com.vaadin.flow.component.dnd.internal.DndUtil Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of flow-dnd Show documentation
The newest version!
/*
 * Copyright 2000-2024 Vaadin Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.vaadin.flow.component.dnd.internal;

import com.vaadin.flow.component.Component;
import com.vaadin.flow.component.ComponentUtil;
import com.vaadin.flow.component.dependency.NpmPackage;
import com.vaadin.flow.component.dnd.DragSource;
import com.vaadin.flow.component.dnd.DropTarget;
import com.vaadin.flow.internal.UsageStatistics;
import com.vaadin.flow.server.Command;
import com.vaadin.flow.shared.Registration;

/**
 * Internal class for drag and drop related utility methods. This class is not
 * meant for external usage and can be removed at any point.
 *
 * @author Vaadin Ltd
 * @since 2.0
 */
public class DndUtil {

    /**
     * Resource path for importing dnd connector.
     */
    public static final String DND_CONNECTOR = "./dndConnector.js";

    /**
     * Property name for storing the
     * {@link com.vaadin.flow.component.dnd.EffectAllowed} on element level.
     */
    public static final String EFFECT_ALLOWED_ELEMENT_PROPERTY = "__effectAllowed";

    /**
     * Key for storing server side drag data for a
     * {@link com.vaadin.flow.component.dnd.DragSource}.
     */
    public static final String DRAG_SOURCE_DATA_KEY = "drag-source-data";

    /**
     * Key for storing server side drag image for a
     * {@link com.vaadin.flow.component.dnd.DragSource}.
     */
    public static final String DRAG_SOURCE_IMAGE = "drag-source-image";

    /**
     * Key for storing an internal drag start listener registration for a
     * {@link com.vaadin.flow.component.dnd.DragSource}.
     */
    public static final String START_LISTENER_REGISTRATION_KEY = "_startListenerRegistration";

    /**
     * Key for storing an internal drag end listener registration for a
     * {@link com.vaadin.flow.component.dnd.DragSource}.
     */
    public static final String END_LISTENER_REGISTRATION_KEY = "_endListenerRegistration";

    /**
     * Property name for storing drop target activity data for an element.
     */
    public static final String DROP_TARGET_ACTIVE_PROPERTY = "__active";

    /**
     * Property name for storing the
     * {@link com.vaadin.flow.component.dnd.DropEffect} on element level.
     */
    public static final String DROP_EFFECT_ELEMENT_PROPERTY = "__dropEffect";

    /**
     * Key for storing detach listener for a drop target to component data.
     */
    private static final String DETACH_LISTENER_FOR_DROP_TARGET = "_detachListenerForDropTarget";

    private DndUtil() {
        // no instances from this class
    }

    /**
     * Triggers drag source activation method in JS connector once when the
     * component has been attached.
     *
     * @param dragSource
     *            the drag source to update active status on
     * @param 
     *            the type of the drag source component
     */
    public static  void updateDragSourceActivation(
            DragSource dragSource) {
        Command command = () -> dragSource.getDraggableElement().executeJs(
                "window.Vaadin.Flow.dndConnector.updateDragSource($0)",
                dragSource.getDraggableElement());
        runOnAttachBeforeResponse(dragSource.getDragSourceComponent(), command);
    }

    /**
     * Triggers drop target activation method in JS connector once when the
     * component has been attached. Will make sure the activation in JS is done
     * again when the component is detached and attached again, because
     * otherwise the element will not be a drop target again.
     *
     * @param dropTarget
     *            the drop target to update active status on
     * @param 
     *            the type of the drop target component
     */
    public static  void updateDropTargetActivation(
            DropTarget dropTarget) {
        Command command = () -> dropTarget.getElement().executeJs(
                "window.Vaadin.Flow.dndConnector.updateDropTarget($0)",
                dropTarget.getElement());

        runOnAttachBeforeResponse(dropTarget.getDropTargetComponent(), command);

        // add a detach listener which will make sure the activation is done
        // again on the client side if the component is removed and added again
        if (ComponentUtil.getData(dropTarget.getDropTargetComponent(),
                DETACH_LISTENER_FOR_DROP_TARGET) == null) {
            Registration detachRegistration = dropTarget.getElement()
                    .addDetachListener(event -> runOnAttachBeforeResponse(
                            dropTarget.getDropTargetComponent(), command));
            ComponentUtil.setData(dropTarget.getDropTargetComponent(),
                    DETACH_LISTENER_FOR_DROP_TARGET, detachRegistration);
        }
    }

    private static void runOnAttachBeforeResponse(Component component,
            Command command) {
        component.getElement().getNode().runWhenAttached(ui -> ui
                .beforeClientResponse(component, context -> command.execute()));
    }

    /**
     * Reports DnD feature usage from mixin interfaces.
     */
    public static void reportUsage() {
        UsageStatistics.markAsUsed("flow/generic-dnd", null);
    }
}