In the following code, only the second method works for me (.NET 4.0). FormStartPosition.CenterParent does not center the child form over its parent.
Why?
Source: this SO question
using System;
using System.Drawing;
using System.Windows.Forms;
class Program
{
private static Form f1;
public static void Main()
{
f1 = new Form() { Width = 640, Height = 480 };
f1.MouseClick += f1_MouseClick;
Application.Run(f1);
}
static void f1_MouseClick(object sender, MouseEventArgs e)
{
Form f2 = new Form() { Width = 400, Height = 300 };
switch (e.Button)
{
case MouseButtons.Left:
{
// 1st method
f2.StartPosition = FormStartPosition.CenterParent;
break;
}
case MouseButtons.Right:
{
// 2nd method
f2.StartPosition = FormStartPosition.Manual;
f2.Location = new Point(
f1.Location.X + (f1.Width - f2.Width) / 2,
f1.Location.Y + (f1.Height - f2.Height) / 2
);
break;
}
}
f2.Show(f1);
}
}
This is because you are not telling f2 who its Parent is.
If this is an MDI application, then f2 should have its MdiParent set to f1.
Form f2 = new Form() { Width = 400, Height = 300 };
f2.StartPosition = FormStartPosition.CenterParent;
f2.MdiParent = f1;
f2.Show();
If this is not an MDI application, then you need to call the ShowDialog method using f1 as the parameter.
Form f2 = new Form() { Width = 400, Height = 300 };
f2.StartPosition = FormStartPosition.CenterParent;
f2.ShowDialog(f1);
Note that CenterParent does not work correctly with Show since there is no way to set the Parent, so if ShowDialog is not appropriate, the manual approach is the only viable one.
If you set the owner of the child form like so:
Form2 f = new Form2();
f.Show(this);
You can then center it easily like this:
Form2_Load(object sender, EventArgs e)
{
if (Owner != null)
Location = new Point(Owner.Location.X + Owner.Width / 2 - Width / 2,
Owner.Location.Y + Owner.Height / 2 - Height / 2);
}
I'm using this code inside my main form, hope it helps:
var form = new MyForm();
form.Show();
if (form.StartPosition == FormStartPosition.CenterParent)
{
var x = Location.X + (Width - form.Width) / 2;
var y = Location.Y + (Height - form.Height) / 2;
form.Location = new Point(Math.Max(x, 0), Math.Max(y, 0));
}
I found setting the location manually is the only reliable option in some more complex cases when form is auto-sized and dynamically modified.
However rather than computing the coordinates manually, I'd suggest using existing method:
this.CenterToParent();
I had the same problem, I eventually went with this:
protected override void OnActivated(EventArgs e) {
if(this.Modal == false && this.StartPosition == FormStartPosition.CenterParent) {
if(!(this.Owner is Form)) {
// Center to the last form opened before this one
int numforms = Application.OpenForms.Count;
this.Owner = Application.OpenForms[numforms - 2];
}
this.CenterToParent();
Application.DoEvents();
}
base.OnActivated(e);
}
Used as:
MyForm form = new MyForm();
form.Show(this); // with or without
The main advantage is that it does what your colleagues expect it to do, without requiring any hack in the calling form.
I found a solution that will center modeless window position to parent's position, and the child window can be still covered by parent window.
You just have to call
f2.Show(f1);
which will set f2 owner to f1, f2 will show over the f1 at it's center position.
Next you set
f2.Owner = null;
and there you go, f2 is a separate window, with correct startup position.
I realize this is an old question, but I was recently having the same problem and for reasons I won't get in to, I did not want to use the form.ShowDialog() method and my application was not an MDI application, therefore the CenterParent method was not having any effect. This is how I solved the problem, by computing the coordinates for the form that I wanted centered and triggering the new location in the main form's LocationChanged event. Hopefully this will help someone else having this problem.
In the example below, the parent form is called MainForm and the form I want centered in MainForm is called pleaseWaitForm.
private void MainForm_LocationChanged(object sender, EventArgs e)
{
Point mainFormCoords = this.Location;
int mainFormWidth = this.Size.Width;
int mainFormHeight = this.Size.Height;
Point mainFormCenter = new Point();
mainFormCenter.X = mainFormCoords.X + (mainFormWidth / 2);
mainFormCenter.Y = mainFormCoords.Y + (mainFormHeight / 2);
Point waitFormLocation = new Point();
waitFormLocation.X = mainFormCenter.X - (pleaseWaitForm.Width / 2);
waitFormLocation.Y = mainFormCenter.Y - (pleaseWaitForm.Height / 2);
pleaseWaitForm.StartPosition = FormStartPosition.Manual;
pleaseWaitForm.Location = waitFormLocation;
}
If you have a resizable parent form and you wanted your sub form to also be centered whenever the main form is resized, you should, in theory, be able to place this code in a method and then call the method on both the LocationChanged and SizeChanged events.
