第一步：In Visual Studio, create a Smart Device project.

第二部：Add the Gradientfill and GradientFilledButton classes to your project.

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public sealed class GradientFill
{
??? // This method wraps the PInvoke to GradientFill.
??? // Parmeters:
??? //? gr - The Graphics object we are filling
??? //? rc - The rectangle to fill
??? //? startColor - The starting color for the fill
??? //? endColor - The ending color for the fill
??? //? fillDir - The direction to fill
??? //
??? // Returns true if the call to GradientFill succeeded; false
??? // otherwise.
??? public static bool Fill(
??????? Graphics gr,
??????? Rectangle rc,
??????? Color startColor, Color endColor,
??????? FillDirection fillDir)
??? {

??????? // Initialize the data to be used in the call to GradientFill.
??????? Win32Helper.TRIVERTEX[] tva = new Win32Helper.TRIVERTEX[2];
??????? tva[0] = new Win32Helper.TRIVERTEX(rc.X, rc.Y, startColor);
??????? tva[1] = new Win32Helper.TRIVERTEX(rc.Right, rc.Bottom, endColor);
??????? Win32Helper.GRADIENT_RECT[] gra = new Win32Helper.GRADIENT_RECT[] {
??? new Win32Helper.GRADIENT_RECT(0, 1)};

??????? // Get the hDC from the Graphics object.
??????? IntPtr hdc = gr.GetHdc();

??????? // PInvoke to GradientFill.
??????? bool b;

??????? b = Win32Helper.GradientFill(
??????????????? hdc,
??????????????? tva,
??????????????? (uint)tva.Length,
??????????????? gra,
??????????????? (uint)gra.Length,
??????????????? (uint)fillDir);
??????? System.Diagnostics.Debug.Assert(b, string.Format(
??????????? "GradientFill failed: {0}",
??????????? System.Runtime.InteropServices.Marshal.GetLastWin32Error()));

??????? // Release the hDC from the Graphics object.
??????? gr.ReleaseHdc(hdc);

??????? return b;
??? }

??? // The direction to the GradientFill will follow
??? public enum FillDirection
??? {
??????? //
??????? // The fill goes horizontally
??????? //
??????? LeftToRight = Win32Helper.GRADIENT_FILL_RECT_H,
??????? //
??????? // The fill goes vertically
??????? //
??????? TopToBottom = Win32Helper.GRADIENT_FILL_RECT_V
??? }
}

// Extends the standard button control and performs
// custom drawing with a GradientFill background.

public class GradientFilledButton : Control
{
??? private System.ComponentModel.IContainer components = null;

??? public GradientFilledButton()
??? {
??????? components = new System.ComponentModel.Container();
??????? this.Font = new Font(this.Font.Name, this.Font.Size, FontStyle.Bold);
??? }

??? // Controls the direction in which the button is filled.
??? public GradientFill.FillDirection FillDirection
??? {
??????? get
??????? {
??????????? return fillDirectionValue;
??????? }
??????? set
??????? {
??????????? fillDirectionValue = value;
??????????? Invalidate();
??????? }
??? }
??? private GradientFill.FillDirection fillDirectionValue;

??? // The start color for the GradientFill. This is the color
??? // at the left or top of the control depeneding on the value
??? // of the FillDirection property.
??? public Color StartColor
??? {
??????? get { return startColorValue; }
??????? set
??????? {
??????????? startColorValue = value;
??????????? Invalidate();
??????? }
??? }
??? private Color startColorValue = Color.Red;

??? // The end color for the GradientFill. This is the color
??? // at the right or bottom of the control depending on the value
??? // of the FillDirection property
??? public Color EndColor
??? {
??????? get { return endColorValue; }
??????? set
??????? {
??????????? endColorValue = value;
??????????? Invalidate();
??????? }
??? }
??? private Color endColorValue = Color.Blue;

??? // This is the offset from the left or top edge
??? //? of the button to start the gradient fill.
??? public int StartOffset
??? {
??????? get { return startOffsetValue; }
??????? set
??????? {
??????????? startOffsetValue = value;
??????????? Invalidate();
??????? }
??? }
??? private int startOffsetValue;

??? // This is the offset from the right or bottom edge
??? //? of the button to end the gradient fill.
??? public int EndOffset
??? {
??????? get { return endOffsetValue; }
??????? set
??????? {
??????????? endOffsetValue = value;
??????????? Invalidate();
??????? }
??? }
??? private int endOffsetValue;

