Creating a Windows Explorer clone with complete shell browsing
GUI in your Visual C++ MFC application with Shell MegaPack
ActiveX
Original article at
http://www.ssware.com/articles/creating-explorer-clone-in-visualc
++-mfc.htm Link : Original Article
Introduction
Any developer who has ever wanted to provide file/folder
browsing or file-selection functionality in his own application
knows the utter lack of simple, extensible and customizable MFC
components for this purpose.
Even as simple a task such as letting the user select a folder
has to be accomplished by using complex shell programming APIs
like SHBrowseForFolder. And all you get after all this is
exactly the ability to let a user select a folder. The
disadvantages of this approach, apart from the fact that it is
very inflexible and non-customizable, is that this approach
shows a modal dialog to the user, meaning the user has to deal
with the dialog before moving on - either select the folder or
cancel the operation.
Another option is to use the 'common dialogs' - the MFC
CFileDialog class - which is almost as inflexible and
narrow-minded in its goals and features. Sure it can be extended
to add more controls, but only after you have spent 20 hours
wrestling with subclassing and hooks and WindowProc.
To do away with the modal madness, you can a listbox and
combobox in your own own dialog and use an API like the
DlgDirList to list all drives, directories or files. All you get
with these APIis is a textual list of filenames. Compare this to
Windows Explorer which shows the entire shell's namespace
including filesystem items and virtual items like Control Panel,
Network Neighborhood etc in all their glory - with pretty icons,
a hierarchical display of folders, Thumbnail or Details or Group
Views, infotips, dragdrop, context menus, etc.
And with Shell MegaPack, you can get all this in your
application. If you want drop-in Windows Explorer shell browsing
functionality in your own application, with all features of
Windows Explorer's features, along with the advanced behavior
control and customization, and you want all of this with minimal
time and effort, then Shell MegaPack is the way to go.
Inserting the controls in your dialog.
To insert the ActiveX controls in your MFC project, right click
on the dialog at design time and select 'Insert ActiveX
Control..'. In the dialog box that comes up, select 'Sky
Software FolderView ActiveX Control" and click 'OK'. Repeat this
procedure for FileView and ShComboBox. Now that all three
controls are on your dialog, position and size the controls as
per your needs and give them the desired IDs.
Next, we will add variables for all the three controls. To do
so, right-click on the FileView control at design-time and
select 'ClassWizard..'. Select the 'Member Variables' tab,
select the ID for the FileView control in the 'Control IDs'
listbox and click 'Add Variable..'. At this stage, Visual C++
will ask whether it should generate wrapper classes for the
control. Click 'OK' and give the control the desired variable
name and click 'OK again'. Repeat this step for the other two
controls as well.
Setting properties
All three controls can be fully customized at design-time. To
set properties, right click on the controls at design time and
select 'Sky Software FolderView ActiveX Control Object' -->
'Properties..'. This will bring up the property pages from where
you can customize the controls as per your needs. You can change
the appearance and colors, set filtering modes (hide virtual
items, hide hidden items, show folders), set the starting
folder, set whether context menus, infotips, etc are shown and
whether dragdrop is allowed. Almost every aspect of the controls
can be customized at design time in this way.
Linking the controls together
Linking the three controls with each other enables them to
synchronize automatically with each other. For example, if a new
folder is selected in FolderView, FileView will automatically
update itself to show the contents of that folder. Linking can
be done in just 2 lines of code :
m_shCmbBox.SetFolderView((LPDISPATCH)m_fldrVw.GetControlUnknown()
);
m_fldrVw.SetFileView((LPDISPATCH)m_fileVw.GetControlUnknown());
Event Handling and behavior control
The controls come with a large number events which are fired
when certain things occur, such as when the current folder has
changed or an item has been clicked or double-clicked or
selected or checked. The other use of events is to give you the
opportunity to do advanced customization. For example, you might
want to allow the display of context menus for one item but not
another, or allow dropping of files on some particular folders
or disallow execution of some files. Simply setting Cancel =
True in the proper event allows you to accomplish this.
To handle an event, right click on the control at design time
and select the 'Events..' menu item. In the dialog that comes
up, select the appropriate event and click 'Add and Edit'. For
example, to prevent display of context menus for folders, handle
the OnItemRightClick event of FileView and use the following
code :
CListItem i; i.AttachDispatch(Item,FALSE);
if(i.GetAttributes(FOLDER) & FOLDER) *Cancel=TRUE;
Advanced customization
The controls allow you to replace or extend the default
attributes of items. You can change the display names (text) of
files and folders ( for example, prefix an asterisk(*) before
all files ), change the default icons shown for files and
folders, add, remove or modify items from the context menu of
files and folders, add custom columns in Details View. You can
even add your own custom items to the controls. With this
feature, you can recreate an entire shell namespace extension
within your own application with minimal effort.
Conclusion
A Windows Explorer like shell browsing UI is required in many
applications, yet there is no simple way to add such
functionality in your application without spending countless
hours for the most basic functionality. If you desire even a
little semblance to the explorer UI and a little customization,
then the corresponding time required grows exponentially. Shell
MegaPack brings a drop-in shell browsing UI to your app within
minutes and shields you from all the complexities and pains and
the modal madness discussed above. Just the gains in terms of
the time saved is more than worth it.
About the author:
Atul Godbole is the President of Sky Software, a leading
developer of user interface components based on ActiveX and .Net
technologies. To contact him or to find more information about
Sky Software and its products, please visit
http://www.ssware.com.
|
