Maintains the stack of redo and undo logs.Each entry in the undo stack represents a single property change
Syntax
| JScript | |
|---|
public class ModificationHistory implements IExportAll |
Example
| C# |  Copy Code |
|---|
<html>
<head>
<script type="text/javascript" src="../webControl/vdWebControl.js"></script>
<script type="text/javascript">
var vdcanvas; // keep the vdcanvas control global for quick access inside the functions since it is the only one in the this page
function vdrawInitPageLoad() {//Intiallize theweb control inside this function.It must be called inside onload event of this page
vdmanager.AttachCanvas("canvas"); //create a new web control andattch it to the canvas elemement
vdcanvas = vdmanager.vdrawObject(); //return a refence to the attached web control
vdcanvas.vdAfterOpenDocument = _vdAfterOpenDocument; //defines the function that will be fire when a web control document loaded.
vdcanvas.vdPrompt = _onprompt; //defines the function that will be fire when a vdcanvas.Prompt is called in order to print the message on this page
vdcanvas.vdError = _vdError; //defines the function that will be fire when an error ocured in order to print the message on this page
}
function printInfo(text) {//print messages in the 'info' element of this page
document.getElementById("info").innerHTML = ":" + text;
}
function _vdError(sender, ErrCategoryId, statusId, info) {
printInfo("Error status code = " + statusId.toString() + ". " + (info ? info : ""));
}
function _onprompt(sender, msg) {
printInfo(msg);
}
function _vdAfterOpenDocument() {//fire when a web control document loaded.
vdcanvas.Prompt("Document opened successfully");
createTestobject();
}
function createTestobject() {
var k = 0;
var line;
for (k = 0; k < 2; k++) {
line = vdcanvas.AddLine([-5, k, 0], [5, k, 0]);
vdcanvas.UndoHistory().store(line, "Deleted", true); //add the new line object to history
vdcanvas.UndoHistory().store(line, "PenColor"); //add the Pencolor property to history
line.PenColor = vdConst.createNewColor(k.toString()); //change the PenColor
}
vdcanvas.UndoHistory().group_start(); //start a new undo group
//same code with previous loop but inside a group
for (k = 2; k < 4; k++) {
line = vdcanvas.AddLine([-5, k, 0], [5, k, 0]);
vdcanvas.UndoHistory().store(line, "Deleted", true);
vdcanvas.UndoHistory().store(line, "PenColor");
line.PenColor = vdConst.createNewColor(k.toString());
}
vdcanvas.UndoHistory().group_end(); //end the undo group
vdcanvas.redraw();
}
function undo() {
vdcanvas.UndoHistory().undo(); //make a single undo . Call it multi times until everything undone
setTimeout(vdcanvas.redraw, 0); //send a redraw to timeout
}
function redo() {
vdcanvas.UndoHistory().redo(); //make a single redo.Call it multi times until everything redone.
setTimeout(vdcanvas.redraw, 0); //send a redraw to timeout
}
function test() {
//select a new document for the web control.
//NOTE: Always a document must be selected to the web control.Else the web control is unusable
vdcanvas.SelectDocument("vddocument.vds");
}
</script>
</head>
<body onload="vdrawInitPageLoad()">
<div>
<label>First Select Test to open a new drawing and create some entities, then select Undo and Redo buttons</label>
</div>
<div>
<button onclick="test()">
Test</button>
<button onclick="undo()">
Undo</button>
<button onclick="redo()">
Redo</button>
</div>
<div>
<label id="info">
:</label></div>
<div>
<canvas id="canvas" width="520" height="480">
</canvas>
</div>
</body>
</html> |
See Also
