In the Windows API,
x,y = win32api.GetCursorPos()
...will get the mouse position regardless of whether it's inside your window or whether your program even has a GUI. (MSDN) (Python question)
Is there a similar function to get the scrollwheel (mousewheel)'s current rotation?
The mouse wheel's rotation is not an absolute value like the cursor position. Rather, the wheel position is the delta from the previous wheel position, either positive or negative, expressed as a multiple of 120 (120 = 1 line.). So, if the user scrolls up three lines, the delta might be +360 whereas if they scroll down three lines the delta might be -360.
You can keep an internal variable that you update every time your app gets a WM_MOUSEWHEEL message which will allow you to track the cumulative change in rotation since your app started. So if a user scrolls up 10 lines and down 20 lines the cumulative delta would be -1200.
Related
I am writing an application for Windows 10 using Delphi 11 and Steema TeeChart pro 11 components.
I use AddXY(….) to plot a DateTime series of about 1000 values as points in Chart1 with BottomAxis set to DateTime and the Leftaxis set to float.
Thereafter I zoom in a small part of the data in Chart1 using the mouse wheel or drawing a rectangle.
Then I want to plot a new time series (AddXY(….)) of 1000 values in Chart1, keeping the zoomed in min and max values for the bottom axes, but use automatic scaling for LeftAxis. Before plotting the second series I delete the first.
The second series have the same DateTime values as the first series, but the Y values are sometimes very different compared with the first series and may not be visible in the graph.
Now the problem occurs. The Left axis will be automatic scaled based on all the data points and not on the points only falling within the zoomed X boundaries.
Does TChart have a simple method to find the min and max Y-values for the second series within the zoomed in time period. I thought of using the LeftAxis.AdjustMinMax() procedure for rescaling the left axis?
Of course I could scan through all the Y-values within the zoomed in period and calculate the min and max value. Then, how do I know the starting and ending valueindex of the data points falling within the zoomed in time period? I hoped to avoid using this method due to speed resons if number of points are > 1000.
Hopefully someone more experienced TeeChart programmer than I am can give me some suggestions of the best way to achieve this.
I'm working with mouse events, specifically OnMouseWheel. Many code samples refer to distance the view changes (or zoom f.i. in 3D application) as Distance = Sign(WheelDelta)*Constant or Distance = WheelDelta / WHEEL_DELTA or something of that kind - assuming that WheelDelta is always a multiple of 120 (WHEEL_DELTA constant = 120).
I already found that in touch interfaces / tablets input may depend on scrolling length.
I was wondering why Microsoft has set default WheelDelta to 120, why not 100 or 10 or anything else? In what other cases wheel delta may be something different from 120?
The Qt Documentation elaborates a bit more on why it is actually 120:
QPoint QWheelEvent::angleDelta() const
Returns the distance that the wheel is rotated, in eighths of a degree. A
positive value indicates that the wheel was rotated forwards away from the
user; a negative value indicates that the wheel was rotated backwards toward
the user.
Most mouse types work in steps of 15 degrees, in which case the delta value is
a multiple of 120; i.e., 120 units * 1/8 = 15 degrees.
However, some mice have finer-resolution wheels and send delta values that are
less than 120 units (less than 15 degrees). To support this possibility, you
can either cumulatively add the delta values from events until the value of 120
is reached, then scroll the widget, or you can partially scroll the widget in
response to each wheel event.
https://doc.qt.io/qt-5/qwheelevent.html#angleDelta
WHEEL_DELTA is not fixed anymore to 120. As I understand it this constant was chosen to allow for finer resolutions in the future, which obviously is NOW.
See this article from MSDN
The question is marked as answered already I thought I might provide some more information.
If I understand correctly, WHEEL_DELTA is actually 40 not 120, the 120 comes from the mouse driver multiplying the raw WHEEL_DELTA value by the number of lines to scroll, which is by default 3. You can obtain the scroll line number using
My.Computer.Mouse.WheelScrollLines
This can most easily be seen using a NumericUpDown control, which on scroll adjusts the value by the increment multiplied by that line count.
