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POHow to get the exact text margins used by TextRenderer
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copied!<p><code>System.Windows.Forms.TextRenderer.DrawText</code> method renders formatted text with or without left and right padding depending on the value of the <code>flags</code> parameter:</p> <ul> <li><code>TextFormatFlags.NoPadding</code> - fits the text tightly into the bounding box,</li> <li><code>TextFormatFlags.GlyphOverhangPadding</code> - adds some left and right margins,</li> <li><code>TextFormatFlags.LeftAndRightPadding</code> - adds even bigger margins.</li> </ul> <p>Now, my question is <strong>how can I get the exact amount of padding (left and right) added by <code>DrawText</code> to the text</strong> for a given device context, string, font etc?</p> <p>I've dug into .NET 4 with .NET Reflector and found that TextRenderer calculates "overhang padding" which is 1/6 of the font's height and then multiplies this value to calculate left and right margins using these coefficients:</p> <ul> <li>left 1.0, right 1.5 for <code>TextFormatFlags.GlyphOverhangPadding</code>,</li> <li>left 2.0, right 2.5 for <code>TextFormatFlags.LeftAndRightPadding</code>.</li> </ul> <p>The resulting values are rounded up and passed to the <code>DrawTextExA</code> or <code>DrawTextExW</code> native API functions. It's difficult to recreate this process because font's height is taken not from <code>System.Drawing.Font</code> but from <code>System.Windows.Forms.Internal.WindowsFont</code> and these classes return different values for the same font. And a lot of other internal BCL classes from the <code>System.Windows.Forms.Internal</code> namespace are involved. Decompiling all of them and reusing their code in my app is not an option, because that would be a serious .NET implementation dependency. That's why I need to know if there is some public API in WinForms or at least which Windows functions I can use to get the values of left and right margins.</p> <hr> <p><strong>Note:</strong> I've tried to <code>TextRenderer.MeasureText</code> with and without padding and compare the results but that gave me only the sum of left and right margins and I need them separately.</p> <hr> <p><strong>Note 2:</strong> In case you wonder why I need this: I want to draw one string with multiple fonts/colors. That involves calling <code>DrawText</code> once for every uniformly formatted substring with <code>NoPadding</code> option (so that the text doesn't spread) but I also want to add manually normal <code>GlyphOverhangPadding</code> at the very beginning and very end of the whole multi-format text.</p>

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