HOWTO create text2skin-skins

Sascha Volkenandt

english translation by Thomas Wehrspann

16.12.2004
Last update 13.07.2009

Table of Contents
 1. General Structure of XML Documents
 2. General Structure of the Skin file
 3. Structure of the individual Sections
 4. Drawing Objects
 5. Tokens and Texts
 6. Token Attributes
 7. Complex Conditions and Block Objects
 8. List in the Main Menu
 9. Creation of Image-Maps for Menu Logos
10. List of all Functions
11. Scaling of Images
12. Colors
13. True-type Fonts


1. General Structure of XML Documents
=====================================
Those, who already worked with XML can skip this section.

XML files have a tree-like structure of elements. Each document starts with a
root element (a container) which includes all other elements hierarchically.
Elements, so called tags, are written in spiky brackets, a slash before the
name marks an end tag.

  <element>
    <subelement>
      ...
    </subelement>
  </element>

Every element can provide attributes to specify further properties. Attributes
are following the element name inside the brackets, their values are written
after an equal in quotation marks

  <element attribute="value" anotherattribute="another value"
    ...
  </element>

Empty elements include no other elements and must be empty even a line break
is not allowed.

  <element attribute="value"></element>

It is possible to write those elements in a simpler way

  <element attribute="value" />

Normal XML files start with a control instruction to specify the XML version
used

  <?xml version="1.0"?>


2. General Structure of the Skin file
=====================================
Each skin file (ending with the extension ".skin") starts with the XML
declaration (see above) followed by the root element <skin>. This element has
three attributes which must be specified

* version    - Version of the skin format (current: "1.0")
* name       - Name of the skin
* screenBase - Specifies, if the skin is drawn "relative" to the VDR setup of
               "absolute" to the coordinates 720x576.

  <?xml version="1.0"?>
  <skin version="1.0" name="brushed Aluminium" screenBase="relative">
    ...
  </skin>


3. Structure of the individual Sections
=======================================
The different sections of the VDR-OSD are defined in several <display>
elements. The <display> elements get the "id" attribute which specifies the
actual section

* channelInfo
* channelSmall
* volume
* message
* replayInfo
* replaySmall
* menu

Each <display> definition starts with the definition of drawing areas, so
called windows. The quantity and color depth of windows depends on the output
device.

  <display id="replayInfo">
    <window x1="0" x2="619" y1="-113" y2="-84" bpp="4"/>
    <window x1="20" x2="99" y1="-83" y2="-44" bpp="4"/>
    ...
  </display>


4. Drawing Objects
==================
After the definition of the drawing areas objects can be drawn on it
freely. There are three types of objects

* simple objects
  * rectangle  - draws a filled rectangle
  * text       - static or compound text
  * image      - draws a image
  * ellipse    - ellipse of (pitch)circle
  * slope      - a curve

* extended or connected objects
  * progress   - shows a progress bar
  * scrolltext - multiline text
  * scrollbar  - a scrollbar

* group and special objects
  * block      - groups several objects
  * list       - defines the list in the menu
  * item       - defines one item in the list

The simple object are mostly self-explanatory, they all have attributes "x1",
"y1", "x2" and "y2" which describe the position and dimension (exception:
<image>, which only uses "x" and "y" when no scaling should be applied) and
"color" which is a symbolic or hexadecimal color description. Images need
furthermore the attributes "path" and can have the attributes "bgColor" and
"alpha" (transparency 0-255). Texts can have the attribute align (with values
"left", "right" and "center"), scrolltexts furthermore "font". Ellipses will
be pitch circles with the "arc" attribute curves get the direction with it.
Scroll- and progress-bars also need "bgColor", progress-bars "current" and
"total".

  <image x="0" y="-70" path="Aluminium_volumebar.png"/>
  <rectangle x1="20" x2="99" y1="-83" y2="-44" color="#00000000"/>
  <text x1="42" x2="571" y1="-113" y2="-86" color="#FF000000" font="Osd">{ReplayTitle}</text>
  <progress x1="124" x2="577" y1="-70" y2="-55" color="#FF84ff00" bgColor="#FFFFFFFF" current="{ReplayPositionIndex}" total="{ReplayDurationIndex}"/>
  <scrolltext x1="24" y1="138" y2="-72" x2="583" font="Sans Serif@20" color="#AFFFFF00">
  {PresentShortText}
  {PresentDescription}
  </scrolltext> 


5. Tokens and Texts
===================
In the example above text in curly braces used. These are so called tokens,
variables which actual embodiment depends on information of VDR. A complete
list of all tokens is in the reference and the demo skins can be used as
examples. Normal text and paths can be mixed with token for dynamic display of
information

  <image x="0" y="0" path="logos/{ChannelName}.mng" />

Each object, in addition to its own attributes, can have the attribute
"condition" which is a complex function. Conditions are used to bound the
actual display of an element or block to information provided by VDR. A token
can also be a condition. A token without content is evaluate to false. Strings
included in functions are quoted in quotation marks. Quotation marks are
escaped with a backslash.

