c# - 为什么 TextRenderer 在测量文本时添加边距？

Question

由于在我的应用程序的某些地方缺少 Graphics 对象，我决定使用 TextRenderer 类。令人惊讶的是，它为测量文本增加了很多边距。例如:

private void button1_Click(object sender, EventArgs e) {

    using (var g = this.CreateGraphics()) {

        Font font = new Font("Calibri", 20.0f, GraphicsUnit.Pixel);
        Size size = TextRenderer.MeasureText("Ala ma kota", font);

        g.DrawRectangle(Pens.Red, new Rectangle(new Point(10, 10), size));
        TextRenderer.DrawText(g, "Ala ma kota", font, new Point(10, 10), Color.Black);
    }
}

给出以下结果:

为什么会这样？有没有办法强制它获得真实的文字大小？ (当然，在它返回的同一个矩形中绘制它)

Answer 1

来自 MSDN :

For example, the default behavior of the TextRenderer is to add padding to the bounding rectangle of the drawn text to accommodate overhanging glyphs. If you need to draw a line of text without these extra spaces, use the versions of DrawText and MeasureText that take a Size and TextFormatFlags parameter, as shown in the example.

您还必须传递 Graphics 对象以获得正确的结果，因为:

This overload of MeasureText(String, Font, Size, TextFormatFlags) will ignore a TextFormatFlags value of NoPadding or LeftAndRightPadding. If you are specifying a padding value other than the default, you should use the overload of MeasureText(IDeviceContext, String, Font, Size, TextFormatFlags) that takes a IDeviceContext object.

Size size = TextRenderer.MeasureText(g,
                                     "Ala ma kota",
                                     font,
                                     new Size(int.MaxValue, int.MaxValue),
                                     TextFormatFlags.NoPadding);

TextRenderer.DrawText(g, "Ala ma kota", font,
                      new Point(10, 10),
                      Color.Black,
                      TextFormatFlags.NoPadding);

g.DrawRectangle(Pens.Red, new Rectangle(new Point(10, 10), size));

另请查看直接使用 Graphics 方法:GDI+ MeasureString() is incorrectly trimming text