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Hello, are you sure it's a deadlock or it is a generic timeout? A table can't deadlock just because many users try to insert.
Deadlock means someone is blocking record A then try to lock record B while other process locked B then try to lock A.
If that happens just have both the process lock the resources in the same order (first A then B) this will avoid the deadlock, by definition, and can be done saving all records sorted by primary key, for example, within a trasaction.
Best Regards
Andrea
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hi all,
i want to copy control from one flowlayoutpanel to other,
but when i copy it from panel 1 to panel 2,control from panel 1 automatically deleted.
please help me for this.
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That means you are moving not copying. But exactly how and when you are doing this is a total mystery to anyone reading your question.
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foreach (Control ctrl in panel1.Controls)
{
panel2.Controls.Add(ctrl);
}
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A Control can only ever have one Parent: when you add it to a different Controls collection it is automatically removed from the existing collection.
If you want a visually similar control in two different places, you have to Copy it - but that means that it's a different control, any changes to one will not be reflected in the other.
To clone it isn't difficult using reflection:
public static class GeneralMethods
{
public static T Clone<T>(this T control) where T : Control
{
T result = Activator.CreateInstance<T>();
PropertyInfo[] piCollection = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (PropertyInfo pi in piCollection)
{
if (pi.CanWrite)
{
if (pi.Name != "WindowTarget")
{
pi.SetValue(result, pi.GetValue(control, null), null);
}
}
}
return result;
}
}I suspect that you don't really want to do this - why are you trying? What are you trying to achieve? There may be a better way.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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it means i have to use here cloning for the controls.
thanks its done now
modified 20-Aug-16 3:47am.
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Hi,
I'm trying to make a simulation of an object going down an inclined plane with friction. I have all the calculations I need, but I'm having some problems with figuring out how to actually draw this using GDI+.
At the moment I can draw the inclined plane and the object at a custom angle using Matrix.RotateAt. I also use a timer tick event to set the coordinates of the object and then invalidate the form to refresh it.
But what I can't figure out is how to calculate the coordinates of my object so it moves down on the inclined plane like it is actually sliding on it?
Any idea is appreciated!
Thanks in advance!
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Start with the math: Mass on incline[^] - the acceleration is g * sin(angle in radians) so for Earth, and a 45 degree slope the acceleration is 9.81 * sin (45 * 3.1415 / 180) = 6.93 ms-2
So you know the initial speed, you know the acceleration, you should be able to work out the distance from the start point at any moment in time (i.e. when the Timer ticks.)
Handle the Paint event for a Panel or similar, and Invalidate the panel each tick. In the event handler, draw the object in it's current position.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Thanks for the reply, but you almost said the same as I said...
I know the calculations for the acceleration and how to work with the timer ticks and invalidate the panel.
It's the calculation and the coding of the object on the incline plane that I can't figure out. I'm having trouble with this, because everything is at an angle and I used Matrix.RotateAt for that (which I'm not sure if it's the right way to do it).
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If you know the calculations, then you know how far away from the start point it needs to be at time "t", yes? So all you have to do is draw it that far away!
And you've already said that you can draw it and the plane, so what is the problem?
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Yes, I can draw it on the plane at the starting point. But when I try to add movement to the object, it starts moving away from the plane. So that is the problem. To rotate the plane and the object I use the following:
public void Rotate(Graphics g, Rectangle r, float angle, float x , float y)
{
using (Matrix m = new Matrix())
{
m.RotateAt(angle, new PointF(x, y));
g.Transform = m;
g.DrawRectangle(Pens.Red, r);
g.ResetTransform();
}
}
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Why are you rotating the plane and the object when the acceleration you calculate is a vector parallel to the plane?
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Because that is the only thing I found and that is why I'm here asking for help. But the only thing I get I answers with questions that point out how bad I am at trying to solve this... :s
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I'm obviously doing this wrong, but would be nice if somebody pointed me in the good direction(keeping in mind that I'm new at this)...
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We ask questions because all we get to work with is what you type - we don't get any context beyond that to work from.
So start by ignoring the object and use a "placeholder" - a circle or dot is fine - and get that working first.
