KLayout Documentation (Qt 5): Main Index » Programming scripts » The Application API
The Application API
This section covers the basic application API. The application API consists of the main application class
and several classes that represent the user interface. This sections presents a selection of classes
that make up the application API. These classes provide the main entry points into the application API.
Further classes are documented in RBA Class Index.
All classes discussed herein are contained in the RBA namespace. In you code you either have to use
qualified names (i.e. RBA::Application) or include the RBA module in you macro's namespace.
The Application class
The Application class is documented in detail in Application. It represents the application
and because there is just one application, there also is just one instance of the application object.
That instance can be obtained through the "instance" class method:
Application::instance
The application object is the main entry point into the API. It offers several methods and attributes. In particular:
- Application#application_data_path: returns the user-local storage path. This is where KLayout saves
user-specific files, for example the configuration file.
- Application#execute: runs the application. Normally, this method is called implicitly when the application
is started. It is possible to use KLayout as a Ruby interpreter by supplying a Ruby script on the command
line with the "-r" option. Such scripts must run the application explicitly if they want to.
- Application#exit: exits the application. This method unconditionally terminates the application in a clean
way.
- Application#get_config and Application#set_config: read and write the configuration database.
The configuration database
is a storage of name/value pairs which is stored in the configuration file. These methods can be used
to manipulate that storage. Use the Application#get_config_names method to retrieve the names of the configuration
parameters stored inside the configuration database. Use the Application#commit_config method to activate
settings that have been made with "set_config".
- Application#inst_path: returns the installation path. That is where the executable is located.
- Application#is_editable?: returns true, if KLayout runs in editable mode.
- Application#klayout_path: returns the KLAYOUT_PATH value. This is the search path where
KLayout looks for library files or macros. This method delivers the application data path and
can be used to look up files required by the macro.
- Application#main_window: delivers the MainWindow object which represents the application's main window.
See below for a description of that class.
- Application#process_events: process pending events. If that method is called periodically during
long operations, the application will be able to process events and thus handle clicks on a "Stop"
button for example. Please note that calling this method is not safe in every context, because
not every execution context is reentrant.
- Application#read_config and Application#write_config: reads
and writes the configuration database from a file.
- Application#version: delivers KLayout's version string. This string can be used to switch
the implementation of a script depending on KLayout's version.
The MainWindow class
The MainWindow class is documented in detail in MainWindow. It represents the main application
window. The main window instance can be obtained with:
Application::instance.main_window
The main window object is the entry point to all user-interface related objects.
It offers a couple of methods. In particular:
The MainWindow supplies three events.
See Events And Callbacks for details about events.
These are the events:
- on_current_view_changed:
This event is triggered when the current tab changes. The signal is available with an integer parameter: this is the index of the
previous tab. The new tab is already the current tab when this event is triggered.
- on_view_created:
This event is triggered when a new view is created. The signal is available with an integer parameter: this is the index of the
new tab.
- on_view_closed:
This event is triggered when a new view is closed. The signal is available with an integer parameter: this is the index of the
tab that was closed.
In addition, the MainWindow class features many parameterless methods starting with "cm_...". These methods are identical with
the methods called when the respective menu functions are triggered. They are of use when menu events need to be emulated
in code, for example to implement special key bindings.
The LayoutView class
The LayoutView class is documented in detail in LayoutView. It represents one layout tab in the
main window. A single layout view can show multiple layouts. The CellView objects represent one
layout loaded into a view. They specific the layout loaded plus the cell selected for drawing.
Each LayoutView has a list of CellView objects corresponding to the layouts shown in the same panel.
A LayoutView object can be obtained from the main window either by reading the current view or by getting
the view object for a tab by the tab index:
# Current view:
Application::instance.main_window.current_view
# or short:
LayoutView::current
# By index:
Application::instance.main_window.view(index)
# Note: the index of the current view is
Application::instance.main_window.current_view_index
# and the number of views is
Application::instance.main_window.views
The index is 0 for the first tab. Note that the value returned by LayoutView#current
or MainWindow#current_view can be "nil" if no layout is shown.
A layout view is the container for a variety of "visual" objects. These resources are mainly display objects like
annotations, markers and images. In addition, the report database system is anchored in the LayoutView object.
The following resources are managed in the layout view:
- Annotations (rulers): an arbitrary number of annotations can be registered in the view.
The annotations are objects of the Annotation class (Annotation). Annotations
are independent of layouts and are defined in micron units.
