Implement UI Navigation

Create & integrate toolbars

Handling menu & toolbar selections (02/04/2000)

MFC framework -> handlers placed inside class most closely associated with handler function, e.g. connection to remote DB may be best handled by application as whole, therefore by the CMyApp class.

Handlers added via ClassWizards Message Map tab – specify class that will contain handler, object id that acts as source and message to be handled.

 

Dynamic updates menus & toolbars

MFC framework provides mechanisms to update appearance & status of menu commands and toolbars via handlers for user interface update command messages.

Framework generates UI update messages to signal app to update status of UI in response to menu openings and toolbar button presses. Message maps of command target objects in command routing searched for ON_UPDATE_COMMAND_UI entries.

Implement handler functions to modify UI appearance. Framework passes function pointer to CCmdUI object giving access to UI element associated with handler. This object permits enabling, disabling, checking of menu items, setting of radio buttons, etc.

 

Implement and Write to Status Bar

Often updating menu / toolbar appearance not enough to reflect info. Status bar provides area for further info to be displayed. AppWizard by default provides CAPS LOCK, NUM LOCK and SCROLL LOC indicators.

Status bar support handed by CStatusBar.

Indicator info held in array, leftmost position at locn 0. Each entry in array = resource ID of string table entry.

Fist indicator is elastic – takes up space not used by other, right aligned indicators. Entries in string table, usually ID_INDICATOR_*, associated with corresponding framework indicators. Entry in table should be of maximum length indicator will be so framework can set out indicators.

To update text in status bar use ON_UPDATE_COMMAND_UI entry in message map to associate UI entry with handler function – must be added manually as not supported by ClassWizard. Without handler the framework will disable and blank out the indicator.

Indicator text updated via CStatusBar::SetPaneText().

 

Create new app using MFC AppWizard (05/03/2000)

Project is source code + associated resources and their relationships (build rules, etc.).

Independent settings (debug, release, etc.) for build tools (compiler, linker, etc.) via Project Settings dialog. AppWizard creates debug and release configurations initially - can add more.

 

Workspace is container for project(s). Default = 1 project, can add others. Project dependencies can be defined. Only active project at a time (name displayed in bold).

 

Project Types

MFC is class based framework Develop apps, dlls, ActivX controls,etc.. Save time + effort but size + performance overhead = not suitable for small apps. Requires access to MFC DLLs (either static or dynamic linking).

 

Win32 is for simple apps without MFC overhead.

Wizards:

·         create empty or skeleton Window apps - register window classes, create message loop, basic window processing.

·         create empty of skeleton dlls - sample code to export classes, functions & variables.

·         create empty or skeleton console app

·         create empty or skeleton static library for linking to executable

·         can include MFC support (take advantage of strings, collections, etc.

 

ATL is templates for small, fast, COM objects. Create COM server, dll or exes. Can add ATL com objects to project - include simple objects, transaction services, MMC, etc.

 

Miscellaneous = Not fit into other categories, e.g. DLL resources for IIS or Cluster Server, Visual Studio add-ins, custom AppWizards, etc.

 

Create application using MFC AppWizard (12/03/2000)

1. Choose application type (SDI, MDI, Dialog)

2. Chose DB support

3. ActiveX technologies - ActiveX isuse of COM to enable component interactivity. OLE provides compound docs.

4. Misc features such as toolbars, 3D controls, MAPI, Sockets, etc.

5. Advanced options - associates a file extension with the app and specify display characteristics (width of border, etc.)

7. Project style - type of presentation (standard or Explorer like), generation of comments and static / dynamic MFC link

8. Adjust names of classes generated and their inheritance

 

 

Create and edit UI objects with resource editors (26/03/2000)

App & doc resources

App & doc icons

To meet certification requirements must provide both standard (32*32) and small (16*16) icons for application and associated document type.

MFC framework automatically provides default icons for you.

 

Application resources (icons, menus, etc.) have numeric resource identifier (resource ID).

 

Editors

Graphics Editor Part of IDE – use to edit icons, plus other bitmaps, jpgs, etc.

 

Application Menuspermit convenient + consistent grouping of commands. Wizard generates menus appropriate to selections chosen by developer. Associated with resource ID of IDR_MAINFRAME. Can change menus through menu editor. Use of ‘&’ within menu caption specifies shortcut key used in conjunction with ALT key to quickly select menu.

 

Shortcut keys (previously accelerator) provide quick access to program commands available from menu / toolbar, e.g. associate CTRL+U with data upload. Held in accelerator table manipulated by accelerator editor that maps key combinations to message identifiers (e.g. ID_DATA_UPLOAD).

