Gallery2:Modules:imagenotes:Design - Gallery Codex
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Revision as of 14:24, 29 August 2009 by Ckdake (Talk | contribs)

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  • Keep extensible.
    It is hoped that this module will be extensible so that features not envisioned here can be included later and so that administrators can enable only the features they desire, minimising page load time, client side operation time and resource usage.


Image regions
  • An image region is a specific area of an image that has some importance. This image region exists on all versions of the same image (i.e. on all derivatives of the source image). Note that a derivative image may have a different scale AND orientation to the original.
  • An image region is represented by a rectangular DIV or other 2d shape within the bounds of the image.
It should be possible to convert a rectangular DIV selection into a proper 2d shape.
  • All image region's no matter what shape will have a 2d bounding box, which will make collision detection faster.
  •  ?? An image region usually represents a complex 3 dimensional object in 2 dimensional space. Rather than just representing a 2d area, the image region may define the 3d properties of the object in the 2d space, such as the rotation of a face, head and torso. ?? Should this instead be an annotation/other association?
  •  ?? An image region should be able to provide a scalable view of that region for re-use in the page.
Image region sets
  • An image region set is a grouping of related image regions. Because a 3d object may be represented by disjoint regions in 2d space, we need to be able to link separate image regions together. (This becomes important when, for instance, a person is being tagged and their arm goes behind someone else. We tag the image region set rather than each individual 2d image region)

Image region hierarchy... does it make sense to have an image region made up of image region parts, and a part can be a parent to another image region part? Image region always has a root, which is the bounding DIV and then 1 or more children? Does it make sense to do this?

  • An annotation is something that is drawn in the browser (may not be visible due to style, but added into the DOM) and is associated with the image.
  •  ?? Does an image region need an annotation so that it can be displayed and interacted with? Or should we be able to attach style to an image region itself? If annotation required, need special circumstances to shape the annotation to the image region.
  • The annotation, unlike an image region, is not necessarily desired on all sizes of the same image.
  • An annotation may have a number of different style attributes depending on the derivative image (and Annotation set) it is being displayed with. Scale and rotation of the annotation may not be as simple as image regions, which are based purely on image co-ordinates.
e.g. A speech bubble annotation may not want to scale the same amount as the derivative image does.
  • An annotation may be, but is not necessarily associated with an image region.
i.e. Tags and notes are associated with an image region, but a quirky speech bubble isn't.
  • An annotation may be shown, hidden, or animated by some event.
  • An annotation can be displayed in various positions:
    • Absolutely positioned, relative to the image.
    • Absolutely positioned, relative to another anotation.
    • Absolutely positioned, relative to the cursor.
    • In the imagenotes block area?
    • In a special annotation region for the annotation type.
    • In other special block areas of the correct type?
 ??Annotation parts
  • An annotation may be made up of different parts and shapes and we may not want a database entry for every individual part. This may make the job of referencing different things more difficult however. And parts may want to be attached to different annotation regions. Examples:
    • Annotating a tag, we may want to display it at the cursor on mouse over, underneath the image (if a large group of people shown, a table of who's in the picture) and in the imagenotes block.
    • Quirky speech bubble animation contains multiple bubbles, animated together so when one bubble appears the other disappears. They together form a whole annotation, so may not want to be separated.
Annotation sets
  • We may have lots of data about an image and not want to display all the data at the same time. Also, we may want different behaviours for interacting with the image when it is being viewed.
  • An annotation belongs in one or more annotation sets.
  • Annotations may have different properties per annotation set.
  • Only one annotation set is viewable at a given time, otherwise different properties of an annotation being displayed may conflict. It should be possible to merge sets into one another, giving the opportunity to resolve conflicts.
  •  ?? Only one annotation set is rendered at a time (the others are not merely hidden, but don't exist in the DOM)?
Image region associations
  • There may be reasons for creating associations with an image region that aren't visual markup. Not sure what yet though. :-)
  • As with the rest of G2, site owners may want to make imagenotes appear in different ways. Though CSS styles may control a lot, there are instances where non-simple elements are needed. For instance, a selected area may want the inside of the area transparent, whilst not making the border transparent.
Imagenotes regions
There are a number of potentially desirable regions for use with Imagenotes, all with different purposes.
  • Imagenotes block. When editing, all of the various image regions/annotations are shown here somehow. This allows you to interact with specific items potentially more easily than when editing over the image.
  • Image area. The area within which the image is rendered.
  • Sub image area. (Potentially another block?) Somewhere annotations such as who is in the image can be displayed.
  • Annotation set selection. When viewing the image, something to choose which annotation set is being displayed (possible hidden when the user can only see one of the available sets).
  • By the cursor. This is a special region that moves everywhere the cursor does. Potentially some logic is needed here for keeping this area on screen when the cursor is near the browser/frame border. Also, don't want to call code for moving the region when there is nothing being displayed in it.
  • Toolbox. Buttons and/or labels for selection of viewing/editing modes and potentially all their sub toolkits.
  • Docking areas (provided by themes or blocks?). Areas where toolboxes can be dragged to and inserted into the flow of the page.
  • By an image region. When an image region is first created (or edited) and tags/notes are being applied, a convienient place to get the appropriate options is right next to the image region (or maybe just a modal dialog)
When adding/editing the following operations will probably be needed for both image regions and annotations.
  • Dragging
    • Constrained
  • Scaling
    • Constrained
    • Aspect ratio
    • Min and Max
  • Z-ordering (layering)
  • Grouping/ungrouping
    • Image region in multiple groups?
    • Set operations for shapes (Union, Intersection, Negation) Keep the operators?
  • Node moving (when not a simple rectangle, points of the shape can be moved individually)
    • Constrained. Does a shape stop a node being moved to certain places to maintain the shape?
  • Rotation
  • 3d manipulation
Certain modes (and sub-modes) will be in use when interacting with the image. The mode will determine the behaviour.
  • Viewing.
  • Editing:
    • Editing image regions.
    • Editing tags.
    • Editing notes.
    • Editing non-image region annotations (drawings?)
  • User suggestions (Can an image region be suggested without anything associated to it? Probably not):
    • Suggesting tags.
    • Suggesting notes.
    • Suggesting drawing.
  • Viewing suggestions? Viewing may look different to when you are editing suggestions.
  • Moderating (Suggestion response).
    • View shows who/what made the various suggestion. Can limit view to a specific suggester.

