I need someone to help me with this little problem I have. Here's a code fragment:
void shuffle()
{
for (int i = 0; i < 4; i++) {
// here should be the computations of x and y
buttons[i].Click += (s, e) => { show_coordinates(x, y); };
// shuffling going on
}
}
void show_coordinates(int x, int y)
{
MessageBox.Show(x + " " + y);
}
as you can see I create a new event handler with different x and y for each button every time I run the loop. There's another button in my form which shuffles the buttons randomly.
So here's the problem: If I press the shuffle button say 10 times and then press any of the shuffled buttons, event handlers stack up and I get 10 message boxes displaying x and y values.
So how can I overwrite the previous event handler with a new one each time I press shuffle.
Thanks in advance.
I would redesign the code instead to do something like this:
private PointF[] points = new PointF[4];
//Run once
public void Initialize()
{
for (int i = 0; i < 4; i++)
buttons[i].Click += (s, e) => { show_coordinates(i); };
}
public void Shuffle()
{
for (int i = 0; i < 4; i++)
{
// here should be the computations of x and y
points[i] = new PointF(x,y);
// shuffling going on
}
}
public void show_coordinates(int index)
{
var point = points[index];
MessageBox.Show(point.X + " " + point.Y);
}
Reflection is a one way to do it, but i would prefer a delegate and adding/removing that delegate. This leads to easier maintainable code than using a reflection:
How to remove a lambda event handler
In your for loop first remove the event handlers then re-add them.
However take into account that this is bad practice. You should use the button's datacontext and bind an object to it containing your x and y values.
This way you only have to attach your event handler once. Instead of every time shuffle get's called. Then updating your buttons datacontext is way more convenient.
Example PseudoCode:
public MainWindow() {
ForEach Button addEvent(DoSomething);
ForEach Button Button.Datacontext = new Data();
}
public class Data {
prop X;
prop Y;
ctor(x,y)
ctor()
}
public void DoSomething()
{
var data = Button.datacontext as data
MessageBox(data.x, data.y)
}
public void Shuffle()
{
calc x, y
foreach Button (Button.datacontext as data).x = x, ...
}
Related
This question already has answers here:
Pass extra parameters to an event handler?
(10 answers)
Closed 2 years ago.
I use the loop for a two dimensions array of buttons. I don't know how to know exactly which buttons in array were clicked or not
Here are my code:
for (int i = 0; i < 100 ; i++)
{
for (int j=0 ; j< 100; i++)
{
arrButton[i, j] = new Button();
arrButton[i,j].Size = new Size(size1button, size1button);
arrButton[i,j].Location = new Point(j*size1button, i*size1button);
arrButton.Click += new EventHandler(arrButton_Click);
}
}
Can I use parameters i, j for mouse click event like:
private void arrButton_Click(object sender, EventArgs e, int i, int j)
{
//my idea : add i, j to another int[,] array to keep track of buttons which were clicked
}
If this exits, how to write it correctly? Or can you recommend or method to know exactly where the button was clicked in array ?
Try this
public class Indeces
{
public int IndexI { get; set; }
public int IndexJ { get; set; }
}
Now in loop set Tag
for (int i = 0; i < 100 ; i++)
{
for (int j=0 ; j< 100; i++)
{
arrButton[i, j] = new Button();
arrButton[i,j].Size = new Size(size1button, size1button);
arrButton[i,j].Location = new Point(j*size1button, i*size1button);
arrButton.Click += new EventHandler(arrButton_Click);
arrButton.Tag = new Indeces {IndexI = i,IndexJ = j};
}
}
Get values from Tag here as
private void arrButton_Click(object sender, EventArgs e)
{
var button = sender as Button;
var indeces = (Indeces) button.Tag;//get indeces here
var i = indeces.IndexI;
var j = indeces.IndexJ;
}
You cannot change the EventHandler signature to include your i and j.
However, you can get that information from what is already passed to the arrButton_Click method. Since you set the location of each button as new Point(j*size1button, i*size1button), you can get each i and j component back by dividing the location of your button by size1button.