 

Toolbars provide easy access to common commands. AppWizard generates standard toolbar providing access to file and edit commands. Toolbar resource associated with bitmap containing button images, additional bitmap files created for each toolbar defined. Images in toolbar of same size, usually 16*15. Bitmap image contains buttons side by side in resource id order – for this reason use provided graphic editor (displays one button at a time). Each button has associated command identifier.

 

Add Message Handler for event using ClassWizard

OnOK() = example of control notification message handler for BN_CLICKED message of IDOK control.

Different sets of notification messages associated with different controls – Message Maps tab of ClassWizard provides reference to all those available.

Control notification messages prefixed by abbreviation for control type followed by an N:

 

BN_	Button
CBN_	Combo box
CLBN_	Check list box
EN_	Edit control
LBN_	List box
STN_	Static text control

 

ClassWizard add macros to message map to handle notification messages for above control types. Macros constructed by prefixing message ID with ON_, e.g. handler for EN_UPDATE for IDC_USERID results in:

 

ON_EN_UPDATE(IDC_USERID, OnUpdateUserid)

 

Note, BN_CLICKED for IDOK and IDCANCEL mapped directly by overridden versions of OnOK and OnCancel – no manipulation available.

 

 

Creating data input forms and dialog boxes

Creating Dialog Box using dialog editor (03/04/2000)

Child window of main app window – display or retrieve status info.

Contains controls (small, standard window objects) through which info displayed/manipulated.

Two types

·         Modal – take control of interface. Require closure of box before use of app can continue. Example = apps About dialog.

·         Modeless – do not take control of app interface, can work on other areas of app without closing dialog. Less common than modal. Example is Properties dialog box used within resource editor of IDE.

Property sheet = special dialog box. Presents user with tabbed, index card like selection of pages within single frame.

 

Creating dialog box template

Use dialog editor to create dialog box template – reusable app resource that is binary description of dialog box + its controls layout.

Template edited by resource editor.

Each control within template (including itself) has associated identifier – IDD_* for dialog, IDC_* for control.

 

When using controls within dialog box, only one item has focus – indicated by outline around control.

 

Select control with mouse or TAB key. Specify TAB order (sequence of control selection) within dialog editor.

 

Creating dialog box class

Class representing dialog box within your program, derived from CDialog. Contains member variables representing controls and data items within dialog box + methods to handle events arising from user interactions with dialog.

 

Creating dialog box class simplified by ClassWizard.

 

To create class open from dialog box template, launch ClassWizard that will prompt for new class to be created (as none is currently associated with template).

 

Displaying dialog box

Achieved by calling CDialog::DoModal(). Default handlers for OK and Cancel buttons via CDialog::OnOK() and CDialog::OnCancel().

Example of creation:

 

{

CAboutDlg aboutDlg;

AboutDlg.DoModal();

}

 

Modeless dialogs handled differently. Don’t call CDialog::DoModal(), instead call CDialog::Create() passing in resource ID of dialog box template. Use ShowWindow() to show and hide the dialog box.

 

Modal dialogs usually created as required, typically on stack. Modeless dialogs (e.g. toolbars) usually last for the lifetime of the application and hence are created at application instantiation.

 

Can make window always appear above others by ensuring it has WS_EX_TOPMOST style set. Can achieve this through the CWnd::SetWindowPos() function (added into the Create() function). Has side effect of making dialog appear above all windows in system (not just those of the application). Resolve this by hiding dialog when application looses focus – achieve this by adding handler for WM_ACTIVATEAPP message.

 

Common dialog classes

MFC supplies several classes derived form CDialog to handle common tasks; CColorDialog, CFileDialog, CFindReplaceDialog, CFontDialog, CPrintDialog.

 

Creating property sheets by using ClassWizard

3 main parts; containing dialog box, 1+ property pages, tabs at top of each page used to select page.

Used when have number of groups of similar settings / options, e.g. property sheet in MSDEV IDE.

 

Implemented by two classes – CPropertySheet for containing dialog box and CPropertyPage for individual pages of property sheet.

 

Recipe:

·         Create dialog template for each property page. Aim for consistent layout and size. Ensure thin style, child and disabled properties set. Caption for dialog template appears on the page tab.

·         Derive classes’ from CProperyPage for each dialog.

·         Create member variables +DDX/DDV to hold values for property pages.

·         Create CPropertySheet object in source code

·         Create objects for each of the property pages.

