D2DGraphics: fixed MeasureText() is not correct

Author: d2phap

Source/DXControl/Graphics/D2DGraphics.cs

@@ -394,7 +394,7 @@ public SizeF MeasureText(string text, string fontFamilyName, float fontSize, Siz
     {
         // fix DPI
         var dpiScale = textDpi / 96.0f;
-        fontSize += fontSize * dpiScale;
+        fontSize = (fontSize + dpiScale) * dpiScale;
 
         // format text
         var fontWeight = isBold

Source/DXControl/Graphics/GdipGraphics.cs

@@ -241,9 +241,11 @@ public SizeF MeasureText(string text, string fontFamilyName, float fontSize, flo
 
     public SizeF MeasureText(string text, string fontFamilyName, float fontSize, SizeF size, float textDpi = 96, bool isBold = false, bool isItalic = false)
     {
-        var dpiFactor = textDpi / 96.0f;
-        fontSize = (fontSize + dpiFactor) * dpiFactor;
+        // fix DPI
+        var dpiScale = textDpi / 96.0f;
+        fontSize = (fontSize + dpiScale) * dpiScale;
 
+        // format text
         var style = FontStyle.Regular;
         if (isBold) style |= FontStyle.Bold;
         if (isItalic) style |= FontStyle.Italic;