A Form is a specialization of
Control that supports top-level windows such as
tool windows, frame windows, application pop-ups, and MDI child
windows.
The appearance of the form's non-client imagery can
be set using the FormBorderStyle to determine the
basic appearance, along with the SizeGripStyle to
determine whether to show the resizing grippy. The non-client
controls are enabled and disabled with the
ControlBox (which enables the system menu and
close button), MaximizeBox,
MinimizeBox, and HelpButton
properties. You can also set the Icon to use for
the ControlBox.
The Form can also show a Menu,
and a MergedMenu can be retrieved for the current
context if you are using the MDI idiom.
You can create and Show() a form modelessly as
with any other control, or use the ShowDialog()
method to create and show a modal window. The
Modal property can be used to determine which
method is used to display the form. How the Form
is initially positioned is determined by the
StartPosition property. You can subsequently
minimize or maximize the form by setting the
WindowState. It will float above all other windows
if you set TopMost to true. While it is showing,
it can be made to appear in the taskbar by setting the
ShowInTaskbar property.
When the Form is closed, the ShowDialog() method returns the DialogResult.
Default button processing is handled through the
AcceptButton and CancelButton
properties. You can assign any
IButtonControl-derived class to this property
(which includes Button and
LinkLabel, for example). When the button is
clicked, it will close the window, setting the
DialogResult property appropriately.
Normally, a Form cannot be contained by another
control. There are two exceptions to this rule. MDI support is
provided through the MdiParent property. If you
host a Form in another by setting its
MdiParent, it will appear in the containing
Form objects MdiChildren array,
and the ActiveMdiChild can also be retrieved.
Alternatively, you can set the TopLevel property
to false to allow you to embed the form in another
ContainerControl. Note that if the control has
MdiChildren, TopLevel must
remain set to true. You can tile or stack the
MdiChildren by calling the LayoutMdi() method.
Unlike Win32, there are two separate, well-defined
Form hierarchies: the Parent,
which determines containment relationships of non-toplevel objects
(as with all Control objects), and the
Owner, which determines the message routing and
ownership hierarchy of toplevel windows. For example, a
Form object should be the Owner
of its pop-up tool windows, dialogs, etc.
The Form has the ability to intercept keyboard
messages destined for its child controls. You can set the
KeyPreview property to true, and then receive
KeyPress, KeyUp, and
KeyDown events that would normally (and will
eventually) be sent to a child.
A Form can automatically resize itself and scale
its contained controls when the Font size
changes—the same kind of behavior as Win32 dialogs, only
without the horrible complexities of dialog units to pixel mapping.
This is enabled using the AutoScale property.
Before you show the Form, you can set the
AutoScaleBaseSize to specify the size of the
default Font. The designer environment will set
this property for you, but if you need to do it yourself, you should
set it to the font's em-height and average character
width. While on the subject of sizing, you can specify a
MinimumSize and a MaximumSize,
and you can get the DesktopBounds and
DesktopLocation, in addition to the standard
Location and Bounds.
Finally, you can support transparent forms in two ways. You can set
the overall Opacity of the form (1.00 is
completely opaque, and 0.00 is completely transparent, with 0.50
partially transparent). Note that this is different to the 0-255
range for the alpha value of System.Drawing.Color
objects. Alternatively, you can set a
TransparencyKey for a simple chroma-key effect.
Any pixel painted in that System.Drawing.Color
will become transparent. Note that the transparency features are
supported only on Windows 2000 and above, and there is absolutely no
per-pixel alpha transparency support.
