代码
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Text;
using System.Windows.Forms;
using System.Windows.Forms.Design;
using System.Diagnostics;
namespace CustomControls {

[Designer(typeof(ScrollbarControlDesigner))]
public class CustomScrollbar : UserControl {

protected Color moChannelColor = Color.Empty;
protected Image moUpArrowImage = null;
//protected Image moUpArrowImage_Over = null;
//protected Image moUpArrowImage_Down = null;
protected Image moDownArrowImage = null;
//protected Image moDownArrowImage_Over = null;
//protected Image moDownArrowImage_Down = null;
protected Image moThumbArrowImage = null;

protected Image moThumbTopImage = null;
protected Image moThumbTopSpanImage = null;
protected Image moThumbBottomImage = null;
protected Image moThumbBottomSpanImage = null;
protected Image moThumbMiddleImage = null;

protected int moLargeChange = 10;
protected int moSmallChange = 1;
protected int moMinimum = 0;
protected int moMaximum = 100;
protected int moValue = http://www.mamicode.com/0;
private int nClickPoint;

protected int moThumbTop = 0;

protected bool moAutoSize = false;

private bool moThumbDown = false;
private bool moThumbDragging = false;

public new event EventHandler Scroll = null;
public event EventHandler ValueChanged = null;

private int GetThumbHeight()
{
int nTrackHeight = (this.Height - (UpArrowImage.Height + DownArrowImage.Height));
float fThumbHeight = ((float)LargeChange / (float)Maximum) * nTrackHeight;
int nThumbHeight = (int)fThumbHeight;

if (nThumbHeight > nTrackHeight)
{
nThumbHeight = nTrackHeight;
fThumbHeight = nTrackHeight;
}
if (nThumbHeight < 56)
{
nThumbHeight = 56;
fThumbHeight = 56;
}

return nThumbHeight;
}

public CustomScrollbar() {

InitializeComponent();
SetStyle(ControlStyles.ResizeRedraw, true);
SetStyle(ControlStyles.AllPaintingInWmPaint, true);
SetStyle(ControlStyles.DoubleBuffer, true);

moChannelColor = Color.FromArgb(51, 166, 3);
UpArrowImage = Resource.uparrow;
DownArrowImage = Resource.downarrow;

ThumbBottomImage = Resource.ThumbBottom;
ThumbBottomSpanImage = Resource.ThumbSpanBottom;
ThumbTopImage = Resource.ThumbTop;
ThumbTopSpanImage = Resource.ThumbSpanTop;
ThumbMiddleImage = Resource.ThumbMiddle;

this.Width = UpArrowImage.Width;
base.MinimumSize = new Size(UpArrowImage.Width, UpArrowImage.Height + DownArrowImage.Height + GetThumbHeight());
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Behavior"), Description("LargeChange")]
public int LargeChange {
get { return moLargeChange; }
set { moLargeChange = value;
Invalidate();
}
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Behavior"), Description("SmallChange")]
public int SmallChange {
get { return moSmallChange; }
set { moSmallChange = value;
Invalidate();
}
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Behavior"), Description("Minimum")]
public int Minimum {
get { return moMinimum; }
set { moMinimum = value;
Invalidate();
}
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Behavior"), Description("Maximum")]
public int Maximum {
get { return moMaximum; }
set { moMaximum = value;
Invalidate();
}
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Behavior"), Description("Value")]
public int Value {
get { return moValue; }
set { moValue = http://www.mamicode.com/value;

int nTrackHeight = (this.Height - (UpArrowImage.Height + DownArrowImage.Height));
float fThumbHeight = ((float)LargeChange / (float)Maximum) * nTrackHeight;
int nThumbHeight = (int)fThumbHeight;

if (nThumbHeight > nTrackHeight)
{
nThumbHeight = nTrackHeight;
fThumbHeight = nTrackHeight;
}
if (nThumbHeight < 56)
{
nThumbHeight = 56;
fThumbHeight = 56;
}

