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前提
入行已经7,8年了，一直想做一套漂亮点的自定义控件，于是就有了本系列文章。
GitHub：https://github.com/kwwwvagaa/NetWinformControl
码云：https://gitee.com/kwwwvagaa/net_winform_custom_control.git
如果觉得写的还行，请点个 star 支持一下吧
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NuGet
Install-Package HZH_Controls
目录
https://www.cnblogs.com/bfyx/p/11364884.html
用处及效果
此效果只是牛刀小试，需要注意的是，像textbox这样的控件并不起作用，请注意。
你可以向目标控件绘图，画任何你想画的东西，此效果只是向控件覆盖一个半透明随机颜色
准备工作
没什么可准备的
开始
添加一个类GraphicalOverlay ，继承Component
代码比较少，一次全上了，主要就是用控件的paint事件搞事情，逻辑比较简单
using System;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms; namespace HZH_Controls.Controls
{
[DefaultEvent("Paint")]
public partial class GraphicalOverlay : Component
{
public event EventHandler<PaintEventArgs> Paint; public GraphicalOverlay()
{
InitializeComponent();
} public GraphicalOverlay(IContainer container)
{
container.Add(this); InitializeComponent();
}
private Control owner;
public Control Owner
{
get { return owner; }
set
{
// The owner form cannot be set to null.
if (value == null)
throw new ArgumentNullException(); // The owner form can only be set once.
if (owner != null)
throw new InvalidOperationException(); // Save the form for future reference.
owner = value; // Handle the form's Resize event.
owner.Resize += new EventHandler(Form_Resize); // Handle the Paint event for each of the controls in the form's hierarchy.
ConnectPaintEventHandlers(owner);
}
} private void Form_Resize(object sender, EventArgs e)
{
owner.Invalidate(true);
} private void ConnectPaintEventHandlers(Control control)
{
// Connect the paint event handler for this control.
// Remove the existing handler first (if one exists) and replace it.
control.Paint -= new PaintEventHandler(Control_Paint);
control.Paint += new PaintEventHandler(Control_Paint); control.ControlAdded -= new ControlEventHandler(Control_ControlAdded);
control.ControlAdded += new ControlEventHandler(Control_ControlAdded); // Recurse the hierarchy.
foreach (Control child in control.Controls)
ConnectPaintEventHandlers(child);
} private void Control_ControlAdded(object sender, ControlEventArgs e)
{
// Connect the paint event handler for the new control.
ConnectPaintEventHandlers(e.Control);
} private void Control_Paint(object sender, PaintEventArgs e)
{
// As each control on the form is repainted, this handler is called. Control control = sender as Control;
Point location; // Determine the location of the control's client area relative to the form's client area.
if (control == owner)
// The form's client area is already form-relative.
location = control.Location;
else
{
// The control may be in a hierarchy, so convert to screen coordinates and then back to form coordinates.
location = owner.PointToClient(control.Parent.PointToScreen(control.Location)); // If the control has a border shift the location of the control's client area.
location += new Size((control.Width - control.ClientSize.Width) / , (control.Height - control.ClientSize.Height) / );
} // Translate the location so that we can use form-relative coordinates to draw on the control.
if (control != owner)
e.Graphics.TranslateTransform(-location.X, -location.Y); // Fire a paint event.
OnPaint(sender, e);
} private void OnPaint(object sender, PaintEventArgs e)
{
// Fire a paint event.
// The paint event will be handled in Form1.graphicalOverlay1_Paint(). if (Paint != null)
Paint(sender, e);
}
}
} namespace System.Windows.Forms
{
using System.Drawing; public static class Extensions
{
public static Rectangle Coordinates(this Control control)
{
// Extend System.Windows.Forms.Control to have a Coordinates property.
// The Coordinates property contains the control's form-relative location.
Rectangle coordinates;
Form form = (Form)control.TopLevelControl; if (control == form)
coordinates = form.ClientRectangle;
else
coordinates = form.RectangleToClient(control.Parent.RectangleToScreen(control.Bounds)); return coordinates;
}
}
}
最后的话
如果你喜欢的话，请到 https://gitee.com/kwwwvagaa/net_winform_custom_control 点个星星吧