- Images: images are also objects independent of layouts. Any number of images can be
placed below the drawn layout.
- Markers: markers are temporary overlay objects which can be used a highlights or to
add some elaborate annotation to a layout view. Markers can be layout database objects, hence
it is possible to draw polygons or other objects over the layout. Markers can be configured
to a large degree, so different colors can be used for example. Markers are objects of class
Marker (Marker).
- Local configuration: be default, the layout view pulls its configuration from the global
configuration database. It is possible however to override certain configuration parameters for a
particular view. This allows for example to set the background color for a particular view without
affecting the other views.
- Layer properties: the layer properties tree is also managed by the layout view.
Since there can be multiple layer properties trees in different tabs in the layer properties panel,
there are method to access either the current or a specific one of the layer properties trees.
- Custom stipples and line pattern: custom stipplesu and line styles can be set in the
layout view and used in the layer properties. Custom stipples are bitmaps that define the fill
pattern used for the inside area of a polygon. Line styles are bit pattern that make lines being
resolved into dots.
- Selection: the layout view also manages the selection. This is a set of objects and their
instantiation path in the layout database. It represents the set of selected objects. Each
selected object is described by a instantiation path and the object itself. That information is
combined in the ObjectInstPath object (ObjectInstPath).
- Transient selection: this is the object that is highlighted briefly when the mouse
hovers over it.
- Cell views: the list of layouts and cells shown in the layout view as overlays. Cell views
are created when layouts are loaded and deleted when layouts are closed.
One of the cell views is the "active" one. That is the one which is selected in the drop-down box
in the cell tree and for which the cell tree is shown.
- Cell visibility: the information about what cell is visible and what cell is not. Each
cell can be made invisible. In that case, only the cell frame is drawn and the cell is shown
stroked out in the cell tree.
- Hierarchy levels: this attribute controls which hierarchy levels are shown by default.
- Viewport: the geometrical dimensions of the area which is drawn in micron space.
- Report databases: a layout view can have multiple report databases attached to it.
Report databases can be shown in the marker browser and are collections of general information
or geometrical information related to a certain position or area.
- Transactions: transactions are grouped layout operations which form an atomic operation which
can be undone. Transactions can be created within the layout view. Transactions must be opened and closed
before they are available as operations on the undo stack.
- Plugins: plugins are a way to implement new functionality inside the layout view related
to mouse actions. By using plugins it is possible to track the mouse and implement actions related
to mouse activity.
- Title: finally, a layout view has a title which is shown in the tab.
Being the central class, the layout view naturally offers many methods and attributes.
Here's a brief explanation of some of these methods:
- LayoutView#active_cellview and LayoutView#active_cellview_index:
gets the active CellView object or index of this object. The active cell view is the one that
is selected in the drop-down box above the cell tree. CellView#active gets the active cellview
of the current layout view.
- LayoutView#add_missing_layers will add the layers to the layer tree for which there is no
layer properties entry yet. This method can be used after a layout has been created and populated to show all
layers of the layout.
- LayoutView#add_stipple, LayoutView#clear_stipples and LayoutView#remove_stipple:
manage custom stipples.
- LayoutView#add_line_style, LayoutView#clear_line_styles and LayoutView#remove_line_style:
manage custom line styles.
- LayoutView#ascend and LayoutView#descend: moves the context cell up or down in the
hierarchy.
- LayoutView#begin_layers and LayoutView#end_layers:
gets an start or end iterator object that allows traversing of the layer properties tree
in a recursive or non-recursive fashion.
See below for a description of how to deal with the layer properties.
- LayoutView#each_layer is a convenient alternative way of iterating over the layers
without directly using the layer tree iterator.
- LayoutView#box:
gets the display area in micron units (the viewport).
- LayoutView#cancel:
returns the view into idle state (nothing selected, no editing in progress, "Select" mode is active).
- LayoutView#cellview:
gets the CellView object for a given index.
- LayoutView#cellviews:
gets the number of cell views registered.
- LayoutView#clear_annotations, LayoutView#insert_annotation, LayoutView#erase_annotation and LayoutView#replace_annotation:
manage annotations (rulers).
- LayoutView#clear_images, LayoutView#insert_image, LayoutView#erase_image and LayoutView#replace_image:
manage images.
- LayoutView#clear_config, LayoutView#get_config, LayoutView#set_config and LayoutView#commit_config:
allow manipulation of the configuration for that layout view
only. For example it is possible to set a different background color for that specific layout view.
