This document is part of the Dasher Version Six Specification. It defines and illustrates basic terms that are used in the specification.
See also the previous section of the specification, and the table of contents.
Zoom boxes in a zooming user interface, see above, can be described in the following terms.
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There is a Zoom Box Hierarchy, as follows.
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There is a single Root Box at the top of the hierarchy.
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Every zoom box other than the root has exactly one Parent Box.
The rectangle of a zoom box will always be entirely within the rectangle of its parent box.
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In relation to its parent box, a zoom box can be referred to as a Child Box. A box can be the parent box to zero, one, or more than one child boxes.
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In relation to another box with the same parent, a zoom box can be referred to as a Sibling Box.
The rectangle of a zoom box never overlaps with any of the rectangles of any sibling box.
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Every zoom box has a numeric Level. The root box has level zero. Every other zoom box has a level of one more than the level of its parent.
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Zoom boxes move; the origin doesn't move. The origin might, at any time be inside one or more zoom box rectangles. The hierarchical structure of the zoom boxes means that:
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If the origin is inside a zoom box, the origin will also be inside its parent box.
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If the origin is inside a zoom box, the origin won't be inside any of its sibling boxes.
A zoom box can be described as Across The Origin if it meets all the following conditions.
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The origin is inside the zoom box's rectangle.
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The origin isn't inside any of the zoom box's child boxes' rectangles.
Put another way, the zoom box with the highest level number that contains the origin is the box that is described as being across the origin.
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One application of the zooming user interface, see above, is text entry. Text entry in a zooming user interface can be described in the following terms.
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There is a Working Text that the user is editing. The working text is sometimes called the message but that term isn't used in this discussion.
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Every zoom box has a Box Text. The box text can be empty. The root box text is empty.
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If there is a zoom box that is across the origin, see above, its box text will be the working text. That is a fundamental feature of the zooming user interface.
When the zoom boxes move so that a different box is across the origin, the working text changes to the text of that box.
If there isn't a zoom box that is across the origin, then the working text is empty.
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A zoom box can have Incremental Text, in addition to its box text.
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If a box has incremental text, then its box text will be its incremental text appended to the box text of its parent.
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If a box doesn't have incremental text, then its box text will be the same as the box text of its parent.
In Dasher Version Six at time of writing, incremental texts are always single characters.
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Zoom boxes without incremental text could be used for either of the following purposes, for example.
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As a Group for their child boxes. For example, boxes with incremental texts that are numerals, 0 to 9, are in a separate group to boxes with incremental texts that are capital letters, A to Z.
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To enable the user to select an Action within a zooming interaction. For example, sending the working text to a speech synthesis function. Dasher Version Six doesn't support action boxes at time of writing.
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The zooming area of a zooming user interface, see above, is two-dimensional. The following terms can be used in descriptions.
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The two dimensions can be referred to:
- As horizontal and vertical.
- In Cartesian terms, as X and Y.
- In lay terms, as left-right and up-down.
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In the zooming area of a zooming user interface, one dimension will be designated as the Sequential Dimension.
In some versions of Dasher, the user can select which dimension is designated as the sequential dimension. In the Dasher Version Six user interface at time of writing, horizontal is designated as the sequential dimension and the user cannot change it.
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The other dimension, which will be perpendicular to the sequential dimension, is always designated as the Lateral Dimension.
In the Dasher Version Six user interface at time of writing, vertical is always designated as the lateral dimension.
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The line that passes through the origin and is parallel to the sequential dimension can be referred to as the Sequential Axis.
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The line that passes through the origin and is parallel to the lateral dimension can be referred to as the Lateral Axis.
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In the sequential dimension, one direction will be designated as the Forward direction.
In some versions of Dasher, the user can change which select whether positive or negative is designated as the sequential forward direction. In the Dasher Version Six user interface at time of writing, the sequential forward direction is Cartesian positive X, which is to the right.
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The opposite to the forward direction in the sequential dimension is always designated as the Reverse direction.
In the Dasher Version Six user interface at time of writing, the sequential reverse direction is Cartesian negative X, which is to the left.
The position and size of a zoom box in a zooming user interface, see above, can be described in the following terms.
A zoom box rectangle has four sides:
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Two sides, referred to as the Front and the Back, will be perpendicular to the sequential axis. By definition: a vector from the middle of the front to the middle of the back would be parallel to the sequential axis and in the forward direction.
The distance from the origin to the front side, in the sequential forward direction, can be referred to as the Front Position of the zoom box.
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The other two sides will be perpendicular to the lateral axis.
The distance between these sides can be referred to as the Lateral Size. The lateral size is a scalar value, i.e. it is unsigned.
The distance from the origin to a midpoint between these sides, in the lateral dimension can be referred to as the Lateral Centre.
The following diagram illustrates some of the terms defined above. It is based on a screen capture image of the Dasher Version Six zooming area.
Notes on the diagram:
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In generic terms:
- Left is the Front Position.
- Middle is the Lateral Centre.
- Height is the Lateral Size.
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There are sibling boxes in between "ha" and "he": "hb", "hc", and "hd". They were too small to render at the time of capture. The same is true of sibling boxes in between "he" and "hi".
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ZoomBox outlines have been switched on, for clarity. Outlines aren't shown by default.
The following diagram illustrates some of the terms defined above.
In this diagram, the lateral and sequential dimensions, and the forward and reverse directions, reflect the Dasher Version Six user interface designations.
The next section in the specification is the Zooming Rules.
See also the table of contents.
This document is part of the Dasher project and is under revision control here:
https://github.com/dasher-project/dasher-web
(c) 2020 The ACE Centre-North, UK registered charity 1089313.
MIT licensed, see https://opensource.org/licenses/MIT