·         Add each page to the sheet by calling the CPropertySheet::AddPage() function

·         Bring in to use via DoModal or Create functions depending on modal nature.

 

For modal property sheets the framework provides OK, Cancel and Apply buttons and DDX/DDV for control on each page. If additional controls required on property sheet then use class wizard to generate class derived from CPropertySheet.

 

For modeless property sheets it is necessary to provide own CPropertySheet derived class as the Create() function does not create default controls for the sheet.

 

Handling Apply Button

The Apply button allows users to exchange and validate changes made without closing property sheet – useful if wanting to save changes made on one page before proceeding to next.

By default Apply button is unavailable. To make available after data changed, call to CPropertyPage::SetModifed(TRUE) is required.

 

 

Validating user input

Dialog data exchange (DDX) and validation (DDV)

DDX = easy way to set and retrieve control values within dialog.

DDV = easy validation of data entry within dialog box.

DDX and DDV implemented within dialog class, architecture similar to message maps.

DDX and DDV functions = global MFC functions. A number of standard DDX and DDV functions provided for common dialog components.

Member variables within dialog class represent controls with global MFC functions used to transfer values between the two.

 

Framework DDX/DDV

ClassWizard implements basic DDX/DDV architecture. It will:

·         Add member variables to class definition (within AFX comments)

·         Initialise member variables in constructor (within AFX comments)

·         Add DDX functions to transfer values between variables and controls (within AFX comments in DoDataExchange())

·         Optionally add DDV functions to validate data entry (within AFX comments in DoDataExchange())

 

Overriden version of DoDataExchange() provided by ClassWizard for dialog class.

Both DDX and DDV functions take a pointer to a CDataExhange object (represents data exchange context – including direction of exchange) as their first parameter.

 

DoDataExchange() called by CWnd::UpdateData(). UpdateData() takes parm indicating direction of exchange (set or read values) which is passed to DDX/DDV functions via CDataExchage object. Can call UpdateData() at any point to perform data exchange.

 

Custom DDX/DDV

Can define own DDX/DDV functions – first parm always pointer to CDataExchange object. Extra parms can be provided as required by function.

All custom DDX/DDV function definitions and calls must be placed outside AFX comment blocks.

DDV functions must always be placed directly after DDX functions to which they refer.

Control Initialisation

Some controls require more initialisation than can be easily achieved via DDX functions, e.g. filling list boxes with info determined at run time.

Can achieve by overloading CDialog::OnInitDialog(). Note, OnInitDialog calls UpdateData() and hence DDX/DDV functions.

OnInitDialog called by framework after control creation but before display – provide opportunity to populate with data.

Enabling / Disabling Controls

To minimise DDV complexity controls on dialogs should be disabled until they can be realistically used – for example when connecting to DB only allow connect button o be clicked when name of database supplied elsewhere on dialog.

Controls derived from CWnd, therefore use EnableWindow() to set control availability.

 

 

Use MFC AppWizard to create ISAPI DLL

ISAPI Server Extensions

Server-side program running in response to client request. Implemented as DLL loaded by IIS, browser can run program by specifying its name in the url, as in:

 

http://myserver/apps/charts.dll

 

Specific functions can be invoked by appending their name to the function name as follows:

 

http://myserver/apps/charts.dll?GetChart

 

All ISAPI dlls must define default function to be called when client does not specify one. Parameters passed in similar way:

 

http://myserver/apps/charts.dll?GetChart?Fund=ASRC

 

Can link ISAPI dlls into HTML forms via the ACTION statement for FORMS, which specifies what action to carry out when submitting a form.

 

ISAPI server extensions based on CGI. Without altering specifications, ISAP permits any browser to load and run extension dll. As DLLs execute in same process space as webserver they are quicker than CGI scripts which require separate processes.

 

Creating

Use MFC ISAPI Extension Wizard to create server extension object. Creates single class (name derived from project name, e.g. CMySampleExtension) derived from CHttpServer. Add member function to this class to implement DLL exported functionality.

 

MFC uses a parse map (declared in the .h and implemented in .cpp) to map DLL functions to member functions of the CHttpServer derived class. One of members marked as default by DEFAULT_PARSE_COMMAND macro.

 

All ISAPI extension functions take a pointer to CHttpServerContext as first parm – provides details on client / server connection (a separate class created for each connection). Use this class to obtain access to clients HTTP request, insert entries (using << operator) into file sent back to client, etc.

