Note to non-wiki readers: This documentation is generated from the GEF@github.com wiki - if you have corrections or additions it would be awesome if you could contribute them to the original wiki page .

## Introduction

The Zest component provides support for visualizing Graph-based graph models, applying automatic layout as provided by Layout. It is internally decomposed into the Zest.FX, Zest.FX.JFace, and Zest.FX.UI modules. In addition, there is a deployed Zest Graph Example as well as some undeployed Zest Examples and Zest JFace Examples.

## Zest.FX

- feature: org.eclipse.gef.zest.fx
- bundle: org.eclipse.gef.zest.fx

The Zest.FX module of Zest provides a graph viewer and implements all functionality therefore. It uses JavaFX and FX for visualization purposes and is internally based on MVC, and can thus also be used standalone. Integrating with the Eclipse UI is realized by the Zest.FX.UI module.

Being based on MVC, the Zest.FX module specifies a content model and provides a related controller hierarchy and corresponding JavaFX-based visualizations. Zest.FX is capable of rendering a graph with nodes, (binary) edges, and related labels. A node can contain a (nested) graph. A node visualization is composed of a shape, an icon, a label, and a compartment for nodes and edges of a nested graph (if any). It may also have an external label that can be freely placed. An edge visualization is composed of a curve and source/target decorations. It may have freely placable source label, target label, (center) label, and external (center) label.

The content model is a Graph model of which specific attributes are recognized and utilized by Zest.FX for visualization and layout purposes. A utility class ( ZestProperties) is provided that can be used to access the visualization-related attributes. Similarly, Layout provides a utility class ( org.eclipse.gef.layout.LayoutProperties) that can be used to access the layout-related attributes.

Visualization-related attributes specify the to be visualized contents. The appearance is controlled via JavaFX CSS. For this purpose, CSS classes are assigned to the visuals so that an external stylesheet can be used. Additionally, a CSS class, ID, and style can be specified for a graph content element using dedicated ZestProperties.

Zest.FX provides content part implementations for the individual graph abstractions, i.e. GraphPart, NodePart, and EdgePart. Additionally, NodeLabelPart and EdgeLabelPart are provided as controllers for external node/edge labels. The label parts are anchored to their respective controllers.

In order to implement automatic layout, every content part is accompanied by an AbstractLayoutBehavior implementation that is responsible for transferring visualization-related attributes to layout-related attributes (and vice versa) within the content Graph model: GraphLayoutBehavior, NodeLayoutBehavior, and EdgeLayoutBehavior.

Furthermore, Zest.FX provides a HidingModel that maintains a set of currently hidden nodes. The hidden nodes are neither shown, nor taken into account when performing automatic layout. AbstractHidingBehavior implementations are used to hide/show nodes in response to HidingModel changes. The behaviors also generate HiddenNeighborsFeedbackParts that indicate the number of hidden neighbor nodes. Per default, the user can hide/show nodes using dedicated hover handles, or interaction policies.

In order to navigate nested/nesting graphs, interaction policies are registered that open a nested/parent graph on double-click ( OpenNestedGraphOnDoubleClickPolicy, OpenParentGraphOnDoubleClickPolicy), and a SemanticZoomPolicy is registered that carries out zooming and scrolling interactions, so that the user can zoom into and out of (nested) graphs. The viewport of a previously opened graph is stored in the NavigationModel and restored when that graph is opened again.

Besides, a TranslateSelectedAndRelocateLabelsOnDragPolicy is registered so that nodes and labels can be relocated via mouse drag interaction.

### {Root}

- package: org.eclipse.gef.zest.fx

The {Root} package provides a com.google.inject.Module ( ZestFxModule) with bindings, as well as a utility class ( ZestProperties) to work with the visualization and layout attributes/properties recognized by Zest.

#### ZestFxModule

The `ZestFxModule` defines various (default) bindings, concerning parts, policies, etc. needed to realize the graph visualization.

#### ZestProperties

`ZestProperties` defines attributes that are associated to graphs, nodes, and edges (of Graph), to control the visualization as well as the layout.

