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Controlling Map Refresh Operations, Using the autoRefresh Flag

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Page 45 highlights

Controlling Map Refresh Operations You can ensure that Autodesk MapGuide Viewer will not enter a busy state by controlling when display refreshes occur. The first step is to remember that display refreshes always occur in the following instances: I When the autoRefresh flag is set to True with MGMap.setAutoRefresh, and the application calls an API method that requires an automatic refresh such as MGMap.zoomSelected. Methods requiring an automatic refresh are noted in the Autodesk MapGuide Viewer API Help. I Your application calls zoomGotoDlg, zoomGotoLocation, setUrl, or refresh. These methods always invoke a display refresh, even if the autoRefresh flag is set to false. The only exception is if you call one of these methods from onViewChanging or onMapLoaded event handling code. Under these circumstances, the methods will fail and will set error code to -14 (refresh disabled) because the onViewChanging and onMapLoaded events always disable the autoRefresh flag. Using the autoRefresh Flag To develop an application that executes smoothly, you need to prevent busy states while the application calls methods in the API that do not work during the busy state. To do this, you need to disable the autoRefresh flag. To disable the autoRefresh Flag 1 Set the autoRefresh flag to False immediately before calling the first method. 2 Reset the autoRefresh flag to True. 3 Call the refresh method immediately after your application calls the other methods that do not work during the busy state. Simply setting the autoRefresh flag back to True with MGMap.setAutoRefresh does not refresh the map. For example: function selectAndZoomToPointObject(mgObj) { var map = getMap(); var sel = map.getSelection(); map.setAutoRefresh(false); // Prevent busy state from happening // when zoomSelected is called sel.clear(); sel.addObject(mgObj); map.zoomSelected(); map.setWidth(5, "KM"); map.setAutoRefresh(true); // Reset the autoRefresh flag map.refresh(); // Update the display } Handling Busy State and Map Refresh | 45

Section	Page
Developer’s Guide	1
Contents	3
Introduction	7
What’s New in Release 6	8
Autodesk DWG Data Source Support	8
Enhanced Support for Map Redraw Operations	8
Symbol Bitmap Support	8
Map Mode Retrieval Support	9
Java Edition Platform Support Changes	9
Before You Begin	9
Familiarity with Autodesk MapGuide	9
Programming and Scripting Languages	10
Your Audience	10
User Help	11
About the Autodesk MapGuide Viewer API	11
Autodesk MapGuide Viewer API Help	13
Autodesk MapGuide Web Site	13
What Is an Autodesk MapGuide Viewer API Application	13
Viewing Maps	14
Querying and Updating Data	14
Creating an Autodesk MapGuide Viewer API Application	15
Displaying Maps	17
Overview	18
Map Display for ActiveX Control and Plug-In	20
Linking to a Map	20
Displaying a Linked Map in a Different Window or Frame	21
Displaying a Specific Area of the Map	21
Embedding a Map	22
Embedding a Map in a Frame-Based Page	23
Map Display for the Java Edition	24
Map Display for Autodesk MapGuide LiteView	26
Installing Viewers on Client Machines	27
Accessing Maps	31
Overview	32
Map Access for ActiveX Control and Plug-In	32
Required Software for Autodesk MapGuide Viewer Plug-In	34
Map Access for the Java Edition	35
Map Access from HTML	35
Using JavaScript or JScript	35
Map Access Using Java	38
Wrapper Java Applet	38
Peer Java Applet	38
Wrapper Java Application	38
Required Software for the Java Edition	39
Java Edition Differences	39
Functional Differences with Java Edition	39
Browser Differences with Java Edition	40
Communicating with the Plug-In from a Java Applet	40
Accessing the Plug-In from a Java Applet	41
Calling JavaScript Functions from a Java Applet	42
Accessing Secure Data	43
Handling Busy State and Map Refresh	43
About the Busy State	43
Controlling Map Refresh Operations	45
Using the autoRefresh Flag	45
AutoRefresh Flag Caveats	46
Detecting Map Refreshes	46
Detecting a Change in the Busy State	46
Controlling Intermediate Update Map Redraw Operations	47
Handling Errors	47
Getting Error Codes	47
Checking for Incorrect Argument Types	48
Debugging an Application	48
Working with Map Layers, Map Features, and Printing	49
Overview	50
Working with Map Layers	50
Counting Map Layers	50
Listing Map Layers	51
Adding a Map Layer	53
Linking Map Layers	53
Toggling Map Layer Visibility On and Off	55
Working with Map Features	56
Getting Keys of Selected Map Features	56
Getting Coordinates of a Selected Map Feature	58
Invoking Select Radius Mode	61
Zooming In on Selected Features	61
Counting Map Features	62
Working with Printing	64
Setting the Print Priority	65
Enabling the Print Events	66
Positioning Page Elements with Page Coordinate System Units	67
Adding Custom Page Elements	68
Handling Events	69
Overview	70
Working with Event Handlers	70
Browser Differences	71
Event Observer Set Methods	71
Setting Up Event Handlers	72
Plug-In and Java Edition Event Handlers	72
ActiveX Control Event Handlers	75
Plug-In and ActiveX Control Event Handlers	75
VBScript Example	75
JavaScript Example	77
VBScript and JavaScript Example	78
Writing Event Handlers	78
Page Setup Event Handler Example	79
Print Event Handler Example	81
Plug-In Event Handler Example	83
Using Reports to Query and Update Data Sources	85
Overview	86
How Reports Are Generated	86
Specifying the Report Script	86
The Request	87
Launching the Report	87
Introducing ColdFusion and ASP	88
Creating Report Scripts with ColdFusion	89
Listing File Contents with ColdFusion	89
Setting Up the Query	90
Controlling the Output	90
Seeing the Results	90
Querying and Displaying Data via the Map with ColdFusion	92
Setting Up the Report in Autodesk MapGuide Author	92
Creating the Report Script	94
Creating an HTML Page to Display the Map	95
Seeing the Results	95
Redirecting Report Output	96
Adding a Button with the Viewer API	100
Modifying a Database via the Map with ColdFusion	102
Setting Up the Report in Autodesk MapGuide Author	103
Creating the Report Scripts	104
Creating an HTML Page to Display the Map	107
Creating a Custom Menu Item	107
Accessing Your Application with the Viewer API	108
Creating Report Scripts with ASP	109
Summary of ASP Objects, Components, and Events	110
Listing File Contents with ASP	111
Specifying a Scripting Language	112
Selecting Database Records	112
Controlling the Output	113
Seeing the Results	114
Querying and Displaying Data via the Map with ASP	115
Setting Up the Report in Autodesk MapGuide Author	116
Creating the Report Script	117
Creating an HTML Page to Display the Map	118
Seeing the Results	119
Redirecting Report Output	120
Adding a Button with the Viewer API	122
Modifying a Database via the Map with ASP	125
Setting Up the Report in Autodesk MapGuide Author	126
Creating the Report Scripts	127
Creating an HTML Page to Display the Map	131
Creating a Custom Menu Item	132
Accessing Your Application with the Viewer API	133
Applications	135
Overview	136
Custom Redlining Application	136
Redlining Example Code	137
Municipal Application	140
Municipal Application Example Code	141
Facility Management Application	156
Facilities Management Application Example Code	157
DWG Filtering Application	164
Understanding Layers in Autodesk MapGuide	165
Changing Map Layer Data Source Properties	165
DWG Filtering Application Example Code	166
Selection Changed Function (selChanged)	166
Show Properties Function (showProperties)	168
SDF Component Toolkit Applications	171
Updating SDF Files—an ASP Example	171
Converting to an SDF File—a Visual Basic Example	181
Getting SDF File Information—a Visual Basic Example	188
Copying an SDF File—a Visual Basic Example	196
Index	203
A	203
B	203
C	203
D	204
E	204
F	205
G	205
H	205
I	205
J	205
K	205
L	205
M	206
N	206
O	206
P	206
Q	207
R	207
S	207
U	207
V	207
W	208
X	208