//figure out value
int nPixelRange = nTrackHeight - nThumbHeight;
int nRealRange = (Maximum - Minimum)-LargeChange;
float fPerc = 0.0f;
if (nRealRange != 0)
{
fPerc = (float)moValue / (float)nRealRange;

}

float fTop = fPerc * nPixelRange;
moThumbTop = (int)fTop;

Invalidate();
}
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Skin"), Description("Channel Color")]
public Color ChannelColor
{
get { return moChannelColor; }
set { moChannelColor = value; }
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Skin"), Description("Up Arrow Graphic")]
public Image UpArrowImage {
get { return moUpArrowImage; }
set { moUpArrowImage = value; }
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Skin"), Description("Up Arrow Graphic")]
public Image DownArrowImage {
get { return moDownArrowImage; }
set { moDownArrowImage = value; }
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Skin"), Description("Up Arrow Graphic")]
public Image ThumbTopImage {
get { return moThumbTopImage; }
set { moThumbTopImage = value; }
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Skin"), Description("Up Arrow Graphic")]
public Image ThumbTopSpanImage {
get { return moThumbTopSpanImage; }
set { moThumbTopSpanImage = value; }
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Skin"), Description("Up Arrow Graphic")]
public Image ThumbBottomImage {
get { return moThumbBottomImage; }
set { moThumbBottomImage = value; }
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Skin"), Description("Up Arrow Graphic")]
public Image ThumbBottomSpanImage {
get { return moThumbBottomSpanImage; }
set { moThumbBottomSpanImage = value; }
}

[EditorBrowsable(EditorBrowsableState.Always), Browsable(true), DefaultValue(false), Category("Skin"), Description("Up Arrow Graphic")]
public Image ThumbMiddleImage {
get { return moThumbMiddleImage; }
set { moThumbMiddleImage = value; }
}

protected override void OnPaint(PaintEventArgs e) {

e.Graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.NearestNeighbor;

if (UpArrowImage != null) {
e.Graphics.DrawImage(UpArrowImage, new Rectangle(new Point(0,0), new Size(this.Width, UpArrowImage.Height)));
}

Brush oBrush = new SolidBrush(moChannelColor);
Brush oWhiteBrush = new SolidBrush(Color.FromArgb(255,255,255));

//draw channel left and right border colors
e.Graphics.FillRectangle(oWhiteBrush, new Rectangle(0,UpArrowImage.Height, 1, (this.Height-DownArrowImage.Height)));
e.Graphics.FillRectangle(oWhiteBrush, new Rectangle(this.Width-1, UpArrowImage.Height, 1, (this.Height - DownArrowImage.Height)));

//draw channel
e.Graphics.FillRectangle(oBrush, new Rectangle(1, UpArrowImage.Height, this.Width-2, (this.Height-DownArrowImage.Height)));

//draw thumb
int nTrackHeight = (this.Height - (UpArrowImage.Height + DownArrowImage.Height));
float fThumbHeight = ((float)LargeChange / (float)Maximum) * nTrackHeight;
int nThumbHeight = (int)fThumbHeight;

if (nThumbHeight > nTrackHeight) {
nThumbHeight = nTrackHeight;
fThumbHeight = nTrackHeight;
}
if (nThumbHeight < 56) {
nThumbHeight = 56;
fThumbHeight = 56;
}

//Debug.WriteLine(nThumbHeight.ToString());

float fSpanHeight = (fThumbHeight - (ThumbMiddleImage.Height + ThumbTopImage.Height + ThumbBottomImage.Height)) / 2.0f;
int nSpanHeight = (int)fSpanHeight;

int nTop = moThumbTop;
nTop += UpArrowImage.Height;