Just messing with my wheel mouse, there are 18 detents in a full revolution, being 20 degrees per detent (Sure I know that's a small sample size of mouses in the world...!). 40 suggests they felt half degrees were fine enough though this last paragraph is supposition.
EDIT: Not one to spread misinformation, on further study WHEEL_DELTA is in fact 120, NumericUpDown proved to be a false positive. Nonetheless, the rest of the discussion is valid, if one can apply a factor of three to the logic.
As you have noticed laptop Touchpads can scroll (either two-finger or scroll zone on right hand size), in which case there can be lots of events with very small wheelDelta values (either needing integration, or perhaps timeouts to prevent too many redraws).
Also different OS's or configurations or devices can have different meanings for scrolling - pixels, lines, or pages. e.g. DOM event.deltaMode
Finally some devices (mice and touchpads) also allow horizontal scrolling.
The above is more specific to browser DOM events, but the same issues may apply to Win events too.
Edit:
From the Firefox MDN docs there are three events you are probably interested in: WM_MOUSEWHEEL, WM_MOUSEHWHEEL, and WM_GESTURE (panning on touch devices).
A search of the Mozilla Bugzilla database shows a variety of problems with some Symantics and ALPS touch drivers sending WM_VSCROLL instead of WM_MOUSEWHEEL (may be relevant if supporting touchpads).
If you want horizontal mouse scrolling support, this article from a flash dev says: [mousewheel support] was added in Vista so if you are using XP or 2000 you need IntelliType Pro and/or IntelliPoint installed for WM_MOUSEHWHEEL support.
#Krom: more speculations and loose facts but maybe useful to others :-)
I'd like to get mouse movements in high resolution and high framerate on OSX.
"High framerate" = 60 fps or higher (preferably > 120)
"High resolution" = Subpixel values
Problem
I've got an opengl view running at about the monitor refresh rate, so it's ~60 fps. I use the mouse to look around, so I've hidden the mouse cursor and I'm relying on mouse delta values.
The problem is the mouse events come in at much too low framerate, and values are snapped to integer (whole pixels). This causes a "choppy" viewing experience. Here's a visualization of mouse delta values over time:
mouse delta X
^ xx
2 | x x x x xx
| x x x x xx x x x
0 |x-x-x--xx-x-x-xx--x-x----x-xx-x-----> frame
|
-2 |
v
This is a typical (shortened) curve created from the user moving the mouse a little bit to the right. Each x represent the deltaX value for each frame, and since deltaX values are rounded to whole numbers, this graph is actually quite accurate. As we can see, the deltaX value will be 0.000 one frame, and then 1.000 the next, but then it will be 0.000 again, and then 2.000, and then 0.000 again, then 3.000, 0.000, and so on.
This means that the view will rotate 2.000 units one frame, and then rotate 0.000 units the next, and then rotate 3.000 units. This happens while the mouse is being dragged with more or less constant speed. Nedless to say, this looks like crap.
So, how can I 1) increased the event framerate of the mouse? and 2) get subpixel values?
So far
I've tried the following:
- (void)mouseMoved:(NSEvent *)theEvent {
CGFloat dx, dy;
dx = [theEvent deltaX];
dy = [theEvent deltaY];
// ...
actOnMouse(dx,dy);
}
Well, this one was obvious. dx here is float, but values are always rounded (0.000, 1.000 etc.). This creates the graph above.
So the next step was to try and tap the mouse events before they enter the WindowServer, I thought. So I've created a CGEventTrap:
eventMask = (1 << kCGEventMouseMoved);
eventTap = CGEventTapCreate(kCGHIDEventTap, kCGHeadInsertEventTap,
0, eventMask, myCGEventCallback, NULL);
//...
myCGEventCallback(...){
double dx = CGEventGetDoubleValueField(event, kCGMouseEventDeltaX);
double dy = CGEventGetDoubleValueField(event, kCGMouseEventDeltaY);
}
Still values are n.000, although I believe the rate of event firing is a little higher. But it it's still not at 60 fps. I still get the chart above.
