react-dnd-html5-backend/lib/HTML5Backend.js

import EnterLeaveCounter from './EnterLeaveCounter';
import { isFirefox } from './BrowserDetector';
import { getNodeClientOffset, getEventClientOffset, getDragPreviewOffset, } from './OffsetUtils';
import { createNativeDragSource, matchNativeItemType, } from './NativeDragSources';
import * as NativeTypes from './NativeTypes';
import { OptionsReader } from './OptionsReader';
export default class HTML5Backend {
    constructor(manager, globalContext) {
        this.sourcePreviewNodes = new Map();
        this.sourcePreviewNodeOptions = new Map();
        this.sourceNodes = new Map();
        this.sourceNodeOptions = new Map();
        this.dragStartSourceIds = null;
        this.dropTargetIds = [];
        this.dragEnterTargetIds = [];
        this.currentNativeSource = null;
        this.currentNativeHandle = null;
        this.currentDragSourceNode = null;
        this.altKeyPressed = false;
        this.mouseMoveTimeoutTimer = null;
        this.asyncEndDragFrameId = null;
        this.dragOverTargetIds = null;
        this.getSourceClientOffset = (sourceId) => {
            return getNodeClientOffset(this.sourceNodes.get(sourceId));
        };
        this.endDragNativeItem = () => {
            if (!this.isDraggingNativeItem()) {
                return;
            }
            this.actions.endDrag();
            this.registry.removeSource(this.currentNativeHandle);
            this.currentNativeHandle = null;
            this.currentNativeSource = null;
        };
        this.isNodeInDocument = (node) => {
            // Check the node either in the main document or in the current context
            return this.document && this.document.body && document.body.contains(node);
        };
        this.endDragIfSourceWasRemovedFromDOM = () => {
            const node = this.currentDragSourceNode;
            if (this.isNodeInDocument(node)) {
                return;
            }
            if (this.clearCurrentDragSourceNode()) {
                this.actions.endDrag();
            }
        };
        this.handleTopDragStartCapture = () => {
            this.clearCurrentDragSourceNode();
            this.dragStartSourceIds = [];
        };
        this.handleTopDragStart = (e) => {
            if (e.defaultPrevented) {
                return;
            }
            const { dragStartSourceIds } = this;
            this.dragStartSourceIds = null;
            const clientOffset = getEventClientOffset(e);
            // Avoid crashing if we missed a drop event or our previous drag died
            if (this.monitor.isDragging()) {
                this.actions.endDrag();
            }
            // Don't publish the source just yet (see why below)
            this.actions.beginDrag(dragStartSourceIds || [], {
                publishSource: false,
                getSourceClientOffset: this.getSourceClientOffset,
                clientOffset,
            });
            const { dataTransfer } = e;
            const nativeType = matchNativeItemType(dataTransfer);
            if (this.monitor.isDragging()) {
                if (dataTransfer && typeof dataTransfer.setDragImage === 'function') {
                    // Use custom drag image if user specifies it.
                    // If child drag source refuses drag but parent agrees,
                    // use parent's node as drag image. Neither works in IE though.
                    const sourceId = this.monitor.getSourceId();
                    const sourceNode = this.sourceNodes.get(sourceId);
                    const dragPreview = this.sourcePreviewNodes.get(sourceId) || sourceNode;
                    if (dragPreview) {
                        const { anchorX, anchorY, offsetX, offsetY, } = this.getCurrentSourcePreviewNodeOptions();
                        const anchorPoint = { anchorX, anchorY };
                        const offsetPoint = { offsetX, offsetY };
                        const dragPreviewOffset = getDragPreviewOffset(sourceNode, dragPreview, clientOffset, anchorPoint, offsetPoint);
                        dataTransfer.setDragImage(dragPreview, dragPreviewOffset.x, dragPreviewOffset.y);
                    }
                }
                try {
                    // Firefox won't drag without setting data
                    dataTransfer.setData('application/json', {});
                }
                catch (err) {
                    // IE doesn't support MIME types in setData
                }
                // Store drag source node so we can check whether
                // it is removed from DOM and trigger endDrag manually.
                this.setCurrentDragSourceNode(e.target);
                // Now we are ready to publish the drag source.. or are we not?
                const { captureDraggingState } = this.getCurrentSourcePreviewNodeOptions();
                if (!captureDraggingState) {
                    // Usually we want to publish it in the next tick so that browser
                    // is able to screenshot the current (not yet dragging) state.
                    //
                    // It also neatly avoids a situation where render() returns null
                    // in the same tick for the source element, and browser freaks out.
                    setTimeout(() => this.actions.publishDragSource(), 0);
                }
                else {
                    // In some cases the user may want to override this behavior, e.g.