//draw top
e.Graphics.DrawImage(ThumbTopImage, new Rectangle(1, nTop, this.Width - 2, ThumbTopImage.Height));

nTop += ThumbTopImage.Height;
//draw top span
Rectangle rect = new Rectangle(1, nTop, this.Width - 2, nSpanHeight);

e.Graphics.DrawImage(ThumbTopSpanImage, 1.0f,(float)nTop, (float)this.Width-2.0f, (float) fSpanHeight*2);

nTop += nSpanHeight;
//draw middle
e.Graphics.DrawImage(ThumbMiddleImage, new Rectangle(1, nTop, this.Width - 2, ThumbMiddleImage.Height));

nTop += ThumbMiddleImage.Height;
//draw top span
rect = new Rectangle(1, nTop, this.Width - 2, nSpanHeight*2);
e.Graphics.DrawImage(ThumbBottomSpanImage, rect);

nTop += nSpanHeight;
//draw bottom
e.Graphics.DrawImage(ThumbBottomImage, new Rectangle(1, nTop, this.Width - 2, nSpanHeight));

if (DownArrowImage != null) {
e.Graphics.DrawImage(DownArrowImage, new Rectangle(new Point(0, (this.Height-DownArrowImage.Height)), new Size(this.Width, DownArrowImage.Height)));
}

}
public override bool AutoSize {
get {
return base.AutoSize;
}
set {
base.AutoSize = value;
if (base.AutoSize) {
this.Width = moUpArrowImage.Width;
}
}
}

private void InitializeComponent() {
this.SuspendLayout();
//
// CustomScrollbar
//
this.Name = "CustomScrollbar";
this.MouseDown += new System.Windows.Forms.MouseEventHandler(this.CustomScrollbar_MouseDown);
this.MouseMove += new System.Windows.Forms.MouseEventHandler(this.CustomScrollbar_MouseMove);
this.MouseUp += new System.Windows.Forms.MouseEventHandler(this.CustomScrollbar_MouseUp);
this.ResumeLayout(false);

}

private void CustomScrollbar_MouseDown(object sender, MouseEventArgs e) {
Point ptPoint = this.PointToClient(Cursor.Position);
int nTrackHeight = (this.Height - (UpArrowImage.Height + DownArrowImage.Height));
float fThumbHeight = ((float)LargeChange / (float)Maximum) * nTrackHeight;
int nThumbHeight = (int)fThumbHeight;

if (nThumbHeight > nTrackHeight) {
nThumbHeight = nTrackHeight;
fThumbHeight = nTrackHeight;
}
if (nThumbHeight < 56) {
nThumbHeight = 56;
fThumbHeight = 56;
}

int nTop = moThumbTop;
nTop += UpArrowImage.Height;

Rectangle thumbrect = new Rectangle(new Point(1, nTop), new Size(ThumbMiddleImage.Width, nThumbHeight));
if (thumbrect.Contains(ptPoint))
{

//hit the thumb
nClickPoint = (ptPoint.Y - nTop);
//MessageBox.Show(Convert.ToString((ptPoint.Y - nTop)));
this.moThumbDown = true;
}

Rectangle uparrowrect = new Rectangle(new Point(1, 0), new Size(UpArrowImage.Width, UpArrowImage.Height));
if (uparrowrect.Contains(ptPoint))
{

int nRealRange = (Maximum - Minimum)-LargeChange;
int nPixelRange = (nTrackHeight - nThumbHeight);
if (nRealRange > 0)
{
if (nPixelRange > 0)
{
if ((moThumbTop - SmallChange) < 0)
moThumbTop = 0;
else
moThumbTop -= SmallChange;

//figure out value
float fPerc = (float)moThumbTop / (float)nPixelRange;
float fValue = http://www.mamicode.com/fPerc * (Maximum - LargeChange);

moValue = http://www.mamicode.com/(int)fValue;
Debug.WriteLine(moValue.ToString());

if (ValueChanged != null)
ValueChanged(this, new EventArgs());

if (Scroll != null)
Scroll(this, new EventArgs());