JYelton's answer worked for me, but the form is only centered the first time Show() is called.
If you want to Hide() the form, and then have it re-centered on the parent every time Show() is called you need use the following in your form:
public new void Show(IWin32Window owner)
{
base.Show(owner);
if (Owner != null)
Location = new Point(Owner.Location.X + Owner.Width / 2 - Width / 2,
Owner.Location.Y + Owner.Height / 2 - Height / 2);
}
Maybe this can help somebody.
Form frmMessage = new Form();
From experience, although they look similar, they behave different:
This variant doesn't work:
if (frmMessage.Parent != null)
frmMessage.CenterToParent();
else
frmMessage.CenterToScreen();
And this variant works
if (frmMessage.Parent != null)
frmMessage.StartPosition = FormStartPosition.CenterParent;
else
frmMessage.StartPosition = FormStartPosition.CenterScreen;
Using
form.Show(this);
throws an exception if you call it a second time. Manually setting the location seems to be the only reliable option :/ (wasn't it fairly recently that CenterParent used to work?)
just put the code in the constructor of your form.
public FrmSample()
{
InitializeComponent();
// must be after the InitializeComponent()
this.StartPosition = FormStartPosition.CenterParent;
}
Small Change to JYelton's answer
Form2_Load(object sender, EventArgs e)
{
if (Owner != null && Parent == null && StartPosition == FormStartPosition.CenterParent)
Location = new Point(Owner.Location.X + Owner.Width / 2 - Width / 2,
Owner.Location.Y + Owner.Height / 2 - Height / 2);
}
An old question, I know, but I had the same issue but for a different reason.
The Form I was opening had an overridden OnLoad method:
protected override void OnLoad(EventArgs e)
{
//... etc.
}
but was not calling the base implementation as it must do:
protected override void OnLoad(EventArgs e)
{
//... etc.
base.OnLoad(e);
}
When overriding OnLoad(EventArgs) in a derived class, be sure to call the base class's OnLoad(EventArgs) method so that registered delegates receive the event.
Building off the answer by deerchao,
if (form.StartPosition == FormStartPosition.CenterParent) {
form.Location = new Point(Location.X + (Width - form.Width) / 2, Location.Y + (Height - form.Height) / 2);
}
Do this after form.Show(), this will work on multi-monitors also
Related
I have the following code:
namespace ExtendedDisplay{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
}
public static void ThreadProc(object arg)
{
Form2 form = arg as Form2;
Application.Run(form);
}
int iWidth = 0;
int iHeight = 0;
private void button2_Click(object sender, EventArgs e)
{
Rectangle rect = new Rectangle(int.MaxValue, int.MaxValue, int.MinValue, int.MinValue);
int iMonitorCount = Screen.AllScreens.Length;
foreach (Screen screen in Screen.AllScreens)
rect = Rectangle.Union(rect, screen.Bounds);
Console.WriteLine("(width, height) = ({0}, {1})", rect.Width, rect.Height);
label2.Text = ("Resolution: " + rect.Width + "x" + rect.Height);
iWidth = rect.Width;
iHeight = rect.Height;
}
[STAThread]
private void button1_Click(object sender, EventArgs e)
{
Rectangle rect = new Rectangle(int.MaxValue, int.MaxValue, int.MinValue, int.MinValue);
int iMonitorCount = Screen.AllScreens.Length;
foreach (Screen screen in Screen.AllScreens)
rect = Rectangle.Union(rect, screen.Bounds);
Form2 form = new Form2() { Text = "test" };
Thread t = new Thread(ThreadProc);
if (!Screen.AllScreens[1].Bounds.IsEmpty)
{
form.StartPosition = FormStartPosition.Manual;
form.Bounds = Screen.AllScreens[1].Bounds;
t.Start(form);
}
else
{
t.Start(form);
}
The code is running fine, however
I can only get one of the condition to run
Example:
if (screen1 is not empty & screen 0 is not empty)
display at screen 1
else if (screen 0 is not empty)
display at screen 0
this if and else if
it will only run if
Is it a bug?
currently the code is
if and else only
however only the if can be run
if I don't have screen 1
it will crash (thus else is not working)
That code is pretty messy, most of it needs junking as it seems to be redundant. The problem line is probably:
if (!Screen.AllScreens[1].Bounds.IsEmpty)
{
You just flat assume the user has 2 screens here, by referring to the second screen without checking if the Screen.AllScreens array even has a [1]th element. Why not something more like:
if(Screen.AllScreens.Length > 1) //does the user have at least 2 screens?
