title: $:/plugins/tiddlywiki/dynaview/docs

! Documentation

The components of this plugin include:

* A background task that:
** performs specified actions when elements are scrolled into view
** updates certain base classes on the `document.body` according to the current zoom level
** if enabled in the DynaView config panel - dynamically stores the viewport dimensions in $:/state/viewport/width and $:/state/viewport/height
* Pre-configured CSS classes to simplify using those base classes
* Usage examples

! Scroll Features

!! Set tiddler field when visible

The background task detects when elements with the class `tc-dynaview-set-tiddler-when-visible` scroll into view. The first time that they do, the background task assigns the value in the attribute `data-dynaview-set-value` to the tiddler whose title is in the attribute `data-dynaview-set-tiddler`. This assignment can be tied to a reveal widget to cause content to be displayed when it becomes visible. If the class `tc-dynaview-expand-viewport` is set then the viewport is expanded so that the processing occurs when elements move near the viewport.

!! Update address bar when scrolling

The background task detects the tiddler at the top of the viewport and sets the address bar location hash to the title of that tiddler.

! Viewport Size Features

!! Viewport Size Tracking

The background task can optionally dynamically update a pair of state tiddlers with the dimensions of the browser viewport.

* Set the configuration tiddler $:/config/DynaView/ViewportDimensions to the text "yes" to enable this feature
* The viewport dimensions can be found in $:/state/DynaView/ViewportDimensions/Width and $:/state/DynaView/ViewportDimensions/Height

!! Font "Optisizer"

The background task can optionally dynamically optimise the font size of a passage of text to match a desired line length.

* Set the configuration tiddler $:/config/DynaView/Optisizer to the text "yes" to enable this feature
* Optionally, update the configuration tiddler $:/config/DynaView/Optisizer/Text with the "maquette" -- a character string matchng the desired length (this string should not include spaces).
* Assign the following CSS classes to appropriate elements on the page:
** `.tc-dynaview-optisizer-site` for an HTML element whose `offsetWidth` property gives the desired output width
** `.tc-dynaview-optisizer-maquette` for an HTML element that will contain the maquette
* The computed optimum font size can be found in the tiddler $:/state/DynaView/Optisizer/FontSize

The tiddler $:/plugins/tiddlywiki/dynaview/optisizer-maquette contains an example configuration that can be used to adjust the size of tiddler body text. To use it:

* Set $:/config/DynaView/Optisizer to the text "yes"
* Set $:/themes/tiddlywiki/vanilla/metrics/bodyfontsize to `{{$:/state/DynaView/Optisizer/FontSize}}`
* Set $:/themes/tiddlywiki/vanilla/metrics/bodylineheight to `1.5` to ensure that the line height matches the font size

! Zoom Features

!! Document Body Zoom Classes

The background task sets the following classes on `document.body` according to the current zoom level.

|!Class |!Description |
|`tc-dynaview-zoom-factor-1` |Set when the zoom level is less than 2.00 |
|`tc-dynaview-zoom-factor-2` |Set when the zoom level is greater than 2.00 and less than 3.00 |
|`tc-dynaview-zoom-factor-3` |Set when the zoom level is greater than 3.00 and less than 4.00 |
|`tc-dynaview-zoom-factor-4` |Set when the zoom level is greater than 4.00 |
|`tc-dynaview-zoom-factor-1-and-above` |Set when the zoom level is greater than or equal to 1.00 |
|`tc-dynaview-zoom-factor-1a-and-above` |Set when the zoom level is greater than or equal to 1.14 |
|`tc-dynaview-zoom-factor-1b-and-above` |Set when the zoom level is greater than or equal to 1.33 |
|`tc-dynaview-zoom-factor-1c-and-above` |Set when the zoom level is greater than or equal to 1.60 |
|`tc-dynaview-zoom-factor-2-and-above` |Set when the zoom level is greater than or equal to 2.00 |
|`tc-dynaview-zoom-factor-2a-and-above` |Set when the zoom level is greater than or equal to 2.66 |
|`tc-dynaview-zoom-factor-3-and-above` |Set when the zoom level is greater than or equal to 3.00 |
|`tc-dynaview-zoom-factor-4-and-above` |Set when the zoom level is greater than or equal to 4.00 |

!! Pre-configured Classes

These classes can be used on any element to control its visibility at different zoom levels.

|!Class |!Description |
|`tc-dynaview-zoom-visible-1-and-above` |Visible when the zoom level is 1.00 or more |
|`tc-dynaview-zoom-visible-1a-and-above` |Visible when the zoom level is 1.14 or more |
|`tc-dynaview-zoom-visible-1b-and-above` |Visible when the zoom level is 1.33 or more |
|`tc-dynaview-zoom-visible-1c-and-above` |Visible when the zoom level is 1.60 or more |
|`tc-dynaview-zoom-visible-2-and-above` |Visible when the zoom level is 2.00 or more |
|`tc-dynaview-zoom-visible-2a-and-above` |Visible when the zoom level is 2.66 or more |
|`tc-dynaview-zoom-visible-3-and-above` |Visible when the zoom level is 3.00 or more |
|`tc-dynaview-zoom-visible-4-and-above` |Visible when the zoom level is 4.00 or more |
|`tc-dynaview-zoom-visible-1` |Visible when the zoom level is less than 2.00 |
|`tc-dynaview-zoom-visible-2` |Visible when the zoom level is greater than or equal to 2.00 and less than 3.00 |
|`tc-dynaview-zoom-visible-3` |Visible when the zoom level is greater than or equal to 3.00 and less than 4.00 |
|`tc-dynaview-zoom-visible-4` |Visible when the zoom level is greater than or equal to 4.00 |