                    // to work around IE not supporting custom drag previews.
                    //
                    // When using a custom drag layer, the only way to prevent
                    // the default drag preview from drawing in IE is to screenshot
                    // the dragging state in which the node itself has zero opacity
                    // and height. In this case, though, returning null from render()
                    // will abruptly end the dragging, which is not obvious.
                    //
                    // This is the reason such behavior is strictly opt-in.
                    this.actions.publishDragSource();
                }
            }
            else if (nativeType) {
                // A native item (such as URL) dragged from inside the document
                this.beginDragNativeItem(nativeType);
            }
            else if (dataTransfer &&
                !dataTransfer.types &&
                ((e.target && !e.target.hasAttribute) ||
                    !e.target.hasAttribute('draggable'))) {
                // Looks like a Safari bug: dataTransfer.types is null, but there was no draggable.
                // Just let it drag. It's a native type (URL or text) and will be picked up in
                // dragenter handler.
                return;
            }
            else {
                // If by this time no drag source reacted, tell browser not to drag.
                e.preventDefault();
            }
        };
        this.handleTopDragEndCapture = () => {
            if (this.clearCurrentDragSourceNode()) {
                // Firefox can dispatch this event in an infinite loop
                // if dragend handler does something like showing an alert.
                // Only proceed if we have not handled it already.
                this.actions.endDrag();
            }
        };
        this.handleTopDragEnterCapture = (e) => {
            this.dragEnterTargetIds = [];
            const isFirstEnter = this.enterLeaveCounter.enter(e.target);
            if (!isFirstEnter || this.monitor.isDragging()) {
                return;
            }
            const { dataTransfer } = e;
            const nativeType = matchNativeItemType(dataTransfer);
            if (nativeType) {
                // A native item (such as file or URL) dragged from outside the document
                this.beginDragNativeItem(nativeType);
            }
        };
        this.handleTopDragEnter = (e) => {
            const { dragEnterTargetIds } = this;
            this.dragEnterTargetIds = [];
            if (!this.monitor.isDragging()) {
                // This is probably a native item type we don't understand.
                return;
            }
            this.altKeyPressed = e.altKey;
            if (!isFirefox()) {
                // Don't emit hover in `dragenter` on Firefox due to an edge case.
                // If the target changes position as the result of `dragenter`, Firefox
                // will still happily dispatch `dragover` despite target being no longer
                // there. The easy solution is to only fire `hover` in `dragover` on FF.
                this.actions.hover(dragEnterTargetIds, {
                    clientOffset: getEventClientOffset(e),
                });
            }
            const canDrop = dragEnterTargetIds.some(targetId => this.monitor.canDropOnTarget(targetId));
            if (canDrop) {
                // IE requires this to fire dragover events
                e.preventDefault();
                if (e.dataTransfer) {
                    e.dataTransfer.dropEffect = this.getCurrentDropEffect();
                }
            }
        };
        this.handleTopDragOverCapture = () => {
            this.dragOverTargetIds = [];
        };
        this.handleTopDragOver = (e) => {
            const { dragOverTargetIds } = this;
            this.dragOverTargetIds = [];
            if (!this.monitor.isDragging()) {
                // This is probably a native item type we don't understand.
                // Prevent default "drop and blow away the whole document" action.
                e.preventDefault();
                if (e.dataTransfer) {
                    e.dataTransfer.dropEffect = 'none';
                }
                return;
            }
            this.altKeyPressed = e.altKey;
            this.actions.hover(dragOverTargetIds || [], {
                clientOffset: getEventClientOffset(e),
            });
            const canDrop = (dragOverTargetIds || []).some(targetId => this.monitor.canDropOnTarget(targetId));
            if (canDrop) {
                // Show user-specified drop effect.
                e.preventDefault();
                if (e.dataTransfer) {
                    e.dataTransfer.dropEffect = this.getCurrentDropEffect();
                }
            }
            else if (this.isDraggingNativeItem()) {
                // Don't show a nice cursor but still prevent default
                // "drop and blow away the whole document" action.
