Content Alignment For Custom Control

Question

I'm writing my own library of controls. I'm working on the check box control and one of the final things that I need help on is drawing the check box in relation to the text. I have a ContentAlignment property that can change where the text appears in the control, but I'm not sure how to adjust the check box in relation to that because I don't know how to get the location of the text in the control.

    protected override void OnPaint(PaintEventArgs e)
    {
        Graphics canvas = e.Graphics;
        canvas.SmoothingMode = SmoothingMode.HighQuality;
        int x = 0;
        int y = (int)(canvas.MeasureString(this.Text, this.Font).Height - 12) / 2;
        switch (this.Style)
        {
            case E.CheckBoxStyle.Check:
                canvas.DrawRectangle(new Pen(this.BorderColor), new Rectangle(x, y, 12, 12));
                if (this.Checked)
                    canvas.DrawString("√", new Font("serif", 7f, FontStyle.Bold), Brushes.Black, 1f, 3f);
                break;
            case E.CheckBoxStyle.Round:
                canvas.DrawEllipse(new Pen(this.BorderColor), new Rectangle(x, y, 12, 12));
                if (this.Checked)
                {
                    Rectangle region = new Rectangle(x + 1, y + 1, 10, 10);
                    canvas.FillEllipse(Functions.CreateGradient(region, this.FillColor, 90), region);
                }
                break;
            case E.CheckBoxStyle.Square:
                canvas.DrawRectangle(new Pen(this.BorderColor), new Rectangle(x, y, 12, 12));
                if (this.Checked)
                {
                    Rectangle region = new Rectangle(x + 1, y + 1, 10, 10);
                    canvas.FillRectangle(Functions.CreateGradient(region, this.FillColor, 90), region);
                }
                break;
        }
        if (!this.AutomaticSize)
        {
            StringFormat format = new StringFormat();
            switch (this.Alignment)
            {
                case ContentAlignment.TopRight:
                    format.Alignment = StringAlignment.Far;
                    format.LineAlignment = StringAlignment.Near;
                    break;
                case ContentAlignment.TopLeft:
                    format.Alignment = StringAlignment.Near;
                    format.LineAlignment = StringAlignment.Near;
                    break;
                case ContentAlignment.TopCenter:
                    format.Alignment = StringAlignment.Center;
                    format.LineAlignment = StringAlignment.Near;
                    break;
                case ContentAlignment.MiddleRight:
                    format.Alignment = StringAlignment.Far;
                    format.LineAlignment = StringAlignment.Center;
                    break;
                case ContentAlignment.MiddleLeft:
                    format.Alignment = StringAlignment.Near;
                    format.LineAlignment = StringAlignment.Center;
                    break;
                case ContentAlignment.MiddleCenter:
                    format.Alignment = StringAlignment.Center;
                    format.LineAlignment = StringAlignment.Center;
                    break;
                case ContentAlignment.BottomRight:
                    format.Alignment = StringAlignment.Far;
                    format.LineAlignment = StringAlignment.Far;
                    break;
                case ContentAlignment.BottomLeft:
                    format.Alignment = StringAlignment.Near;
                    format.LineAlignment = StringAlignment.Far;
                    break;
                case ContentAlignment.BottomCenter:
                    format.Alignment = StringAlignment.Center;
                    format.LineAlignment = StringAlignment.Far;
                    break;
            }
            canvas.DrawString(this.Text, this.Font, new SolidBrush(this.ForeColor), ClientRectangle, format);
        }
        else
        {
            canvas.DrawString(this.Text, this.Font, new SolidBrush(this.ForeColor), 14f, 0f);
            Size newSize = Size.Round(canvas.MeasureString(this.Text, this.Font));
            this.Size = new Size(newSize.Width + 14, newSize.Height);
        }
    }

One solution is to take away the property completely, I suppose. But that's not ideal. Another, I thought make a rectangle that contains the check box as well as the text and to move that rectangle accordingly but I don't know how to implement that. Thanks for any help! Here's a picture that might help show the problem:

Answer 1

Instead of any of the excessive code used for the switch statement you can use this extension I wrote:

public static Point AlignDrawingPoint(this Graphics g, Size objectSize, Rectangle clientRectangle, ContentAlignment alignment)
{
    int margin = 4;
    Point center = new Point((clientRectangle.Width >> 1) - (objectSize.Width >> 1), (clientRectangle.Height >> 1) - (objectSize.Height >> 1));
    int rightMargin = clientRectangle.Width - (objectSize.Width + margin);
    int bottomMargin = clientRectangle.Height - (objectSize.Height + margin);
    Point p = Point.Empty;
    switch (alignment)
    {
        case ContentAlignment.TopLeft:
            p = new Point(margin, margin);
            break;
        case ContentAlignment.TopCenter:
            p = new Point(center.X, margin);
            break;
        case ContentAlignment.TopRight:
            p = new Point(rightMargin, margin);
            break;
        case ContentAlignment.MiddleLeft:
            p = new Point(margin, center.Y);
            break;
        case ContentAlignment.MiddleCenter:
            p = new Point(center.X, center.Y);
            break;
        case ContentAlignment.MiddleRight:
            p = new Point(rightMargin, center.Y);
            break;
        case ContentAlignment.BottomLeft:
            p = new Point(margin, bottomMargin);
            break;
        case ContentAlignment.BottomCenter:
            p = new Point(center.X, bottomMargin);
            break;
        case ContentAlignment.BottomRight:
            p = new Point(rightMargin, bottomMargin);
            break;
    }
    p.Offset(clientRectangle.X, clientRectangle.Y);
    return p;
}

You can use this extension not just for drawing strings, you can use this extension when needing to align anything you need to draw within a rectangle.

But in your case you would do something like this:

g.DrawString(this.Text, this.Font, new SolidBrush(this.ForeColor), AlignDrawingPoint(g.MeasureString(this.Text, this.Font).ToSize(), this.ClientRectangle, this.TextAlign));