SIMPOL Documentation

The graphical elements in the dataform1 family are fairly thin wrappers around the wxformgraphic controls. What they add are the necessary components to link them together and additional information, such as the support for named colors (colors that are not fixed but that are based on the operating system settings for that user, and therefore use symbolic names such as "Button Face" or "Window Text".

All of the data types named above have a common type tag, called dataform1graphic. All the graphical elements are located in a dring property (doubly-linked ring) called graphics. Both the dataform1 and the dataform1page have a property with this name. The form contains a ring of all graphics from all pages. The page ring contains the graphics from that page.

Unlike the graphical elements, the form controls often contain quite a few more properties and methods than the original wxformcontrol objects. This is because of the requirement to store information about their binding to a database field and table, the required display format, whether the control is part of a detail block (a set of controls displayed in rows where each row represents a record in a related database table), and if so in which row it is. Some controls require even more information. The dataform1list and dataform1combo controls allow quite a bit of flexibility in determining where the data comes from (including showing one value in the list but assigning another to the control). The dataform1datagrid type provides a grid that has columns associated with fields from a table, and it can be linked like a detail block to the master table of the form. Here is the list of form controls:

The form control types are all type tagged dataform1control. They are located in a dring property (doubly-linked ring) called controls. Both the dataform1 and the dataform1page have a controls property. The form contains a ring of all controls from all pages. The page ring contains the controls from that page.

There are a number of important utility types that play various roles in making the whole package work. Here is a list of them:

The dataform1bitmapsource type was created to store the original location of a bitmap that is loaded into a form. The reason for it is simple, without that information it would be impossible to save the form later and to know what value to store in the output file for the location of the image. For each image used on a form, a bitmap source object is created and is then associated with the resulting bitmap so that it can be found later.

The same is true of the dataform1controlsource type. This stores the actual field reference associated with the control, plus the dataform1table object, and optionally a display format. This information is necessary in order to read from and write to the database field and to correctly display and interpret the data in the control itself.

A dataform1datagridcolumn is similar in that it also stores information about its control source, it may also store a reference to a dataform1link object if the column is not from the master table of the grid.

The dataform1datasource stores information about the data source, either its file name and path, or its IP address and port number. It also contains a list of the database tables that are part of the data source.

One of the most complex objects is the dataform1detailblock, which is a special type of container that provides a replicated group of controls, in rows and columns, that can be linked to the master table of a form. It can work in two different ways: either as a block of rows of data (records) that are related to the master record of the form, or else as a completely independent block of data, the content of which is governed by a query. In both cases, the data is read only (from the user's perspective). There are features in the design that allow for retrieving the database record for a given row, for updating that record or even replacing it, and also for removing the row from the result set. It also contains methods for scrolling the block up or down, a page or a row at a time. The detail block is currently not optimized for reducing the records read, so if the link results in reading 100,000 records, then it will do so, delaying everything until it is done. As such, it is important to choose the links and data design wisely.

The dataform1link contains the information that links two tables together, and it also stores the record sets that are read as a result of using the link to read records.

The dataform1optiongroup acts as the management object for a group of dataform1option controls. In this special case, the data source is associated with the group object, and not with the controls. It also ensures that if one option button in the group is selected, that the others are deselected.

The dataform1record contains properties that assist it in knowing if the record has been changed, but not yet saved, and provides a place to define events such as onsaverecord or ondeleterecord.

Similarly, the dataform1table object stores information about the current state of the table, such as the current index, an array of field information including display formats, and events like onnewrecord, onsaverecord, and ondeleterecord.

The dataform1page is the container of all items specific to a single page of the form.