Write a method to draw a plane, and a dot on the plane corresponding to a time you pass as the parameter, along with the Graphics object to draw onto (you get given this in the Paint event handler arguments).
The Plane is easy, a 45 degree incline is just:
g.DrawLine(Pens.Black, 0, 0, 0, 200);
g.DrawLine(Pens.Black, 0, 200, 200, 200);
g.DrawLine(Pens.Black, 200, 200, 0, 0);
And drawing a dot is trivial:
g.DrawEllipse(Pens.Red, x - 1, y - 1, 3, 3); Add a Panel to your form, handle the
Paint event, and call the method, passing it the number of seconds since the movement started.
All you have to do then is call Invalidate on the Panel in the Tick event of your timer after workign out the time since the start.
Does that make sense?
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Yes, that makes sense. But the angle needs to variable, so I'm going to use the following to calculate the inclined line:
x1 = startx
y1 = starty
x2 = x1 + cos(angle) * length
y2 = y1 + sin(angle) * length
I also know that my info is not clear, but that is because I don't understand it enough to formulate a good description of my problem. But the placeholder makes it a bit less complicated (still don't have a clue how to draw the rectangle at an angle without using the rotate method);
Thanks for your patience!
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Member 12688377 wrote: still don't have a clue how to draw the rectangle at an angle without using the rotate method
 Worry about it later!
(But... How different is it to drawing the inclined plane? The equation you give will draw two of the lines for you, and the other two are just joining them up - so it's just a case of four Point values which you need to offset by the X and Y of the time-based location. Think about it when you have the basics working.)
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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I was able to complete this! Thanks for the help!!!
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You're welcome!
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Member 12688377 wrote: that point out how bad I am
As OG said asking questions helps us get some context, none of them were designed to make you look bad, we all had to learn at some stage and that is what you are doing, bad has nothing to do with it.
You managed to get a comprehensive answer out of the forum, not bad at all. Take heart this was a well asked and answered question.
Never underestimate the power of human stupidity
RAH
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The path is in 2D space; i.e. relative to x and y for your purposes. Why make the object "relative to the incline of the plane" ?
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I would consider using WPF.
WPF has "storyboard" controls that can animate multiple properties; on different elements; at different rates; at the same time.
You should be able to find WPF Storyboard samples in the docs and be up and running in no time.
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Yes, that would be nice. But I can only use GDI+ for this project...
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It sounds like you're trying to implement an animation of the block sliding down the plane. If so, here's what you need to do...
Grab the wallclock time when you start the animation, then at each refresh, find out the difference between the starting wallclock time and the current wallclock time, and solve the equations to determine where to draw the block for that point in time.
You could also do delta times and solve the equation incrementally, but errors start to creep in that way, so you might as well do the above.
.NET wise, You're looking to capture DateTime.Now and then get TimeSpan from the differences. TimeSpan.TotalSeconds is probably what you want or your formulas.
We can program with only 1's, but if all you've got are zeros, you've got nothing.
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in many mvc application i have seen people use virtual keyword. i like to know the reason.
i have seen a video from this url https://www.youtube.com/watch?v=BSgAA8y5ViU which generate UI from model with scaffolding
so see this code first
public class Student
{
public int StudentId;
public string StudentName;
public int CourseId;
public virtual Course Courses { get; set; }
}
public class Course
{
public int CourseId;
public string CourseName;
public string Description;
public ICollection<Student> Students {get;set;}
public ICollection<Lecture> Lectures { get; set; }
}
public class Lecture
{
public int LectureId;
public string LectureName;
public int CourseId;
public virtual Course Courses { get; set; }
}
1) why lecture and student class has common property called CourseId ?
2) see below code
public ICollection<Student> Students {get;set;}
public ICollection<Lecture> Lectures { get; set; }
why they use ICollection ? they can use here list etc ?
3) why Courses property has been declared with virtual keyword in lecture and student class ?
please help me to understand the real use of virtual keyword
public virtual Course Courses { get; set; }
in what kind of scenario we use virtual keyword ? what is advantage ?
please explain the reason why people use virtual keyword with EF ?
thanks
tbhattacharjee
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