"HOW TO: Create a Smooth Progress Bar in Visual C# .NET"的学习笔记

现在使用.net老是感觉.net自带的控件的很多的功能不尽人意,所以参考微软的学习资料,感觉自己编一个符合自己要求的Control还是很简单的

HOW TO: Create a Smooth Progress Bar in Visual C# .NET就是叫我们怎么样做自己的控件的

其实做好其中的几个重要函数的重写工作就可以了

例如OnResize(),OnPaint()

protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
SolidBrush brush = new SolidBrush(BarColor);
float percent = (float)(val - min) / (float)(max - min);
Rectangle rect = this.ClientRectangle;

// Calculate area for drawing the progress.
rect.Width = (int)((float)rect.Width * percent);

// Draw the progress meter.
g.FillRectangle(brush, rect);

// Draw a three-dimensional border around the control.
Draw3DBorder(g);

// Clean up.
brush.Dispose();
g.Dispose();
}
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));
}
这一段程序就是自己绘制控件外观的,很简单吧

可以自己添加控件的事件,特性(property),方法

public int Minimum
{
get
{
return min;
}

set
{
// Prevent a negative value.
if (value < 0)
{
min = 0;
}

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

// Ensure value is still in range
if (val < min)
{
val = min;
}

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

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);//注意这是强制重绘的,一定要有,不然图形不会改变的^_^
 }
}

public Color ProgressBarColor//控制颜色的
{
get
{
return BarColor;
}

set
{
BarColor = value;

// Invalidate the control to get a repaint.
this.Invalidate();
}
}
这是自己添加的特性(property)

虽然这是一个很小的示例,但是向我们这种菜鸟展示的.net的强大.通过这种方式我们完全可以做到开发符合自己要求的控件.

程序来自微软网站

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