/// <summary>
/// Opens an object using the main thread containing a message handler.
/// </summary>
/// <param name="viewerObject">The object to be opened.</param>
private void OpenObjectInForeground(object viewerObject)
{
try
{
// Activate the application when opening an object. This is used in situations where a notification comes in while
// another application is active. When the user clicks on the notification widow, they will be routed to this
// application, which then needs to be active to take the user's input.
this.Activate();
// Close down any documents that are currently open in the viewer.
if (this.activeViewer != null)
{
this.activeViewer.Close();
}
// If an object type was selected that doesn't have a viewer (or the viewer couldn't be loaded), then
// reject the operation and leave the last viewer up.
Viewer viewer = this.viewerTable[viewerObject.GetType()];
if (viewer == null)
{
throw new Exception("Viewer not found");
}
// This will synchronize the navigators with the open document.
this.folderList.Open(viewerObject);
this.guardianBar.Open(viewerObject);
this.Text = viewerObject.ToString() + " - " + Properties.Settings.Default.ApplicationName;
// This is an optimization: if the viewer for the current object is the same as the viewer for the last
// object, then we'll skip the step of swapping the screen elements around and just reuse the current
// viewer. Otherwise, there's some modest reorgainization of the screen required to activate the proper
// viewer.
if (this.activeViewer != viewer)
{
// The code below will modify the layout of the FormMain frame window. It will swap out the current
// viewer its menus and toolbars and replace it with the new viewer and it's resources. Suspending
// the layout will minimize the screen distractions.
SuspendLayout();
// Swap the new active viewer with the previous one. Also, have the viewer cleared out so it's empty
// the next time it's activated. This gets rid of the disturbing effect of seeing the previous data
// when you select a new report. It shows up momentarily while the new document is constructed.
// Clearing it out now will give it a chance to create a blank report in the background.
viewer.BringToFront();
this.menuStrip.SuspendLayout();
this.toolStrip.SuspendLayout();
// Clear the previous menu and tools from the child viewer out of the main container area.
ToolStripManager.RevertMerge(this.menuStrip);
ToolStripManager.RevertMerge(this.toolStrip);
// Merge the container's menu with the menu of the active viewer.
ToolStripManager.Merge(viewer.MenuStrip, this.menuStrip);
ToolStripManager.Merge(viewer.ToolBarStandard, this.toolStrip);
this.menuStrip.ResumeLayout();
this.toolStrip.ResumeLayout();
// Let the screen process the changes.
this.ResumeLayout();
this.activeViewer = viewer;
}
// Opening is a somewhat involved operation. Because it may take a few seconds to open a report, the
// message loop can't be suspended while the user waits. The operation is done asynchronously. This
// operation will kick off an asynchronous operation in the viewer that will gather all the resources
// needed and draw the document. When that operation is complete, the viewer will kick off an event that
// will signal the 'Open' operation is complete. At that point, a message will be broadcast from the
// control and picked up by the 'viewer_EndOpenDocument' method below which will complete the operation of
// opening the viewer and document.
this.activeViewer.Open(viewerObject);
}
catch (Exception exception)
{
// These user interface errors need to be show to the users.
MessageBox.Show(exception.Message, "Guardian Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
}
/// <summary>Initializes the Dynamically Loaded Viewers</summary>
/// <remarks>
/// The application is constructed as a container for navigators, document viewers and special purpose dialog boxes. Said
/// differently, we want the application to be extensible and have incremental upgrades, so there's no hard coded way of
/// saying "If I click on this icon, I want this user control displayed." The binding between the database objects and the
/// Viewers (special purpose user interface controls) is done dynamically through a configuration file. The configuration
/// file has a list of DLLs and the objects in those DLLs that can be used for viewing. Each of the viewers or special
/// purpose dialog boxes has an integer associated with it. This integer is the 'type code' which corresponds to the type
/// codes found in the 'types' table on the database. When we get a request to open up one of these objects, we use the
/// type code to map the 'Open' request to one of the dynamically loaded modules. This hash table is used to associate the
/// type code with the proper viewer.
/// </remarks>
public void InitializeViewers()
{
// The viewing area of the frame can have several viewers which all sit on top of each other in the same space. The
// active viewer is the one that is visible and sits on top of all the rest.
this.activeViewer = null;
// This table contains a mapping between all the object types and the viewers used to present the data in those
// types. When an object is opened, this table is searched for that object's type and the viewer that is part of the
// key pair is loaded into the viewer area and the object is opened up into that viewer.
this.viewerTable = new Dictionary <Type, Viewer>();
// Though a viewer can be specified to display several different types, only one instance of that viewer will be
// created. This table helps organize the viewers during initialization so there is only one instance of a viewer for
// the entire application.
this.viewerTypeTable = new Dictionary <Type, Viewer>();
// Load any dynamic viewers into the application.
ViewerSection viewerSection = (ViewerSection)ConfigurationManager.GetSection("viewers");
if (viewerSection != null)
{
// This loop will load each add-in module and associate it with an object type code.
foreach (ViewerInfo viewerInfo in viewerSection)
{
// The most likely error to catch is the dynamically loaded control doesn't exist. In any case, a failure to
// load any of the add-ins is not fatal.
try
{
// This holds the next viewer to be initialized from the application settings.
Viewer viewer = null;
// If the specified viewer has already been created for another type, it will be re-used. The idea here is
// that the viewer will have the intelligence to work out how to display any given data type.
if (!viewerTypeTable.TryGetValue(viewerInfo.ViewerType, out viewer))
{
viewer = (Viewer)viewerInfo.ViewerType.Assembly.CreateInstance(viewerInfo.ViewerType.ToString());
this.viewerTypeTable.Add(viewerInfo.ViewerType, viewer);
}
// This is where the mapping between the object type and the viewer used to display that object is kept.
// When a navigator selects an object, it will send it to a Viewer. The Viewer will pull apart the data in
// the object and determine how to show it to the user. But the first step is to pass the object on to the
// appropriate Viewer.
this.viewerTable.Add(viewerInfo.Type, viewer);
// The Viewer will fill the panel in which it is placed.
viewer.Dock = DockStyle.Fill;
// This will give the viewers a method to ask the container to open a new object.
viewer.ObjectOpen += new OpenObjectEventHandler(this.OpenObject);
// This is the panel where all the viewers will be displayed.
this.splitContainer2.Panel2.Controls.Add(viewer);
}
catch (Exception exception)
{
// Catch the most general errors and emit them to the debug devide.
string errorMessage = String.Format("Viewer {0} couldn't be loaded: {1}", viewerInfo.ViewerType, exception.Message);
MessageBox.Show(errorMessage, "Guardian Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}
}
