Two First Controls - A Shape and an inherited Label Control

Daniel Ortiz Acuna

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Mar 26, 2007

2 min read

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This article describes the creation of a Shape custom control and an inherited Label control.

Introduction

This article describes the creation of a gradient Shape and an inherited Label control. For information on how to create a Control, check out the article "Divider Panel - A tutorial on creating a custom Windows Forms Control from Start to Toolbox" by Furty.

In .NET, there are many classes and interfaces for painting and manipulating graphics and text. The book of Charles Petzold "Programming Microsoft Windows with C#" has a good explanation of many useful methods for development in GDI+.

The Shape Source Code

Sample Image - maximum width is 600 pixels

Shape Properties

The Shape has seven added properties:

BackgroundGradientColor1 - First background gradient color
BackgroundGradientColor2 - Second background gradient color
BackgroundGradientAngle - Background gradient angle
SwirlColors - Swirl/twist colors in background gradient
Radius - Radius of rounded borders
ShapeBorderStyle - Style of the border to be drawn around the control
BorderColor - Color of the border to be drawn around the control

Shape Methods

The Shape has four simple methods: OnPaint, DrawShapeBackground, DrawBorder and GetPath.

This is the OnPaint method.

protected override void OnPaint(PaintEventArgs e)
{
    // AntiAlias provides better quality
    SmoothingMode sm = e.Graphics.SmoothingMode;
    e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
    DrawShapeBackground(e.Graphics);
    if (_borderStyle == ShapeBorderStyles.ShapeBSFixedSingle)
        DrawBorder(e.Graphics);
    e.Graphics.SmoothingMode = sm;
}

This is the DrawShapeBackground method.

private void DrawShapeBackground(Graphics g)
{
    Rectangle rect = this.ClientRectangle;
    rect.X++;
    rect.Y++;
    rect.Width -= 2;
    rect.Height -= 2;
    // Draw the gradient in the client rectangle
    GraphicsPath path = GetPath(rect, _radius);
    using (LinearGradientBrush br =
        new LinearGradientBrush(rect, _color1, _color2, _angle))
    {
        br.GammaCorrection = true;
        if (_swirlColors)
            br.SetBlendTriangularShape(.5f, .75f);
            br.WrapMode = WrapMode.Tile;
            g.FillPath(br, path);
    }
    Region rgn = new Region(path);
    this.Region = rgn; //Do invisible the container control
}

This is the DrawBorder method.

private void DrawBorder(Graphics g)
{
    Rectangle rect = this.ClientRectangle;
    rect.X++;
    rect.Y++;
    rect.Width -= 3;
    rect.Height-= 3;
    using (GraphicsPath bp = GetPath(rect, _radius))
    {
        using (Pen p = new Pen(_borderColor))
        {
            g.DrawPath(p, bp);
        }
    }
}

And this is the GetPath method.

protected GraphicsPath GetPath(Rectangle rc, int r)
//  Build the path with the round corners in the rectangle
//  r is the radious of rounded corner.
{
    int x = rc.X, y = rc.Y, w = rc.Width   , h = rc.Height ;
    r = r << 1;
    GraphicsPath path = new GraphicsPath();
    if (r > 0)
    //  If the radious of rounded corner is 
    //  greater than one side then
    //  do the side rounded
    {
        if (r > h) { r = h; }; //Rounded
        if (r > w) { r = w; }; //Rounded
        path.AddArc(x, y, r, r, 180, 90); 
            //Upper left corner
        path.AddArc(x + w - r, y, r, r, 270, 90); 
            //Upper right corner
        path.AddArc(x + w - r, y + h - r, r, r, 0, 90); 
            //Lower right corner
        path.AddArc(x, y + h - r, r, r, 90, 90); 
            //Lower left corner
        path.CloseFigure();
    }
    else
    //  If the radious of rounded corner is zero then the 
    //  path is a rectangle
    {
        path.AddRectangle(rc);
    }
        return path;
}

The Label Source Code

We use the Shape as the base for the new Label control.

public partial class DOALabel : DOAShape

Label Properties

We add seven new properties:

Text - The text associated with the control
Font - The font used to display text in the control
Forecolor - The foreground color of this component, which is used to display the text
TextAlign - Text alignment (Left, Right or Center), only with Moving None
Moving - Text Moving (None, RightToLeft, DownToUp, LeftToRight, UpToDown)
MovingActive - Activate text movement
DimmedColor - Dims the text color when the mouse is passing over the control

For the Text, Font and ForeColor properties, we override the base properties.

