在 Visual C# .NET 中建立平滑的进度条（2）

public int Maximum
{
get
{
return max;
}

set
{
　　　// Make sure that the maximum value is never set lower than the minimum value.
if (value < min)
{
min = value;
}

max = value;

　　　// Make sure that value is still in range.
if (val > max)
{
val = max;
}
　　　// Invalidate the control to get a repaint.
this.Invalidate();
}
}

public int Value
{
get
{
return val;
}

set
{
int oldValue = val;
　　　// Make sure that the value does not stray outside the valid range.
if (value < min)
{
val = min;
}
else if (value > max)
{
val = max;
}
else
{
val = value;
}

　　　// Invalidate only the changed area.
float percent;

Rectangle newValueRect = this.ClientRectangle;
Rectangle oldValueRect = this.ClientRectangle;

　　　// Use a new value to calculate the rectangle for progress.
percent = (float)(val - min) / (float)(max - min);
newValueRect.Width = (int)((float)newValueRect.Width * percent);

　　　// Use an old value to calculate the rectangle for progress.
percent = (float)(oldValue - min) / (float)(max - min);
oldValueRect.Width = (int)((float)oldValueRect.Width * percent);

Rectangle updateRect = new Rectangle();

　　　// Find only the part of the screen that must be updated.
if (newValueRect.Width > oldValueRect.Width)
{
updateRect.X = oldValueRect.Size.Width;
updateRect.Width = newValueRect.Width - oldValueRect.Width;
}
else
{
updateRect.X = newValueRect.Size.Width;
updateRect.Width = oldValueRect.Width - newValueRect.Width;
}

updateRect.Height = this.Height;

　　　// Invalidate the intersection region only.
this.Invalidate(updateRect);
}
}

public Color ProgressBarColor
{
get
{
return BarColor;
}

set
{
BarColor = value;

　　　// Invalidate the control to get a repaint.
this.Invalidate();
}
}

private void Draw3DBorder(Graphics g)
{
int PenWidth = (int)Pens.White.Width;

g.DrawLine(Pens.DarkGray,
new Point(this.ClientRectangle.Left, this.ClientRectangle.Top),
new Point(this.ClientRectangle.Width - PenWidth, this.ClientRectangle.Top));

g.DrawLine(Pens.DarkGray,
new Point(this.ClientRectangle.Left, this.ClientRectangle.Top),
new Point(this.ClientRectangle.Left, this.ClientRectangle.Height - PenWidth));

g.DrawLine(Pens.White,
new Point(this.ClientRectangle.Left, this.ClientRectangle.Height - PenWidth),
new Point(this.ClientRectangle.Width - PenWidth, this.ClientRectangle.Height - PenWidth));

g.DrawLine(Pens.White,
new Point(this.ClientRectangle.Width - PenWidth, this.ClientRectangle.Top),
new Point(this.ClientRectangle.Width - PenWidth, this.ClientRectangle.Height - PenWidth));
}