Ok, we are close to a new release of VSLab. It will contain two major changes that are very very important. The first one is, as far as I know, the first implementation of Lightweight Controls for Windows Forms, made available for programming viewlets with ease but also available to all .NET applications. Wonder why are Lightweight Controls so important? Let's start with an example in C#:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
var lc = new LightweightContainer();
var lb = new LightweightButton();
var rb = new RoundButton();
var rb2 = new RoundButton();
lc.Dock = DockStyle.Fill;
lb.Position = new Point(0, 0);
lb.Text = "Hello World";
lc.BackColor = Color.AliceBlue;
lc.Add(lb);
rb.Position = new Point(0, 100);
rb.Size = new Size(50, 50);
rb.Text = "Hello with very long text";
lc.Add(rb);
rb2.Position = new Point(0, 110);
rb2.Size = new Size(50, 50);
rb2.Text = "Hello 2";
lc.Add(rb2);
this.Controls.Add(lc);
}
}
This is a simple code meant for creating three buttons into a canvas. The LightweightContainer class is a sort of panel capable of hosting lightweight controls (classes derived from LightweightControl). The library features a number of predefined controls such as buttons (in Vista style) and scrollbars. In the example the lb variable holds an instance of a LightweightButton. The lightweight control container is docked within the form. The other two buttons are instances of RoundButton class which is a simple example of how to write a lightweight control:
public class RoundButton : LightweightControl {
public string Text = "";
public override void OnMouseMove(MouseEventArgs e) {
base.OnMouseMove(e);
BackColor = Color.Red;
Invalidate();
}
public override void OnClick(EventArgs e) {
base.OnClick(e);
Position = new Point(Position.X, Position.Y + 10);
Invalidate();
}
public override void OnPaint(PaintEventArgs e) {
var g = e.Graphics;
using (var b = new SolidBrush(Color.FromArgb(40, BackColor))) {
g.FillEllipse(b, e.ClipRectangle);
g.DrawEllipse(Pens.Black, e.ClipRectangle);
var sf = new StringFormat();
sf.Alignment = StringAlignment.Center;
sf.LineAlignment = StringAlignment.Center;
g.DrawString(Text, Font, Brushes.Black, new RectangleF(e.ClipRectangle.X, e.ClipRectangle.Y, e.ClipRectangle.Width, e.ClipRectangle.Height), sf);
}
}
}
The RoundButton is written as a standard UserControl except for the fact that it inherits from LightweightControl (and that not all the features of UserControl are available). The output is shown in the following picture:
Here is a more complete screenshot of one of our regression tests running inside VSLab:
Lightweight controls are important for viewlets because it is not possible using the standard controls, therefore having user control abstractions makes viewlet development a lot easier. One of the example is the addition of a button over the Chart and the 3D Chart viewlets as shown in this screenshot:
The other important update in this new release is the implementation of double buffering for Viewlets (the Chart viewlet sample does not flicker anymore once enabled) which has been challenging to implement because of the internals of VSLab. The overall code has been cleaned up and reviewed in order to offer a more consistent programming API.
Now we are getting back to the original ideas of featuring new viewlets for data visualization and system shell replacement. In the meantime we are using VSLab in projects involving biomedical engineers.
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