display: Replace hard-coded display with new config based display

Introduce a new config based system for specifying the on-screen
contents of an lcd screen.  The default screen configuration (found in
klippy/extras/display/display.cfg) is the same as the previous
hard-coded display, so this should not change behavior for existing
users.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

1 files changed, 43 insertions, 0 deletions

diff --git a/config/example-extras.cfg b/config/example-extras.cfg
index eee10fd5..dbf3a6f4 100644
--- a/config/example-extras.cfg
+++ b/config/example-extras.cfg
@@ -1774,6 +1774,12 @@
 #   A reset pin may be specified on ssd1306 displays. If it is not
 #   specified then the hardware must have a pull-up on the
 #   corresponding lcd line.
+#display_group:
+#   The name of the display_data group to show on the display. This
+#   controls the content of the screen (see the description of
+#   [display_data] below for more information). The default is
+#   _default_20x4 for hd44780 displays and _default_16x4 for other
+#   displays.
 #menu_root:
 #   Entry point for menu, root menu container name. If this parameter
 #   is not provided then default menu root is used. When provided
@@ -1825,6 +1831,43 @@
 #   The resistance range for a 'kill' button. Range minimum and maximum
 #   comma-separated values must be provided when using analog button.
 
+# Support for displaying custom data on an lcd screen. One may create
+# any number of display groups and any number of data items under
+# those groups. The display will show all the data items for a given
+# group if the display_group option in the [display] section is set to
+# the given group name.
+#[display_data my_group_name my_data_name]
+#position: 0, 0
+#   Comma separated row and column of the display position that should
+#   be used to display the information. This parameter must be
+#   provided.
+#text:
+#   The text to show at the given position. This field is evaluated
+#   using command templates (see docs/Command_Templates.md). This
+#   parameter must be provided.
+
+# Display data text "macros" (one may define any number of sections
+# with a display_template prefix). This feature allows one to reduce
+# repetitive definitions in display_data sections. One may use the
+# builtin render() function in display_data sections to evaluate a
+# template. For example, if one were to define [display_template
+# my_template] then one could use "{ render('my_template') }" in a
+# display_data section.
+#[display_template my_template_name]
+#param_<name>:
+#   One may specify any number of options with a "param_" prefix. The
+#   given name will be assigned the given value (parsed as a Python
+#   literal) and will be available during macro expansion. If the
+#   parameter is passed in the call to render() then that value will
+#   be used during macro expansion. For example, a config with
+#   "param_speed = 75" might have a caller with
+#   "render('my_template_name', param_speed=80)". Parameter names may
+#   not use upper case characters.
+#text:
+#   The text to return when the render() function is called for this
+#   template. This field is evaluated using command templates (see
+#   docs/Command_Templates.md). This parameter must be provided.
+
 
 ######################################################################
 # Filament sensors