X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=mf%2FREADME;h=adf02251458d7da4fc5a1de0a8a63c14a2cc4bae;hb=2a3bafbcac63918eb9f72d8269c64beffe9f7ec1;hp=1d6c4c74e50fc3912ae51e640acfbf44ac6e9c91;hpb=4621b224369d7a2894a4ea029bc228ba2817c761;p=lilypond.git diff --git a/mf/README b/mf/README index 1d6c4c74e5..adf0225145 100644 --- a/mf/README +++ b/mf/README @@ -1,27 +1,28 @@ -This is a font of music symbols. All MF sources are original. Most -of the documentation is in comments in the MF code. +This is a font of music symbols. All MF sources are original. Most of the +documentation is in comments in the MF code. Non-square pixels are not supported; with other words, the horizontal and vertical resolution of the output device must be the same. Currently, outline fonts are created by using `autotrace', but we are -already in the process to convert the MF code directly to PostScript code +already in the process of converting the MF code directly to PostScript code with a tool called `mf2pt1', which in turn calls `FontForge' to postprocess the output (mainly to remove outline overlaps and to add hints). The recommended calling sequence of mf2pt1 is - mf2pt1 --rounding=0.001 + mf2pt1 --rounding=0.0001 You need mf2pt1 version 2.1 or newer. + Here some guidelines to assure a clean conversion. . Never use `---'. Replace it with `--' together with explicit path directions (if necessary). -. Don't use self-intersecting outlines in general since it can confuse +. Don't use self-intersecting outlines in general since they can confuse mf2pt1's algorithm to get the orientation of a closed path. Note that MetaPost's implementation of the `turningnumber' primitive (which would immediately give the orientation of a path) is severely broken before @@ -29,7 +30,7 @@ Here some guidelines to assure a clean conversion. to work around this bug. . If outlines intersect, avoid grazing intersections. In case two outlines - intersect in an explicitly defined point, include this point into both + intersect in an explicitly defined point, include this point in both intersecting paths to avoid problems due to rounding errors. . Don't use `draw' with a polygonal pen but for straight lines (consisting @@ -43,6 +44,25 @@ Here some guidelines to assure a clean conversion. overlaps. +Some glyph name rules: + +. Most glyph names have the form ., where is defined + with the `fet_begingroup' command, and is given with + `fet_beginchar' (within a `fet_begingroup' block). Example: + `clefs.vaticana.fa'. + +. Sometimes it would be sensible to use negative numbers in glyph names. + However, the `-' character shouldn't be used in a glyph name. Replace it + with `M'. For example, write `rests.M3mensural' instead of + `rests.-3mensural'. + +. Glyphs which exist in both an `up' and `down' version should start the + part with either `u' or `d', respectively. Example: `flags.d3', + `flags.u3'. Glyphs which are neutral w.r.t. the direction, and where + members of the glyph group exist which have `up' and `down' versions, + should start with an `s'. Example: `noteheads.s0re'. + + Some design rules: . Always use smooth curve transitions. Since this is difficult to see in @@ -57,7 +77,38 @@ Some design rules: . Use rounded corners. -Finally, some rules to assure that rasterization at low resolutions give +Hints for stem attachment: + +. Stem attachment of glyphs is controlled by two special variables called + `charwx' and `charwy'. Stems can be regarded as (very oblonged) + rectangles with slightly rounded corners. For stems pointing upwards the + lower right corner of this rectangle is attached to the glyph at position + (charwx, charwy). For stems pointing downwards it works analogously but + with the upper left corner, where the position of the attachment point is + additionally reflected horizontally about the center of the glyph -- this + ensures that in most cases charwx and charwy can be set to the same values + for up and down stems even though these are attached at the right/left end + of the note, respectively. To make this more precise, the upper left + corner of a down stem is attached at position (charwd/2 - charwx, charwy), + where `charwd' is an internal metafont variable representing the glyph + width as specified by the `set_char_box' command. + +. In case different stem attachments for upward and downward pointing stems + are needed, two separate glyphs must be defined in the Metafont file; of + course, this also applies if two entirely different shapes are needed. + These have the same name but are prefixed by `u' and `d', respectively + (for `up' and `down', obviously). In each of these glyphs the variables + charwx and charwy must be set accordingly. If, on the other hand, the + attachment point is the `same' for both directions (with the + abovementioned horizontal reflection taken into account), then the prefix + `s' (for `symmetric') should be used. See the existing files for + examples. The numbers in the glyph names refer to the duration of the + note; e.g., `s0cross' in feta-noteheads.mf defines the notehead for a + whole cross-shaped note (similarly, `s1cross' and `s2cross' are for half + and quarter notes, respectively). + + +Finally, some rules to assure that rasterization at low resolutions gives good results. Today, this is a minor issue, but in some cases it might show design flaws.