Docs on the theme format

Themes are in a simple XML-subset format.

<?xml version="1.0"?>
<metacity_theme>
<!-- Only one info section is allowed -->
<info>
  <name>Foo</name>
  <author>Foo P. Bar</author>
  <copyright>whoever, 2002</copyright>
  <date>Jan 31 2005</date>
  <description>A sentence about the theme.</description>
</info>

<!-- define a frame geometry to be referenced later -->
<!-- frame_geometry has an optional has_title attribute which 
     determines whether the title text height is included in the 
     height calculation. if not specified, defaults to true.
     It also has an optional text_size="medium" attribute
     (same sizes as with Pango markup, xx-small thru medium thru
     xx-large) 

     Finally it has optional args rounded_top_left=true, 
     rounded_top_right=true, rounded_bottom_left=true,
     rounded_bottom_right=true.

     -->
<frame_geometry name="normal" has_title="true" title_scale="medium">
  <distance name="left_width" value="6"/>
  <distance name="right_width" value="6"/>
  <distance name="bottom_height" value="7"/>
  <distance name="left_titlebar_edge" value="6"/>
  <distance name="right_titlebar_edge" value="6"/>
  <distance name="button_width" value="17"/>
  <distance name="button_height" value="17"/>
  <!-- alternative to button_width button_height distances -->
  <aspect_ratio name="button" value="1.0"/>
  <distance name="title_vertical_pad" value="4"/>
  <border name="title_border" left="3" right="12" top="4" bottom="3"/>
  <border name="button_border" left="0" right="0" top="1" bottom="1"/>
</frame_geometry>

<!-- inheritance is allowed; simply overwrites values from parent -->
<frame_geometry name="borderless" parent="normal">
  <distance name="left_width" value="0"/>
  <distance name="right_width" value="0"/>
  <distance name="bottom_height" value="0"/>
  <distance name="left_titlebar_edge" value="0"/>
  <distance name="right_titlebar_edge" value="0"/>
</frame_geometry>

<!-- define a constant to use in positions/sizes of draw operations;
     constant names must start with a capital letter.
  -->
<constant name="LineOffset" value="3"/>

<!-- define drawing operations to be referenced later; 
     these draw-op lists can also be placed inline. 

     Positions/lengths are given as expressions.
     Operators are: +,-,*,/,%,`max`,`min`
     All operators are infix including `max` and `min`, 
      i.e. "2 `max` 5"
     
     Some variables are predefined, and constants can also 
     be used. Variables are:

       width - width of target area
       height - height of target area
       object_width - natural width of object being drawn
       object_height - natural height of object being drawn
       left_width - distance from left of frame to client window
       right_width - distance from right of frame to client window
       top_height - distance from top of frame to client window
       bottom_height - distance from bottom of frame to client window
       mini_icon_width - width of mini icon for window
       mini_icon_height - height of mini icon
       icon_width - width of large icon
       icon_height - height of large icon
       title_width - width of title text
       title_height - height of title text

    All these are always defined, except object_width/object_height 
    which only exists for <image> right now.

  -->

<draw_ops name="demo_all_ops">
  <line color="#00FF00" x1="LineOffset" y1="0" x2="0" y2="height"/>
  <line color="gtk:fg[NORMAL]" 
        x1="width - 1" y1="0" x2="width - 1" y2="height" 
        width="3" dash_on_length="2" dash_off_length="3"/>
  <rectangle color="blend/gtk:fg[NORMAL]/gtk:bg[NORMAL]/0.7"
             x="0" y="0" width="width - 1" height="height - 1" filled="true"/>
  <arc color="dark gray" x="0" y="0" width="width - 1" height="height - 1" 
       filled="false" start_angle="30" extent_angle="180"/>
  <tint color="orange" alpha="0.5" x="0" y="0" width="width" height="height"/>
 <!-- may be vertical, horizontal, diagonal -->
  <gradient type="diagonal" 
            x="10" y="30" width="width / 3" height="height / 4">
    <!-- any number of colors allowed here. A color can be 
         a color name like "blue" (look at gcolorsel), a hex color
         as in HTML (#FFBB99), or a color from the gtk theme 
         given as "gtk:base[NORMAL]", "gtk:fg[ACTIVE]", etc.
       -->
    <color value="gtk:fg[SELECTED]"/>
    <!-- color obtained by a 0.5 alpha composite of the second color onto the first -->
    <color value="blend/gtk:bg[SELECTED]/gtk:fg[SELECTED]/0.5"/>
  </gradient>
  <!-- image has an optional colorize="#color" attribute to give the
       image a certain color -->
  <image filename="foo.png" alpha="0.7"
         x="10" y="30" width="width / 3" height="height / 4"/>
  <gtk_arrow state="normal" shadow="in" arrow="up"
             filled="true"
             x="2" y="2" width="width - 4" height="height - 4"/>
  <gtk_box state="normal" shadow="out"
           x="2" y="2" width="width - 4" height="height - 4"/>
  <gtk_vline state="normal" x="2" y1="0" y2="height"/>
  <!-- window's icon -->
  <icon alpha="0.7"
        x="10" y="30" width="width / 3" height="height / 4"/>
  <!-- window's title -->
  <title color="gtk:text[NORMAL]" x="20" y="30"/>
  <!-- include another draw ops list; has optional x/y/width/height attrs -->
  <include name="some_other_draw_ops"/>
  <!-- tile another draw ops list; has optional
       x/y/width/height/tile_xoffset/tile_yoffset -->
  <tile name="some_other_draw_ops" tile_width="10" tile_height="10"/>
</draw_ops>