I've also tried setting the mouse sensitivity really high, and then scale the values down on my side. But it seems OSX adds some sort of acceleration or something—the values get really "unstable" and consequently unusable, and the rate of fire is still too low.
With no luck, I've been starting to follow the mouse events down the rabbit hole, and I've arrived at IOKit. This is scary for me. It's the mad hatter. The Apple documentation gets weird and seems to say "if you're this deep down, all you really need is header files".
So I have been reading header files. And I've found some interesting tidbits.
In <IOKit/hidsystem/IOLLEvent.h> on line 377 there's this struct:
struct { /* For mouse-down and mouse-up events */
UInt8 subx; /* sub-pixel position for x */
UInt8 suby; /* sub-pixel position for y */
// ...
} mouse;
See, it says sub-pixel position! Ok. Then on line 73 in <IOKit/hidsystem/IOLLParameter.h>
#define kIOHIDPointerResolutionKey "HIDPointerResolution"
Hmm.
All in all, I get the feeling OSX knows about sub-pixel mouse coordinates deep down, and there just has to be a way to read raw mouse movements every frame, but I've just no idea how to get those values.
Questions
Erh, so, what am I asking for?
Is there a way of getting high framerate mouse events in OSX? (Example code?)
Is there a way of getting sub-pixel mouse coordinates in OSX? (Example code?)
Is there a way of reading "raw" mouse deltas every frame? (Ie not rely on an event.)
Or, how do I get NXEvents or set HIDParameters? Example code? (So I can dig deeper into this on my own...)
(Sorry for long post)
(This is a very late answer, but one that I think is still useful for others that stumble across this.)
Have you tried filtering the mouse input? This can be tricky because filtering tends to be a trade-off between lag and precision. However, years ago I wrote an article that explained how I filtered my mouse movements and wrote an article for a game development site. The link is http://www.flipcode.com/archives/Smooth_Mouse_Filtering.shtml.
Since that site is no longer under active development (and may go away) here is the relevant excerpt:
In almost every case, filtering means averaging. However, if we simply average the mouse movement over time, we'll introduce lag. How, then, do we filter without introducing any side-effects? Well, we'll still use averaging, but we'll do it with some intelligence. And at the same time, we'll give the user fine-control over the filtering so they can adjust it themselves.
We'll use a non-linear filter of averaged mouse input over time, where the older values have less influence over the filtered result.
How it works
Every frame, whether you move the mouse or not, we put the current mouse movement into a history buffer and remove the oldest history value. So our history always contains X samples, where X is the "history buffer size", representing the most recent sampled mouse movements over time.
If we used a history buffer size of 10, and a standard average of the entire buffer, the filter would introduce a lot of lag. Fast mouse movements would lag behind 1/6th of a second on a 60FPS machine. In a fast action game, this would be very smooth, but virtually unusable. In the same scenario, a history buffer size of 2 would give us very little lag, but very poor filtering (rough and jerky player reactions.)
The non-linear filter is intended to combat this mutually-exclusive scenario. The idea is very simple. Rather than just blindly average all values in the history buffer equally, we average them with a weight. We start with a weight of 1.0. So the first value in the history buffer (the current frame's mouse input) has full weight. We then multiply this weight by a "weight modifier" (say... 0.2) and move on to the next value in the history buffer. The further back in time (through our history buffer) we go, the values have less and less weight (influence) on the final result.
To elaborate, with a weight modifier of 0.5, the current frame's sample would have 100% weight, the previous sample would have 50% weight, the next oldest sample would have 25% weight, the next would have 12.5% weight and so on. If you graph this, it looks like a curve. So the idea behind the weight modifier is to control how sharply the curve drops as the samples in the history get older.
Reducing the lag means decreasing the weight modifier. Reducing the weight modifier to 0 will provide the user with raw, unfiltered feedback. Increasing it to 1.0 will cause the result to be a simple average of all values in the history buffer.
We'll offer the user two variables for fine control: the history buffer size and the weight modifier. I tend to use a history buffer size of 10, and just play with the weight modifier until I'm happy.