I can't imagine the Rectangle that is Screen.Bounds will ever be empty either - this isn't testing if there is nothing on screen, it's testing if the screen is 0x0 pixels in size. Probably not what you want.
https://learn.microsoft.com/en-us/dotnet/api/system.drawing.rectangle.isempty?view=netframework-4.7.2
Ask another question with the actual problem you're trying to solve, perhaps something like "How can I test if my user has 2 monitors and if they do, open my app on the second monitor, but if they don't, then open it on the first monitor?" - I think this is an XY problem, where you've got some issue, you're written some code to try and solve it, it doesn't work/won't work, and you're asking for help fixing that code - instead tell use the original problem you're trying to solve, not the problem with the broken solution
I'm trying to change Form position to center after changing from a primary screen on a secondary screen
private void Form2_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Space)
{
ff = !ff;
if(ff)
showOnScreen(1,this);
else
showOnScreen(0,this);
}
}
void showOnScreen(int screenNumber,Form frm)
{
Screen[] screens = Screen.AllScreens;
if (screenNumber >= 0 && screenNumber < screens.Length)
{
Location = screens[screenNumber].WorkingArea.Location;
this.Location = new Point((screens[screenNumber].Bounds.Size.Width / 2) - (this.Size.Width / 2), (screens[screenNumber].Bounds.Size.Height / 2) - (this.Size.Height / 2));
}
}
The form is moved in center of screen but only in my primary screen
You need to set StartPosition manual of form to set start position value in Location Property.
public Form1()
{
InitializeComponent();
this.StartPosition = FormStartPosition.Manual;
this.Location = new Point(0, 0);
}
Also Take Reference From Here and also check my Another Reference
Now
Try to setting WindowStartUpLocation parameter as "manual" inside your showOnScreen method.
I want to grow a form when I click the button and it should be in the center of the screen .so I wrote following code snippet.
private void ord_Click(object sender, EventArgs e)
{
this.StartPosition = FormStartPosition.CenterScreen;
this.Size = new Size(1308,599);
this.Show();
}
But when I click the button window grows but half of the window can not see.Here is the picture of that.
GUI after growing
How can I get rid of this problem.?
Whats wrong with my code?
You have to compute both Size and Location:
private void ord_Click(object sender, EventArgs e) {
// Ensure that suggested form size doesn't exceed the screen width and height
this.Size = new System.Drawing.Size(
Screen.GetWorkingArea(this).Width >= 1308 ? 1308 : Screen.GetWorkingArea(this).Width,
Screen.GetWorkingArea(this).Height >= 599 ? 599 : Screen.GetWorkingArea(this).Height);
// locate the form in the center of the working area
this.Location = new System.Drawing.Point(
(Screen.GetWorkingArea(this).Width - Width) / 2,
(Screen.GetWorkingArea(this).Height - Height) / 2);
}
You can use the PrimaryScreen property of the Screen class.
//this.StartPosition = FormStartPosition.CenterScreen;
//this.Show();
Omit these lines you've written, except setting the Size property of the form:
private void ord_Click(object sender, EventArgs e)
{
this.Size = new Size(1308,599);
CenterForm();
}
Create a method named CenterForm() which will set a new location of the form. You can achieve this by calling this method in your button click event.
private void CenterForm()
{
int getWidth = Screen.PrimaryScreen.Bounds.Width;
int getHeight = Screen.PrimaryScreen.Bounds.Height;
int X = getWidth - this.Width;
int Y = getHeight - this.Height;
this.Location = new Point(X / 2, Y / 2);
}
Note: Always remember to anchor your controls when the size of the form has changed.
I created default Windows Forms Application project in Visual Studio 2012. When I run program then saw that width of form can not be less than 140 pixels. Why? And how to overcome this strange restriction?
I was looking for a solution and MinimumSize(0,0) didn't had any effect. Figured out, that MinimumSize set to (1,1) actually fixed the problem and after showing my form it was properly sized smaller than 140px.
Column click event on (ListView)_csvLv that should trigger a popup dialog:
var topAnchor = _csvLv.PointToScreen(new Point(
_csvLv
.Columns
.OfType<ColumnHeader>()
.Where(c => c.DisplayIndex < e.Column)
.Sum(c => c.Width),
0));
Left = topAnchor.X;
Top = topAnchor.Y;
MinimumSize = new Size(1,1);
ClientSize = new Size(_csvLv.Columns[e.Column].Width, 100);
ShowDialog();
Users wouldn't be able to use the window's minimize, maximize, and close buttons at that top. I don't believe you can change that behaviour with the Sizable FormBorderStyle. It's a usability thing.