- LayoutView#clear_layers, LayoutView#delete_layer, LayoutView#delete_layer_list,
LayoutView#insert_layer, LayoutView#insert_layer_list, LayoutView#replace_layer_node
and LayoutView#remove_unused_layers:
manage the layer properties. See below for a detailed explanation.
- LayoutView#clear_transactions:
clears all transactions (clears the undo stack).
- LayoutView#transaction and LayoutView#commit:
starts or ends a transaction. All operations between the
start and end of a transaction can be undone in one step.
- LayoutView#clear_object_selection:
clears the selection of geometrical objects (shapes or cell instances).
- LayoutView#create_layout and LayoutView#load_layout:
creates a new layout or loads a layout. In both cases, you can either
replace the current layouts or add the new one to the layouts present.
- LayoutView#current_layer:
returns an iterator pointing to the current layer (the one that has the focus
frame in the layer tree.
- LayoutView#current_layer_list:
returns the index of the current layer list (if multiple tabs are present
in the layer control panel, the current layer list is the tab that is selected).
- LayoutView#each_annotation and LayoutView#each_annotation_selected:
delivers all or the selected annotations.
- LayoutView#each_image and LayoutView#each_image_selected:
delivers all or the selected images.
- LayoutView#each_object_selected and LayoutView#each_object_selected_transient:
delivers ObjectInstPath objects (ObjectInstPath)
that point to one selected object each.
- LayoutView#erase_cellview:
close a cell view, i.e. remove that specific layout from the list of loaded layouts.
- LayoutView#enable_edits: Enables or disables editing. This method will enable or disable all editing
features. This is intended for temporarily disallowing edits. This is not the same than edit and viewer mode.
- LayoutView#get_image, LayoutView#get_image_with_options and LayoutView#get_screenshot:
dumps the screen content into a QImage with or without a specific resolution.
- LayoutView#init_layer_properties: provides an initialization of a "LayerProperties" object for a new layer
according to the current settings of the view.
- LayoutView#is_cell_hidden?, LayoutView#hide_cell, LayoutView#show_cell and LayoutView#show_all_cells:
manages cell visibility.
- LayoutView#load_layer_props and LayoutView#save_layer_props:
loads or saves layer properties files.
- LayoutView#max_hier, LayoutView#max_hier_levels= and LayoutView#min_hier_levels=:
manages hierarchy levels shown.
- LayoutView#object_selection, LayoutView#object_selection=, LayoutView#select_object and LayoutView#clear_object_selection:
return or manipulate the selection of geometrical objects (shapes, instances). The key descriptor object for that purpose
is ObjectInstPath, which refers to a geometrical object throug an instantiation path.
- LayoutView#pan_center (and other pan... methods), LayoutView#zoom_box (and other zoom... methods):
changes the viewport.
- LayoutView#reload_layout:
reloads a given layout.
- LayoutView#create_rdb, LayoutView#remove_rdb, LayoutView#rdb
and LayoutView#num_rdbs: Create, delete and get report databases stored inside the LayoutView object.
- LayoutView#rename_cellview:
changes the name of a cellview.
- LayoutView#title, LayoutView#title= and LayoutView#reset_title:
sets or resets the layout view's title.
- LayoutView#save_as: Saves a layout to a file (with options).
- LayoutView#show_image:
shows or hides an image.
- LayoutView#viewport_width, LayoutView#viewport_height and LayoutView#viewport_trans:
gets the viewport parameters.
Implementing Undo/Redo
Undo/Redo functionality is implemented by using "transactions". Transactions are
groups of operations which implement one user operation. Transactions are built internally
and automatically once a transaction is initiated. Most operations performed in the framework
of the LayoutView and Layout objects are tracked within these transactions. When a transacting
is finished, it needs to be committed. After that, a new operation will be available for
"Undo" or "Redo".
Transactions can be initiated with LayoutView#transaction and committed with LayoutView#commit.
To ensure, every initiation of a transaction is matched by a "commit", it is recommended to employ "ensure":
begin
view.transaction("Some operation")
... do your thing here ...
ensure
view.commit
end
Manipulating the selection
The selection of geometrical objects can be manipulated by providing the necessary ObjectInstPath objects.