The visualization is based on the following attribute, which are associated with graphs (g), nodes (n), or edges (e):

- `SHAPE__N`, javafx.scene.Node (n): Stores the node that is used to display the border and background of the node.
- `LABEL__NE`, java.lang.String (n, e): Stores the label for the element.
- `EXTERNAL_LABEL__NE`, java.lang.String (n, e): Stores the external label for the element, which can be freely placed.
- `ICON__N`, javafx.scene.image.Image (n): The image that is displayed next to the node's label.
- `TOOLTIP__N`, java.lang.String (n): Text, which is shown as a tooltip, i.e. when the mouse hover the node and does not move for a short time.
- `CURVE__E`, javafx.scene.Node (n): Stores the node that is used to render the stroke of the edge.
- `SOURCE_LABEL__E`, java.lang.String (e): Stores the source label for the edge.
- `TARGET_LABEL__E`, java.lang.String (e): Stores the target label for the edge.
- `SOURCE_DECORATION__E`, javafx.scene.Node (n): Stores the node that is used to render the source decoration of the edge.
- `TARGET_DECORATION__E`, javafx.scene.Node (n): Stores the node that is used to render the target decoration of the edge.
- `CSS_CLASS__NE`, java.lang.String (n, e): Stores the CSS class that is assigned to the element.
- `CSS_ID__NE`, java.lang.String (n, e): Stores the CSS id that is assigned to the element.
- `SHAPE_CSS_STYLE__N`, java.lang.String (n): Stores the CSS style that is assigned to the shape of this node.
- `LABEL_CSS_STYLE__NE`, java.lang.String (n, e): Stores the CSS style that is assigned to the javafx.scene.text.Text which displays the label of the element.
- `CURVE_CSS_STYLE__E`, java.lang.String (e): Stores the CSS style that is assigned to the curve of the edge.
- `SOURCE_LABEL_CSS_STYLE__E`, java.lang.String (e): Stores the CSS style that is assigned to the source label of this edge.
- `TARGET_LABEL_CSS_STYLE__E`, java.lang.String (e): Stores the CSS style that is assigned to the target label of this edge.
- `SOURCE_DECORATION_CSS_STYLE__E`, java.lang.String (e): Stores the CSS style that is assigned to the source decoration of this edge.
- `TARGET_DECORATION_CSS_STYLE__E`, java.lang.String (e): Stores the CSS style that is assigned to the target decoration of this edge.
- `ROUTER__E`, org.eclipse.gef.fx.nodes.IConnectionRouter (e): Stores the router that is used to manipulate the waypoints of the edge
- `INTERPOLATOR__E`, org.eclipse.gef.fx.nodes.IConnectionInterpolator (e): Stores the interpolator that is used to manipulate the appearance of the edge.
- `INVISIBLE__NE`, java.lang.Boolean (n,e): Stores whether this element is to be visual or not.

The layout is based on the following attributes, which are associated with graphs (g), nodes (n), or edges (e):

- `LAYOUT_ALGORITHM__G`, org.eclipse.gef.layout.ILayoutAlgorithm (g): Stores the algorithm that will be used to layout the nodes and edges of this graph.
- `LAYOUT_IRRELEVANT__NE`, java.lang.Boolean (n, e): If set to `true`, this element will not get layed out.
- `POSITION__N`, org.eclipse.gef.geometry.planar.Point (n) : Stores the position of the node.
- `SIZE__N`, org.eclipse.gef.geometry.planar.Dimension (n): Stores the size of the node.
- `START_POINT__E`, org.eclipse.gef.geometry.planar.Point (e): Stores the start point of the edge.
- `END_POINT__E`, org.eclipse.gef.geometry.planar.Point (e): Stores the end point of the edge.
- `CONTROL_POINTS__E`, List of org.eclipse.gef.geometry.planar.Points (e): Stores the control/way-points of the edge.
- `LABEL_POSITION__E`, org.eclipse.gef.geometry.planar.Point (e): Stores the position of the label of the edge.
- `SOURCE_LABEL_POSITION__E`, org.eclipse.gef.geometry.planar.Point (e): Stores the position of the source label of the edge.
- `TARGET_LABEL_POSITION__E`, org.eclipse.gef.geometry.planar.Point (e): Stores the position of the target label of the edge.

### Behaviors

- package: org.eclipse.gef.zest.fx.behaviors

The Behaviors package contains specific IBehavior implementations for exchanging layout information ( AbstractLayoutBehavior, NodeLayoutBehavior, EdgeLayoutBehavior) and the hiding/showing of nodes and related edges ( AbstractHidingBehavior, NodeHidingBehavior, EdgeHidingBehavior, EdgeLabelHidingBehavior).