Invalidate();
}
}
}

Rectangle downarrowrect = new Rectangle(new Point(1, UpArrowImage.Height+nTrackHeight), new Size(UpArrowImage.Width, UpArrowImage.Height));
if (downarrowrect.Contains(ptPoint))
{
int nRealRange = (Maximum - Minimum) - LargeChange;
int nPixelRange = (nTrackHeight - nThumbHeight);
if (nRealRange > 0)
{
if (nPixelRange > 0)
{
if ((moThumbTop + SmallChange) > nPixelRange)
moThumbTop = nPixelRange;
else
moThumbTop += SmallChange;

//figure out value
float fPerc = (float)moThumbTop / (float)nPixelRange;
float fValue = http://www.mamicode.com/fPerc * (Maximum-LargeChange);

moValue = http://www.mamicode.com/(int)fValue;
Debug.WriteLine(moValue.ToString());

if (ValueChanged != null)
ValueChanged(this, new EventArgs());

if (Scroll != null)
Scroll(this, new EventArgs());

Invalidate();
}
}
}
}

private void CustomScrollbar_MouseUp(object sender, MouseEventArgs e) {
this.moThumbDown = false;
this.moThumbDragging = false;
}

private void MoveThumb(int y) {
int nRealRange = Maximum - Minimum;
int nTrackHeight = (this.Height - (UpArrowImage.Height + DownArrowImage.Height));
float fThumbHeight = ((float)LargeChange / (float)Maximum) * nTrackHeight;
int nThumbHeight = (int)fThumbHeight;

if (nThumbHeight > nTrackHeight) {
nThumbHeight = nTrackHeight;
fThumbHeight = nTrackHeight;
}
if (nThumbHeight < 56) {
nThumbHeight = 56;
fThumbHeight = 56;
}

int nSpot = nClickPoint;

int nPixelRange = (nTrackHeight - nThumbHeight);
if (moThumbDown && nRealRange > 0) {
if (nPixelRange > 0) {
int nNewThumbTop = y - (UpArrowImage.Height+nSpot);

if(nNewThumbTop<0)
{
moThumbTop = nNewThumbTop = 0;
}
else if(nNewThumbTop > nPixelRange)
{
moThumbTop = nNewThumbTop = nPixelRange;
}
else {
moThumbTop = y - (UpArrowImage.Height + nSpot);
}

//figure out value
float fPerc = (float)moThumbTop / (float)nPixelRange;
float fValue = http://www.mamicode.com/fPerc * (Maximum-LargeChange);
moValue = http://www.mamicode.com/(int)fValue;
Debug.WriteLine(moValue.ToString());

Application.DoEvents();

Invalidate();
}
}
}

private void CustomScrollbar_MouseMove(object sender, MouseEventArgs e) {
if(moThumbDown == true)
{
this.moThumbDragging = true;
}

if (this.moThumbDragging) {

MoveThumb(e.Y);
}

if(ValueChanged != null)
ValueChanged(this, new EventArgs());

if(Scroll != null)
Scroll(this, new EventArgs());
}

}

internal class ScrollbarControlDesigner : System.Windows.Forms.Design.ControlDesigner {

public override SelectionRules SelectionRules {
get {
SelectionRules selectionRules = base.SelectionRules;
PropertyDescriptor propDescriptor = TypeDescriptor.GetProperties(this.Component)["AutoSize"];
if (propDescriptor != null) {
bool autoSize = (bool)propDescriptor.GetValue(this.Component);
if (autoSize) {
selectionRules = SelectionRules.Visible | SelectionRules.Moveable | SelectionRules.BottomSizeable | SelectionRules.TopSizeable;
}
else {
selectionRules = SelectionRules.Visible | SelectionRules.AllSizeable | SelectionRules.Moveable;
}
}
return selectionRules;
}
}
}
}

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