                e.preventDefault();
            }
            else {
                e.preventDefault();
                if (e.dataTransfer) {
                    e.dataTransfer.dropEffect = 'none';
                }
            }
        };
        this.handleTopDragLeaveCapture = (e) => {
            if (this.isDraggingNativeItem()) {
                e.preventDefault();
            }
            const isLastLeave = this.enterLeaveCounter.leave(e.target);
            if (!isLastLeave) {
                return;
            }
            if (this.isDraggingNativeItem()) {
                this.endDragNativeItem();
            }
        };
        this.handleTopDropCapture = (e) => {
            this.dropTargetIds = [];
            e.preventDefault();
            if (this.isDraggingNativeItem()) {
                this.currentNativeSource.mutateItemByReadingDataTransfer(e.dataTransfer);
            }
            this.enterLeaveCounter.reset();
        };
        this.handleTopDrop = (e) => {
            const { dropTargetIds } = this;
            this.dropTargetIds = [];
            this.actions.hover(dropTargetIds, {
                clientOffset: getEventClientOffset(e),
            });
            this.actions.drop({ dropEffect: this.getCurrentDropEffect() });
            if (this.isDraggingNativeItem()) {
                this.endDragNativeItem();
            }
            else {
                this.endDragIfSourceWasRemovedFromDOM();
            }
        };
        this.handleSelectStart = (e) => {
            const target = e.target;
            // Only IE requires us to explicitly say
            // we want drag drop operation to start
            if (typeof target.dragDrop !== 'function') {
                return;
            }
            // Inputs and textareas should be selectable
            if (target.tagName === 'INPUT' ||
                target.tagName === 'SELECT' ||
                target.tagName === 'TEXTAREA' ||
                target.isContentEditable) {
                return;
            }
            // For other targets, ask IE
            // to enable drag and drop
            e.preventDefault();
            target.dragDrop();
        };
        this.options = new OptionsReader(globalContext);
        this.actions = manager.getActions();
        this.monitor = manager.getMonitor();
        this.registry = manager.getRegistry();
        this.enterLeaveCounter = new EnterLeaveCounter(this.isNodeInDocument);
    }
    // public for test
    get window() {
        return this.options.window;
    }
    get document() {
        return this.options.document;
    }
    setup() {
        if (this.window === undefined) {
            return;
        }
        if (this.window.__isReactDndBackendSetUp) {
            throw new Error('Cannot have two HTML5 backends at the same time.');
        }
        this.window.__isReactDndBackendSetUp = true;
        this.addEventListeners(this.window);
    }
    teardown() {
        if (this.window === undefined) {
            return;
        }
        this.window.__isReactDndBackendSetUp = false;
        this.removeEventListeners(this.window);
        this.clearCurrentDragSourceNode();
        if (this.asyncEndDragFrameId) {
            this.window.cancelAnimationFrame(this.asyncEndDragFrameId);
        }
    }
    connectDragPreview(sourceId, node, options) {
        this.sourcePreviewNodeOptions.set(sourceId, options);
        this.sourcePreviewNodes.set(sourceId, node);
        return () => {
            this.sourcePreviewNodes.delete(sourceId);
            this.sourcePreviewNodeOptions.delete(sourceId);
        };
    }
    connectDragSource(sourceId, node, options) {
        this.sourceNodes.set(sourceId, node);
        this.sourceNodeOptions.set(sourceId, options);
        const handleDragStart = (e) => this.handleDragStart(e, sourceId);
        const handleSelectStart = (e) => this.handleSelectStart(e);
        node.setAttribute('draggable', 'true');
        node.addEventListener('dragstart', handleDragStart);
        node.addEventListener('selectstart', handleSelectStart);
        return () => {
            this.sourceNodes.delete(sourceId);
            this.sourceNodeOptions.delete(sourceId);
            node.removeEventListener('dragstart', handleDragStart);
            node.removeEventListener('selectstart', handleSelectStart);
            node.setAttribute('draggable', 'false');
        };
    }
    connectDropTarget(targetId, node) {
        const handleDragEnter = (e) => this.handleDragEnter(e, targetId);
        const handleDragOver = (e) => this.handleDragOver(e, targetId);
        const handleDrop = (e) => this.handleDrop(e, targetId);
        node.addEventListener('dragenter', handleDragEnter);
        node.addEventListener('dragover', handleDragOver);
        node.addEventListener('drop', handleDrop);
        return () => {
            node.removeEventListener('dragenter', handleDragEnter);
            node.removeEventListener('dragover', handleDragOver);
            node.removeEventListener('drop', handleDrop);
        };
    }
    addEventListeners(target) {
        // SSR Fix (https://github.com/react-dnd/react-dnd/pull/813
        if (!target.addEventListener) {
            return;
        }
        target.addEventListener('dragstart', this
            .handleTopDragStart);
