创建显示进度的 Windows 窗体控件

创建显示进度的 Windows 窗体控件

下面的代码示例演示一个名为 FlashTrackBar 的自定义控件，该控件可用于向用户显示应用程序的级别或进度。它使用渐变以直观的方式表示进度。

FlashTrackBar 控件阐释了以下概念：

定义自定义属性。

定义自定义事件。(（FlashTrackBar 定义 ValueChanged 事件。）

重写 OnPaint 方法以提供绘制控件的逻辑。

通过使用其 ClientRectangle 属性计算可用于绘制控件的区域。FlashTrackBar 在其 OptimizedInvalidate 方法中执行此计算。

当在 Windows 窗体设计器中更改属性时实现属性的序列化（持久性）。FlashTrackBar 定义 ShouldSerializeStartColor 和 ShouldSerializeEndColor 方法以序列化其 StartColor 和 EndColor 属性。

下表显示由 FlashTrackBar 定义的自定义属性。

属性 说明
AllowUserEdit
指示用户是否可以通过单击和拖动来更改闪烁跟踪条的值。

EndColor
指定跟踪条的结束颜色。

DarkenBy
指定根据前景渐变加深背景颜色的程度。

Max
指定跟踪条的最大值。

Min
指定跟踪条的最小值。

StartColor
指定渐变的开始颜色。

ShowPercentage
指示是否在渐变之上显示百分比。

ShowValue
指示是否在渐变之上显示当前值。

ShowGradient
指示跟踪条是否应显示表明当前值的颜色渐变。

Value
指定跟踪条的当前值。

下表显示由 FlashTrackBar: 定义的附加成员：property-changed 事件以及引发该事件的方法。

成员 说明
ValueChanged
当跟踪条的 Value 属性改变时引发的事件。

OnValueChanged
引发 ValueChanged 事件的方法。

注意
FlashTrackBar 将 EventArgs 类用于事件数据，将 EventHandler 用于事件委托。

为了处理相应的 EventName 事件，FlashTrackBar 重写它从 System.Windows.Forms.Control 继承的以下方法：

OnPaint

OnMouseDown

OnMouseMove

OnMouseUp

OnResize

为了处理相应的 property-changed 事件，FlashTrackBar 重写它从 System.Windows.Forms.Control 继承的以下方法：

OnBackColorChanged

OnBackgroundImageChanged

OnTextChanged

示例
FlashTrackBar 控件定义两种用户界面类型编辑器：FlashTrackBarValueEditor 和 FlashTrackBarDarkenByEditor，如下面的代码清单所示。HostApp 类在 Windows 窗体上使用 FlashTrackBar 控件。

namespace Microsoft.Samples.WinForms.Cs.FlashTrackBar {
using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Design;
using System.Windows.Forms;
using System.Diagnostics;

[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
public class FlashTrackBar : System.Windows.Forms.Control {
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.Container components;

private const int LeftRightBorder = 10;
private int value = 0;
private int min = 0;
private int max = 100;
private bool showPercentage = false;
private bool showValue = false;
private bool allowUserEdit = true;
private bool showGradient = true;
private int dragValue = 0;
private bool dragging = false;
private Color startColor = Color.Red;
private Color endColor = Color.LimeGreen;
private EventHandler onValueChanged;
private Brush baseBackground = null;
private Brush backgroundDim = null;
private byte darkenBy = 200;

public FlashTrackBar() {
//
// Required for Windows Form Designer support
//
InitializeComponent();

SetStyle(ControlStyles.Opaque, true);
SetStyle(ControlStyles.ResizeRedraw, true);
Debug.Assert(GetStyle(ControlStyles.ResizeRedraw), "Should be redraw!");
}

/// <summary>
/// Clean up any resources being used.
/// </summary>
protected override void Dispose(bool disposing)
{
if (disposing) {
if (components != null) {
components.Dispose();
}
}
base.Dispose(disposing);
}

/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
void InitializeComponent () {
this.components = new System.ComponentModel.Container ();
this.ForeColor = System.Drawing.Color.White;
this.BackColor = System.Drawing.Color.Black;
this.Size = new System.Drawing.Size(100, 23);
this.Text = "FlashTrackBar";
}

[
Category("Flash"),
DefaultValue(true)
]
public bool AllowUserEdit {
get {
return allowUserEdit;
}
set {
if (value != allowUserEdit) {
allowUserEdit = value;
if (!allowUserEdit) {
Capture = false;
dragging = false;
}
}
}
}