  <image x="20" y="-83" alpha="180" condition="file('replay/{ReplayMode}.png')" path="replay/{ReplayMode}.png" />
  <image x="20" y="-83" alpha="180" condition="not(file('replay/{ReplayMode}.png'))" path="replay/common.png" />
  <image x="314" y="-34" condition="{IsPlaying}" path="symbols/play_sml.xpm" />
  <image x="334" y="-34" condition="{IsFastForward:2}" path="symbols/ffwd_sml.xpm" />
  <image x="420" y="25" condition="or({HasVPS},{HasTimer},{IsRunning})" path="Aluminium_epgbottom.png" />

Shows the image only, if ...

1) ...file exists
2) ...the does not exist
3) ...the ReplayMode is ''Replay''
4) ...the ReplayMode is ''Forward Level 2'' ('':0'' is normal Replay without
      Multi-Speed and with '':X'' every level is meant)
5) ...the current Event is either VPS, or is currently aired, or programmed as
      Timer.


6. Token Attributes
===================
Some tokens can also have attributes (these are no XML attributes). At the
moment these tokens are "{MenuTitle}", "{MenuCurrent}" and all
date/time-token. Attributes follow follow the token name separated by a colon
":". Colons in the attribute content are escaped with a backslash.

  <text .....>{DateTime:%H\:%M}</text>

For date/time-token the same rules as for strftime applies (see "man
strftime") for "{MenuTitle}" and "{MenuCurrent}" only the attribute "clean"
exists, which removes tabs and hotkey numbers from the text.


7. Complex Conditions and Block Objects
=======================================
Complex conditions are used to bound the display of elements to the existent
of certain VDR information. Block objects group several element together for
easier use of the complex condition.

The following example shows the channel logo with a shadow only if the file
exists, otherwise a transparent display is used.

  <rectangle x1="0" x2="67" y1="0" y2="51" color="#00000000" condition="not(file('logos/{ChannelName}.mng'))"/>   

  <block condition="file('logos/{ChannelName}.mng')"> 
    <rectangle x1="4" x2="67" y1="4" y2="51" color="#AF000000"/>
    <image x="0" y="0" path="logos/{ChannelName}.mng"/>
  </block>

Grouping of a long text with scroll-bars which are only shown if the text does
not fit on one page.

  <block condition="{MenuText}"> 
    <scrolltext x1="30" y1="60" x2="519" y2="343" color="#FFFFFFFF" font="Sml">{MenuText}</scrolltext>

    <image condition="or({CanScrollUp},{CanScrollDown})" x="561" y="52" path="menu-scrollbar.png" /> 
    <scrollbar condition="or({CanScrollUp},{CanScrollDown})" x1="569" y1="69" x2="578" y2="315" color="#FF975000" bgColor="#DAB38D13" /> 

    <image condition="and(not({CanScrollUp}),{CanScrollDown})" x="561" y="39" path="symbols/arrowup-off.png" />
    <image condition="and(not({CanScrollUp}),{CanScrollDown})" x="561" y="319" path="symbols/arrowdown-on.png" />

    <image condition="and({CanScrollUp},not({CanScrollDown}))" x="561" y="39" path="symbols/arrowup-on.png" />
    <image condition="and({CanScrollUp},not({CanScrollDown}))" x="561" y="319" path="symbols/arrowdown-off.png" />

    <image condition="and({CanScrollUp},{CanScrollDown})" x="561" y="39" path="symbols/arrowup-on.png" />
    <image condition="and({CanScrollUp},{CanScrollDown})" x="561" y="319" path="symbols/arrowdown-on.png" />
  </block>


8. List in the Main Menu
========================
The special element <list> specifies the display area of a list of entries.
The only attributes are "x1", "y1", "x2" and "y2". The first subelement has to
be the special element <item> whose only attribute is "height". After <item>
elements can be placed as normal. The "height" of <item> defines the dimension
of the area a list entry can draw on.