To get that location, you can use the sender, which is your Button (a cast is necessary):
private void arrButton_Click(object sender, EventArgs e)
{
Button btnClicked = (Button) sender;
int i = btnClicked.Location.Y / size1button;
int j = btnClicked.Location.X / size1button;
}
Also, the code you're currently using to create the buttons have a couple errors.
First, you're never incrementing j; the second loop does i++.
Second, if you want your buttons to appear, you have to add them to your Form's Controls.
Finally, I don't think you can have 10 000 active buttons on your form, try a lower number, like 25.
So the corrected code would look like:
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 5; j++)
{
arrButton[i, j] = new Button();
arrButton[i, j].Size = new Size(size1button, size1button);
arrButton[i, j].Location = new Point(j*size1button, i*size1button);
arrButton[i, j].Click += arrButton_Click;
Controls.Add(arrButton[i,j]);
}
}
You can also notice that I removed your declaration of new EventHandler, which was redundant.
If you are only interested in Location then whats wrong with this? -
private void arrButton_Click(object sender, EventArgs e)
{
var button = sender as Button;
//now use button.Location
}
But if you want more data other than just location. Here is an example
Use a custom button class -
public class CustomButton<T> : Button {
public T Data{get;set;}
public CustomButton(T data){
this.Data = data; //i didn't compile it, so data type might mismatch.
}
}
Then use this button class -
for (int i = 0; i < 100 ; i++)
{
for (int j=0 ; j< 100; i++)
{
arrButton[i, j] = new CustomButton<T> (...some data);
arrButton[i,j].Size = new Size(size1button, size1button);
arrButton[i,j].Location = new Point(j*size1button, i*size1button);
arrButton.Click += new EventHandler(arrButton_Click);
}
}
In the event handler Cast to CustomButton and voila, there is your location -
private void arrButton_Click(object sender, EventArgs e)
{
var cButton = sender as CustomButton<T>;
// cButton.Datais your point. Have fun
}
BTW, you cannot change the default signature of event handlers, if you want you have to implement your own event/delegate.
I'm developing a theatre reservation software. I'm using Windows Forms, the seats is represented by a 2-dimensioned array. And I draw the buttons as following:
public void DrawSeats()
{
// pnl_seats is a Panel
pnl_seats.Controls.Clear();
// Here I store all Buttons instance, to later add all buttons in one call (AddRange) to the Panel
var btns = new List<Control>();
// Suspend layout to avoid undesired Redraw/Refresh
this.SuspendLayout();
for (int y = 0; y < _seatZone.VerticalSize; y++)
{
for (int x = 0; x < _seatZone.HorizontalSize; x++)
{
// Check if this seat exists
if (IsException(x, y))
continue;
// Construct the button with desired properties. SeatSize is a common value for every button
var btn = new Button
{
Width = SeatSize,
Height = SeatSize,
Left = (x * SeatSize),
Top = (y * SeatSize),
Text = y + "" + x,
Tag = y + ";" + x, // When the button clicks, the purpose of this is to remember which seat this button is.
Font = new Font(new FontFamily("Microsoft Sans Serif"), 6.5f)
};
// Check if it is already reserved
if (ExistsReservation(x, y))
btn.Enabled = false;
else
btn.Click += btn_seat_Click; // Add click event
btns.Add(btn);
}
}
// As said before, add all buttons in one call
pnl_seats.Controls.AddRange(btns.ToArray());
// Resume the layout
this.ResumeLayout();
}
But already with a seat zone of 20 by 20 (400 buttons), it spent almost 1 minute to draw it, and in debug I checked that the lack of performance, is the instantiation of the buttons.
There is a way to make it faster? Perhaps disable all events during the instatiation or another lightweight Control that has the Click event too?
UPDATE:
lbl was a test, the correct is btn, sorry.