??? // Used to double-buffer our drawing to avoid flicker
??? // between painting the background, border, focus-rect
??? // and the text of the control.
??? private Bitmap DoubleBufferImage
??? {
??????? get
??????? {
??????????? if (bmDoubleBuffer == null)
??????????????? bmDoubleBuffer = new Bitmap(
??????????????????? this.ClientSize.Width,
??????????????????? this.ClientSize.Height);
??????????? return bmDoubleBuffer;
??????? }
??????? set
??????? {
??????????? if (bmDoubleBuffer != null)
??????????????? bmDoubleBuffer.Dispose();
??????????? bmDoubleBuffer = value;
??????? }
??? }
??? private Bitmap bmDoubleBuffer;

??? // Called when the control is resized. When that happens,
??? // recreate the bitmap used for double-buffering.
??? protected override void OnResize(EventArgs e)
??? {
??????? DoubleBufferImage = new Bitmap(
??????????? this.ClientSize.Width,
??????????? this.ClientSize.Height);
??????? base.OnResize(e);
??? }

??? // Called when the control gets focus. Need to repaint
??? // the control to ensure the focus rectangle is drawn correctly.
??? protected override void OnGotFocus(EventArgs e)
??? {
??????? base.OnGotFocus(e);
??????? this.Invalidate();
??? }
??? //
??? // Called when the control loses focus. Need to repaint
??? // the control to ensure the focus rectangle is removed.
??? protected override void OnLostFocus(EventArgs e)
??? {
??????? base.OnLostFocus(e);
??????? this.Invalidate();
??? }

??? protected override void OnMouseMove(MouseEventArgs e)
??? {
??????? if (this.Capture)
??????? {
??????????? Point coord = new Point(e.X, e.Y);
??????????? if (this.ClientRectangle.Contains(coord) !=
??????????????? this.ClientRectangle.Contains(lastCursorCoordinates))
??????????? {
??????????????? DrawButton(this.ClientRectangle.Contains(coord));
??????????? }
??????????? lastCursorCoordinates = coord;
??????? }
??????? base.OnMouseMove(e);
??? }

??? // The coordinates of the cursor the last time
??? // there was a MouseUp or MouseDown message.
??? Point lastCursorCoordinates;

??? protected override void OnMouseDown(MouseEventArgs e)
??? {
??????? if (e.Button == MouseButtons.Left)
??????? {
??????????? // Start capturing the mouse input
??????????? this.Capture = true;
??????????? // Get the focus because button is clicked.
??????????? this.Focus();

??????????? // draw the button
??????????? DrawButton(true);
??????? }

??????? base.OnMouseDown(e);
??? }

??? protected override void OnMouseUp(MouseEventArgs e)
??? {
??????? this.Capture = false;

??????? DrawButton(false);

??????? base.OnMouseUp(e);
??? }

??? bool bGotKeyDown = false;
??? protected override void OnKeyDown(KeyEventArgs e)
??? {
??????? bGotKeyDown = true;
??????? switch (e.KeyCode)
??????? {
??????????? case Keys.Space:
??????????? case Keys.Enter:
??????????????? DrawButton(true);
??????????????? break;
??????????? case Keys.Up:
??????????? case Keys.Left:
??????????????? this.Parent.SelectNextControl(this, false, false, true, true);
??????????????? break;
??????????? case Keys.Down:
??????????? case Keys.Right:
??????????????? this.Parent.SelectNextControl(this, true, false, true, true);
??????????????? break;
??????????? default:
??????????????? bGotKeyDown = false;
??????????????? base.OnKeyDown(e);
??????????????? break;
??????? }
??? }

??? protected override void OnKeyUp(KeyEventArgs e)
??? {
??????? switch (e.KeyCode)
??????? {
??????????? case Keys.Space:
??????????? case Keys.Enter:
??????????????? if (bGotKeyDown)
??????????????? {
??????????????????? DrawButton(false);
??????????????????? OnClick(EventArgs.Empty);
??????????????????? bGotKeyDown = false;
??????????????? }
??????????????? break;
??????????? default:
??????????????? base.OnKeyUp(e);
??????????????? break;
??????? }
??? }