#### AbstractLayoutBehavior, GraphLayoutBehavior, NodeLayoutBehavior, EdgeLayoutBehavior

The `GraphLayoutBehavior` maintains a org.eclipse.gef.layout.LayoutContext, i.e. it is responsible for the creation of such a layout context, updating the layout bounds (based on the corresponding GraphPart), and initiating layout passes (based on content or bounds changes). It also registers pre- and post-layout-passes at the org.eclipse.gef.layout.LayoutContext, including those of related `NodeLayoutBehavior`s and `EdgeLayoutBehavior`s. The `NodeLayoutBehavior` provides location and size of its corresponding NodePart before a layout pass is applied, and, accordingly, copies the location and size from the org.eclipse.gef.layout.LayoutContext to its corresponding NodePart afterwards. Afterwards it initiates a refresh of the visualization and updates the external label position, which is ignored by the Layout algorithms. The `EdgeLayoutBehavior` does not need to provide layout information, but only refreshes the visualization of its corresponding EdgePart after a layout pass, as well updating the positions of external labels. The `AbstractLayoutBehavior` provides common functionality for all layout related behaviors.

#### AbstractHidingBehavior, NodeHidingBehavior, EdgeHidingBehavior, EdgeLabelHidingBehavior

The `NodeHidingBehavior`, `EdgeHidingBehavior`, and `EdgeLabelHidingBehavior` react to changes in the HidingModel by hiding/showing the corresponding visuals. In addition, for nodes, a HiddenNeighborsFeedbackPart is created when any neighboring nodes are currently hidden. The `AbstractHidingBehavior` provides common functionality for all hiding related behaviors.

### Models

- package: org.eclipse.gef.zest.fx.models

The Models package provides viewer models to support hiding of nodes ( HidingModel) as well as semantic zooming ( NavigationModel).

#### HidingModel

The `HidingModel` is a viewer model that stores which nodes are currently hidden. Every visible node shows a small marker indicating how many of its neighbors are hidden. You can hide/show nodes using the hover handles, respectively. The visualization is automatically synchronized with the `HidingModel`.

#### NavigationModel

The `NavigationModel` is a viewer model needed to persist viewport configurations. It is used to keep track of all viewports that are passed during nested graph navigation when zooming in and can be used to restore viewports when zooming out again.

### Operations

- package: org.eclipse.gef.zest.fx.operations

The Operations package currently provides operations for the hiding (visible) and showing (invisible) nodes, as well as for navigating and manipulating of attributes.

#### HideOperation, ShowHiddenNeighboursOperation

The `HideOperation` and `ShowHiddenNeighboursOperation` are used by HidePolicy to hide or show nodes. It adds/removes a respective content part to/from the HidingModel.

#### NavigateOperation

The `NavigateOperation` is used by the SemanticZoomPolicy to realize navigation into and out of nested graphs.

#### ChangeAttributesOperation

The `ChangeAttributesOperation` is a general operation used to change values of attributes of an org.eclipse.gef.common.attributes.IAttributeStore, i.e for a Graph model element.

### Parts

- package: org.eclipse.gef.zest.fx.parts

The Parts package provides a specific org.eclipse.gef.mvc.fx.parts.LayeredRootPart which adds support for CSS styling.

It furthermore provides specific org.eclipse.gef.mvc.fx.parts.AbstractContentPart implementations ( GraphPart, NodePart, NodeLabelPart, EdgePart, and EdgeLabelPart) to control the visualizations of graphs, nodes, and edges.

In addition, it provides specific org.eclipse.gef.mvc.fx.parts.AbstractHandlePart implementations ( HideHoverHandlePart and ShowHiddenNeighborsHoverHandlePart) to realize hiding and showing of nodes via hover handles.

There is also specific org.eclipse.gef.mvc.fx.parts.AbstractFeedbackPart implementation ( HiddenNeighborsFeedbackPart) to indicate feedback for hidden nodes.

#### ZestFxRootPart

The `ZestFxRootPart` is a specific org.eclipse.gef.mvc.fx.parts.LayeredRootPart that adds support for CSS styling. In detail, it loads a file with default CSS styles ( `STYLES_CSS_FILE`) and applies it as stylesheet to the javafx.scene.Scene.