        target.addEventListener('dragstart', this.handleTopDragStartCapture, true);
        target.addEventListener('dragend', this.handleTopDragEndCapture, true);
        target.addEventListener('dragenter', this
            .handleTopDragEnter);
        target.addEventListener('dragenter', this.handleTopDragEnterCapture, true);
        target.addEventListener('dragleave', this.handleTopDragLeaveCapture, true);
        target.addEventListener('dragover', this.handleTopDragOver);
        target.addEventListener('dragover', this.handleTopDragOverCapture, true);
        target.addEventListener('drop', this.handleTopDrop);
        target.addEventListener('drop', this.handleTopDropCapture, true);
    }
    removeEventListeners(target) {
        // SSR Fix (https://github.com/react-dnd/react-dnd/pull/813
        if (!target.removeEventListener) {
            return;
        }
        target.removeEventListener('dragstart', this.handleTopDragStart);
        target.removeEventListener('dragstart', this.handleTopDragStartCapture, true);
        target.removeEventListener('dragend', this.handleTopDragEndCapture, true);
        target.removeEventListener('dragenter', this
            .handleTopDragEnter);
        target.removeEventListener('dragenter', this.handleTopDragEnterCapture, true);
        target.removeEventListener('dragleave', this.handleTopDragLeaveCapture, true);
        target.removeEventListener('dragover', this
            .handleTopDragOver);
        target.removeEventListener('dragover', this.handleTopDragOverCapture, true);
        target.removeEventListener('drop', this.handleTopDrop);
        target.removeEventListener('drop', this.handleTopDropCapture, true);
    }
    getCurrentSourceNodeOptions() {
        const sourceId = this.monitor.getSourceId();
        const sourceNodeOptions = this.sourceNodeOptions.get(sourceId);
        return {
            dropEffect: this.altKeyPressed ? 'copy' : 'move',
            ...(sourceNodeOptions || {}),
        };
    }
    getCurrentDropEffect() {
        if (this.isDraggingNativeItem()) {
            // It makes more sense to default to 'copy' for native resources
            return 'copy';
        }
        return this.getCurrentSourceNodeOptions().dropEffect;
    }
    getCurrentSourcePreviewNodeOptions() {
        const sourceId = this.monitor.getSourceId();
        const sourcePreviewNodeOptions = this.sourcePreviewNodeOptions.get(sourceId);
        return {
            anchorX: 0.5,
            anchorY: 0.5,
            captureDraggingState: false,
            ...(sourcePreviewNodeOptions || {}),
        };
    }
    isDraggingNativeItem() {
        const itemType = this.monitor.getItemType();
        return Object.keys(NativeTypes).some((key) => NativeTypes[key] === itemType);
    }
    beginDragNativeItem(type) {
        this.clearCurrentDragSourceNode();
        this.currentNativeSource = createNativeDragSource(type);
        this.currentNativeHandle = this.registry.addSource(type, this.currentNativeSource);
        this.actions.beginDrag([this.currentNativeHandle]);
    }
    setCurrentDragSourceNode(node) {
        this.clearCurrentDragSourceNode();
        this.currentDragSourceNode = node;
        // A timeout of > 0 is necessary to resolve Firefox issue referenced
        // See:
        //   * https://github.com/react-dnd/react-dnd/pull/928
        //   * https://github.com/react-dnd/react-dnd/issues/869
        const MOUSE_MOVE_TIMEOUT = 1000;
        // Receiving a mouse event in the middle of a dragging operation
        // means it has ended and the drag source node disappeared from DOM,
        // so the browser didn't dispatch the dragend event.
        //
        // We need to wait before we start listening for mousemove events.
        // This is needed because the drag preview needs to be drawn or else it fires an 'mousemove' event
        // immediately in some browsers.
        //
        // See:
        //   * https://github.com/react-dnd/react-dnd/pull/928
        //   * https://github.com/react-dnd/react-dnd/issues/869
        //
        this.mouseMoveTimeoutTimer = setTimeout(() => {
            return (this.window &&
                this.window.addEventListener('mousemove', this.endDragIfSourceWasRemovedFromDOM, true));
        }, MOUSE_MOVE_TIMEOUT);
    }
    clearCurrentDragSourceNode() {
        if (this.currentDragSourceNode) {
            this.currentDragSourceNode = null;
            if (this.window) {
                this.window.clearTimeout(this.mouseMoveTimeoutTimer || undefined);
                this.window.removeEventListener('mousemove', this.endDragIfSourceWasRemovedFromDOM, true);
            }
            this.mouseMoveTimeoutTimer = null;
            return true;
        }
        return false;
    }
    handleDragStart(e, sourceId) {
        if (e.defaultPrevented) {
            return;
        }
        if (!this.dragStartSourceIds) {
            this.dragStartSourceIds = [];
        }
        this.dragStartSourceIds.unshift(sourceId);
    }
    handleDragEnter(e, targetId) {
        this.dragEnterTargetIds.unshift(targetId);
    }
    handleDragOver(e, targetId) {
        if (this.dragOverTargetIds === null) {
            this.dragOverTargetIds = [];
        }
        this.dragOverTargetIds.unshift(targetId);
    }
    handleDrop(e, targetId) {
        this.dropTargetIds.unshift(targetId);
    }
}