If you remove the border, by setting it to None for example, you can set it to whatever you want programmatically by doing:
form.Width = [...];
You can resize further forms with border types: None, FixedToolWindow, and SizableToolWindow. The ToolWindows won't let you go below a certain amount as well, but None will let you do anything above 2px. You could set it to some value below that, without getting an exception, but it won't do anything.
Try this.
Autosize no
AutosizeMode growOnly
FormBorderStyle SizableToolWindow <== this one did it
I still can move the form and resize it (width) less tan 112
I never use formborders.. I always like to go with FormBorderstyle.None
To resize, you have to add some code.
Put a pictureBox, add a grip img in it and place it in the corner.
public Form1()
{
InitializeComponent();
pictureBox1.MouseDown += new MouseEventHandler(Form1_MouseDown);
pictureBox1.MouseMove += new MouseEventHandler(Form1_MouseMove);
pictureBox1.MouseUp += new MouseEventHandler(Form1_MouseUp);
}
void Form1_MouseUp(object sender, MouseEventArgs e)
{
isHolding = false;
}
void Form1_MouseMove(object sender, MouseEventArgs e)
{
if (isHolding)
{
int diffX = this.Width - pictureBox1.Left;
int diffY = this.Height - pictureBox1.Top;
pictureBox1.Left += e.X - curX;
pictureBox1.Top += e.Y - curY;
this.Width = pictureBox1.Left + diffX;
this.Height = pictureBox1.Top + diffY;
}
}
void Form1_MouseDown(object sender, MouseEventArgs e)
{
isHolding = true;
curX = e.X;
curY = e.Y;
}
int curX = 0, curY = 0;
bool isHolding = false;
I didn't find a way in C# for creating a button which will support opacity - instead of just appearing when show method is called, to have the ability to slowly fade it into view.
I created my own button and I would like to know what you think of the implementation.
Basically, I created a Windows Form, which supports opacity property and handled all the corner cases regarding "adding" a form to another form, specifically:
- location changed event
- the owner form lost focus
The form consist of a label, which represents the button's text and that's all.
The form constructor gets the text for the label, the desired size of the button and the speed (based on an Enum) for the button appear.
In the form load method the label is being located in the middle of the button
when the label or the form itself clicked a simple graphic is performed and an event is raised to whoever catches it.
My Code:
Created a Form - named buttonForm
Constructor
InitializeComponent();
this.Owner = owner;
_buttonText = buttonText;
_buttonSize = buttonSize;
_usedSpeedOpacity = SelectSpeedOpacity(showSpeed);
A method to illustrate click command - being called when the user clicks on the form and on the label itself:
this.Location = new Point(this.Location.X + 1, this.Location.Y);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
Thread.Sleep(50);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedToolWindow;
this.Location = new Point(this.Location.X - 1, this.Location.Y);
if (Button_Clicked != null)
{
Button_Clicked();
}
form load - locating the label in the middle of the control etc
labelButtonText.Text = _buttonText;
this.Size = _buttonSize;
double remainning = this.Width - labelButtonText.Size.Width;
Point labelNewLocation = new Point(
(int)(remainning / 2),
(int)(this.Height / 2 - this.Font.Height / 2));
labelButtonText.Location = labelNewLocation;
FadeShow (and FadeHide the same)
int tempCounter = 0;
Opacity = 0;
Show();
while (tempCounter <= 1000)
{
if (Opacity == 1.0)
{
break;
}
if (tempCounter % 10 == 0)
{
Opacity += _usedSpeedOpacity;
}
Refresh();
tempCounter++;
}
this.Visible = true;
this.BringToFront();
Update location method so when the parent form moves i call this method
this.Location = new Point(
this.Location.X - (ParentFormLocation.X - newLocation.X),
this.Location.Y - (ParentFormLocation.Y - newLocation.Y));
ParentFormLocation = newLocation;
An event of my button_click
Thanks in advance,
Oz.
I did something similar with a windows form that changed its height. The way I did it was to implement a timer within the code so every half a second the opacity changed.
While the below is not a 100% correct answer without your code its difficult to show you.
void timer_Tick(object sender, EventArgs e)
{
if (btnName.Opacity < 100)
{
btnName.Opacity++;
timer2.Stop();
timer2.Interval = 5000;
timer2.Start();
} else {
timer2.Stop();
}
}