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A metafile that is created by an application and then passed to another application is likely to be scaled. Scaling can alter the desired image in a way that was not anticipated by the originating application, which does not scale the image. Every logical measure defined in a logical object is scaled before the object is realized into physical form.
For a logical object such as pens, the width is transformed from logical to physical as an x-scalar value. If the metafile is scaled in y but not in x, the pen width is unchanged. If the metafile is scaled in x but not in y, the pen width does scale. Thus, using a pen of width 1 in a metafile results in a pen that is wider (thick and slow) when the metafile is scaled. If a nominal width pen (width of 1 at all times) is wanted, use 0 as the width because it is not affected by mapping modes. A 0-width pen is drawn as having a width of 1.
Font sizing is more complicated. The two values that scale in a logical font are the height and the width. Most applications use a width of 0 to define a font, which results in a physical font with a width that was designed for the given height. As the metafile is stretched in x, the font remains the same size. As the metafile is stretched in y, however, the physical font grows bigger and probably wider. In and of itself, this is not bad, but problems arise when the metafile makes assumptions about the width of the font by placing the characters of a text string individually, using META_EXTTEXTOUT Record (section 2.3.3.5) with a width array, or using a META_TEXTOUT Record (section 2.3.3.20) for each character. In either case, the x-placement of each character scales with the metafile, but the font's width does not necessarily scale accordingly, which causes characters to overlap or be widely spaced.
The simplest way to overcome this problem is not to place the characters individually but to use META_TEXTOUT (or META_EXTTEXTOUT with no width array) to output the whole string. The text string remains intact, but its size can change in relation to the rest of the image when x and y are not scaled identically. Another possibility is to define the font with a nonzero width so that it scales in x as well as in y. However, doing so is problematic, because its bitmapped fonts might not scale independently in x and y. Scaling a font's width is also possible; unfortunately, any time a font's width is scaled, the look of the typeface changes in ways not necessarily intended by the designers, and a typographically "incorrect" typeface results.