[
Category("Flash")
]
public Color EndColor {
get {
return endColor;
}
set {
endColor = value;
if (baseBackground != null && showGradient) {
baseBackground.Dispose();
baseBackground = null;
}
Invalidate();
}
}

public bool ShouldSerializeEndColor() {
return !(endColor == Color.LimeGreen);
}

[
Category("Flash"),
Editor(typeof(FlashTrackBarDarkenByEditor), typeof(UITypeEditor)),
DefaultValue((byte)200)
]
public byte DarkenBy {
get {
return darkenBy;
}
set {
if (value != darkenBy) {
darkenBy = value;
if (backgroundDim != null) {
backgroundDim.Dispose();
backgroundDim = null;
}
OptimizedInvalidate(Value, max);
}
}
}

[
Category("Flash"),
DefaultValue(100)
]
public int Max {
get {
return max;
}
set {
if (max != value) {
max = value;
Invalidate();
}
}
}

[
Category("Flash"),
DefaultValue(0)
]
public int Min {
get {
return min;
}
set {
if (min != value) {
min = value;
Invalidate();
}
}
}

[
Category("Flash")
]
public Color StartColor {
get {
return startColor;
}
set {
startColor = value;
if (baseBackground != null && showGradient) {
baseBackground.Dispose();
baseBackground = null;
}
Invalidate();
}
}

public bool ShouldSerializeStartColor() {
return !(startColor == Color.Red);
}

[
Category("Flash"),
RefreshProperties(RefreshProperties.Repaint),
DefaultValue(false)
]
public bool ShowPercentage {
get {
return showPercentage;
}
set {
if (value != showPercentage) {
showPercentage = value;
if (showPercentage) {
showValue = false;
}
Invalidate();
}
}
}

[
Category("Flash"),
RefreshProperties(RefreshProperties.Repaint),
DefaultValue(false)
]
public bool ShowValue {
get {
return showValue;
}
set {
if (value != showValue) {
showValue = value;
if (showValue) {
showPercentage = false;
}
Invalidate();
}
}
}

[
Category("Flash"),
DefaultValue(true)
]
public bool ShowGradient {
get {
return showGradient;
}
set {
if (value != showGradient) {
showGradient = value;
if (baseBackground != null) {
baseBackground.Dispose();
baseBackground = null;
}
Invalidate();
}
}
}

[
Category("Flash"),
Editor(typeof(FlashTrackBarValueEditor), typeof(UITypeEditor)),
DefaultValue(0)
]
public int Value {
get {
if (dragging) {
return dragValue;
}
return value;
}
set {
if (value != this.value) {
int old = this.value;
this.value = value;
OnValueChanged(EventArgs.Empty);
OptimizedInvalidate(old, this.value);
}
}
}

// ValueChanged Event
[Description("Raised when the Value displayed changes")]
public event EventHandler ValueChanged {
add {
onValueChanged += value;
}
remove {
onValueChanged -= value;
}
}

private void OptimizedInvalidate(int oldValue, int newValue) {
Rectangle client = ClientRectangle;

float oldPercentValue = ((float)oldValue / ((float)Max - (float)Min));
int oldNonDimLength = (int)(oldPercentValue * (float)client.Width);

float newPercentValue = ((float)newValue / ((float)Max - (float)Min));
int newNonDimLength = (int)(newPercentValue * (float)client.Width);

int min = Math.Min(oldNonDimLength, newNonDimLength);
int max = Math.Max(oldNonDimLength, newNonDimLength);

Rectangle invalid = new Rectangle(
client.X + min,
client.Y,
max - min,
client.Height);

Invalidate(invalid);

string oldToDisplay;
string newToDisplay;

if (ShowPercentage) {
oldToDisplay = Convert.ToString((int)(oldPercentValue * 100f)) + "%";
newToDisplay = Convert.ToString((int)(newPercentValue * 100f)) + "%";
}
else if (ShowValue) {
oldToDisplay = Convert.ToString(oldValue);
newToDisplay = Convert.ToString(newValue);
}
else {
oldToDisplay = null;
newToDisplay = null;
}

if (oldToDisplay != null && newToDisplay != null) {
Graphics g = CreateGraphics();
SizeF oldFontSize = g.MeasureString(oldToDisplay, Font);
SizeF newFontSize = g.MeasureString(newToDisplay, Font);
RectangleF oldFontRect = new RectangleF(new PointF(0, 0), oldFontSize);
RectangleF newFontRect = new RectangleF(new PointF(0, 0), newFontSize);
oldFontRect.X = (client.Width - oldFontRect.Width) / 2;
oldFontRect.Y = (client.Height - oldFontRect.Height) / 2;
newFontRect.X = (client.Width - newFontRect.Width) / 2;
newFontRect.Y = (client.Height - newFontRect.Height) / 2;

