使用 GDI，沿公共基线对齐文本（以多种不同字体绘制）的最简单方法是什么？

Question

我的问题：

我目前正在开发一个自定义用户控件，该控件在一行上显示文本片段（每个文本片段可能具有不同的字体）。我想将所有这些文本位完全沿着公共基线对齐。例如：

  Hello,    I am    George.  
------------------------------   <- all text aligns to a common baseline
    ^         ^        ^
    |         |        |
 Courier    Arial    Times       <- font used for a particular bit of text
  20pt      40pt     30pt

因为我还没有找到任何 GDI+ 功能来直接执行此操作，所以我想出了自己的方法（概述如下）。但是：

我想知道是否真的没有更简单的方法来完成此任务？

我当前的方法：

1)收集将用于绘制文本的所有System.Drawing.Font的列表。

2) 对于每个 Font，使用以下代码查找基线的垂直位置（以像素为单位）：

// variables used in code sample (already set)
Graphics G;
Font font;
...

// compute ratio in order to convert from font design units to pixels:
var designUnitsPerPixel = font.GetHeight(G) / 
                          font.FontFamily.GetLineSpacing(font.Style);

// get the cell ascent (baseline) position in design units:
var cellAscentInDesignUnits = font.FontFamily.GetCellAscent(font.Style);

// finally, convert the baseline position to pixels:
var baseLineInPixels = cellAscentInDesignUnits * designUnitsPerPixel;

3) 对于所有 Font 使用时，确定上面计算的最大baseLineInPixels值，并将该值存储到maxBaseLineInPixels。

4) 按照以下方式绘制每一位文本：

// variables used in code sample (already set):
Graphics G;
Font font;
string text;
...

// find out how much space is needed for drawing the text
var measureF = G.MeasureString(text, font);

// determine location where text will be drawn:
var layoutRectF = new RectangleF(new PointF(0f, 0f), measureF);
layoutRectF.Y += maxBaseLineInPixels - baseLineInPixels;
// ^ the latter value 'baseLineInPixels' is specific to the font used

// draw text at specified location
G.DrawString(text, font, Brushed.Black, layoutRectF);

我是否遗漏了什么，或者真的没有更简单的方法吗？

Answer 1

我认为这个方法可行，请你尝试一下。

List<RectangleF> rects = new List<RectangleF>();

private void Form1_Paint(object sender, PaintEventArgs e)
{
    ////////////////////Not Set baseLine
    //baseline
    e.Graphics.DrawLine(Pens.Red , new Point(100,200),new Point(800,200));

    //words
    Point point = new Point(100,100);
    e.Graphics.DrawString("hello world", new Font("Times", 30), Brushes.Black, point);
    RectangleF rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Times", 30)));
    e.Graphics.DrawRectangle(Pens.Green,rectangleF.X ,rectangleF.Y , rectangleF.Width , rectangleF.Height);
    rects.Add(rectangleF);

    point = new Point(400, 100);
    e.Graphics.DrawString("hello world", new Font("Arial", 40), Brushes.Black, point);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Arial", 40)));
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

    point = new Point(800, 100);
    e.Graphics.DrawString("hello world", new Font("Courier", 20), Brushes.Black, point);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Courier", 20)));
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

    ///////////////////SetBaseLine/////////////////////////////
    var maxHeight = GetMaxHeight();
    ///////////////////

    //baseLine
    e.Graphics.DrawLine(Pens.Pink, new Point(100, (int) (400 + maxHeight / 2)), new Point(800, (int) (400 + maxHeight / 2)));

    StringFormat stringFormat = new StringFormat();
    stringFormat.LineAlignment = StringAlignment.Center;

    //words
    point = new Point(100, 400);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Times", 30)));
    e.Graphics.DrawString("hello world", new Font("Times", 30), Brushes.Black, new RectangleF(rectangleF.X ,rectangleF.Y , rectangleF.Width , maxHeight) , stringFormat);
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

    point = new Point(400, 400);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Arial", 40)));
    e.Graphics.DrawString("hello world", new Font("Arial", 40), Brushes.Black, new RectangleF(rectangleF.X, rectangleF.Y, rectangleF.Width, maxHeight), stringFormat);
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

    point = new Point(800, 400);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Courier", 20)));
    e.Graphics.DrawString("hello world", new Font("Courier", 20), Brushes.Black, new RectangleF(rectangleF.X, rectangleF.Y, rectangleF.Width, maxHeight), stringFormat);
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

}

private float GetMaxHeight()
{
    float temp = 0;
    foreach (RectangleF rectangleF in rects)
        if (rectangleF.Height > temp)
            temp = rectangleF.Height;

    return temp;
}

Answer 2

过去几天我一直在研究同样的事情，终于找到了答案在此博客页面。这段代码（在文章底部）对我来说非常有效，希望能帮助其他人解决这个问题：

private void DrawOnBaseline(string s, Graphics g, Font f, Brush b, Point pos)
    {
      float baselineOffset=f.SizeInPoints/f.FontFamily.GetEmHeight(f.Style)*f.FontFamily.GetCellAscent(f.Style);
      float baselineOffsetPixels = g.DpiY/72f*baselineOffset;

      g.DrawString(s,f,b,new Point(pos.X,pos.Y-(int)(baselineOffsetPixels+0.5f)),StringFormat.GenericTypographic);
    }