Browser Extensions

Browserextensions, introduced in Microsoft Internet Explorer 5, allowdevelopers to add functionality to the browser and enhance the userinterface in a way that is not directly related to the viewable contentof Web pages. This class of extensibility includes add-on functionalitythat users might install to enhance their browsing experience.
Shortcut menu extensions. It is possible to extend Windows Internet Explorer by adding options to the shortcut menu. This is accomplished by adding registry keys that link the menu command to the task to be performed. For more information, seeAdding Entries to the Standard Context Menu.
Toolbars. Custom toolbars complement Internet Explorer's standard toolbars. An example is theMSN Toolbar. For more information, seeCreating Custom Explorer Bars, Tool Bands, and Desk Bands.
Explorer Bars. Use Explorer Bars to reserve part of the browser window, either the side or the bottom of the browser window. For more information, seeCreating Custom Explorer Bars, Tool Bands, and Desk Bands.
Browser Helper Objects. A Browser Helper Object (BHO) runs within Internet Explorer and offers additional services, often without any obvious user interface. For example, a BHO might highlight terms of interest to the user, such as addresses. For more information, seeBrowser Helper Objects: The Browser the Way You Want It.
Overviews/Tutorials
About Browser Extensions
Browser extensions allow developers to provide easy access to theirbrowser enhancements by adding elements (like an Explorer Bar) to thedefault user interface. Introduced in Internet Explorer 4.0, thisfeature enables developers to create Explorer Bars and add entries intothe standard context menus. Beginning with Internet Explorer 5, thisfeature allows developers to add entries into the Tools menu andbuttons to the toolbar.
About the Browser
This section explains the architecture of Internet Explorer 4.0 andlater and provides information you will find helpful when reusing thesecomponents.
Adding Explorer Bars
This tutorial explains how to add an Explorer Bar in Internet Explorer.
Adding Menu Items
This tutorial explains how to add a menu item that runs a Microsoft Windows application or that runs a script to the Tools menu or Help menu in Internet Explorer.
Adding Toolbar Buttons
This tutorial explains how to add a toolbar button to the Internet Explorer user interface.
Content Extensions
This category of extension is invoked specifically by Internet Explorercontent. It includes Microsoft ActiveX controls, binary behaviors, andActive documents.
Customizing the Browser Toolbar
This tutorial explains how to customize the appearance of the toolbar area in Internet Explorer.
Explorer Bar Style Guide
This guide will help you design Explorer Bars to add to the Internet Explorer user interface.
Implementing a Custom Download Manager
The ability to implement a custom download manager was introduced inInternet Explorer 5.5. This feature enables you to extend thefunctionality of Internet Explorer andWebBrowser applications by implementing a Component Object Model (COM) object to handle the file download process.
Toolbar Button Style Guide
This guide will help you design icons for toolbar buttons that you add to the Internet Explorer user interface.
Web Accessories
Web Accessories are browser enhancements that any developer can create using browser extensions.Users can then add these Web Accessories to their copy of InternetExplorer. By creating Web Accessories, developers have a very powerfulway to enable new features and functionality.
Writing Stable Browser Extensions
The stability of Internet Explorer is adversely affected by poorlyimplemented extensions such as BHOs, toolbars, or ActiveX controls.This article summarizes important guidelines developers should followwhen creating COM extensions to customize the browser and provides tipsand best practices for well-behaved browser extensions that do notcause Internet Explorer to crash or become unresponsive ("hang").
Methods
IDownloadManager::Download
Called by Internet Explorer and WebBrowser applications to download a file.
IMapMIMEToCLSID::EnableDefaultMappings
Sets whether to enable default mappings.
IDeskBand::GetBandInfo
Gets the information for a band object.
IImageDecodeEventSink::GetSurface
Returns a drawing surface of the requested size and format.
IImageDecodeFilter::Initialize
Called when the filter is activated by Internet Explorer.
IImageDecodeEventSink2::IsAlphaPremultRequired
Called by the filter to determine whether to remove the opacity of a layer by premultiplying it against the palette colors.
IMapMIMEToCLSID::MapMIMEToCLSID
Maps MIME to CLSID.
IImageDecodeEventSink::OnBeginDecode
Called by the filter to determine which image formats are supported.
IImageDecodeEventSink::OnBitsComplete
Called by the filter after image bits have been downloaded.
IImageDecodeEventSink::OnDecodeComplete
Called by the filter after image has been decoded.
IImageDecodeEventSink::OnPalette
Called by the filter when the palette associated with surface changes.
IImageDecodeEventSink::OnProgress
Called by filter as incremental progress is made during decode.
IImageDecodeFilter::Process
Called when a source file is ready to be processed.
IMapMIMEToCLSID::SetMapping
Sets the mapping mode.
IImageDecodeFilter::Terminate
Called when the filter is deactivated.
Interfaces
IDeskBand
Gets information about a band object.
IDownloadManager
Provides access to the method of a custom download manager object that Internet Explorer and WebBrowser applications use to download a file.
IImageDecodeEventSink
Exposes methods that are called byIImageDecodeFilter during a decode operation.
IImageDecodeEventSink2
Exposes the method to support alpha channel transparency of Portable Network Graphics (PNG).
IImageDecodeFilter
Exposes methods used to implement a custom image source handler inInternet Explorer. This handler is invoked when rendering images fortheIMG element'sSRC attribute.
IMapMIMEToCLSID
Provides methods that implement mappings.
Structures
DESKBANDINFO
Contains and receives information for a band object. This structure is used with theIDeskBand::GetBandInfo method.