Client side


  • Make all actions responsive
    • Keep event handlers simple and quick.
    • Be wary of multiple super classes as call times may get out of hand.
    • Keep the item being displayed as simple as possible so there is less in the DOM. i.e. don't use templates for editing (with resize handles) when merely displaying.
    •  ? Destroy classes when changing between modes or not? Memory consumed by keeping, CPU consumed by recreating.
  • Minimise resource usage
  • Minimise page load time
  • Only load required features. Load features as required? (dynamically load JS then eval?)
  • Degrade gracefully?


  • This all really only works when javascript is enabled. It may be possible to render the markup server side without to atleast some degradeble functionality, but for now this is not being considered (would require the theme to put things in the right place).
  • Image notes manager object handles all interactions with any given image (of course, within the scope of the imagenotes module) and is responsible for any page regions associated with the imagenotes (image, block area, toolkit)
  • The image notes manager will be instanciated when the imagenotes block is included on photo pages.
  • The image notes manager has to be pointed to the image it is managing. Currently a utility function searches out an <img> tag matching the item being displayed (this may not always work), with the image src URL passed in through the imagenotes block smarty template.
  • The image notes manager is responsible for putting the image notes into the normal flow of browser focus, so when tabbing through the document editable regions and keyboard input works correctly.
  • The image notes manager is responsible for client/server communication, plug in modules will communicate through it (is this bad design?, maybe it's more efficient for plugins to do their own thing to save unnecessary stuff being loaded, but structure the calls through an interface method).
  • The image notes manager has a notion of 'mode'. The mode can be changed to allow editing of image regions, creation of annotations, and to generally change the view and behaviour of the imagenotes. An interface class will define the mode and other G2 modules will be able to add modes (collected through factory methods server side).
  • The image notes manager will have rubber band functionality (just within the image area?) that is available to modes. Initially intended only for dragging out an image region, it may be useful for selection.
  • Mode types, view, edit(/add/delete), suggest.
  • Themes can define placement of toolbox, dock areas, annotation areas.
  • A class will define an interface for a handler for imagenotes types. It handles a specific imagenote type. (e.g. for image tagging, the handler will look after the tag/image region relationship, even when an annotation doesn't exist)
  • A class will define an interface for imagenotes types. An imagenote type is something that may be rendered to the page? and will probably fit into the imagenotes manager mode system. Will have events for it's selection, mouseover, etc.
  • Can create annotation areas that fit into page flow and are not absolute(?) Can we determine this with javascript? Does it have to be done per item being displayed? Definitely theme specific. Will it be easily upset by adding other blocks? Sounds too complicated! :-)

Server side


  • Minimise page load time, whilst being extensible


  • Image region at client end should stick to co-ordinates on local image. Server side should convert co-ordinates to full size image co-ordinates for storage and to derivative size co-ordinates for client display.
  • Only include javascript in page when necessary. Restrict to needed JS based on user permissions (i.e. edit code is not needed for someone that cannot edit)

Database structure


  • Minimise page load time
  • Design so it's easy and quick to search for interesting things


  • Image region needs a unique ID, probably built from a key on the image it's attached to and it's own unique ID for the particular image. Maybe image region ID should have a single unique key to simplify cross referencing from other tables. Image region needs layer information to ensure the desired z-ordering is applied on rendering.