If you are using the IOHIDDevice callbacks for the mouse you can use this to get a double value:
double doubleValue = IOHIDValueGetScaledValue(inIOHIDValueRef, kIOHIDTransactionDirectionTypeOutput);
The possibility of subpixel coordinates exists because Mac OS X is designed to be resolution independent. A square of 2x2 hardware pixels on a screen could represent a single virtual pixel in software, allowing the cursor to be placed at (x + 0.5, y + 0.5).
On any actual Mac using normal 1x scaling, you will never see subpixel coordinates because the mouse cursor cannot be moved to a fractional pixel position on the screen--the quantum of mouse movement is precisely 1 pixel.
If you need to get access to pointer device delta information at a lower level than the event dispatching system provides then you'll probably need to use the user-space USB APIs.
I want to write a paint program in the style of MS Paint.
For painting things on screen when the user moves the mouse, I have to wait for mouse move events and draw on the screen whenever I receive one. Apparently, mose move events are not sent very often, so I have to interpolate the mouse movement by drawing a line between the current mouse position and the previous one. In pseudocode, this looks something like this:
var positionOld = null
def handleMouseMove(positionNew):
if mouse.button.down:
if positionOld == null:
positionOld = positionNew
screen.draw.line(positionOld,positionNew)
positionOld = positionNew
Now my question: interpolating with straight line segments looks too jagged for my taste, can you recommend a better interpolation method? What method do GIMP or Adobe Photoshop implement?
Alternatively, is there a way to increase the frequency of the mouse move events that I receive? The GUI framework I'm using is wxWidgets.
GUI framework: wxWidgets.
(Programming language: Haskell, but that's irrelevant here)
EDIT: Clarification: I want something that looks smoother than straight line segments, see the picture (original size):
EDIT2: The code I'm using looks like this:
-- create bitmap and derive drawing context
im <- imageCreateSized (sy 800 600)
bitmap <- bitmapCreateFromImage im (-1) -- wxBitmap
dc <- memoryDCCreate -- wxMemoryDC
memoryDCSelectObject dc bitmap
...
-- handle mouse move
onMouse ... sw (MouseLeftDrag posNew _) = do
...
line dc posOld posNew [color := white
, penJoin := JoinRound
, penWidth := 2]
repaint sw -- a wxScrolledWindow
-- handle paint event
onPaint ... = do
...
-- draw bitmap on the wxScrolledWindow
drawBitmap dc_sw bitmap pointZero False []
which might make a difference. Maybe my choices of wx-classes is why I'm getting a rather low frequency of mouse move events.
Live demos
version 1 - more smooth, but more changing while you draw: http://jsfiddle.net/Ub7RV/1/
version 2 - less smooth but more stable: http://jsfiddle.net/Ub7RV/2/
The way to go is
Spline interpolation of the points
The solution is to store coordinates of the points and then perform spline interpolation.
I took the solution demonstrated here and modified it. They computed the spline after you stop drawing. I modified the code so that it draws immediately. You might see though that the spline is changing during the drawing. For real application, you probably will need two canvases - one with the old drawings and the other with just the current drawing, that will change constantly until your mouse stops.
Version 1 uses spline simplification - deletes points that are close to the line - which results in smoother splines but produce less "stable" result. Version 2 uses all points on the line and produces much more stable solution though (and computationally less expensive).
You can make them really smooth using splines:
http://freespace.virgin.net/hugo.elias/graphics/x_bezier.htm
But you'll have to delay the drawing of each line segment until one frame later, so that you have the start and end points, plus the next and previous points available for the calculation.
so, as I see the problem of jagged edge of freehand made curve, when the mouse are moved very fast, is not solved !!! In my opinion there are need to work around with the polling frequency of mousemove event in the system i.e. using different mouse driver or smf.. And the second way is the math.. using some kind of algorithm, to accuratly bend the straight line between two points when the mouse event is polled out.. For clear view you can compare how is drawed free hand line in photoshop and how in mspaint.. thanks folks.. ;)
I think you need to look into the Device Context documentation for wxWidgets.