UPDATE 2:
Here is the IsException and ExistsReservations methods:
private bool IsException(int x, int y)
{
for (var k = 0; k < _seatsExceptions.GetLength(0); k++)
if (_seatsExceptions[k, 0] == x && _seatsExceptions[k, 1] == y)
return true;
return false;
}
private bool ExistsReservation(int x, int y)
{
for (var k = 0; k < _seatsReservations.GetLength(0); k++)
if (_seatsReservations[k, 0] == x && _seatsReservations[k, 1] == y)
return true;
return false;
}
Suppose that you change your arrays for reservations and exclusions to
public List<string> _seatsExceptions = new List<string>();
public List<string> _seatsReservations = new List<string>();
you add your exclusions and reservations in the list with something like
_seatsExceptions.Add("1;10");
_seatsExceptions.Add("4;19");
_seatsReservations.Add("2;5");
_seatsReservations.Add("5;5");
your checks for exclusions and reservations could be changed to
bool IsException(int x, int y)
{
string key = x.ToString() + ";" + y.ToString();
return _seatsExceptions.Contains(key);
}
bool ExistsReservation(int x, int y)
{
string key = x.ToString() + ";" + y.ToString();
return _seatsReservations.Contains(key);
}
of course I don't know if you are able to make this change or not in your program. However consider to change the search on your array sooner or later.
EDIT I have made some tests, and while a virtual grid of 20x20 buttons works acceptably well (31 millisecs 0.775ms on average), a bigger one slows down noticeably. At 200x50 the timing jumps to 10 seconds (1,0675 on average). So perhaps a different approach is needed. A bound DataGridView could be a simpler solution and will be relatively easy to handle.
I also won't use such a myriad of controls to implement such a thing. Instead you should maybe create your own UserControl, which will paint all the seats as images and reacts on a click event.
To make it a little easier for you i created such a simple UserControl, that will draw all the seats and reacts on a mouse click for changing of the state. Here it is:
public enum SeatState
{
Empty,
Selected,
Full
}
public partial class Seats : UserControl
{
private int _Columns;
private int _Rows;
private List<List<SeatState>> _SeatStates;
public Seats()
{
InitializeComponent();
this.DoubleBuffered = true;
_SeatStates = new List<List<SeatState>>();
_Rows = 40;
_Columns = 40;
ReDimSeatStates();
MouseUp += OnMouseUp;
Paint += OnPaint;
Resize += OnResize;
}
public int Columns
{
get { return _Columns; }
set
{
_Columns = Math.Min(1, value);
ReDimSeatStates();
}
}
public int Rows
{
get { return _Rows; }
set
{
_Rows = Math.Min(1, value);
ReDimSeatStates();
}
}
private Image GetPictureForSeat(int row, int column)
{
var seatState = _SeatStates[row][column];
switch (seatState)
{
case SeatState.Empty:
return Properties.Resources.emptySeat;
case SeatState.Selected:
return Properties.Resources.choosenSeat;
default:
case SeatState.Full:
return Properties.Resources.fullSeat;
}
}
private void OnMouseUp(object sender, MouseEventArgs e)
{
var heightPerSeat = Height / (float)Rows;
var widthPerSeat = Width / (float)Columns;
var row = (int)(e.X / widthPerSeat);
var column = (int)(e.Y / heightPerSeat);
var seatState = _SeatStates[row][column];
switch (seatState)
{
case SeatState.Empty:
_SeatStates[row][column] = SeatState.Selected;
break;
case SeatState.Selected:
_SeatStates[row][column] = SeatState.Empty;
break;
}
Invalidate();
}
private void OnPaint(object sender, PaintEventArgs e)
{
var heightPerSeat = Height / (float)Rows;
var widthPerSeat = Width / (float)Columns;
e.Graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
e.Graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
e.Graphics.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
for (int row = 0; row < Rows; row++)
{
for (int column = 0; column < Columns; column++)
{
var seatImage = GetPictureForSeat(row, column);
e.Graphics.DrawImage(seatImage, row * widthPerSeat, column * heightPerSeat, widthPerSeat, heightPerSeat);
}
}
}
private void OnResize(object sender, System.EventArgs e)
{
Invalidate();
}
private void ReDimSeatStates()
{
while (_SeatStates.Count < Rows)
_SeatStates.Add(new List<SeatState>());
if (_SeatStates.First().Count < Columns)
foreach (var columnList in _SeatStates)
while (columnList.Count < Columns)
columnList.Add(SeatState.Empty);
while (_SeatStates.Count > Rows)
_SeatStates.RemoveAt(_SeatStates.Count - 1);
if (_SeatStates.First().Count > Columns)
foreach (var columnList in _SeatStates)
while (columnList.Count > Columns)
columnList.RemoveAt(columnList.Count - 1);
}
}
This will currently draw forty rows and columns (so there are 800 seats) and you can click on each seat to change its state.
