正确测量像素中的字符 [英] Proper Measurement of Characters in Pixels

问题描述

我从头开始编写一个文本框，以优化它的语法高亮。但是，我需要得到的字符的宽度的像素，确切的，不是垃圾Graphics :: MeasureString给我。我在网络上找到了很多东西，具体来说

I'm writing a text box from scratch in order to optimize it for syntax highlighting. However, I need to get the width of characters in pixels, exactly, not the garbage Graphics::MeasureString gives me. I've found a lot of stuff on the web, specifially this, however, none of it seems to work, or does not account for tabs. I need the fastest way to measure the exact dimensions of a character in pixels, and tab spaces. I can't seem to figure this one out...

Should mention I'm using C++, CLR/CLI, and GDI+

---

Here is my measuring function. In another function the RectangleF it returns is drawn to the screen:

RectangleF TextEditor::MeasureStringWidth(String^ ch, Graphics^ g, int xDistance, int lineYval)
{
    RectangleF measured;
    Font^ currentFont = gcnew Font(m_font, (float)m_fontSize);
    StringFormat^ stringFormat = gcnew StringFormat;
    RectangleF layout = RectangleF(xDistance,lineYval,35,m_fontHeightPix);
    array<CharacterRange>^ charRanges = {CharacterRange(0,1)};
    array<Region^>^ strRegions;

    stringFormat->FormatFlags = StringFormatFlags::DirectionVertical;
    stringFormat->SetMeasurableCharacterRanges(charRanges);

    strRegions = g->MeasureCharacterRanges(ch, currentFont, layout, stringFormat);

    if(strRegions->Length >= 1)
        measured = strRegions[0]->GetBounds(g);
    else
        measured = RectangleF(0,0,0,0);

    return measured;
}

I don't really understand what MeasureCharacterRanges layoutRect parameter does. I modified the code from Microsofts example to only work with, or only measure, one character.

解决方案

You should not be using Graphics for any text rendering.

Starting with .NET Framework 2.0 use of Graphics.MeasureString and Graphics.DrawString was deprecated in favor of a newly added helper class TextRenderer:

• TextRenderer.MeasureText
• TextRenderer.DrawText

The GDI+ text renderer has been abandoned, and hasn't gotten any improvements or fixes for over 10 years; as well as being software rendered.

GDI rendering (which TextRenderer is a simple wrapper of) is hardware accelerated, and continues to get rendering improvements (ligatures, Uniscribe, etc).

Note: GDI+ text rendering is wrapped by Graphics.DrawString and MeasureString

Here's a comparison of the measure results of Graphics and TextRenderer:

The GDI+ measurements aren't "wrong", they are doing exactly what they intend - return the size that the text would be if it were rendered as the original font author intended (which you can achieve using Anti-alias rendering):

But nobody really wants to look at text the way the font designer intended, because that causes stuff to not line-up on pixel boundaries - making the text too fuzzy (i.e. as you see on a Mac). Ideally the text should be snapped to line up on actual pixel boundaries (i.e. Windows' Grid Fitting)

Bonus Reading

• See my answer over here, with more information.

这篇关于正确测量像素中的字符的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！