Each such object provides a "pointer" to a shape or instance through the hierarchy. Specifically it lists all the
cells and their instantiation transformations down to the shape selected. By accumulating these selections, a shape can be
addressed in a flat view, even if the shape is instantiated many levels down in the hierarchy.
Generating such instantiation path objects is somewhat tedious, but usually the requirement is not
to generate such paths, but to take an existing selecting, manipulate it somehow and then to set the selection
to the new one.
This is fairly easy by taking a copy of the selection, manipulation of the shapes and setting the
manipulated selection as the new one.
The following is a sample which replaces all shapes by their hull polygons. Note that is provides
undo/redo support through a "transaction":
view = mw.current_view
begin
view.transaction("Convert selected shapes to polygons")
sel = view.object_selection
sel.each do |s|
if !s.is_cell_inst? && !s.shape.is_text?
ly = view.cellview(s.cv_index).layout
# convert to polygon
s.shape.polygon = s.shape.polygon
end
end
view.object_selection = sel
ensure
view.commit
end
Events
The LayoutView object supplies several events.
See Events And Callbacks for details about events.
These are the events:
- on_active_cellview_changed:
This event is triggered when the active cellview changes. The active cellview is the one indicated
by the drop-down-box atop of the cell list if multiple layouts are loaded into one view.
- on_annotation_changed:
This event is triggered if an annotation is changed. The ID of the annotation is sent along
with the event.
- on_annotation_selection_changed:
This event is triggered if the selection of annotations is changed.
- on_annotations_changed:
This event is triggered if an annotation is added or deleted.
- on_cell_visibility_changed:
This event is triggered when the visibility of a cell changes. The visibility of a cell is changed by using
"Hide Cell" or "Show Cell" from the cell tree's context menu.
- on_cellviews_changed:
This event is triggered when a new cellview is added or a cellview is removed.
- on_cellview_changed:
This event is triggered when a cellview changed (i.e. the current cell has been changed. The index of
the changed cell view is sent along with the event.
- on_close:
This event is triggered when a cell view is closed.
- on_file_open:
This event is triggered when a file is loaded.
- on_hide:
This event is triggered when a cell view is going to become invisible (i.e the tab changed).
- on_current_layer_list_changed:
This event is triggered when the current layer list was changed (i.e. the tab in the layer list
has been changed).
- on_image_changed:
This event is triggered when an image was edited. The ID of the image is sent along with the event.
- on_image_selection_changed:
This event is triggered when an image was selected or unselected.
- on_images_changed:
This event is triggered when an image was added or deleted.
- on_layer_list_changed:
This event is triggered if a layer was changed, added or deleted.
- on_layer_list_deleted:
This event is triggered if a layer list was deleted (i.e. a tab was removed).
- on_layer_list_inserted:
This event is triggered if a layer list was inserted (i.e. a tab was added).
- on_rdb_list_changed:
This event is triggered when a report database is opened or removed.
- on_selection_changed:
This event is triggered when the selection has changed.
- on_show:
This event is triggered when a cell view is going to become visible (i.e the tab changed).
- on_transient_selection_changed:
This event is triggered when the transient selection has changed.
- on_viewport_changed:
This event is triggered when the viewport has changed, for example the view is zoomed in or panned.
Working with layer properties
The API provides methods by which the layer properties list of the layout view can be traversed and manipulated in many ways.
In particular:
Many of these functions use LayerPropertiesIterator objects
to identify entries in the layer tree. Such an object is basically a pointer into the tree. The term "iterator"
refers means that such a pointer can be moved to neighboring entries in the layer tree.
By default, the LayerPropertiesIterator performs a preorder, depth-first traversal of the layer properties tree (the
virtual root object is omitted).
This is how to work with LayerPropertiesIterator objects:
layout_view = Application::instance.main_window.current_view
# Get the iterator for the first entry:
lp = layout_view.begin_layers
# advance to the next entry (preorder, depth-first traversal):
lp.next
# advance to the next sibling
lp.next_sibling(1)
# advance to the previous sibling
lp.next_sibling(-1)
# move down in the hierarchy to the first child
lp.down_first_child
# move down in the hierarchy to the last child
lp.down_last_child
# move up to the parent node
lp.up
# get the value of the current node
props = lp.current
The LayerPropertiesIterator has a couple of attributes:
Iterators can be compared against each other. If two iterators point to the same object, the equality
operator "==" returns true.
The actual entry that the iterators "current" property is a LayerPropertiesNodeRef object (a reference to a LayerPropertiesNode object).
