在制作Winforms ImageButton类（C#）时遇到一点麻烦。我的 ImageButton 类实现了 IButtonControl 接口，但是当我将其添加到窗体中，并将按钮的 DialogResult 设置为"确定"，然后在窗体上调用 ShowDialog（） 时，按下按钮不会关闭窗体并返回 DialogResult，就像普通的 Winforms Button 控件一样。
这是我对ImageButton的实现，随意使用它做任何你喜欢的事情。
/// <summary>
/// A control that displays an image and responds to mouse clicks on the image.
/// </summary>
[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
[Designer(typeof(ImageButtonDesigner))]
[ToolboxItem(typeof(ImageButtonToolboxItem))]
public class ImageButton : PictureBox, IButtonControl, INotifyPropertyChanged
{
#region Constructors
/// <summary>
/// Initializes a new instance of the ImageButton class using the default initial values.
/// </summary>
public ImageButton()
{
DoubleBuffered = true;
BackColor = Color.Transparent;
SizeMode = PictureBoxSizeMode.AutoSize;
}
#endregion
#region Properties
/// <summary>
/// Backing field for the DialogResult property.
/// </summary>
private DialogResult dialogResult;
/// <summary>
/// Gets or sets a value that is returned to the parent form when the button is clicked.
/// </summary>
[Category("Behavior")]
[Description("The dialog-box result produced in a modal form by clicking the button")]
public DialogResult DialogResult
{
get
{
return dialogResult;
}
set
{
if (Enum.IsDefined(typeof(DialogResult), value))
dialogResult = value;
else
throw new InvalidEnumArgumentException("value", (int)value, typeof(DialogResult));
}
}
/// <summary>
/// Backing field for the Idle property.
/// </summary>
private Image idle;
/// <summary>
/// The image that will be displayed on the control when the mouse is not over a visible part of it.
/// </summary>
[Category("Appearance")]
[Description("The image that will be displayed on the Control when the mouse is not over a visible part of it.")]
public Image Idle
{
get
{
return idle;
}
set
{
idle = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Backing field for the Mouseover property
/// </summary>
private Image mouseover;
/// <summary>
/// The image that will be displayed on the control when the mouse is over a visible part of it.
/// </summary>
[Category("Appearance")]
[Description("The image that will be displayed on the control when the mouse is over a visible part of it.")]
public Image Mouseover
{
get { return mouseover; }
set
{
mouseover = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Backing field for the Mousedown property
/// </summary>
private Image mousedown;
/// <summary>
/// The image that will be displayed on the control when the left mouse button is held down and the mouse is over a visible part of it.
/// </summary>
[Category("Appearance")]
[Description("The image that will be displayed on the control when the left mouse button is held down and the mouse is over a visible part of it.")]
public Image Mousedown
{
get { return mousedown; }
set
{
mousedown = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Gets or sets the text associated with the control.
/// </summary>
[Browsable(true)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
[Category("Appearance")]
[Description("The text associated with the control.")]
public override string Text
{
get
{
return base.Text;
}
set
{
base.Text = value;
}
}
/// <summary>
/// Gets or sets the font of the text displayed by the control.
/// </summary>
[Browsable(true)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
[Category("Appearance")]
[Description("The font used to display text in the control.")]
public override Font Font
{
get
{
return base.Font;
}
set
{
base.Font = value;
}
}
/// <summary>
/// Gets or sets the image that is displayed by the PictureBox.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
[Browsable(false)]
[Category("Appearance")]
[Description("The image displayed in the PictureBox.")]
new public Image Image
{
get
{
return base.Image;
}
set
{
base.Image = value;
}
}
/// <summary>
/// Backing field for the ButtonState property.
/// </summary>
private ButtonStates buttonState = ButtonStates.None;
/// <summary>
/// The current state of the button.
/// </summary>
private ButtonStates ButtonState
{
get { return buttonState; }
set
{
buttonState = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Gets the default size of the control.
/// </summary>
protected override Size DefaultSize
{
get
{
return new Size(75, 23);
}
}
#endregion
#region Enums
/// <summary>
/// Specifies the current state of a button.
/// </summary>
[Flags]
private enum ButtonStates : byte
{
/// <summary>
///
/// </summary>
[Description("")]
None = 0,
/// <summary>
///
/// </summary>
[Description("")]
Default = 1 << 0,
/// <summary>
///
/// </summary>
[Description("")]
Mouseover = 1 << 1,
/// <summary>
///
/// </summary>
[Description("")]
Mousedown = 1 << 2
}
#endregion
#region Events
/// <summary>
/// Occurs when a property value changes.
/// </summary>
[Category("Property Changed")]
[Description("Occurs when a property value changes.")]
public event PropertyChangedEventHandler PropertyChanged;
#endregion
#region Methods
/// <summary>
/// Raises the System.ComponentModel.PropertyChanged event.
/// </summary>
/// <param name="propertyName">the name of the property that changed.</param>
protected virtual void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
if (propertyName == "Idle")
Image = Idle;
}
/// <summary>
/// Notifies the button whether it is the default button so that it can adjust its appearance accordingly.
/// </summary>
/// <param name="value">true if the button is to have the appearance of the default button; otherwise, false.</param>
public void NotifyDefault(bool value)
{
ButtonState = value ? ButtonState | ButtonStates.Default : ButtonState & ~ButtonStates.Default;
}
/// <summary>
/// Generates a Click event for a button.