#### GraphPart, NodePart, NodeLabelPart, EdgePart, EdgeLabelPart, ZestFxContentPartFactory

The `GraphPart`, `NodePart`, and `EdgePart` implementations control the visualization of the underlying Graph model elements, i.e. graphs, nodes, and edges. The default visualization for nodes (contributed by `NodePart`) consists of a shape Node for background and border, a javafx.scene.text.Text for the label, and an javafx.scene.image.ImageView for the icon. The default visualization for edges (contributed by `EdgePart` consists of a org.eclipse.gef.fx.nodes.Connection, whose curve node can be exchanged. The external labels of nodes and edges are visualized by javafx.scene.text.Texts, which are controlled by `NodeLabelPart` and `EdgeLabelPart` respectively.

The `NodePart` and `EdgePart` assign the following JavaFX CSS classes to its visuals:

- `"node"` is assigned to the visual of the `NodePart`.
- `"shape"` is assigned to the shape sub-visual of the `NodePart`.
- `"label"` is assigned to the label sub-visual of the `NodePart`.
- `"icon"` is assigned to the icon sub-visual of the `NodePart`.
- `"edge"` is assigned to the visual of the `EdgePart`.
- `"curve"` is assigned to the curve sub-visual of the `EdgePart`.
- `"decoration"` is assigned to the decoration sub-visuals of the `EdgePart`.

#### HideHoverHandlePart, ShowHiddenNeighborsHoverHandlePart, ZestFxHoverHandlePartFactory

The `HideHoverHandlePart` and `ShowHiddenNeighborsHoverHandlePart` are complementary org.eclipse.gef.mvc.fx.parts.AbstractFXSegmentHandlePart implementations that are used as hover handles. Being anchored on a respective NodeParts, they react to mouse clicks to perform hiding or showing of nodes.

#### HiddenNeighborsFeedbackPart

The `HiddenNeighborsFeedbackPart` is a specific org.eclipse.gef.mvc.fx.parts.AbstractFXFeedbackPart that indicates the number of hidden neighbor nodes via a circle decoration (with a number label).

#### ZestFxSelectionHandlePartFactory

The `ZestFxSelectionHandlePartFactory` is a specific handle part factory that does prevent creation of multi selection handles.

### Policies

- package: org.eclipse.gef.zest.fx.policies

The Policies package contains specific IPolicy implementations for hiding/showing of nodes ( HideNodePolicy, HideOnTypePolicy, ShowHiddenNeighborsOnTypePolicy, HideFirstAnchorageOnClickPolicy, and ShowHiddenNeighborsOfFirstAnchorageOnClickPolicy), dragging external labels ( TransformLabelPolicy, TranslateSelectedAndRelocateLabelsOnDragPolicy), and navigating nested graphs via double click ( SemanticZoomPolicy, OpenNestedGraphOnDoubleClickPolicy, OpenParentGraphOnDoubleClickPolicy).

#### HidePolicy, ShowHiddenNeighborsPolicy, HideOnTypePolicy, ShowHiddenNeighborsOnTypePolicy, HideFirstAnchorageOnClickPolicy, ShowHiddenNeighborsOfFirstAnchorageOnClickPolicy

The `HidePolicy` and `ShowHiddenNeighborsPolicy` are transaction policies that are registered as an adapter on NodeParts. They are used by the `HideOnTypePolicy`, `ShowHiddenNeighborsOnTypePolicy`, `HideFirstAnchorageOnClickPolicy`, and `ShowHiddenNeighborsOfFirstAnchorageOnClickPolicy` interaction policies to realize the hiding and showing of nodes.

#### TransformLabelPolicy, TranslateSelectedAndRelocateLabelsOnDragPolicy

The `TranslateSelectedAndRelocateLabelsOnDragPolicy` is a specific IFXOnDragPolicy that enables the positioning of node and edge labels (i.e. NodeLabelPart and EdgeLabelPart) during mouse drag. It uses the underlying `TransformLabelPolicy` to realize the translate operation.

#### SemanticZoomPolicy, OpenNestedGraphOnDoubleClickPolicy, OpenParentGraphOnDoubleClickPolicy

The `OpenNestedGraphOnDoubleClickPolicy` and `OpenParentGraphOnDoubleClickPolicy` policies implement nested graph navigation via double clicking with the mouse. They both rely on the underlying `SemanticZoomPolicy`, which manipulates the NavigationModel via a NavigateOperation. The graph of the node where the current graph is nested is opened when the user double clicks in the background (i.e. in a ZestFxRootPart), and the nested graph is opened when the user double clicks in a NodePart that contains a nested graph.