If behaves the same way than a LayerPropertiesNode object (LayerPropertiesNode), but modifications of the latter
will change the way the layer is displayed in the view.
The LayerPropertiesNode object contributes only a few methods, namely:
The actual properties of the layer are accessible through methods of the LayerProperties object.
Since the parent node may override or contribute properties, a LayerProperties object has a twofold
identity: the way it appears finally ("real") and the way it is configured ("local"). The property
accessors have a "real" parameter and deliver the real value if this parameter is set to true and
the local value otherwise. There are also convenience methods which always deliver the "real" value.
lp = layout_view.begin_layers
# manipulate the layer
lp.current.width = 2
lp.current.fill_color = 0x80ff40
# which is equivalent to this somewhat more efficient way:
props = lp.current.dup
props.width = 2
props.fill_color = 0x80ff40
lp.current.assign(props)
It is possible to directly manipulate the hierarchy this way:
lp = layout_view.begin_layers
# create a copy that we can manipulate
# add two child nodes
cp = RBA::LayerProperties::new
cp.source = "100/0"
lp.current.add_child(cp)
cp = RBA::LayerProperties::new
cp.source = "101/0"
lp.current.add_child(cp)
New entries can be created by using LayoutView's insert_layer method and a LayerPropertiesIterator to
specify the location where the node shall be created. Here is an example how to create a child entry
using that technique. Please note how "down_first_child" is used to navigate into the node's child space
which works even if there are no children yet:
lp = layout_view.begin_layers
# let the iterator point to the first child, even if it does not exist
lp.down_first_child
# (lp.current may not be valid, but still lp is a valid insert position)
# prepare a new entry for insert:
props = RBA::LayerProperties.new
props.source = "100/0"
# insert the child node:
layout_view.insert_layer(lp, props)
# now, lp points to a valid object: lp.current.source == "100/0"
LayerProperties objects
The LayerProperties object represents one entry in the layer properties tree
and has several basic properties. For each of these properties,
a getter for the real and local value exists as well as a setter that installs a local value.
For example, for the width property, the following methods are defined:
- width(real): the getter for the real ("width(true)") or local ("width(false)") value.
- width: the real value.
- width=: the setter for the local value.
Width is a "weak" property. That means that for computing the effective width, child nodes
can override the settings inherited from the parent nodes. A width of 0 is considered "not set" and does not
override parent defined widths. Other properties like visibility are "strong", i.e.
the parent can override the properties set for its children. Another form of combination is "additive" where
the effective property value is the "sum" (or in general combination) of all local properties from parent
to child.
Some properties like "fill_color" do not have a neutral value but instead they can be cleared (in that case with
"clear_fill_color"). The LayerProperties object can be asked whether a fill color is set using the "has_fill_color?" method.
This is a brief list of properties:
In addition, a couple of getters for computed and derived values are present (i.e. "eff_frame_color"). There are
no setters for these properties. The effective frame color for example delivers the frame color which results
from combining the frame color and the frame brightness.
The CellView class
The CellView (CellView) identifies the cell drawn and the context the cell is drawn in. A CellView can be created as a object
but usually it is obtained from a LayoutView object. In the following example, the active cell view is used:
RBA::Application::instance.main_window.current_view.active_cellview
Alternatively, a cell view can be addressed by index:
lv = RBA::Application::instance.main_window.current_view
num_cellviews = lv.cellviews # number of cell views
lv.cellview(0) # first one
A cellview carries the following information:
A cellview can be manipulated to change the cell shown in the layout view. For this purpose, assignment methods
exist which will reconfigure the cellview:
Unspecific and specific path and context cell
In addition to the cell itself, the cell view specifies how the cell is embedded in the hierarchy.
Embedding can happen in two ways: an unspecific and a specific way. Both ways contribute to a path which
leads from a top cell to the cell drawn.
The first part is always the unspecific path. This path specifies, where the cell drawn is located in the cell
tree. That has no effect on the drawing, but is determines what entry in the cell tree is selected.
Giving a path for that information is required, because a cell can be child of different cells which itself can be
children of other cells. The unspecific path lists the top cell and further cells which are all direct or indirect
parents of the cell addressed.
The unspecific path ends at the "context cell" which usually is identical to the cell addressed by the cell view.