I have some code that draws like this:
//screenArea is a wxStaticBitmap
int startx, starty;
void OnMouseDown(wxMouseEvent& event)
{
screenArea->CaptureMouse();
xstart = event.GetX();
ystart = event.GetY();
event.Skip();
}
void OnMouseMove(wxMouseEvent& event)
{
if(event.Dragging() && event.LeftIsDown())
{
wxClientDC dc(screenArea);
dc.SetPen(*wxBLACK_PEN);
dc.DrawLine(startx, starty, event.GetX(), event.GetY());
}
startx = event.GetX();
starty = event.GetY();
event.Skip();
}
I know it's C++ but you said the language was irrelevant, so I hope it helps anyway.
This lets me do this:
which seems significantly smoother than your example.
Interpolating mouse movements with line segments is fine, GIMP does it that way, too, as the following screenshot from a very fast mouse movement shows:
So, smoothness comes from a high frequency of mouse move events. WxWidgets can do that, as the example code for a related question demonstrates.
The problem is in your code, Heinrich. Namely, drawing into a large bitmap first and then copying the whole bitmap to the screen is not cheap! To estimate how efficient you need to be, compare your problem to video games: a smooth rate of 30 mouse move events per second correspond to 30fps. Copying a double buffer is no problem for modern machines, but WxHaskell is likely not optimized for video games, so it's not surprising that you experience some jitter.
The solution is to draw only as much as necessary, i.e. just the lines, directly on the screen, for example as shown in the link above.
I agree with harviz - the problem isn't solved. It should be solved on the operating system level by recording mouse movements in a priority thread, but no operating system I know of does that. However, the app developer can also work around this operating system limitation by interpolating better than linear.
Since mouse movement events don't always come fast enough, linear interpolation isn't always enough.
I experimented a little bit with the spline idea brought up by Rocketmagnet.
Instead of putting a line between two points A and D, look at the point P preceding A and use a cubic spline with the following control points B = A + v' and C = D - w', where
v = A - P,
w = D - A,
w' = w / 4 and
v' = v * |w| / |v| / 4.
This means we fall into the second point with the same angle as the line interpolation would, but go out a starting point in the same angle the previous segment came in, making the edge smooth. We use the length of the segment for both control point distances to make the size of the bend fit its proportion.
The following picture shows the result with very few data points (indicated in grey).
The sequence starts at the top left and ends in the middle.
There is still some level of uneasiness here which may be alleviated if one uses both the previous and the next point to adjust for both angles, but that would also mean to draw one point less than what one has got. I find this result already satisfactory, so I didn't try.
I am implementing a turn based game, there are two sides and each side has several units, at each specific moment only one unit can move across the board.
Since only one unit can move at a time, after i figure out where it should go, as far as the simulation is concerned it Can instantly be teleported there, but playing the game you would want to see the unit moving so that you realise who moved and where he went.
The question is, would you put the movement algorithm (eg interpolating between 2 points in N seconds) in the model and then have the view show the unit in the interpolated position without even knowing that it is moving, or teleport the unit and notify the view that it should show the unit moving as best as it wants.
If you would take the second approach, how would you keep the simulation from running too far ahead of the view, would you put the view in command of resuming the simulation after the movement ended?
Thanks in advance, Xtapodi.
Ah, yet another example that reminds us that MVC was never originally designed for real-time graphics. ;)
I would store the current position and the previous position in the model. When the object moves, the current position is copied into the previous position, the new position is copied into the current position, and a notification is sent to the view that the model has changed. The view can then interpolate between the old and the new position accordingly. It can speed up, slow down, or even remove the interpolation entirely based on the specific view settings, without requiring any extra data to be stored within the model.
Rather than storing the current position and the previous position, you could instead just store the last move with each unit, and the move itself contains the previous position. This is probably more versatile if you ever need to store extra information about a move.
What you probably want is to have the unit image move each frame. How far to move the image each frame is similar to your interpolation.
unitsPerSecond = totalUnits / (framesPerSecond * totalSeconds)
So if I want to move an image from position 0 to position 60 in 2 seconds and my framerate is 30, I need to move 60 units in 60 frames, therefore my speed is 1. So each frame, I move the image 1 unit, and if moving the unit will take me beyond my destination, simply set my location to my destination.