??? // Override this method with no code to avoid flicker.
??? protected override void OnPaintBackground(PaintEventArgs e)
??? {
??? }
??? protected override void OnPaint(PaintEventArgs e)
??? {
??????? DrawButton(e.Graphics, this.Capture &&
??????????? (this.ClientRectangle.Contains(lastCursorCoordinates)));
??? }

??? //
??? // Gets a Graphics object for the provided window handle
??? //? and then calls DrawButton(Graphics, bool).
??? //
??? // If pressed is true, the button is drawn
??? // in the depressed state.
??? void DrawButton(bool pressed)
??? {
??????? Graphics gr = this.CreateGraphics();
??????? DrawButton(gr, pressed);
??????? gr.Dispose();
??? }

??? // Draws the button on the specified Grapics
??? // in the specified state.
??? //
??? // Parameters:
??? //? gr - The Graphics object on which to draw the button.
??? //? pressed - If true, the button is drawn in the depressed state.
??? void DrawButton(Graphics gr, bool pressed)
??? {
??????? // Get a Graphics object from the background image.
??????? Graphics gr2 = Graphics.FromImage(DoubleBufferImage);

??????? // Fill solid up until where the gradient fill starts.
??????? if (startOffsetValue > 0)
??????? {
??????????? if (fillDirectionValue ==
??????????????? GradientFill.FillDirection.LeftToRight)
??????????? {
??????????????? gr2.FillRectangle(
??????????????????? new SolidBrush(pressed ? EndColor : StartColor),
??????????????????? 0, 0, startOffsetValue, Height);
??????????? }
??????????? else
??????????? {
??????????????? gr2.FillRectangle(
??????????????????? new SolidBrush(pressed ? EndColor : StartColor),
??????????????????? 0, 0, Width, startOffsetValue);
??????????? }
??????? }

??????? // Draw the gradient fill.
??????? Rectangle rc = this.ClientRectangle;
??????? if (fillDirectionValue == GradientFill.FillDirection.LeftToRight)
??????? {
??????????? rc.X = startOffsetValue;
??????????? rc.Width = rc.Width - startOffsetValue - endOffsetValue;
??????? }
??????? else
??????? {
??????????? rc.Y = startOffsetValue;
??????????? rc.Height = rc.Height - startOffsetValue - endOffsetValue;
??????? }
??????? GradientFill.Fill(
??????????? gr2,
??????????? rc,
??????????? pressed ? endColorValue : startColorValue,
??????????? pressed ? startColorValue : endColorValue,
??????????? fillDirectionValue);

??????? // Fill solid from the end of the gradient fill
??????? // to the edge of the button.
??????? if (endOffsetValue > 0)
??????? {
??????????? if (fillDirectionValue ==
??????????????? GradientFill.FillDirection.LeftToRight)
??????????? {
??????????????? gr2.FillRectangle(
??????????????????? new SolidBrush(pressed ? StartColor : EndColor),
??????????????????? rc.X + rc.Width, 0, endOffsetValue, Height);
??????????? }
??????????? else
??????????? {
??????????????? gr2.FillRectangle(
??????????????????? new SolidBrush(pressed ? StartColor : EndColor),
??????????????????? 0, rc.Y + rc.Height, Width, endOffsetValue);
??????????? }
??????? }

??????? // Draw the text.
??????? StringFormat sf = new StringFormat();
??????? sf.Alignment = StringAlignment.Center;
??????? sf.LineAlignment = StringAlignment.Center;
??????? gr2.DrawString(this.Text, this.Font,
??????????? new SolidBrush(this.ForeColor),
??????????? this.ClientRectangle, sf);

??????? // Draw the border.
??????? // Need to shrink the width and height by 1 otherwise
??????? // there will be no border on the right or bottom.
??????? rc = this.ClientRectangle;
??????? rc.Width--;
??????? rc.Height--;
??????? Pen pen = new Pen(SystemColors.WindowFrame);

??????? gr2.DrawRectangle(pen, rc);

??????? // Draw from the background image onto the screen.
??????? gr.DrawImage(DoubleBufferImage, 0, 0);
??????? gr2.Dispose();
??? }

??? protected override void Dispose(bool disposing)
??? {
??????? if (disposing && (components != null))
??????? {
??????????? components.Dispose();
??????? }
??????? base.Dispose(disposing);
??? }

}

第三步：Add the Win32Helper class to your project, which contains the platform invoke and structures for native code interoperability.

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第四步：Declare a form variable named gfButton of type GradientFilledButton.

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第六步：Add the event handling code for the button's Click event to form.