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16 A location tag is associated with a
17 <A HREF="noteattr.html#ntag">note,</A>
18 <A HREF="chrdattr.html#ctag">chord,</A>
20 <A HREF="bars.html#btag">barline.</A>
21 It can then be referenced in order to place a second object, like a comment
22 or dotted line, relative to the first object.
25 A tag name can be either a single lower case letter, or an underscore
26 folowed by one or more letters, digits, or underscores.
27 Each location tag is really a collection of six values,
28 namely the north, south, east,
29 west, x, and y values of the tagged object. These are referenced by giving
30 the tag name followed by a dot, followed by the letter n, s, e, w, x, or y.
34 _xyz.e // east of tag _xyz
35 x.x // x coordinate of tag x
39 The n, s, e, and w values describe the smallest rectangle that will
40 completely enclose the object being tagged.
41 The north refers to the top of the object, the south to the bottom, the
42 west to the left edge, and the east the right edge. The x and y values
43 correspond to the "center" coordinate of the object. This is not necessarily
44 the geometric center, but more of a "logical center." In the case of a tag
45 associated with an individual note, it is the geometric center of the note head.
46 However, on tags associated with a chord, the x is at the center line of
47 note heads that are on the "normal" side of the stem. (Normally, when a stem
48 is up, notes are put on the left side of the stem, and when the stem is
49 down they are placed on the right side. However, when two notes adjacent
50 on the staff have to be printed in a single chord, one has to be moved to the
51 opposite side.) The y of a chord is always the middle line of the staff
52 containing the chord. The x of a bar line is its geometric center. The y
53 of a bar line is the center line of the top visible staff.
56 Tag names can be re-used. The value of a tag will always be its most
60 There are also several "pre-defined" tags. They are:
69 the available part of the page
77 The _page tag refers to the entire page.
78 The x and y values of _page are at the geometric center of the page.
80 seldom useful, but is provided in case you want to force something to
81 a specific place on a page.
84 <A NAME="wintag">The _win tag</A>
85 refers to the area of the page available for printing.
86 The name comes from the idea that it provides a view, as if through a window,
87 of a portion of the page. Its precise meaning depends upon the current
89 In header, footer, top, bottom,
90 header2, footer2, top2, bottom2, and block contexts,
91 it refers to the area of the
92 page taken up by the corresponding element. In music context, it refers
93 to the area of the page that remains after excluding the margins and the
94 header, footer, top and bottom for the page.
95 There is no way to access location tags in any other
96 contexts, so _win (and all other location tags)
97 are meaningless in other contexts.
100 The _cur tag refers to the current location on the page. This is a single
101 point, such that east and west values are the same as x, and north and
102 south values are the same as y. It is only useful immediately
103 after a command that explicitly sets the current location, that is, after
104 a printing command or line or curve command. Since Mup places musical
105 data in an arbitrary order, trying to use _cur at other times is likely
106 to cause output at a seemingly random place.
109 Location tags can be referenced by a number of commands, including those
111 <A HREF="prnttext.html">printing text,</A>
113 <A HREF="linecurv.html">drawing lines or curves.</A>
114 In the simplest case, two
115 tag references are given in parentheses. The first tag
116 must refer to a horizontal direction (the "x" direction for mathematicians),
117 namely a tag with a w, e, or x after the dot. The second tag is then a
118 vertical tag, having n, s, or y. For example:
120 (g.x, g.y) // x and y of tag "g"
121 (_tag.w, _item.n) // west of tag "_tag" and
122 // north of tag "_item"
124 The first example refers to the x,y coordinate of tag "g". The second item
125 refers to two different tags. The point referenced has its horizontal
126 location aligned with
127 the west side of the object having the tag "_tag," while its vertical
128 position is in line with the north side of the object having the tag "_item".
129 In other words, if a line were drawn along the west side of the object
130 tagged with "_tag" and another line were drawn along the top edge of the
131 object with tag "_item", the point where those two lines crossed would be
132 the point referenced.
135 Frequently, you may want to place something relative to a tagged object.
136 You can add offsets in both the x and y dimensions. These offsets are given
138 As was mentioned earlier, a stepsize is half the distance between two staff
141 (g.x + 4.5, g.y + 4.5)
143 refers to the point 4.5 stepsizes to the right and above the point (g.x, g.y).
144 Adding an offset moves to the right in the horizontal direction and
145 upward in the vertical direction. You can also subtract an offset:
149 refers to a point 1.3 stepsizes to the left of the
150 west edge of k and 2 stepsizes below the top of m.
153 In the horizontal direction, offsets can be given in terms of "time". This
154 is specified by using the keyword "time" followed by a number of beats.
155 As an example, suppose we have the tag reference:
157 (q.x + time 1, q.y + 2)
160 <A HREF="param.html#time">time signature</A>
161 is 4/4 and tag "q" happens
162 to be associated with a half note, this tag reference
163 would refer to a point halfway between that note and the following chord,
164 since it includes an offset of a quarter note. If "q" had been associated
165 with a whole note, the point would be only 1/4 of the way between the
166 note and the following chord. Since notes are placed based on various
167 constraints and aesthetic considerations, the actual distance will vary
168 depending on which tag is referenced.
172 <A HREF="bars.html#btag">tag associated with a bar line,</A>
173 the time to distance mapping
174 is done based on the distance between the bar (at count "0") and the first
175 chord in the measure (at count "1"). So, for example, in 4/4 time, a reference
176 to a bar line tag + time 0.5 would indicate a place halfway between the bar
177 line and the first chord, whereas tag + time 0.25 would be one fourth of the
181 The mapping of time to distance is done based only on the note, rest, or bar
182 line associated with the tag. For example, if the tag is associated with a
183 quarter note, and the distance between that note and the next was 0.5 inches,
184 specifying "+ time 2" (a half note) would mean 1.0 inch to the right, or
185 specifying "- time 2" would mean 1.0 inch to the left, even if the notes to
186 the left or right happened to be spread somewhat differently than 0.5 inches
187 per quarter note. Thus it is usually advisable not to specify a time offset
188 greater than the time value of the note or rest associated with the tag,
189 nor to subtract a time value. Stated another way, when specifying the X
190 portion of a coordinate using a time offset, it is best to use a location tag
191 based on whichever note, rest, or bar is immediately to the left of the
192 X location you are trying to specify.
195 The various kinds of offsets can be combined.
197 ( _pp + 1.2 - time 3.5, _zz + 2)
201 At least one of the three possible items--tag, stepsize offset, or
202 time offset--must be specified for each direction. Only one
203 tag is allowed for each direction. If no tag is specified, the reference
204 becomes an absolute reference, giving an exact page location. For example:
208 is 10 stepsizes from the left edge and 20 stepsizes
209 above the bottom of the page.
210 Time offsets are not allowed on absolute references, and must follow the tag
214 It is possible to specify multiple offsets of the same type, although
215 this is rarely, if ever, useful. Thus the following are equivalent:
217 ( f.x + 1 - 0.5 + time 1 - time 0.5, f.s + .3 - .1)
218 ( f.x + 0.5 + time 0.5, f.s + .2)
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~mdw / mup / blob