<frame_style name="normal" geometry="normal">
  <!-- How to draw each piece of the frame.
       For each piece, a draw_ops can be given inline or referenced 
       by name. If a piece is omitted, then nothing will be drawn 
       for that piece.

       For each piece, the "width" and "height" variables in 
       coordinate expressions refers to the dimensions of the piece, 
       the origin is at the top left of the piece.
  
       So <rectangle x="0" y="0" width="width-1" height="height-1"/>
       will outline a piece.
    -->

  <piece position="entire_background" draw_ops="demo_all_ops"/>
  <piece position="left_titlebar_edge">
    <draw_ops>
      <line color="#00FF00" x1="0" y1="0" x2="0" y2="height"/>
    </draw_ops>
  </piece>

  <!-- The complete list of frame pieces:

       entire_background: whole frame
       titlebar: entire area above the app's window 
       titlebar_middle: area of titlebar_background not considered
                        part of an edge
       left_titlebar_edge: left side of titlebar background
       right_titlebar_edge: right side of titlebar background
       top_titlebar_edge: top side of titlebar background
       bottom_titlebar_edge: bottom side of titlebar background 
       title: the title area (doesn't include buttons)
       left_edge: left edge of the frame
       right_edge: right edge of the frame
       bottom_edge: bottom edge of the frame
       overlay: same area as entire_background, but drawn after 
                drawing all sub-pieces instead of before

   -->

  <!-- For buttons, drawing methods have to be provided for 
       each of three states: 
          normal, pressed, prelight
       and the button function or position must be provided:
          close, maximize, minimize, menu, 
          left_left_background, left_middle_background,
          left_right_background, right_left_background, 
          right_middle_background, right_right_background
       So a working theme needs 3*4 = 12 button declarations
       and a theme may have up to 3*10 = 30 button declarations
       in order to handle button-rearrangement preferences.
 
       (The name "function" for the attribute is from before the 
        background values existed.)
    -->

  <button function="close" state="normal" draw_ops="previously_named"/>
  <button function="menu" state="normal">
    <draw_ops>
      <icon alpha="0.7"
            x="0" y="0" width="object_width" height="object_height"/>
    </draw_ops>
  </button>

</frame_style>

<!-- styles can inherit from each other with the parent="" attribute. 
     In a subclass anything can be re-specified to override 
     the parent style. -->
<frame_style name="focused" parent="normal">
  <piece position="title">
    <draw_ops>
      <rectangle color="gtk:bg[SELECTED]"
                 x="0" y="0" width="width-1" height="height-1"/>
      <title color="gtk:fg[SELECTED]" x="(width - title_width) / 2"
                                      y="(height - title_height) / 2"/>
    </draw_ops>
  </piece>
</frame_style>

<!-- Maps styles to states of frame. 

     Focus: yes (focused), no (not focused)
     Window states: normal, maximized, shaded, maximized_and_shaded
     Window resizability: none, vertical, horizontal, both

     Everything unspecified just does the same as
     unfocused/normal/both.

     only state="normal" needs a resize="" attribute.
 -->
<frame_style_set name="normal">
<frame focus="yes" state="normal" resize="both" style="focused"/>
<frame focus="no" state="normal" resize="both" style="normal"/>
</frame_style_set>

<!-- Each window type needs a style set 
     Types: normal, dialog, modal_dialog, menu, utility, border
  -->
<window type="normal" style_set="normal"/>


<!-- For menu icons, drawing methods are needed for the same 
     four types as the buttons, and GTK states
     (insensitive,prelight,normal,etc.)
  -->

<menu_icon function="close" state="normal" draw_ops="previously_named"/>


</metacity_theme>