  <list x1="24" y1="62" x2="569" y2="-82">
    <item height="28" />
    <text x1="25" x2="569" y1="3" y2="27" color="#AF00FFFF" font="Sml">{MenuGroup}</text>
    <text x1="25" x2="569" y1="3" y2="27" color="#AFFFFFFF" font="Sml">{MenuItem}</text>
    <rectangle x1="0" x2="579" y1="0" y2="27" color="#FF2B1B9E" condition="{IsMenuCurrent}" />
    <text x1="22" x2="569" y1="0" y2="27" color="#AFFFFFFF" font="Osd">{MenuCurrent}</text>
    <text x1="0" x2="25" y1="0" y2="27" color="#AFFFFFFF" font="Osd" condition="{IsMenuCurrent}">-></text>
  </list>

It might be a bit demanding to understand how a list is rendered. Coordinates
of objects inside a list is relative to the display area of the list itself.
Every object in the list is draw several times, for each entry in the list one
time.  The Y-coordinates are incremented by one <item> "height" each time. The
tokens "{MenuCurrent}", "{MenuItem}" and "{MenuGroup}" are draw per tab (in
separate menus like schedule), whereas "{IsMenuCurrent}", "{IsMenuGroup}" or
"{IsMenuItem}" are drawn only one time per list element.

  <text x1="25" x2="569" y1="3" y2="27" color="#AF00FFFF" font="Sml">{MenuGroup}</text>
  <text x1="25" x2="569" y1="3" y2="27" color="#AFFFFFFF" font="Sml">{MenuItem}</text>
  <rectangle x1="0" x2="579" y1="0" y2="27" color="#FF2B1B9E" condition="{IsMenuCurrent}" />


9. Creation of Image-Maps for Menu Logos
========================================
To show a logo depending on the currently selected element, the cleaned text
(attribute "clean") of the element (e.g. "Aufzeichnungen") is compared with
translations (here "Recordings"). With plugins the main menu entry
(e.g. "MP3") of the plugin (here mp3) is compared to the translations.
(Beware: This element is not part of the list and has also to be quoted
outside the <list> container).

  <image x="25" y="100" path="logos/schedule.png" condition="equal({MenuCurrent:clean},trans('Schedule'))" />
  <image x="25" y="100" path="logos/channels.png" condition="equal({MenuCurrent:clean},trans('Channels'))" />
  <image x="25" y="100" path="logos/timers.png" condition="equal({MenuCurrent:clean},trans('Timers'))" />
  <image x="25" y="100" path="logos/music.png" condition="equal({MenuCurrent:clean},plugin('mp3'))" />

The same applies to "{MenuTitle:clean}" if a logo for the current menu page is
wished, instead of current selected element.


10. List of all Functions
=========================
* not   - negation of the term 
          (e.g. "not(equal({PresentStartDateTime},{PresentVPSDateTime}))" )
* and   - true, if all parameter are true 
          (e.g. "and({CanScrollUp},{CanScrollDown})" )
* or    - true, if one parameter is true 
          (e.g. see above)
* equal - true, if both parameters are true
* file  - returns the parameter, if the file exists in the skin directory 
          (e.g. "file('logos/{ChannelName}.png')" )
* trans - return the translation (i18n) of the parameter, false, if no translation is found 
          (e.g. "equal('Kanäle', trans('Channels'))" )

Normally strings in function are quoted in quotation marks, only if the simply
consists of a token the quotation marks can be omitted.
(e.g. "not({MenuText})" instead of "not('{MenuText}')" )


11. Scaling of Images
=====================
With this function it is possible to scale images independently from the OSD
settings. This function is activated when the attributes "x1", "x2", "y1" and
"y2" with their relative readings are used instead of "x" and "y" (which
disable this function).  The attribute "color" specifies the maximum amount of
colors the must have after scaling.


12. Colors
==========
Colors are given in RGB-format transparency information

  color=#AARRGGBB

* A - alpha value (transparency 0-255)
* R - red value
* G - green value
* B - blue value

Some examples

         AARRGGBB
  color=#00000000 = Black, fully transparent
  color=#FF000000 = Black, full opacity
  color=#7F000000 = Black, half translucent
  color=#7FFFFFFF = White, half translucent


13. True-type Fonts
===================
There are three predefined fonts

* Osd
* Fix
* Sml

It is possible to use True Type fonts installed and configured for
fontconfig's use on the system.  See the fontconfig documentation for details
how to do that; usually it's a matter of copying the font files somewhere and
running fc-cache(1) (as root or the VDR user).

In the skin file the font is defined with

  font="Osd"

or with True Type fonts with the desired size and if desirable width

  font="Sans Serif@size[,width]"
  font="Monospaced:Bold@size[,width]"