Invalidate(new Rectangle((int)oldFontRect.X, (int)oldFontRect.Y, (int)oldFontRect.Width, (int)oldFontRect.Height));
Invalidate(new Rectangle((int)newFontRect.X, (int)newFontRect.Y, (int)newFontRect.Width, (int)newFontRect.Height));
}
}

protected override void OnMouseDown(MouseEventArgs e) {
base.OnMouseDown(e);
if (!allowUserEdit) {
return;
}
Capture = true;
dragging = true;
SetDragValue(new Point(e.X, e.Y));
}

protected override void OnMouseMove(MouseEventArgs e) {
base.OnMouseMove(e);
if (!allowUserEdit || !dragging) {
return;
}
SetDragValue(new Point(e.X, e.Y));
}

protected override void OnMouseUp(MouseEventArgs e) {
base.OnMouseUp(e);
if (!allowUserEdit || !dragging) {
return;
}
Capture = false;
dragging = false;
value = dragValue;
OnValueChanged(EventArgs.Empty);
}

protected override void OnPaint(PaintEventArgs e) {

base.OnPaint(e);
if (baseBackground == null) {
if (showGradient) {
baseBackground = new LinearGradientBrush(new Point(0, 0),
new Point(ClientSize.Width, 0),
StartColor,
EndColor);
}
else if (BackgroundImage != null) {
baseBackground = new TextureBrush(BackgroundImage);
}
else {
baseBackground = new SolidBrush(BackColor);
}
}

if (backgroundDim == null) {
backgroundDim = new SolidBrush(Color.FromArgb(DarkenBy, Color.Black));
}

Rectangle toDim = ClientRectangle;
float percentValue = ((float)Value / ((float)Max - (float)Min));
int nonDimLength = (int)(percentValue * (float)toDim.Width);
toDim.X += nonDimLength;
toDim.Width -= nonDimLength;

string text = Text;
string toDisplay = null;
RectangleF textRect = new RectangleF();

if (ShowPercentage || ShowValue || text.Length > 0) {

if (ShowPercentage) {
toDisplay = Convert.ToString((int)(percentValue * 100f)) + "%";
}
else if (ShowValue) {
toDisplay = Convert.ToString(Value);
}
else {
toDisplay = text;
}

SizeF textSize = e.Graphics.MeasureString(toDisplay, Font);
textRect.Width = textSize.Width;
textRect.Height = textSize.Height;
textRect.X = (ClientRectangle.Width - textRect.Width) / 2;
textRect.Y = (ClientRectangle.Height - textRect.Height) / 2;
}

e.Graphics.FillRectangle(baseBackground, ClientRectangle);
e.Graphics.FillRectangle(backgroundDim, toDim);
e.Graphics.Flush();
if (toDisplay != null && toDisplay.Length > 0) {
e.Graphics.DrawString(toDisplay, Font, new SolidBrush(ForeColor), textRect);
}
}

protected override void OnTextChanged(EventArgs e) {
base.OnTextChanged(e);
Invalidate();
}

protected override void OnBackColorChanged(EventArgs e) {
base.OnTextChanged(e);
if ((baseBackground != null) && (!showGradient)) {
baseBackground.Dispose();
baseBackground = null;
}
}

protected override void OnBackgroundImageChanged(EventArgs e) {
base.OnTextChanged(e);
if ((baseBackground != null) && (!showGradient)) {
baseBackground.Dispose();
baseBackground = null;
}
}

protected override void OnResize(EventArgs e) {
base.OnResize(e);
if (baseBackground != null) {
baseBackground.Dispose();
baseBackground = null;
}
}

protected virtual void OnValueChanged(EventArgs e) {
if (onValueChanged != null) {
onValueChanged.Invoke(this, e);
}
}

private void SetDragValue(Point mouseLocation) {

Rectangle client = ClientRectangle;