public class Form : ContainerControl {
// Public Constructors
public Form();
// Public Static Properties
public static Form ActiveForm{get; }
// Public Instance Properties
public IButtonControl AcceptButton{set; get; }
public Form ActiveMdiChild{get; }
public bool AllowTransparency{set; get; }
public bool AutoScale{set; get; }
public virtual Size AutoScaleBaseSize{set; get; }
public override bool AutoScroll{set; get; }
// overrides ScrollableControl
public override Color BackColor{set; get; }
// overrides Control
public IButtonControl CancelButton{set; get; }
public Size ClientSize{set; get; }
// overrides Control
public bool ControlBox{set; get; }
public Rectangle DesktopBounds{set; get; }
public Point DesktopLocation{set; get; }
public DialogResult DialogResult{set; get; }
public FormBorderStyle FormBorderStyle{set; get; }
public bool HelpButton{set; get; }
public Icon Icon{set; get; }
public bool IsMdiChild{get; }
public bool IsMdiContainer{set; get; }
public bool IsRestrictedWindow{get; }
public bool KeyPreview{set; get; }
public bool MaximizeBox{set; get; }
public Size MaximumSize{set; get; }
public Form[ ] MdiChildren{get; }
public Form MdiParent{set; get; }
public MainMenu Menu{set; get; }
public MainMenu MergedMenu{get; }
public bool MinimizeBox{set; get; }
public Size MinimumSize{set; get; }
public bool Modal{get; }
public double Opacity{set; get; }
public Form[ ] OwnedForms{get; }
public Form Owner{set; get; }
public bool ShowInTaskbar{set; get; }
public Size Size{set; get; }
// overrides Control
public SizeGripStyle SizeGripStyle{set; get; }
public FormStartPosition StartPosition{set; get; }
public int TabIndex{set; get; }
// overrides Control
public bool TopLevel{set; get; }
public bool TopMost{set; get; }
public Color TransparencyKey{set; get; }
public FormWindowState WindowState{set; get; }
// Protected Instance Properties
protected override CreateParams CreateParams{get; }
// overrides ContainerControl
protected override ImeMode DefaultImeMode{get; }
// overrides Control
protected override Size DefaultSize{get; }
// overrides Control
protected Rectangle MaximizedBounds{set; get; }
// Public Static Methods
public static SizeF GetAutoScaleSize(System.Drawing.Font font);
// Public Instance Methods
public void Activate();
public void AddOwnedForm(Form ownedForm);
public void Close();
public void LayoutMdi(MdiLayout value);
public void RemoveOwnedForm(Form ownedForm);
public void SetDesktopBounds(int x, int y, int width, int height);
public void SetDesktopLocation(int x, int y);
public DialogResult ShowDialog();
public DialogResult ShowDialog(IWin32Window owner);
public override string ToString(); // overrides System.ComponentModel.Component
// Protected Instance Methods
protected void ActivateMdiChild(Form form);
protected override void AdjustFormScrollbars(bool displayScrollbars); // overrides ContainerControl
protected void ApplyAutoScaling();
protected void CenterToParent();
protected void CenterToScreen();
protected override ControlCollection CreateControlsInstance();
// overrides Control
protected override void CreateHandle(); // overrides Control
protected override void DefWndProc(ref Message m); // overrides Control
protected override void Dispose(bool disposing); // overrides ContainerControl
protected virtual void OnActivated(EventArgs e);
protected virtual void OnClosed(EventArgs e);
protected virtual void OnClosing(System.ComponentModel.CancelEventArgs e);
protected override void OnCreateControl(); // overrides ContainerControl
protected virtual void OnDeactivate(EventArgs e);
protected override void OnFontChanged(EventArgs e); // overrides Control
protected override void OnHandleCreated(EventArgs e); // overrides Control
protected override void OnHandleDestroyed(EventArgs e); // overrides Control
protected virtual void OnInputLanguageChanged(InputLanguageChangedEventArgs e);
protected virtual void OnInputLanguageChanging(InputLanguageChangingEventArgs e);
protected virtual void OnLoad(EventArgs e);
protected virtual void OnMaximizedBoundsChanged(EventArgs e);
protected virtual void OnMaximumSizeChanged(EventArgs e);
protected virtual void OnMdiChildActivate(EventArgs e);
protected virtual void OnMenuComplete(EventArgs e);
protected virtual void OnMenuStart(EventArgs e);
protected virtual void OnMinimumSizeChanged(EventArgs e);
protected override void OnPaint(PaintEventArgs e); // overrides Control
protected override void OnResize(EventArgs e); // overrides Control
protected override void OnStyleChanged(EventArgs e); // overrides Control
protected override void OnTextChanged(EventArgs e); // overrides Control
protected override void OnVisibleChanged(EventArgs e); // overrides ScrollableControl
protected override bool ProcessCmdKey(ref Message msg, Keys keyData); // overrides Control
protected override bool ProcessDialogKey(Keys keyData); // overrides ContainerControl
protected override bool ProcessKeyPreview(ref Message m); // overrides Control
protected override bool ProcessTabKey(bool forward); // overrides ContainerControl
protected override void ScaleCore(float x, float y); // overrides ScrollableControl
protected override void Select(bool directed, bool forward); // overrides ContainerControl
protected override void SetBoundsCore(int x, int y, int width, int height, BoundsSpecified specified); // overrides Control
protected override void SetClientSizeCore(int x, int y); // overrides Control
protected override void SetVisibleCore(bool value); // overrides Control
protected override void UpdateDefaultButton(); // overrides ContainerControl
protected override void WndProc(ref Message m); // overrides ContainerControl
// Events
public event EventHandler Activated;
public event EventHandler Closed;
public event CancelEventHandler Closing;
public event EventHandler Deactivate;
public event InputLanguageChangedEventHandler InputLanguageChanged;
public event InputLanguageChangingEventHandler InputLanguageChanging;
public event EventHandler Load;
public event EventHandler MaximizedBoundsChanged;
public event EventHandler MaximumSizeChanged;
public event EventHandler MdiChildActivate;
public event EventHandler MenuComplete;
public event EventHandler MenuStart;
public event EventHandler MinimumSizeChanged;
}
System.MarshalByRefObject