<!--
Copyright (c) 2006-2013, JGraph Ltd
Extend canvas example for mxGraph. This example demonstrates implementing
an infinite canvas with scrollbars.
-->
<html>
<head>
<title>Extend canvas example for mxGraph</title>
<!-- Sets the basepath for the library if not in same directory -->
<script type="text/javascript">
mxBasePath = '../src';
</script>
<!-- Loads and initializes the library -->
<script type="text/javascript" src="../src/js/mxClient.js"></script>
<!-- Example code -->
<script type="text/javascript">
// Program starts here. Creates a sample graph in the
// DOM node with the specified ID. This function is invoked
// from the onLoad event handler of the document (see below).
function main(container)
{
// Checks if the browser is supported
if (!mxClient.isBrowserSupported())
{
// Displays an error message if the browser is not supported.
mxUtils.error('Browser is not supported!', 200, false);
}
else
{
// Disables the built-in context menu
mxEvent.disableContextMenu(container);
// Creates the graph inside the given container
var graph = new mxGraph(container);
graph.panningHandler.ignoreCell = true;
graph.setPanning(true);
/**
* Specifies the size of the size for "tiles" to be used for a graph with
* scrollbars but no visible background page. A good value is large
* enough to reduce the number of repaints that is caused for auto-
* translation, which depends on this value, and small enough to give
* a small empty buffer around the graph. Default is 400x400.
*/
graph.scrollTileSize = new mxRectangle(0, 0, 400, 400);
/**
* Returns the padding for pages in page view with scrollbars.
*/
graph.getPagePadding = function()
{
return new mxPoint(Math.max(0, Math.round(graph.container.offsetWidth - 34)),
Math.max(0, Math.round(graph.container.offsetHeight - 34)));
};
/**
* Returns the size of the page format scaled with the page size.
*/
graph.getPageSize = function()
{
return (this.pageVisible) ? new mxRectangle(0, 0, this.pageFormat.width * this.pageScale,
this.pageFormat.height * this.pageScale) : this.scrollTileSize;
};
/**
* Returns a rectangle describing the position and count of the
* background pages, where x and y are the position of the top,
* left page and width and height are the vertical and horizontal
* page count.
*/
graph.getPageLayout = function()
{
var size = (this.pageVisible) ? this.getPageSize() : this.scrollTileSize;
var bounds = this.getGraphBounds();
if (bounds.width == 0 || bounds.height == 0)
{
return new mxRectangle(0, 0, 1, 1);
}
else
{
// Computes untransformed graph bounds
var x = Math.ceil(bounds.x / this.view.scale - this.view.translate.x);
var y = Math.ceil(bounds.y / this.view.scale - this.view.translate.y);
var w = Math.floor(bounds.width / this.view.scale);
var h = Math.floor(bounds.height / this.view.scale);
var x0 = Math.floor(x / size.width);
var y0 = Math.floor(y / size.height);
var w0 = Math.ceil((x + w) / size.width) - x0;
var h0 = Math.ceil((y + h) / size.height) - y0;
return new mxRectangle(x0, y0, w0, h0);
}
};
// Fits the number of background pages to the graph
graph.view.getBackgroundPageBounds = function()
{
var layout = this.graph.getPageLayout();
var page = this.graph.getPageSize();
return new mxRectangle(this.scale * (this.translate.x + layout.x * page.width),
this.scale * (this.translate.y + layout.y * page.height),
this.scale * layout.width * page.width,
this.scale * layout.height * page.height);
};
graph.getPreferredPageSize = function(bounds, width, height)
{
var pages = this.getPageLayout();
var size = this.getPageSize();
return new mxRectangle(0, 0, pages.width * size.width, pages.height * size.height);
};
/**
* Guesses autoTranslate to avoid another repaint (see below).
* Works if only the scale of the graph changes or if pages
* are visible and the visible pages do not change.