if (client.Contains(mouseLocation)) {
float percentage = (float)mouseLocation.X / (float)ClientRectangle.Width;
int newDragValue = (int)(percentage * (float)(max - min));
if (newDragValue != dragValue) {
int old = dragValue;
dragValue = newDragValue;
OptimizedInvalidate(old, dragValue);
}
}
else {
if (client.Y <= mouseLocation.Y && mouseLocation.Y <= client.Y + client.Height) {
if (mouseLocation.X <= client.X && mouseLocation.X > client.X - LeftRightBorder) {
int newDragValue = min;
if (newDragValue != dragValue) {
int old = dragValue;
dragValue = newDragValue;
OptimizedInvalidate(old, dragValue);
}
}
else if (mouseLocation.X >= client.X + client.Width && mouseLocation.X < client.X + client.Width + LeftRightBorder) {
int newDragValue = max;
if (newDragValue != dragValue) {
int old = dragValue;
dragValue = newDragValue;
OptimizedInvalidate(old, dragValue);
}
}
}
else {
if (dragValue != value) {
int old = dragValue;
dragValue = value;
OptimizedInvalidate(old, dragValue);
}
}
}
}
}
}

namespace Microsoft.Samples.WinForms.Cs.FlashTrackBar {
using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Design;
using System.Windows.Forms;
using System.Windows.Forms.ComponentModel;
using System.Windows.Forms.Design;

public class FlashTrackBarDarkenByEditor : FlashTrackBarValueEditor {
protected override void SetEditorProps(FlashTrackBar editingInstance, FlashTrackBar editor) {
base.SetEditorProps(editingInstance, editor);
editor.Min = 0;
editor.Max = byte.MaxValue;
}
}
}

namespace Microsoft.Samples.WinForms.Cs.FlashTrackBar {
using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Design;
using System.Windows.Forms;
using System.Windows.Forms.ComponentModel;
using System.Windows.Forms.Design;

[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
public class FlashTrackBarValueEditor : System.Drawing.Design.UITypeEditor {

private IWindowsFormsEditorService edSvc = null;

protected virtual void SetEditorProps(FlashTrackBar editingInstance, FlashTrackBar editor) {
editor.ShowValue = true;
editor.StartColor = Color.Navy;
editor.EndColor = Color.White;
editor.ForeColor = Color.White;
editor.Min = editingInstance.Min;
editor.Max = editingInstance.Max;
}

public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value) {

if (context != null
&& context.Instance != null
&& provider != null) {

edSvc = (IWindowsFormsEditorService)provider.GetService(typeof(IWindowsFormsEditorService));

if (edSvc != null) {
FlashTrackBar trackBar = new FlashTrackBar();
trackBar.ValueChanged += new EventHandler(this.ValueChanged);
SetEditorProps((FlashTrackBar)context.Instance, trackBar);
bool asInt = true;
if (value is int) {
trackBar.Value = (int)value;
}
else if (value is byte) {
asInt = false;
trackBar.Value = (byte)value;
}
edSvc.DropDownControl(trackBar);
if (asInt) {
value = trackBar.Value;
}
else {
value = (byte)trackBar.Value;
}
}
}

return value;
}

public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context) {
if (context != null && context.Instance != null) {
return UITypeEditorEditStyle.DropDown;
}
return base.GetEditStyle(context);
}

private void ValueChanged(object sender, EventArgs e) {
if (edSvc != null) {
edSvc.CloseDropDown();
}
}
}
}

namespace Microsoft.Samples.WinForms.Cs.HostApp {
using System;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;
using Microsoft.Samples.WinForms.Cs.FlashTrackBar;

public class HostApp : System.Windows.Forms.Form {
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.Container components;
protected internal Microsoft.Samples.WinForms.Cs.FlashTrackBar.FlashTrackBar flashTrackBar1;

public HostApp() {
//
// Required for Windows Form Designer support
//
InitializeComponent();

}

/// <summary>
/// Clean up any resources being used.
/// </summary>
protected override void Dispose(bool disposing)
{
if (disposing) {
if (components != null) {
components.Dispose();
}
}
base.Dispose(disposing);
}

/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent() {
this.components = new System.ComponentModel.Container ();
this.flashTrackBar1 = new Microsoft.Samples.WinForms.Cs.FlashTrackBar.FlashTrackBar ();
this.Text = "Control Example";
this.ClientSize = new System.Drawing.Size (600, 450);
flashTrackBar1.BackColor = System.Drawing.Color.Black;
flashTrackBar1.Dock = System.Windows.Forms.DockStyle.Fill;
flashTrackBar1.TabIndex = 0;
flashTrackBar1.ForeColor = System.Drawing.Color.White;
flashTrackBar1.Text = "Drag the Mouse and say Wow!";
flashTrackBar1.Value = 73;
flashTrackBar1.Size = new System.Drawing.Size (600, 450);
this.Controls.Add (this.flashTrackBar1);
}

/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
public static void Main(string[] args) {
Application.Run(new HostApp());
}

}
}