### Providers

- package: org.eclipse.gef.zest.fx.providers

The Providers package contains a specific anchor provider for NodeParts.

#### NodePartAnchorProvider

The `NodePartAnchorProvider` is a specific org.eclipse.gef.mvc.fx.providers.DefaultAnchorProvider that uses the NodePart's shape outline.

## Zest.FX.JFace

- feature: org.eclipse.gef.zest.fx.jface
- bundle: org.eclipse.gef.zest.fx.jface

The Zest.FX.JFace module of Zest provides a JFace-based API to populate a Zest viewer (i.e. an FXViewer).

### {Root}

- package: org.eclipse.gef.zest.fx.jface

The Root package provides a specific org.eclipse.jface.viewers.ContentViewer ( ZestContentViewer), related content ( IGraphContentProvider, and attribute ( IGraphAttributesProvider) providers.

#### ZestContentViewer

A `ZestContentViewer` is a specific org.eclipse.jface.viewers.ContentViewer that renders an input model as a directed graph, using Zest.FX.

The to be rendered graph is inferred from the input model by means of a org.eclipse.jface.viewers.IContentProvider. In the context of a `ZestContentViewer`, the content provider has to implement IGraphContentProvider. The content provider is node-based, i.e. edges are not represented as first level entities, but are only inferred from input objects via `getAdjacentNodes(Object)`.

The visualization of the graph (i.e. of its nodes and edges) can be controlled via a org.eclipse.jface.viewers.ILabelProvider. The `getText(Object)` and `getImage(Object)` of the label provider will be used to infer labels and icons for nodes. In case the label provider implements org.eclipse.jface.viewers.IColorProvider, its `getForeground(Object)` will be used to infer the color of the node outline and its label, and `getBackground(Object)` will be used as the node's fill color. In case the label provider implements org.eclipse.jface.viewers.IFontProvider, `getFont(Object)` will be used to infer the name, size, and style (bold or italic) of the font, used by the node label. The label provider may furthermore implement org.eclipse.jface.viewers.IToolTipProvider in case a tooltip should be shown on hovering the node.

Further, the label provider may implement IGraphAttributesProvider, which allows to provide values for all specified ZestProperties for graphs, nodes and edges, via which the visualization can be controlled even more fine-grained. It will overwrite the values returned via the standard label and dedicated provider methods. For edges, this can for instance be used to provide label texts (using the label, external-label, source-label, or target-label attribute).

#### IGraphContentProvider

The `IGraphContentProvider` is responsible of returning those input elements ( `getNodes()`) that are to be visualized as nodes, and to provide information about which nodes are connected via edges to other nodes. The `IGraphContentProvider` is node-based, i.e. the to be visualized edges are only represented implicitly, by providing the connection target nodes of a node via `getAdjacentNodes(Object)`, and are not explicitly mapped to underlying input elements. It further provides information about nested graphs via `getNestedGraphNodes(Object)`.

#### IGraphAttributesProvider

The `IGraphAttributesProvider`can be implemented by a label provider to return attributes, i.e. ZestProperties for a root graph, as well as for nodes and edges.

## Zest.FX.UI

- feature: org.eclipse.gef.zest.fx.ui
- bundle: org.eclipse.gef.zest.fx.ui

The Zest.FX.UI module of Zest contains Eclipse Workbench UI related graph visualization support. This includes a com.google.inject.Module] ( ZestFxUiModule), which augments the bindings of ZestFxModule to realize the Eclipse Workbench UI integration and an Eclipse view ( ZestFxUiView) to render graphs based on Zest.FX.

### {Root}

- package: org.eclipse.gef.zest.fx.ui

The {Root} package provides a com.google.inject.Module ( ZestFxUiModule) with bindings related to the Eclipse UI Workbench integration of Zest.FX.

#### ZestFxUiModule

The `ZestFxUiModule` extends org.eclipse.gef.mvc.ui.MvcUiModule and thus delivers specific bindings related to the integration of Zest.FX with the Eclipse Workbench UI.

### Parts

- package: org.eclipse.gef.zest.fx.ui.parts

The Parts package provides an Eclipse org.eclipse.ui.part.ViewPart ( ZestFxUiView) for visualizing graph models.