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Handling Busy State and Map Refresh

Controlling Map Refresh Operations

You can ensure that Autodesk MapGuide Viewer will not enter a busy state

by controlling when display refreshes occur. The first step is to remember

that display refreshes

always

occur in the following instances:

■

When the

autoRefresh

flag is set to

True

with

MGMap.setAutoRefresh

and

the application calls an API method that requires an automatic refresh

such as

MGMap.zoomSelected

. Methods requiring an automatic refresh

are noted in the

Autodesk MapGuide Viewer API Help

■

Your application calls

zoomGotoDlg

zoomGotoLocation

setUrl

, or

refresh

. These methods

always

invoke a display refresh, even if the

autoRefresh

flag is set to false. The only exception is if you call one of

these methods from

onViewChanging

onMapLoaded

event handling

code. Under these circumstances, the methods will fail and will set error

code to

-14 (refresh disabled)

because the

onViewChanging

and

onMapLoaded

events always disable the

autoRefresh

flag.

Using the autoRefresh Flag

To develop an application that executes smoothly, you need to prevent busy

states while the application calls methods in the API that do not work during

the busy state. To do this, you need to disable the

autoRefresh

flag.

To disable the autoRefresh Flag

Set the

autoRefresh

flag to

False

immediately before calling the first

method.

Reset the

autoRefresh

flag to

True

Call the

refresh

method immediately after your application calls the

other methods that do not work during the busy state. Simply setting the

autoRefresh

flag back to

True

with

MGMap.setAutoRefresh

does not

refresh the map. For example:

function selectAndZoomToPointObject(mgObj)

{

var map = getMap();

var sel = map.getSelection();

map.setAutoRefresh(false); // Prevent busy state from happening

// when zoomSelected is called

sel.clear();

sel.addObject(mgObj);

map.zoomSelected();

map.setWidth(5, "KM");

map.setAutoRefresh(true); // Reset the autoRefresh flag

map.refresh();

// Update the display

}