*/
var graphViewValidate = graph.view.validate;
graph.view.validate = function()
{
if (this.graph.container != null && mxUtils.hasScrollbars(this.graph.container))
{
var pad = this.graph.getPagePadding();
var size = this.graph.getPageSize();
// Updating scrollbars here causes flickering in quirks and is not needed
// if zoom method is always used to set the current scale on the graph.
var tx = this.translate.x;
var ty = this.translate.y;
this.translate.x = pad.x / this.scale - (this.x0 || 0) * size.width;
this.translate.y = pad.y / this.scale - (this.y0 || 0) * size.height;
}
graphViewValidate.apply(this, arguments);
};
var graphSizeDidChange = graph.sizeDidChange;
graph.sizeDidChange = function()
{
if (this.container != null && mxUtils.hasScrollbars(this.container))
{
var pages = this.getPageLayout();
var pad = this.getPagePadding();
var size = this.getPageSize();
// Updates the minimum graph size
var minw = Math.ceil(2 * pad.x / this.view.scale + pages.width * size.width);
var minh = Math.ceil(2 * pad.y / this.view.scale + pages.height * size.height);
var min = graph.minimumGraphSize;
// LATER: Fix flicker of scrollbar size in IE quirks mode
// after delayed call in window.resize event handler
if (min == null || min.width != minw || min.height != minh)
{
graph.minimumGraphSize = new mxRectangle(0, 0, minw, minh);
}
// Updates auto-translate to include padding and graph size
var dx = pad.x / this.view.scale - pages.x * size.width;
var dy = pad.y / this.view.scale - pages.y * size.height;
if (!this.autoTranslate && (this.view.translate.x != dx || this.view.translate.y != dy))
{
this.autoTranslate = true;
this.view.x0 = pages.x;
this.view.y0 = pages.y;
// NOTE: THIS INVOKES THIS METHOD AGAIN. UNFORTUNATELY THERE IS NO WAY AROUND THIS SINCE THE
// BOUNDS ARE KNOWN AFTER THE VALIDATION AND SETTING THE TRANSLATE TRIGGERS A REVALIDATION.
// SHOULD MOVE TRANSLATE/SCALE TO VIEW.
var tx = graph.view.translate.x;
var ty = graph.view.translate.y;
graph.view.setTranslate(dx, dy);
graph.container.scrollLeft += (dx - tx) * graph.view.scale;
graph.container.scrollTop += (dy - ty) * graph.view.scale;
this.autoTranslate = false;
return;
}
graphSizeDidChange.apply(this, arguments);
}
};
// Enables rubberband selection
new mxRubberband(graph);
// Gets the default parent for inserting new cells. This
// is normally the first child of the root (ie. layer 0).
var parent = graph.getDefaultParent();
// Adds cells to the model in a single step
graph.getModel().beginUpdate();
try
{
var v1 = graph.insertVertex(parent, null, 'Hello,', 20, 20, 80, 30);
var v2 = graph.insertVertex(parent, null, 'World!', 200, 150, 80, 30);
var e1 = graph.insertEdge(parent, null, '', v1, v2);
}
finally
{
// Updates the display
graph.getModel().endUpdate();
}
// Sets initial scrollbar positions
window.setTimeout(function()
{
var bounds = graph.getGraphBounds();
var width = Math.max(bounds.width, graph.scrollTileSize.width * graph.view.scale);
var height = Math.max(bounds.height, graph.scrollTileSize.height * graph.view.scale);
graph.container.scrollTop = Math.floor(Math.max(0, bounds.y - Math.max(20, (graph.container.clientHeight - height) / 4)));
graph.container.scrollLeft = Math.floor(Math.max(0, bounds.x - Math.max(0, (graph.container.clientWidth - width) / 2)));
}, 0);
}
};
</script>
</head>
<!-- Page passes the container for the graph to the program -->
<body onload="main(document.getElementById('graphContainer'))">
<!-- Creates a container for the graph with a grid wallpaper -->
<div id="graphContainer"
style="position:relative;overflow:auto;width:321px;height:241px;background:url('editors/images/grid.gif');cursor:default;">
</div>
</body>
</html>