/// </summary>
public void PerformClick()
{
if (CanSelect)
{
OnClick(EventArgs.Empty);
}
}
/// <summary>
/// Raises the System.Windows.Control.TextChanged event.
/// </summary>
/// <param name="e">A System.EventArgs that contains the event data.</param>
protected override void OnTextChanged(EventArgs e)
{
base.OnTextChanged(e);
Refresh();
}
/// <summary>
/// Raises the System.Windows.Forms.Paint event.
/// </summary>
/// <param name="pe">A PaintEventArgs that contains the event data.</param>
protected override void OnPaint(PaintEventArgs pe)
{
base.OnPaint(pe);
if ((!string.IsNullOrEmpty(Text)) && (pe != null) && (base.Font != null))
{
SolidBrush drawBrush = new SolidBrush(base.ForeColor);
// Calculate the size of the text that will be drawn onto the control.
SizeF drawStringSize = pe.Graphics.MeasureString(base.Text, base.Font);
// The registration point used to draw the text.
PointF drawPoint;
if (base.Image != null)
drawPoint = new PointF(base.Image.Width / 2 - drawStringSize.Width / 2, base.Image.Height / 2 - drawStringSize.Height / 2);
else
drawPoint = new PointF(base.Width / 2 - drawStringSize.Width / 2, base.Height / 2 - drawStringSize.Height / 2);
pe.Graphics.DrawString(base.Text, base.Font, drawBrush, drawPoint);
}
}
/// <summary>
/// Raises the System.Windows.Forms.MouseEnter event.
/// </summary>
/// <param name="e">A System.EventArgs that contains the event data.</param>
protected override void OnMouseEnter(EventArgs e)
{
base.OnMouseEnter(e);
ButtonState |= ButtonStates.Mouseover;
Image = Mouseover;
}
/// <summary>
/// Raises the System.Windows.Forms.MouseLeave event.
/// </summary>
/// <param name="e">A System.EventArgs that contains the event data.</param>
protected override void OnMouseLeave(EventArgs e)
{
base.OnMouseLeave(e);
ButtonState &= ~ButtonStates.Mouseover;
Image = Idle;
}
/// <summary>
/// Raises the System.Windows.Forms.MouseDown event.
/// </summary>
/// <param name="e">A System.Windows.Forms.MouseEventArgs that contains the event data.</param>
protected override void OnMouseDown(MouseEventArgs e)
{
base.OnMouseDown(e);
ButtonState |= ButtonStates.Mousedown;
Image = Mousedown;
}
/// <summary>
/// Raises the System.Windows.Forms.MouseUp event.
/// </summary>
/// <param name="e">A System.Windows.Forms.MouseEventArgs that contains the event data.</param>
protected override void OnMouseUp(MouseEventArgs e)
{
base.OnMouseUp(e);
ButtonState &= ~ButtonStates.Mousedown;
Image = ((ButtonState & ButtonStates.Mouseover) != 0) ? Mouseover : idle;
}
#endregion
}
[Serializable]
internal class ImageButtonToolboxItem : ToolboxItem
{
public ImageButtonToolboxItem() : base(typeof(ImageButton)) { }
protected ImageButtonToolboxItem(SerializationInfo info, StreamingContext context)
{
Deserialize(info, context);
}
protected override IComponent[] CreateComponentsCore(IDesignerHost host)
{
ImageButton imageButton = (ImageButton)host.CreateComponent(typeof(ImageButton));
Assembly assembly = Assembly.GetAssembly(typeof(ImageButton));
using (Stream streamMouseover = assembly.GetManifestResourceStream("Mvc.Mouseover.png"))
using (Stream streamMousedown = assembly.GetManifestResourceStream("Mvc.Mousedown.png"))
using (Stream streamIdle = assembly.GetManifestResourceStream("Mvc.Idle.png"))
{
imageButton.Idle = Image.FromStream(streamIdle);
imageButton.Mouseover = Image.FromStream(streamMouseover);
imageButton.Mousedown = Image.FromStream(streamMousedown);
}
return new IComponent[] { imageButton };
}
}
internal class ImageButtonDesigner : ControlDesigner
{
protected override void PostFilterAttributes(System.Collections.IDictionary attributes)
{
base.PostFilterAttributes(attributes);
Attribute dockingBehaviour = new DockingAttribute(DockingBehavior.Never);
attributes[typeof(DockingAttribute)] = dockingBehaviour;
}
public override SelectionRules SelectionRules
{
get
{
return SelectionRules.Moveable;
}
}
}
很抱歉混乱的工具箱项和设计器代码。
我的问题是，是否需要任何特殊的实现才能使按钮控件在模态窗体上工作（与普通按钮的工作方式相同）（注。窗体的边框样式属性设置为"无"，不知道这是否重要）
谢谢，提前！
您需要实际应用分配的 DialogResult 属性，它不是自动的。 通过重写 OnClick（） 方法来实现：
protected override void OnClick(EventArgs e) {
var form = this.FindForm();
if (form != null) form.DialogResult = dialogResult;
base.OnClick(e);
}
从技术上讲，您还应该将状态更改通知辅助功能客户端，目前尚不清楚您是否关心这一点。 对于自定义控件，往往会跳过它，但您通常应该跳过。 在基数之前插入这些语句。OnClick（） 调用：
base.AccessibilityNotifyClients(AccessibleEvents.StateChange, -1);
base.AccessibilityNotifyClients(AccessibleEvents.NameChange, -1);