you want to do
// just for testing...
GetCursorPos(out Point lpPoint);
this.Text = lpPoint.X + ", " + lpPoint.Y;
}
[DllImport("user32.dll")]
public static extern bool GetCursorPos(out Point p);
}
I'm trying to interact with world space UI using a first person controller when Cursor.lockState is set to CursorLockMode.Locked.
world space UI and a character
But when cursor is locked, cursor position is set to (-1, -1),
which is told from the Inspector.
cursor position of (-1, -1)
I performed a graphic raycast with EventSystem.RaycastAll, Sreen.width/2 and PointerEventData. EventSystem.current.RaycastAll collects all UI objects in the middle of screen, but no events is sent to them.
I also tried ExecuteEvents.Execute<IEventSystemHandler> to manully send event to UI targets. This works for button when I send 'submit' event to it. Obviously this is not an elegant solution. I have no idea how to send message to slider either.
// manully send a 'submit' event to UI elements
List<RaycastResult> results = new List<RaycastResult>();
void Update() {
if (Input.GetButtonUp("Fire1")) {
PointerEventData data = new PointerEventData(EventSystem.current);
data.position = new Vector2(Screen.width / 2, Screen.height / 2);
EventSystem.current.RaycastAll(data, results);
foreach (var result in results) {
ExecuteEvents.ExecuteHierarchy<ISubmitHandler>(
result.gameObject, data,
ExecuteEvents.submitHandler
);
}
}
}
This crazy attempt works when played full-screen on Windows. 2333
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern int SetCursorPos ( int x , int y );
void SetCursorPositionToCenter()
{
　　SetCursorPos(Screen.width/2, Screen.height/2);
}
Relavant Resources
I had a lot of problems working with Graphics Raycaster and Global UI elements as well. I tried a lot of things as well but the event system didn't seem to work. But I was simulating a mouse with a touchpad and maybe I didn't completely simulate how a mouse works with UI elements.
I ended up abandoning graphics raycaster and instead add a box collider to all UI elements. That way a regular physics raycaster would be able to detect it and run some code. For the slider, it is just increasing the slider's value as your x or y of your pointer increase.
Hope this helps a little.
What you're doing with the submit handler is similar to the many different ways this can be done. I've not dealt with sliders specifically, because it's not very easy to control sliders in this method (player controller or, in the case of VR, the user's head, does not do straight lines very well). So for slider input we usually go with +/- buttons. Another idea could be that when the user is pointing at a UI element that you release the cursorLock when they click. When click is released you can resume cursor lock.
UI elements are also often in need of states like hover/onEnter, onExit, sometimes pointer up, and usually pointer down. So we've often used Selectable class for this. I think all the interactable UI elements inherit from this so it's a good spot to access the UI element from. This will usually trigger the proper events but it can be a little tricky. Examine some of the many readily available gaze input systems as they're doing the same thing. I don't think I've ever seen one handle sliders though (they're usually meant for VR and gaze-to-slider control would be bad UX).
Cheers and good luck!
If you're trying to access UI elements without affecting gameplay you can simply set Time.TimeScale = 0; which basically pauses time but UI elements will still be active. Then just unlock your cursor and use it freely.
I need to update a label every time the pointer mouse moves, but not only in the form, i need to catch the move in all the desktop.
Is it possible?
Thank you.
Do you just need the label to say "Mouse Moved" or is it dependent on where it moved to. I guess either way you could user a Timer that goes off every once-in-a-while and checks the mouse x and y positions and compares them to the previous positions.
prevMouseX = MouseX;
prevMouseY = MouseY;
mouseX = System.Windows.Forms.Cursor.Position.X;
mouseY = System.Windows.Forms.Cursor.Position.Y;
Then compare is mouseX = prevMouseX etc...
You may want to look at Mouse Capture. I'm not sure of all the circumstances you're working with, but take a look at this MSDN article for an overview of mouse capture. This answer also provides some information.
Is there a way to detect this?
Imagine you would have an application where you are doing something and there is a Backgroundthread which is listening and waiting until the mouse will be moved - (no matter how far):
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Which fires a trigger or calls a specific method.
Any ideas?
Don't see, from the question provided perspective to use another thread for this.
Just listen for MouseMove event over whatevere is it, and detect mouse move direction.
You can do that by substracting corrdinates recived by the event handler itself.
The thing here comes to decision of tollerance you are going to have in detection algo.
To be more clear:
If the difference of X value is bigger then (say) 1, count that as move to right, if it less then -1, count that like move to left.
Something like this.
Get the current position of mouse pointer. Move to new location. If the new location's X-Cordinate is lesser than the previuos position's X-Cordinate then it means mouse has moved left. Similary for moving right. Every time the new position will become base position. You can keep a counter and if count is 5 do what ever you wish.
Use the MouseMove event attached to your window. Store the mouse position each time it fires and compare the current position to the last position to determine if you moved left, right, or not all all (i.e. up or down).
I'm working with a WPF app, more specifically a Canvas with draggable elements.
Once an item is being dragged, I'd like to limit the scope of cursor movement to inside the canvas where the items are being dragged about.
The event which can start a drag is shown below
private void WidgetCanvas_PreviewHeaderLeftMouseDown(object sender, MouseButtonEventArgs e)
{
e.Handled = true;
... logic to figure out if this is a valid drag, blah blah blah ...
this.IsDragging = true;
// TODO: clip the available cursor movement to actual width of Canvas
}
On the Preview-MouseUp, I'd like to simply "unclip" the cursor movement back to it's normal state.
I'll be monitoring the movement of the mouse once I start dragging (PreviewMouseMove), so worst case, I could manually check the position of the mouse and keep it constrained to the canvas, but that seems a little ugly.
Anyone have a better way to limit the cursor boundaries?
There's no clean way to do this and the not-so-clean ways will make your mouse cursor "jitter" at the border of the clipping area.
Moreover, I'd question if this is really a good idea. The user should really own the mouse and he or she generally gets frustrated when you try to artificially limit things that he or she owns.
If you want to provide feedback when the mouse leaves your canvas, maybe you could leave the item being dragged stuck along the border while the mouse button is still down? This would tell the user that he or she has left the target area without trying to impose limitations on where the mouse can go.
Good luck!
You should be able to do it using the ClipCursor native API.