Manages a collection of layout stages that can be executed in a stack-wise manner.
Inheritance Hierarchy
Remarks
The LayoutStageStack class manages a list of layout stages, enabling the composition of complex layout processes by stacking multiple stages together. The stages are executed in the order they are stacked. Each stage can do work before applying its core and after applying it, i.e., the invocation of coreLayout. Thus, the stack forms a complex nesting of stages into each other, so that a stage becomes the core of the previous stage and so on.
It provides various methods to add, remove, and retrieve stages, such as append and prepend, which add stages to the end or beginning of the stack, respectively. The stack can be directly accessed via the stack property for more advanced manipulations, like reordering or clearing all stages.
Additionally, you can add preprocessing and post-processing steps to the stack using addPreprocessor and addPostprocessor, allowing you to inject custom logic before or after all other stages are applied.
The following example shows the effect of adding a stage this way. Note that the custom layout can be an ILayoutAlgorithm or an ILayoutStage.Adding a stage as postprocessor
// Assume the following existing stack with three stages (they all are doing stuff before and after invoking their core) const stages = new LayoutStageStack() stages.append(new SubgraphLayoutStage({ enabled: true })) stages.append(new ComponentLayout({ enabled: true })) stages.append(new OrientationStage({ enabled: true })) stages.addPostprocessor(new MyStage()) /* Resulting order: added MyStage will run after everything else - SubgraphLayoutStage [before core] - ComponentLayout [before core] - OrientationStage [before core] - Core of Main Algorithm - OrientationStage [after core] - ComponentLayout [after core] - SubgraphLayoutStage [after core] - MyStage*/
The following example shows the effect of adding a stage this way. Note that the custom layout can be an ILayoutAlgorithm or an ILayoutStage.Adding a stage as preprocessor
// Assume the following existing stack with three stages (they all are doing stuff before and after invoking their core) const stages = new LayoutStageStack() stages.append(new SubgraphLayoutStage({ enabled: true })) stages.append(new ComponentLayout({ enabled: true })) stages.append(new OrientationStage({ enabled: true })) stages.addPreprocessor(new MyStage()) /* Resulting order: added MyStage will run before everything else - MyStage - SubgraphLayoutStage [before core] - ComponentLayout [before core] - OrientationStage [before core] - Core of Main Algorithm - OrientationStage [after core] - ComponentLayout [after core] - SubgraphLayoutStage [after core]*/
Thrown if the stage instance is already present in the stack.
Examples
The following example shows the effect of appending a stage.Appending a stage.
// Assume the following existing stack with three stages (they all are doing stuff before and after invoking their core) const stages = new LayoutStageStack() stages.append(new SubgraphLayoutStage({ enabled: true })) stages.append(new ComponentLayout({ enabled: true })) stages.append(new OrientationStage({ enabled: true })) stages.append(new MyStage()) /* Resulting order: appended MyStage, it is doing stuff directly before and after the main core - SubgraphLayoutStage [before core] - ComponentLayout [before core] - OrientationStage [before core] - MyStage [before core] - Core of Main Algorithm - MyStage [after core] - OrientationStage [after core] - ComponentLayout [after core] - SubgraphLayoutStage [after core]*/
Thrown if the stage instance is already present in the stack.
Examples
The following example shows the effect of prepending a stage.Prepending a stage.
// Assume the following existing stack with three stages (they all are doing stuff before and after invoking their core) const stages = new LayoutStageStack() stages.append(new SubgraphLayoutStage({ enabled: true })) stages.append(new ComponentLayout({ enabled: true })) stages.append(new OrientationStage({ enabled: true })) stages.prepend(new MyStage()) /* Resulting order: prepended MyStage, it is the first and last to do stuff - MyStage [before core] - SubgraphLayoutStage [before core] - ComponentLayout [before core] - OrientationStage [before core] - Core of Main Algorithm - OrientationStage [after core] - ComponentLayout [after core] - SubgraphLayoutStage [after core] - MyStage [after core]*/
Chains a collection of ILayoutStage instances together and configures them into a stack.
Only enabled stages are included in the chain. The coreLayout is added as the final element in the stack. The method returns the top-most stage, which represents the entry point for the applyLayout call.