JavaScript/jQuery Diagram - Restrict Operations
The Diagram UI component raises the requestEditOperation event every time a user attempts an edit operation. This article contains code samples that demonstrate how to use this event's parameters to prohibit individual edit operations and customize a shape collection in the toolbox and context toolbox.
Refer to the following section for more information on the requestEditOperation event's parameters: Prohibit Individual Operations.
Prohibit Creating Loops
The example below demonstrates how to prevent users from connecting a shape to itself:
- <dx-diagram #diagram id="diagram" (onRequestEditOperation)="requestEditOperationHandler($event)">
- </dx-diagram>
- import { Component, ViewChild} from '@angular/core';
- import { DxDiagramModule, DxDiagramComponent } from 'devextreme-angular';
- @Component({
- selector: 'app-root',
- templateUrl: './app.component.html',
- styleUrls: ['./app.component.css']
- })
- export class AppComponent {
- @ViewChild(DxDiagramComponent, { static: false }) diagram: DxDiagramComponent;
- requestEditOperationHandler(e) {
- if (e.operation === "changeConnection")
- if (e.args.connector && e.args.connector.fromId === e.args.connector.toId)
- e.allowed = false;
- }
- }
Prohibit Adding Shapes Twice
The example below demonstrates how to prevent users from adding more than one shape of each type to a chart:
- <dx-diagram #diagram id="diagram" (onRequestEditOperation)="requestEditOperation($event)">
- </dx-diagram>
- import { Component, ViewChild} from '@angular/core';
- import { DxDiagramModule, DxDiagramComponent } from 'devextreme-angular';
- @Component({
- selector: 'app-root',
- templateUrl: './app.component.html',
- styleUrls: ['./app.component.css']
- })
- export class AppComponent {
- @ViewChild(DxDiagramComponent, { static: false }) diagram: DxDiagramComponent;
- requestEditOperation(e) {
- if (e.operation === 'addShape') {
- // Gets types of shapes the chart contains
- var itemsTypes = e.component.getItems().filter(function(item) {
- return (item.itemType === "shape") && (item.id !== e.args.shape.id);
- }).map(a => a.type);
- // Cancels the operation if the chart contains a shape with the same type as the shape that is about to be added
- if (itemsTypes.indexOf(e.args.shape.type) !== -1) {
- e.allowed = false;
- return;
- }
- }
- }
- }
See Also
Remove Shapes from Toolboxes
In the example below, the Diagram component updates the shape collection in the toolbox and context toolbox as follows:
- Removes a shape from these toolboxes after a user adds it to a chart
- Returns a shape to these toolboxes after a user deletes it from a chart
- <dx-diagram #diagram id="diagram" (onOptionChanged)="optionChanged($event)" (onRequestEditOperation)="requestEditOperation($event)">
- </dx-diagram>
- import { Component, ViewChild} from '@angular/core';
- import { DxDiagramModule, DxDiagramComponent } from 'devextreme-angular';
- @Component({
- selector: 'app-root',
- templateUrl: './app.component.html',
- styleUrls: ['./app.component.css']
- })
- export class AppComponent {
- @ViewChild(DxDiagramComponent, { static: false }) diagram: DxDiagramComponent;
- shapeCount: any;
- optionChanged(e) {
- // Detects changes of the Diagram model
- if (e.name === "hasChanges" && e.value) {
- e.component.option("hasChanges", false);
- var currentShapeCount = e.component.getItems().filter(function(item) {
- return (item.itemType ==="shape")
- }).length;
- // Updates the toolbox and context toolbox if a shape was added or deleted
- if (this.shapeCount !== currentShapeCount) {
- this.shapeCount = currentShapeCount;
- window.setTimeout(function() {
- e.component.updateToolbox();
- }, 0);
- }
- }
- }
- requestEditOperation(e) {
- if (e.operation === "addShapeFromToolbox") {
- e.component.getItems().forEach(function(item) {
- // Removes a shape from the toolboxes if the chart contains a shape of this type
- if (item.itemType === "shape" && item.type === e.args.shapeType)
- e.allowed = false;
- });
- }
- }
- }
See Also
Prohibit Moving Shapes Between Containers
The example below demonstrates how to prevent users from moving a shape from one container to another:
- <dx-diagram #diagram id="diagram" (onSelectionChanged)="selectionChanged($event)" (onRequestEditOperation)="requestEditOperation($event)">
- </dx-diagram>
- import { Component, ViewChild} from '@angular/core';
- import { DxDiagramModule, DxDiagramComponent } from 'devextreme-angular';
- @Component({
- selector: 'app-root',
- templateUrl: './app.component.html',
- styleUrls: ['./app.component.css']
- })
- export class AppComponent {
- @ViewChild(DxDiagramComponent, { static: false }) diagram: DxDiagramComponent;
- containerIds: any = {};
- requestEditOperation(e) {
- if (e.operation === "moveShape")
- // Cancels the operation if a user moves a shape outside its container.
- if (this.containerIds[e.args.shape.id] !== e.args.shape.containerId)
- e.allowed = false;
- }
- selectionChanged(e) {
- e.component.getItems().forEach(item => {
- this.containerIds[item.id] = item.containerId;
- });
- }
- }
Customize Shape Collection in the Context Toolbox
The following example demonstrates how to hide shapes in the context toolbox depending on the connector's start node type:
- <dx-diagram #diagram id="diagram" (onRequestEditOperation)="requestEditOperation($event)">
- <dxo-context-toolbox [enabled]="true" [shapes]='["process", "decision", "terminator"]' [shapeIconsPerRow]="3">
- </dxo-context-toolbox>
- </dx-diagram>
- import { Component, ViewChild} from '@angular/core';
- import { DxDiagramModule, DxDiagramComponent } from 'devextreme-angular';
- @Component({
- selector: 'app-root',
- templateUrl: './app.component.html',
- styleUrls: ['./app.component.css']
- })
- export class AppComponent {
- @ViewChild(DxDiagramComponent, { static: false }) diagram: DxDiagramComponent;
- currentShapeId : number;
- requestEditOperation(e) {
- if (e.operation === "changeConnection" && e.args.connector)
- // Gets the connector's start node identifier
- this.currentShapeId = e.args.connector.fromId;
- if (e.operation === "addShapeFromToolbox") {
- // Gets the connector's start node type
- var currentShape = e.component.getItemById(this.currentShapeId);
- if (e.args.shapeType === "terminator")
- // If the connector's start node type is "decision"
- if (currentShape && currentShape.type === "decision")
- // Hides the "terminator" shape in the context toolbox
- e.allowed = false;
- }
- }
- }
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