Here are the images i used:
EmtpySeat:
ChoosenSeat:
FullSeat:
If you anchor this control and resize it or you click on a seat to change its state there can be some minor lacking for the repainting if you further increase the number of rows or columns, but that is still somewhere far below one second. If this still hurts you, you have to improve the paint method and maybe check the ClipRectangle property of the paint event and only paint the really needed parts, but that's another story.
Rather than using actual button controls, just draw the image of the seats then when the user clicks on a seat translate the mouse X,Y coordinates to determine which seat was clicked. This will be more efficient. Of course, the drawback is that you have to write the method to translate x,y coordinates to a seat, but that really isn't that difficult.
EDIT; it has been pointed out to me this will not work in Windows Forms!
Well, you are Sequentially working through it.
if one iteration costs 1 sec, the full process will take 400*1 in time.
Perhaps you should try and make a collection of your objects, and process it 'parallel'.
try the .Net framework (4 and above) 'parallel foreach' method:
http://msdn.microsoft.com/en-s/library/system.threading.tasks.parallel.foreach(v=vs.110).aspx
edit: so, if you have a list buttonnames, you can say
buttonNames.ForEach(x=>CreateButton(x));
while your CreateButton() method is as following:
private Button CreateButton(string nameOfButton) { Button b = new
Button(); b.Text = nameOfButton; //do whatever you want...
return b; }
I have problem with my C# WinForms project. I have a function that should change the place of buttons if they touch each other. For example, if I have btn1 at oldloction = (4,2) and btn2 at oldlocaction (2,6), then if I will move the buttons and they will touch bt1 new location = (2,6) and bt2 new location = (4,2)
now i did that with 2 buttons and it works.
locationx - means the x location on the button and its orgenize firat place of the location feat to the first buttons[0], the second feat to locationx[1] = buttons[1].location.x;
location - works the same ass locationx but uts the y locaion.
private void myText_MouseUp(object sender, MouseEventArgs e)
{
Point oldlocation = new Point(locationx[0], locationy[0]);
Point oldlocation2 = new Point(locationx[1], locationy[1]);
if (buttons[0].Location.Y == buttons[1].Location.Y)
{
buttons[1].Location = oldlocation;
buttons[0].Location = oldlocation2;
}
}
When I tried to make that as a global function it doesn't work and I don't know why.
This is the code of the global function that doesn't work:
private void myText_MouseUp(object sender, MouseEventArgs e)
{
for (int i = 0; i < counter; i++)
{
Point oldlocation = new Point(locationx[i], locationy[i]);
for (int j = 0; j < counter; j++)
{
if (i != j)
{
Point oldlocation2 = new Point(locationx[j], locationy[j]);
if (buttons[i].Location.Y != buttons[j].Location.Y)
{
buttons[j].Location = oldlocation2;
buttons[i].Location = oldlocation;
}
else if (buttons[i].Location.Y == buttons[j].Location.Y)
{
buttons[j].Location = oldlocation;
buttons[i].Location = oldlocation2;
}
}
}
}
}
Try using the button event for when it is pressed to call the function, rather than creating your own.
If the second function is not part of the control or form containing the buttons, it won't have a way to access the buttons array or locationx and locationy. You may need to pass these values as arguments to your function or ensure that they are provided as members of the class containing the second function. Note that generally a utility function would not take in "sender" and "MouseEventArgs" - pass only the specific data that the utility function needs to do its job.
So in my program i created a struct with a button and a number value... like this
struct box
{
public int numberValue;
public Button button;
}
I then made a 2D array of this struct
box[,] boxes = new box[20, 20];
Now what i did was make 400 buttons and assigned them to each index of the array... like this
private void createBoxes()
{
int positionX;
int positionY;
for (int i = 0; i < 20; i++)
{
for (int j = 0; j < 20; j++)
{
positionX = 20 + (25 * i);
positionY = 20 + (25 * j);
boxes[i, j].button = new System.Windows.Forms.Button();
boxes[i, j].button.Location = new System.Drawing.Point(positionX,positionY);
boxes[i, j].button.Size = new System.Drawing.Size(25, 25);
this.Controls.Add(boxes[i, j].button);
boxes[i, j].button.FlatStyle = System.Windows.Forms.FlatStyle.Flat;
boxes[i, j].button.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
boxes[i, j].button.Visible = true;
boxes[i, j].button.Name = "button";
boxes[i, j].button.Click += new EventHandler(buttonClick);
}
}
}
Now when i make the event handler i want to send "boxes[i,j]" not just "boxes[i,j].button" is there anyway to do this?