public override string Text
{
    get { return base.Text; }
    set { base.Text = value ; this.Invalidate(); }
}

public override Font Font
{
    get { return base.Font; }
    set { base.Font = value; this.Invalidate(); }
}

public override Color ForeColor
{
    get { return base.ForeColor; }
    set { base.ForeColor = value; this.Invalidate(); }
}

Label Methods

This component uses a timer to update and invalidate the Draw event OnPaint.

private void timer1_Tick(object sender, System.EventArgs e)
{
    this.Update();
    this.Invalidate();
}

OnPaint calls the base class and the DrawText method.

protected override void OnPaint(PaintEventArgs pe)
{
    // Calling the base class OnPaint
    base.OnPaint(pe);
    iRect = base.ClientRectangle;
    DrawText(pe);
}

This is DrawText method.

protected void DrawText(PaintEventArgs pe)
{
    //This is a workaround to get MeasureString to work properly
    pe.Graphics.TextRenderingHint = TextRenderingHint.AntiAlias;
    SizeF sz = pe.Graphics.MeasureString(base.Text, base.Font);
    switch (_moving)
    {
        case MoveType.None:
            NoMove();
            break;
        case MoveType.RightToLeft:
            MoveRightToLeft();
            break;
        case MoveType.DownToUp:
            MoveDownToUp();
            break;
        case MoveType.LeftToRight:
            MoveLeftToRight();
            break;
        case MoveType.UpToDown:
            MoveUpToDown();
            break;
    }
    //Rectangle bounds for the text
    txtRect = new Rectangle(this.pointX, this.pointY,
        (int)sz.Width + 1, (int)sz.Height);

    //If the mouse is passing over the text it is selected and will be dimmed
    //otherwise nothing.
    Brush brText = new SolidBrush(base.ForeColor);
    Brush brTextDimmed = new SolidBrush(_dimmedColor);
    if (_isSelected)
        pe.Graphics.DrawString(base.Text,
            base.Font,
            brTextDimmed,
            txtRect);
    else
        pe.Graphics.DrawString(base.Text,
            base.Font,
            brText,
            txtRect);
}

The methods NoMove(), MoveRigntToLeft(), MoveDownToUp(), MoveLeftToRight() and MoveUpToDown()update, for each MoveType, the coordinates of the text rectangle.

protected void NoMove()
{
    //Align text
    switch (_textAlign)
    {
        case TextAlignment.Left:
            pointX = (int)this.iRect.X;
            break;
        case TextAlignment.Center:
            pointX = (this.iRect.Width - this.txtRect.Width ) / 2;
            break;
        case TextAlignment.Right:
            pointX = (this.iRect.Width - this.txtRect.Width);
            break;
        }
        pointY = (this.iRect.Height - this.txtRect.Height) / 2;
    }

    protected void MoveRightToLeft()
    {
        if (pointX < -this.txtRect.Width)
        { 
            pointX = this.iRect.X + this.iRect.Width; 
        }
        else
        { 
            pointX -= 2; 
        }
        pointY = ( this.iRect.Height - this.txtRect.Height) / 2;
    }

    protected void MoveDownToUp()
    {
        pointX = (this.iRect.Width - this.txtRect.Width) / 2;
        if (pointY < -this.txtRect.Height)
        { 
            pointY = (int)this.iRect.Y + this.iRect.Height; 
        }
        else
        { 
            pointY -= 2; 
        }
    }

    protected void MoveLeftToRight()
    {
        if (pointX > this.iRect.X + this.iRect.Width)
        { 
            pointX = this.iRect.X - this.txtRect.Width; 
        }
        else
        { 
            pointX += 2; 
        }
        pointY = (this.iRect.Height - this.txtRect.Height) / 2;
    }

    protected void MoveUpToDown()
    {
        pointX = (this.iRect.Width - this.txtRect.Width) / 2;
        if (pointY > this.iRect.Y + this.iRect.Height)
        { 
            pointY = (int)this.iRect.Y - this.iRect.Height; 
        }
        else
        { 
            pointY += 2; 
        }
}

If the mouse is passing over the text, it will be dimmed. For that, we use the events OnMouseEnter and OnMouseLeave.

protected override void OnMouseEnter(EventArgs e)
{
    base.OnMouseEnter(e);
    _isSelected = true;
    this.Invalidate();
}

protected override void OnMouseLeave(EventArgs e)
{
    base.OnMouseLeave(e);
    _isSelected = false;
    this.Invalidate();
}

History

01/03/2007 First Version
15/05/2007 Second Version
23/08/2007 Third Version
- Better border management
- The missing last character bug was fixed (alandgraf@gmx.at)
- The code was simplified