Tool Palette applications publish their tool data to AutoCAD by storing information in ATC files. These files, which contain XML content, describe the tool palette components provided by the application. The ATC files that your application produces can be used in your installer to deploy your product.
Several different types of tool palette files use the .atc file extension. A working Tool Palette application usually provides at least three types of ATC files, as follows:
- a registered stock tools catalog file
- a workspace catalog file
- a palette definition file (optional)
When AutoCAD launches the Tool Palettes window, the framework first reads the registered stock tools catalog files. These ATC files specify class IDs and ObjectARX modules for stock tools. The framework attempts to load the indicated ObjectARX modules as Windows DLLs. It does not load them as ObjectARX applications, so AutoCAD commands that you may have defined in a loaded module are not accessible until the module is reloaded through the AcRx mechanism.
If the stock tool's information does not include the module path and file name, the framework calls CoCreateInstance() with the tool's CLSID to create the COM object.
Next, AutoCAD inspects the workspace catalog ATC files. An application's workspace catalog describes its palette set configuration. These catalogs provide information to AutoCAD for creating its tool palettes tabs. The following diagram illustrates this sequence of events.
Tool Palette framework startup sequence
A palette definition ATC file conveys information about a single tool palette's UI configuration. It provides data such as tool order, image source, and image size. The framework uses this information to display a tool palette's tool icons and to link tools to their underlying stock tool implementations. Also, each palette definition must reference an ID that matches a palette ID found in your workspace catalog file.
Tool palette definitions also describe the tools they contain. A tool's description references a stock tool for its basic definition, and also provides property values that specialize the stock tool. A tool description should provide at least an icon file path, the tool's label, and its stock tool ID.