Short of defining your own anonymous event handler, there's an easy way to do what you want:
boxes[i, j].button.Tag = boxes[i, j];
Then later:
private void buttonClick(object sender, EventArgs e)
{
var box = ((Button)sender).Tag as box;
}
This can be solved via an anonymous event handler.
var box = boxes[i, j]; // You must use a new variable within this scope
box.button.Click += (obj, args) => buttonClick(box, args);
This is the quickest solution with the least code. Just be aware that anonymous event handlers are notorious for hidden gotchas, and the need to assign a new box variable is an example. The following code will run, but no matter which button you press, the last-assigned values of i and j would be used within the handler.
boxes[i,j].button.Click += (obj, args) => buttonClick(boxes[i,j], args);
No, this is not possible. The individual button control is the one that raises the event, thus it is the object referenced by the sender parameter. The array that contains the button control is irrelevant.
This behavior is by-design. If you wanted to change a property of the button in response to the user clicking on it, it would be impossible to do unless you knew which individual button was clicked. Having only a reference to the array that contains all of the buttons would not provide sufficient information about the individual button that was clicked.
For example I have a list of picture boxes that raise an event once the cursor hover over them.
Yet I need somehow not only to rise this event, but also to pass the "i" variable, so that I would know which picturebox has the cursor over it.
for (int i = 0; i < 25; i++)
{
....
pbList.Add(new PictureBox());
pbList[i].MouseHover += new System.EventHandler(this.beeHideInfo);
//// need to pass "i" here
}
and
private void beeShowInfo(object sender, EventArgs e)
{
lb_beeInfo.Text = "You are hovering over: "+beeList[i].name;
/// need to get this "i"
}
Any ideas?
You cannot pass variables to an event.
Besides, the necessary variable has already been passed to you: sender.
sender is a reference to the object which raised the event. In your case, it's a reference to the PictureBox that raised the event.
The object sender parameter is the PictureBox sending the event. If you need to associate something with that object, you can use its Tag member:
for (int i = 0; i < 25; i++)
{
....
pbList.Add(new PictureBox() { Tag = beeList[i] });
pbList[i].MouseHover += new System.EventHandler(this.beeHideInfo);
}
and
private void beeShowInfo(object sender, EventArgs e)
{
PictureBox pb = (PictureBox)sender;
Bee b = (Bee)pb.Tag;
lb_beeInfo.Text = "You are hovering over: "+b.name;
}
Assuming pbList and beelist contain related items in the same order, you can do something like beeList[ pbList.IndexOf(sender) ].name
You could you do something like:
for (int i = 0; i < 25; i++)
{
...
pbList.Add(new PictureBox());
var index = i;
pbList[i].MouseHover +=
delegate
{
lb_beeInfo.Text = "You are hovering over: "+beeList[index].name;
};
}
I.e. use an anonymous method.
As John Saunders says, there is an easier solution.
The easiest way to do this is use an anonymous function to explicitly pass the PictureBox or index instance into the handler.
for (int i = 0; i < 25; i++)
{
....
var box = new PictureBox();
pbList.Add(box);
box.MouseHover += delegate { this.beeShowInfo(box); }
}
private void beeShowInfo(PictureBox box)
{
lb_beeInfo.Text = "You are hovering over: "+box.Name;
}
another way might be if you create a Custom Picture Box
class CustomPictureBox : PictureBox
{
public int id;
public CustomPictureBox(int ID)
{
id = ID;
}
}
firt place a GLOBAL id to parent and each time if a CustomPicureBox is clicked get the ID
than everywhere you want to make changes to Clicked CustomPicutreBox test it
foreach(CustomPicutreBox i in Control.controls)
{
if(i.ID == sender.ID)
doWhatEveryYouWant();
}
}