KLayout allows addressing of a specific instance of a direct or indirect child cell as the actual cell. In that
case, the specific path comes into play. Bascially that means, that a cell is drawn within a context of embedding
layout. The specific path leads from the context cell to the cell view's target cell and consists of specific instances
(hence the name "specific path"). The "descend" and "ascend" feature
bascially adds or removes instances from that path.
The unspecific path can be obtained with the CellView#path method, the specific path with the CellView#context_path method.
The unspecific path is just an array of cell indexes specifying the top cell and further cells down to the context cell
and includes the context cell. The specific path is an array of InstElement objects (InstElement).
Each InstElement object describes a specific instantiation (a cell instance plus information when a specific array instance
is addressed). When there is no context, the specific path is an empty array.
Using the setters CellView#path= and CellView#context_path= these paths can be changed
to select a new cell into the layout view.
The Image class
Images can be placed onto the drawing canvas and display colored or monochrome images below the layout.
Images are represented by Image objects (Image). Basically an image is a two-dimensional
array of pixel values with a specification how these pixels are to be displayed on the canvas. An image
can be created an placed on the canvas like this:
lv = RBA::Application::instance.main_window.current_view
image = RBA::Image::new("image.png")
lv.insert_image(image)
An image can be configured by using different properties and attributes:
- The images' data can be loaded from a file by using a constructor with a file name. In addition, the image
can use data from an array of floating-point values using either a constructor or the Image#set_data method.
An image can be colored, in which case three channels are present or it can be monochrome. In the latter case,
a single channel is present only. Together with the data, the dimensions of the image have to be specified (width
and height in pixel units).
- The image's data can be manipulated per pixel using the Image#get_pixel or Image#set_pixel method.
- The data range for the data stored in the image can be set using the Image#min_value= and Image#max_value=
attributes. The data range determines which value is considered "maximum intensity" (max_value) and "zero intensity"
(min_value).
- For monochrome images, a data mapping can be specified. A data mapping converts a monochrome value (a scalar)
to a color. Data mapping is specified through a ImageDataMapping object (ImageDataMapping)
using the Image#data_mapping method.
- The geometrical properties of an image are encapsulated in a Matrix3d object (Matrix3d).
Such a matrix describes the transformation from pixel coordinates to the micron unit space of the canvas.
A 3x3 matrix is a generic way to specify a transformation, including translation, rotation, mirror, shear or
perspective distortion. The matrix is obtained and set using the Image#matrix attribute.
Convenience methods like Image#trans, Image#pixel_width and Image#pixel_height allow accessing sub-aspects
of the generic transformation (affine transformation, scaling).
An image can be transformed using one of the Image#transformed methods. It can be hidden or shown using the
Image#visible=
method. The bounding box of the image can be obtained with the Image#box method.
The Annotation class
Annotations (Annotation) are basically rulers and other "overlay objects" but can be used for other purposes as well,
for example to simply add a text object.
Annotations, like images, are objects stored in the LayoutView and can be selected, deleted, transformed etc.
Programmatically, annotations are created this way:
lv = RBA::Application::instance.main_window.current_view
ant = RBA::Annotation::new
ant.p1 = RBA::DPoint.new(0.0, 0.0)
ant.p2 = RBA::DPoint.new(100.0, 0.0)
lv.insert_annotation(ant)
The annotation carries several attributes. Those are the same attributes that can be configured in the
annotation properties dialog.
The most important properties are the two positions (start and end
position) accessible through the Annotation#p1 and Annotation#p2 properties,
the style (Annotation#style property)
and the outline (Annotation#outline property).
If properties are changed using the attribute setters, their appearance will change as well.
The following example demonstrates how rulers are manipulated. In this example, the style of all rulers
is set to "arrow on both sides". Note, how in this example transactions are used to implement
undo/redo:
view = RBA::LayoutView::current
begin
view.transaction("Restyle annotations")
view.each_annotation do |a|
a.style = RBA::Annotation::StyleArrowBoth
end
ensure
view.commit
end
The Marker class
A marker is a temporary highlight object. A marker is represented by the Marker class (Marker).
Markers appear when they are created and disappear when they are destroyed. Since destruction by the garbage
collector happens at undefined times, the destroy method can be used to destroy the marker explicitly.
Markers accept some plain shapes (i.e. a Box) which will be displayed as the marker. Markers can be configures in
manifold ways, i.e. the colors, the fill pattern, line width etc. See the class documentation for details about
the configuration properties.