 

Sample parse map:

 

BEGIN_PARSE_MAP(CMyServerExtension, CHtpServer)

ON_PARSE_COMMAND(Default, CMyServerExtension, ITS_EMPTY)

DEFAULT_PARSE(CMyServerExtension)

ON_PARSE_COMMAND(GetColour, CMyServerExtension, ITS_PTR)

ON_PARSE_COMMAND_PARAMS(“Colour”)

END_PARSE_MAP(CMyServerExtension)

 

Note, the GetColour function takes a parameter named colour. The parameters and their types handled by the function are indicated by the third (and subsequent) entries of ON_PARSE_COMMAND, with their names specified on subsequent ON_PARSE_COMMAND_PARAMS lines.

 

Extension DLLs loaded by IIS at first client request.

 

ISAPI Filters

Sit between client and HTTP server. Enhance IIS with custom features such as HTTP request logging, encryption, compression, etc. Loaded when IIS service started. Can only configure IIS 4.0 to use filters, not supported by Personal Web Server (PWS).

 

Filters receive notification from server when selected events occur, such as starting to process client request, sending data to client, writing information to log files, etc. Filter will have access to data associated with event, e.g. if data being sent to client then filter has access to data about to be sent and can modify it (compress, encrypt, etc.).

 

Creating

Use MFC ISAPI Extension Wizard to create filter object – sits between network connection of client and HTTP server. Creates single class (name derived from project name, e.g. CMySampleFilter) derived from CHttpFilter. Member functions have been added for each notification specified in step 3 of the Wizard – these overload those specified by CHttpFilter. Extend these functions to define filter behaviour.

 

Class also defines GetFilterVersion() which specifies what notifications the class is interested in. The server uses this function to ensure it does not send unnecessary notifications to the filter.

 

If you add additional handler functions later, must update this function to receive them.

 

Functions receive data structures containing information about event. Also receive pointer to CHttpFilterContext object containing info about current client connection + methods to read and modify its values.

 

 

Incorporate Dynamic HTML in Application

DHTML = extension to HTML exposing web page + its elements as scriptable objects. Able to:

·         Modify web page text

·         Modify style sheet elements specifying how text displayed

·         Animate text and images

·         Respond to user actions such as mouse moves or clicks

·         Validate input before submitting to server

 

Automatically reformats document – no need to reload. Does not require additional application support – DHTML documents are self-contained, use style sheets to specify format / appearance and small blocks of script to manipulate HTML tags, attributes, styles, etc.

 

Based on existing HTML standards. Some DHTML features not visible in non-DHTML browsers. Follow basic guidelines to ensure contents always visible, even if formatting wrong.

 

DHTML Object Model

Any HTML page loaded by IE4 (or later) held in representation accessible via DHTML object model. Can access + manipulate anything within document via model. HTML elements represented as individual objects held in collections (similar to those provided by MFC). Iterate collections (such as anchors, applets, frames…) to gain access to individual elements.

 

Model exposes user actions (key press, mouse click, etc.) as events. Create event handlers to intercept and process them.

 

Can identify individual elements on page using ID attribute as in

 

<H3 ID=MyHeading>Welcome to Dynamic HTML!</H3>

 

which can then be modified by scripts within document, for example to turn text green the following piece of java could be used MyHeading.style.color= “green”.

 

WebBrowser Control

ActiveX control used to incorporate web pages within application. It is component of Internet Explorer implementing the main window. Supports hyperlinks, URL navigation, maintains security, history and favourites list. Encapsulated within MFC by CHtmlView.

 

Inserting control in project creates CWebBrowser2 class, a wrapper for the IWebBrowser2 automation interface, through which properties and methods can be accessed in C++ like fashion.

 

Preferred way of using control is to derive view from CHtmlView (specify during AppWizard creation process). Provides web browser functionality within document/view architecture.

 

Access Object Model

Very easy from HTML – refer to object by name as in document.bgColor = “hotpink”. This functionality provided by Internet Explorer interpreter parsing HTML script and calling apparopriate automation interfaces on WebBrowser control. In C++ access DHTML object model by using Automation interfaces directly.

 

DHTML object model exposed through interfaces beginning HTML, as in IHTMLDocument, IHTMLWindow, IHTMLElement, etc. The CHtmlView class provides GetHtmlDocument() which return IDispatch to HTML document currently being displayed. From here can access the IHTML* interfaces.

 

HTML Resources

Can include HTML resources in project – just like bitmaps, dialog templates, etc. Provides safe + convenient way to distribute HTML pages used by application.