#### ZestFxUiView

`ZestFxUiView` is a specific FXView that can render graphs. It uses the bindings provided by ZestFxModule and ZestFxUiModule.

## Migration from Zest 1.x to GEF Zest

Zest was mostly written from scratch, replacing the Zest 1.x API as well as the provisional Zest 2.x API ( Zest 2.0 Layout API) that was developed as an intermediate step.

The Zest 1.x API consists of two parts:

1. a Core API for the visualization of graphs, and
2. a JFace API with specific content and label providers and a viewer dedicated to displaying Zest graphs.

The former has been replaced by Zest.FX and the latter by Zest.FX.UI.

### Migration from Zest 1.x Core to GEF Zest.FX

In comparison to the Zest 1.x Core API, which is based on SWT/Draw2d visualization and interweaves graph data, layout data, and visuals, Zest.FX is based on MVC and maintains distinct object hierarchies for the graph data (content model), the layout data (layout model), and the visuals. As a result, in order to perform structural changes to the visualized graph, you cannot directly affect the visualization as in Zest 1.x Core, but instead modify the underlying graph model which will effect a content synchronization, i.e. update the visualization based on the content changes. Therefore, to transition from Zest 1.x Core to Zest.FX, you have to create/modify a org.eclipse.gef.graph.Graph where previously org.eclipse.zest.core.widgets.Graph, org.eclipse.zest.core.widgets.GraphNode, and org.eclipse.zest.core.widgets.GraphConnection were created/modified.

Since Zest.FX is based on MVC, you should be familiar with the mechanisms and concepts of MVC, which are employed as follows:

- A org.eclipse.gef.mvc.models.ContentModel stores the Graph that is currently rendered.
- A org.eclipse.gef.mvc.parts.IContentPartFactory ( ZestFxContentPartFactory) constructs controller objects (content parts) for graphs, nodes, and edges. These are responsible for updating the visualization, synchronizing visualizations with contents, and layout integration.
- All content parts support an adapter mechanism where you can set/query adapters for distinct keys. Functionality can be added to a content part by setting a corresponding adapter on it. For example, you can enable different interactions (moving nodes via drag, etc.) by setting the corresponding policies as adapters on the content parts.
- A com.google.inject.Module ( ZestFxModule) defines bindings for the context of an application. Using this mechanism, you can specify which adapters should be set on the different content parts. For example, the adapter mechanism is used to integrate Layout into Zest.

The Zest Graph Example "wikilink") demonstrates best how to use the new API. The example is very simple as the rendered graph is not modified later on. However, it contains everything that is needed for a fully functional example. As you can see when taking a look into the source code, attributes are set on the graph model to specify certain visualization features such as label, tooltip, CSS id, etc. Actually, the whole visualization results from those attributes ( Visualization Properties).

Some specific Zest 1.x core functionalities are implemented differently within Zest.FX. The corresponding use case scenerios are as follows.

#### Customizing Styles

Many visual features can be specified via JavaFX CSS within Zest, which would have required either a style provider or a custom figure in previous versions. The CSS styles can be applied to individual elements, or entire classes of elements. There are eight parts of the visualization which can be styled individually (defined by ZestProperties):

- "shape-css-style"
- "label-css-style"
- "external-label-css-style"
- "curve-css-style"
- "source-label-css-style"
- "target-label-css-style"
- "source-decoration-css-style"
- "target-decoration-css-style"

#### Customizing Visualizations

Within MVC, on which Zest.FX is based, an org.eclipse.gef.mvc.parts.IContentPart is responsible of contributing a respective visualization. You can exchange the parts provided by Zest.FX to control nodes and edges, and thereby replace their visualizations. To do so, you have to create a custom org.eclipse.gef.mvc.parts.IContentPartFactory (e.g. by subclassing ZestFxContentPartFactory) to create different content parts.

To exchange the original ZestFxContentPartFactory with your custom implementation, you have to overwrite the respective binding defined within ZestFxModule. This can easily be achieved by subclassing ZestFxModule and overriding `bindIContentPartFactory()`. Your custom module has to be handed into the constructor of the ZestContentViewer, so the specified bindings are evaluated.

