# Introduction

The DateControl plugin is intended to provide a way of displaying vector layers (and tables) filtered by a date range and to move that range forwards or backwards so that a time lapse animation can be produced. It is particularly suitable for historical reconstructions and BCE dates may be specified (see Date formats).

It is comprised of three modules: Date control, Settings, and Convert dates.

The vector layers to be filtered need start and end dates (or a single date) which may be in a variety of formats: date, integer, decimal, text (string). The use of negative integer or decimal numbers for dates allows BCE dates to be specified. Null dates are allowed. (The Convert dates module converts text dates, including BCE dates, to decimal years and vice versa.)

A date range to use as the overall time span and a list of events (dates) is obtained from one of the layers when Date control is opened (see Initialising for details).

The date range and list of events (dates) may also be obtained from any combination of the dated layers and tables. The list used to jump forwards or backwards to the date of the next event. See Using events. The total number of events is shown and the number of the previous or current event, e.g. "61 of 134". The date range may be specified manually. See Initialising

Within the date range, the date may be:

automatically changed by the specified amount, either backwards or forwards, at regular intervals;

changed in several ways by using the Date slider in combination with the keyboard or mouse;

changed by moving to the next or previous event;

set manually by clicking the Current date button.

See Using the animation

It is possible to provide a table of comments, each with a date range, which will be displayed in a dockable window to provide a guide to what is happening. If an historical project is being put together for the plugin, then starting with the table of comments provides a good "to do list" and a record of the main dates to be used.

If required, the settings for a particular project, i.e. the date fields for each layer, the date format, and the name of the comments table, may be saved in a text file in the project directory using the Settings module.

The image above shows the controls for the Date control module with a key to the help topics describing their use.

The image below shows Date control in use with a docked comments window.

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