自定义控件的内容对齐

Question

我正在编写自己的控件库。我正在处理复选框控件，我需要帮助的最后一件事是绘制与文本相关的复选框。我有一个ContentAlignment属性，可以更改文本在控件中的显示位置，但我不确定如何调整与此相关的复选框，因为我不知道如何获取文本的位置在控制中。

    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);
        }
    }

我想，一个解决办法是彻底夺走财产。但那并不理想。另外，我想要制作一个包含复选框和文本的矩形，并相应地移动该矩形，但我不知道如何实现它。谢谢你的帮助！这是一张可能有助于显示问题的图片：

Answer 1

我可以使用这个扩展名代替用于switch语句的任何过多代码：

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;
}

您不仅可以使用此扩展名来绘制字符串，还可以在需要对齐需要在矩形内绘制的任何内容时使用此扩展名。

但在你的情况下，你会做这样的事情：

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