Seadragon.Drawer class
Version 0.8.8 - Back to
Seadragon Ajax API Reference
Overview
This class handles and encapsulates the rendering of Seadragon content. It also provides support for overlays, which are HTML elements that are rendered on top of the content.
Currently, the Drawer supports two rendering methods: the first uses regular <img> elements, while the second uses the HTML 5 <
canvas> element. The rendering method used for a given browser is determined by browser capability and rendering quality.
Constructors
Properties
All properties are aliased; re-assigning them has no effect, but modifying them does.
| Name | Type | Description |
| elmt | HTML Element | The HTML element inside which the content is rendered. This is the same HTML element that is passed into the constructor. The specifics of this element and its children are unspecified and implementation-dependent. |
| profiler |
Seadragon.Profiler | A
Seadragon.Profiler instance that is profiling each update. |
Methods
Overlays
| Name and Signature | Return Type | Description |
| addOverlay(elmt, rect) | - | Adds the given HTML element as an overlay to the content if it has not been added before. This overlay will scale with the content; the element's size will always match the given
Seadragon.Rect, which must be in normalized coordinates (see
Seadragon.Viewport for details). |
| addOverlay(elmt, point, placement?) | - | Adds the given HTML element as an overlay to the content if it has not been added before. This overlay will not scale with the content; its size will remain untouched. The overlay will be placed at the given
Seadragon.Point, which must be a normalized coordinate (see
Seadragon.Viewport for details). An optional
Seadragon.OverlayPlacement value can be given that describes which part of the element is specifically placed at the given point. If none is given, the element is placed by its center. |
| updateOverlay(elmt, rect) | - | Updates the given HTML element overlay to the given
Seadragon.Rect. The overlay will scale with the content. |
| updateOverlay(elmt, point, placement?) | - | Updates the given HTML element overlay to the given
Seadragon.Point. and optionally the given
Seadragon.OverlayPlacement. If no placement is given, the element is placed by its center. The overlay will not scale with the content. |
| removeOverlay(elmt) | - | Removes the given HTML element overlay. |
| clearOverlays() | - | Removes all HTML element overlays. |
Drawing
| Name and Signature | Return Type | Description |
| needsUpdate() | Boolean | Returns true if the drawer needs an update since the last update. |
| reset() | - | Resets this drawer so that the content is re-drawn from scratch. Overlays are maintained, however. |
| update() | - | Updates the drawn content based on the viewport's current values. |