The JFaceCustomNodeExample demonstrates this scenario. However, be aware that colors, fonts, borders, and sizes can already be configured via JavaFX CSS and do not require a custom visualization, as outlined in Customizing Styles.

#### Modifying graphs

Since you cannot modify the visualization directly, you have to adjust the underlying graph model instead. The FullyMeshedLayoutExample demonstrates this scenario.

#### Layout filter

Nodes and edges can be marked as layout-irrelevant, meaning they will not get reported to layout algorithms. The FilterLayoutExample demonstrates this scenario.

### Migration from Zest 1.x JFace to GEF Zest.FX.JFace

Zest.FX.JFace consists of a ZestContentViewer and related specializations of org.eclipse.jface.viewers.IContentProvider and org.eclipse.jface.viewers.ILabelProvider.

In comparison to the org.eclipse.zest.core.viewers.GraphViewer provided by Zest 1.x, the ZestContentViewer is not a org.eclipse.jface.viewers.StructuredViewer, but a org.eclipse.jface.viewers.ContentViewer, which seems to be the more adequate abstraction (as a structured viewer imposes a tree-, list-, or table-based structure, which does not naturally resemble a graph).

#### Content Providers

Probably, the biggest difference between Zest 1.x and Zest.FX.JFace is related to content providers. Zest.FX defines the following ones:

- The IGraphContentProvider provides all content elements that represent nodes for a flat graph. The edges are inferred via a `getAdjacentNodes(Object)` method. This is the equivalent of the Zest 1.x org.eclipse.zest.core.viewers.IGraphEntityContentProvider. It also covers the functionality of the Zest 1.x org.eclipse.zest.core.viewers.INestedContentProvider through its `getNestedGraphNodes(Object)` method.

Both new content providers are node-oriented, i.e. they provide content elements which represent nodes, not edges. The Zest 1.x API additionally defines an org.eclipse.zest.core.viewers.IGraphEntityRelationshipContentProvider which provides content elements that represent edges. This is not yet covered by Zest.FX.JFace.

#### Label Providers

Similar to Zest 1.x, Zest.FX.JFace is based on the default org.eclipse.jface.viewers.ILabelProvider.

#### Dedicated Providers for Styles, Tooltip, Colors, Fonts

Most of the custom Zest 1.x JFace providers have been replaced with the respective standard JFace providers:

- The org.eclipse.zest.core.viewers.IEntityStyleProvider provides tooltip, fisheye, border, and color information. These are now provided via org.eclipse.jface.viewers.IToolTipProvider, org.eclipse.jface.viewers.IColorProvider, and the attribute provide (which provides arbitrary attributes for nodes, edges, and graphs). Additionally, the org.eclipse.jface.viewers.IFontProvider is now supported, which allows to exchange the label font for a node.
- The old org.eclipse.zest.core.viewers. IConnectionStyleProvider (and org.eclipse.zest.core.viewers.IEntityStyleProvider) provide style, color, tooltip, connection router, and connection decorator. These are now provided via the IGraphAttributeProvider. It can also be used to overwrite the values returned by a provider for the font, foreground, and background color, which are transferred into equivalent CSS styles.

The following providers have not been migrated, because their corresponding functionality is implemented by means of default MVC mechanisms, on which Zest.FX and thus Zest.FX.JFace are based:

- The org.eclipse.zest.core.viewers. ISelfStyleProvider provides a custom styling for a node or an edge. This can now be achieved by applying CSS styles as outlined in Customizing Styles.
- The org.eclipse.zest.core.viewers.IFigureProvider provides support for using a custom visualization for a node. This can now be achieved by means of MVC mechanisms, i.e. via providing a custom content part, as outlined in Customizing Visualizations. Therefore, you can create your own content parts instead of the content parts provided by Zest.FX. The JFaceCustomNodeExample demonstrates this scenario.

You can find examples on how to use the different providers in the JFace-API examples.

#### Zooming

Basic support for zooming, which is specifically implemented within org.eclipse.zest.core.viewers.GraphViewer, is already provided as a base feature of MVC.FX, on which Zest.FX and thus also Zest.FX.JFace are based. Within MVC, a ViewportModel maintains a content transformation which can be modified to zoom in/out of a visualization. Zest.FX adds a semantic zoom that allows to zoom into nested graphs. That is, when zooming into a nesting node, it will - from a certain zoom level onwards - show the nested contents and will eventually replace the viewer contents with the nested graph.