c# - Graphics.DrawString 不绘制最后一个 SPACE 字符？

Question

字符串是“Hello World”，最后有 10 个空格字符，但是 右对齐 中的 Graphics.DrawString 省略了所有空格字符，它只绘制了“Hello World”。

protected override void OnPaint(PaintEventArgs e)
    {            
        Rectangle rct = new Rectangle(20, 100, 200, 20);
        e.Graphics.DrawRectangle(new Pen(Color.Lime), rct);            
        e.Graphics.DrawString("Hello World          ", Font, new SolidBrush(SystemColors.ControlText), rct, new StringFormat() { Alignment = StringAlignment.Far});                                                      

        base.OnPaint(e);
    }

Answer 1

在使用 Gdi+ 绘制字符串时包含尾随空格 Graphics.DrawString方法，传递一个 StringFormat适当重载并添加或附加 (|=) StringFormatFlags.MeasureTrailingSpaces StringFormat.FormatFlags 的值属性(property)。

protected override void OnPaint(PaintEventArgs e)
{
    base.OnPaint(e);

    Rectangle rct = new Rectangle(20, 100, 200, 20);
    string s = "Hello World          ";

    using (var sf = new StringFormat(StringFormat.GenericTypographic))
    {
        sf.Alignment = StringAlignment.Far;
        sf.LineAlignment = StringAlignment.Center;
        sf.FormatFlags = StringFormatFlags.MeasureTrailingSpaces;

        e.Graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;
        e.Graphics.DrawString(s, Font, SystemBrushes.ControlText, rct, sf);
    }

    e.Graphics.DrawRectangle(Pens.Lime, rct);
}

考虑使用 Gdi TextRenderer类在控件上绘制字符串，除非遇到类似 drawing on transparent backgrounds 的问题.

之前的代码可以这样写:

protected override void OnPaint(PaintEventArgs e)
{
    base.OnPaint(e);

    Rectangle rct = new Rectangle(20, 100, 200, 20);
    string s = "Hello World          ";

    TextRenderer.DrawText(e.Graphics, s, Font, rct, SystemColors.ControlText,
        TextFormatFlags.Right |
        TextFormatFlags.VerticalCenter);

    e.Graphics.DrawRectangle(Pens.Lime, rct);
}