This is how to create and destroy a marker:
lv = RBA::Application::instance.main_window.current_view
marker = RBA::Marker.new(lv)
marker.set(RBA::DBox::new(0.0, 0.0, 100.0, 200.0))
# to hide the marker:
marker.destroy
Markers are temporary objects intended for highlighting a certain area or shape. Markers are not
persisted in sessions nor can they be edited.
The Plugin and PluginFactory classes
Plugins (Plugin) are objects which provide modular extensions of KLayout. Plugins are
the only way to handle
mouse events in the canvas.
The basic operation of a plugin is the following:
- For each plugin type, a PluginFactory (PluginFactory) object must be provided. KLayout
uses this object to
configure itself and to create a particular plugin instance for each LayoutView. The PluginFactory must provide
certain configuration information and can handle some events in a global manner, for example menu entries that
do not refer to a certain plugin instance. The PluginFactory must register itself in the KLayout framework. After doing
so, KLayout will provide a new button in the tool bar. If this button is selected, the plugin will be activated.
- When a LayoutView is created, it will use the PluginFactory to create a specific Plugin instance for the view.
When the tool bar button is pressed which relates to this plugin, the plugin will be activated and mouse or other
events will be redirected to this plugin.
The PluginFactory itself acts as a singleton per plugin class and provides not only the ability to create
Plugin objects but also a couple of configuration options and a global handler for configuration and menu
events. The configuration includes:
- Menu items: by configuring menu items in the PluginFactory, KLayout can create these items when
the plugin is initialized. Each menu entry is connected with the plugin through a symbol: this is a string
that tells the plugin's Plugin#menu_activated method which menu item was selected. By configuring a menu
rather than creating it explicitly, KLayout has a somewhat better control over what menu items belong to
which plugin. Menu items are configured by calling PluginFactory#add_menu_entry in the PluginFactory's constructor.
- Configuration options: Instead of directly taking values from the configuration database, it is more
convenient to register configuration keys in the PluginFactory's constructor using the PluginFactory#add_option method.
After an option is configured, the individual Plugin objects and the PluginFactory receives "configure" calls
when a configuration option changes or for the initial configuration.
A PluginFactory must be instantiated and register itself. Menu items and configuration options should be
set before the object is registered. Upon registration, a unique name must be specified for the plugin class.
Also, the tool button title and optionally an icon can be specified.
The main objective of the PluginFactory class however is to create the actual plugin object. For this,
the create_plugin method needs to be reimplemented. The implementation is supposed to create an object of
the specific class.
The actual implementation of the plugin is a class derived from Plugin (Plugin).
The plugin comes into life, when it is activated. That is, when the tool button is pressed that is
associated with the plugin. When the plugin is activated, the Plugin#activated method is called. The method
can be reimplemented in order to prepare the plugin for taking actions on mouse events. When the
plugin is not longer active, i.e. because another mode has been selected, the Plugin#deactivated method is called.
Every plugin has the ability to receive and intercept mouse events. Various mouse events are available: mouse moved,
mouse button clicked (button pressed and released), mouse button double clicked, mouse button pressed, mouse button
released, entry or leave of the window and agitation of the mouse wheel. Each event follows a certain protocol depending
whether the plugin is
active or not. In addition, plugins can request exclusive control over the mouse by "grabbing" the mouse.
Each event is associated with a certain callback. The callback has a parameter - "prio" - which determines the
role of the event.
The protocol is described here:
- First, all plugins that grabbed the mouse with grab_mouse will receive an event callback with
'prio' set to true in the reverse order the plugins grabbed the mouse.
If any one of the mouse event handlers returns true, the protocol terminates.
-
If that is not the case or no plugin has grabbed the mouse, the active plugin receives
the mouse event with 'prio' set to true.
-
If no receiver accepted the mouse event by returning true, it is sent again to all plugins with 'prio' set to false.
Again, the loop terminates if one of the receivers returns true. The second pass gives inactive
plugins a chance to monitor the mouse and implement specific actions - i.e. displaying the current position.
In an mouse event handler, the plugin can take any action, i.e. transform objects or create/remove markers.
This allows implementing of interactive functionality upon KLayout's canvas object. Using "set_cursor", the
plugin can set the mouse cursor to a specific shape for example. A plugin should consider implementing "drag_cancel"
in order to terminate any pending dragging operations. Plugin#drag_cancel is called by KLayout to regain control
over the mouse in certain circumstances and is supposed to put the plugin into a "watching" instead of "dragging" state.