119 lines
5.4 KiB
HTML
119 lines
5.4 KiB
HTML
<!DOCTYPE html>
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<html>
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<head>
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<title>Drag Unoccupied</title>
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<meta name="description" content="Limit the dragging of nodes to avoid any overlap with other nodes.">
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<!-- Copyright 1998-2017 by Northwoods Software Corporation. -->
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<meta charset="UTF-8">
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<script src="../release/go.js"></script>
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<script src="../assets/js/goSamples.js"></script> <!-- this is only for the GoJS Samples framework -->
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<script id="code">
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function init() {
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if (window.goSamples) goSamples(); // init for these samples -- you don't need to call this
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var $ = go.GraphObject.make; // for conciseness in defining templates
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// R is a Rect in document coordinates
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// NODE is the Node being moved -- ignore when looking for Parts intersecting the Rect
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function isUnoccupied(r, node) {
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var diagram = node.diagram;
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// nested function used by Layer.findObjectsIn, below
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// only consider Parts, and ignore the given Node and any Links
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function navig(obj) {
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var part = obj.part;
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if (part === node) return null;
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if (part instanceof go.Link) return null;
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return part;
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}
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// only consider non-temporary Layers
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var lit = diagram.layers;
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while (lit.next()) {
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var lay = lit.value;
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if (lay.isTemporary) continue;
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if (lay.findObjectsIn(r, navig, null, true).count > 0) return false;
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}
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return true;
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}
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// a Part.dragComputation function that prevents a Part from being dragged to overlap another Part
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function avoidNodeOverlap(node, pt, gridpt) {
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if (node.diagram instanceof go.Palette) return gridpt;
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// this assumes each node is fully rectangular
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var bnds = node.actualBounds;
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var loc = node.location;
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// use PT instead of GRIDPT if you want to ignore any grid snapping behavior
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// see if the area at the proposed location is unoccupied
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var r = new go.Rect(gridpt.x - (loc.x - bnds.x), gridpt.y - (loc.y - bnds.y), bnds.width, bnds.height);
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// maybe inflate R if you want some space between the node and any other nodes
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r.inflate(-0.5, -0.5); // by default, deflate to avoid edge overlaps with "exact" fits
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// when dragging a node from another Diagram, choose an unoccupied area
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if (!(node.diagram.currentTool instanceof go.DraggingTool) &&
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(!node._temp || !node.layer.isTemporary)) { // in Temporary Layer during external drag-and-drop
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node._temp = true; // flag to avoid repeated searches during external drag-and-drop
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while (!isUnoccupied(r, node)) {
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r.x += 10; // note that this is an unimaginative search algorithm --
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r.y += 10; // you can improve the search here to be more appropriate for your app
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}
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r.inflate(0.5, 0.5); // restore to actual size
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// return the proposed new location point
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return new go.Point(r.x - (loc.x - bnds.x), r.y - (loc.y - bnds.y));
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}
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if (isUnoccupied(r, node)) return gridpt; // OK
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return loc; // give up -- don't allow the node to be moved to the new location
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}
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myDiagram =
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$(go.Diagram, "myDiagramDiv",
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{
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initialContentAlignment: go.Spot.Center,
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"animationManager.isEnabled": false,
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"undoManager.isEnabled": true
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});
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// Define the template for Nodes, just some text inside a colored rectangle
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myDiagram.nodeTemplate =
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$(go.Node, "Auto",
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{ dragComputation: avoidNodeOverlap },
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{ minSize: new go.Size(50, 20), resizable: true },
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new go.Binding("desiredSize", "size", go.Size.parse).makeTwoWay(go.Size.stringify),
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new go.Binding("position", "pos", go.Point.parse).makeTwoWay(go.Point.stringify),
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// temporarily put selected nodes in Foreground layer
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new go.Binding("layerName", "isSelected", function(s) { return s ? "Foreground" : ""; }).ofObject(),
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$(go.Shape, "Rectangle",
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new go.Binding("fill", "color")),
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$(go.TextBlock,
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new go.Binding("text", "color"))
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);
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myDiagram.model = new go.GraphLinksModel([
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{ pos: "0 0", size: "50 300", color: go.Brush.randomColor() },
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{ pos: "120 20", size: "300 50", color: go.Brush.randomColor() },
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{ pos: "100 200", size: "300 50", color: go.Brush.randomColor() },
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{ pos: "500 50", size: "50 300", color: go.Brush.randomColor() },
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{ key: 1, pos: "100 100", size: "50 50", color: "lightgray" },
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{ key: 2, pos: "200 140", size: "50 50", color: "lightgray" }
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]);
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myDiagram.findNodeForKey(1).isSelected = true;
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}
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</script>
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</head>
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<body onload="init()">
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<div id="sample">
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<div id="myDiagramDiv" style="background-color: white; border: solid 1px black; width: 100%;height: 400px"></div>
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<p>
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Drag a node around.
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Notice how you cannot force the dragged node to overlap any other (stationary) node.
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If you drag more than one node, notice how the relative positions of the dragged nodes are maintained
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except when forced to be shifted in order to avoid overlapping other nodes.
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</p>
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<p>
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This functionality is implemented by a custom <a>Part.dragComputation</a> property function,
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which affects how the <a>DraggingTool</a> can move selected nodes.
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</p>
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</div>
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</body>
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</html>
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