Erik Ziegler Merge current dev branches, then the rest of these PRs go into dev

Outstanding Pull Requests

Cornerstone

Issue	Reason	Plan
imageCache :: memory leak (critical)	Large DICOM files with sharedCacheKey will crash the browser	Merge into dev branch
Fix #82: drawInvalidated() should pass true	Required for requestAnimationFrame support	Erik Ziegler
Display the images that have only VOI LUT Sequence properly	Fixes bug with VOI LUT support	Former user (Deleted) will review Evren Ozkan's PR and if it is unacceptable, he will close it. He has investigated this issue and has another fix which may be more appropriate.
Making the canvas, context and its rendering data specific to each enabledElement	Fixes race condition with rendering	Merge immediately
WIP: Prototype of multi-layer composition	Development PR	Leave open
Make cornerstone Promise/A+ compliant	Not sure we intend to make Cornerstone Promise compliant	Erik Ziegler Fix imageLoaders to return Deferred Everywhere else can return promises Fix documentation to specify imageLoaders should return Deferred Why do we want to use Deferreds?: So we can cancel the image loading Start moving towards the removal of the jQuery dependency Future: allow the dev to specify what type of Promises / Promise library Cornerstone should use Create an example of how to use Cornerstone without jQuery for the Promises
Rendering loop	Uses requestAnimationFrame.	Jean-Francois Pambrun (Unlicensed)Review the PR and if it's unacceptable, replace it with your own solution. Move requestAnimationFrame from CornerstoneTools (https://github.com/chafey/cornerstoneTools/blob/master/src/util/requestAnimFrame.js)
Add possibility to display image statically	Useful for Previews	Review / Merge
Rendering using css transform instead of canvas transform	Development PR	Leave open (or close?)
Added canvasToPixel function for easier use in cornerstoneTools	Helper function which will help us clean up Cornerstone Tools	Merge immediately
WIP: WebGL rendering	Adds optional WebGL rendering path. This is stable and has been used in OHIF for months.	Erik Ziegler and Former user (Deleted) Look into non-linear LUT in WebGL branch. That may be the last issue remaining before it can be merged. Non-linear LUTs will be used in large images. Erik Ziegler Force developer to explicitly handle WebGL failure via an event or something like that Erik Ziegler Document the fact that WebGL branch is not the 'final solution' and will change and may be unstable. This is why it is opt-in. Does WebGL cause too much overhead when switching images? Look into changing Cornerstone's API to allow devs to plug in new rendering types to support pyramid type rendering or JF's rendering type

CornerstoneTools

Issue	Reason	Plan
Purge image cache issue (stackPrefetch)	stackPrefetch should not trigger exceptions for disabled elements removed from cache	Merge immediately
Setting a default value for resetPrefetchDelay	Required to fix issues with stackPrefetch for multi-frame instances during CINE play	Merge immediately
Fix issues with rectangleRoi tool	Brings rectangleRoi to parity with other tools	Merge immediately
Fix comments for the timeSeriesPlayer tool	Minor comment issue	Merge immediately
Cornerstone playClip tool now supports playing variable frame rate instances	Necessary for multi-frame support	Merge immediately
use buttons instead of which in the mouse event api	Minor change for Firefox support	Merge immediately
for bower installation dev branch	Very minor change to fix bower installation of dev branch	Merge immediately
WIP: Added simple paintbrush tool & example	Development PR, not to be merged	Leave open
Level of Detail Window Level and Center	Alternative to WWWC tool which downsamples during window/level	Not sure? Useful for many users?

dicomParser

Issue	Reason	Plan
New method to parse VR=AT fields + Tests	Required for multi-frame instance support since it enables Frame Increment Pointer (0028,0009)	Merge immediately
Heap performance	Performance improvement
Don't include tag if not not needed	Unclear

Cornerstone WADO Image Loader

Issue	Reason	Plan
Support for loading frames using WADO-RS (octet-stream)	Required for WADO-RS	Merge immediately
wadors (loadimage) must return a deferred like wadouri does	Required for WADO-RS	Merge immediately
Reject the promise if parsing the dicom file fails	Adds error handling	Merge immediately
Add bitsStored into image object to be used for VOI LUT in cornerstone	Used for VOI LUT. Not certain if we want this in image object or in metadataProvider?	Review
Speeds up RLE decoding significantly by replacing DataView by Int8Array (~10x speedup in Chrome)	Performance improvement	Merge? Rollback if issues arise?
Add support for binary encoded DICOM Segmentation files	Used for DICOM Seg support	Merge immediately
Fix CornerstoneImageLoadProgress for multi-frame images	Useful for multi-frame images	Review
[DicomFile loader] multiframe loading broken	Useful for local dicom file multi-frame support	Not sure this is still relevant. Review

Cornerstone Web Image Loader

Issue	Reason	Plan
gh-pages branch still exists		Delete branch, not necessary anymore

Open Issues

Issue	Reason	Plan
Is there a way to pan a zoomed image, so we can only explore in the image (and not drag the image off the screen)?		Respond to user,

Cache Size Issue

If the cache size is set to 1GB and you load 1GB of data cornerstone will consume at least 2GB. That's because the dataset is cached by dataSetCacheManager and also a color/grayscale image will be created for each frame using a closure keeping the imageData (bytes) allocated in the memory (see getPixelData, getImageData and getCanvas methods). The problem is because imageCache doesn't count the images (frame) size but just the dataset size. Then if you load a 100MB dataset that contains 100 frames it will store 100MB (dataset) + 100 frames (1MB each approx). The size of the images created by wadouri image loader is set to the dataset size and we don’t know the real image size what makes it difficult to know how many MB there are in the cache.

Three ways to fix this issue:

The dataset should have a different structure, storing only the header bytes (removing the pixel data) and the frames converted into a color/grayscale images instead of the raw pixel data. Then each image would re-use the same frame data instead of creating a copy of it. Cornerstone uses the dataset in too many places and maybe this will not be so easy to change.
All caches (dataSetCacheManager, imageCache, etc) should add an entry to a Global Cache responsible for counting and removing items from these caches (like datasetCacheManager and imageCache do through decache method). This way we should be able to count dataset + image + anything else sizes. And also, to avoid removing the dataset before its images from the cache each cache entry could have a priority (property) then sorting by priority/timeStamp would solve this problem.
The image should not create a copy of the bytes but creates the color/grayscale image on-the-fly whenever getCanvas is called. This process saves memory but results in a performance impact because these images would have to be re-created too many times (scroll / cine).

Erik Ziegler Put this on the OHIF roadmap
Figure out a way to make the Cache manager 100% accurate for how much memory Cornerstone is using.
- Look into color images
- Look into compressed images
- Look into CINE usage and cache involvement

RequestPoolManager Improvements

Erik Ziegler Put this on the OHIF roadmap
Allow parallel downloads when loading multi frame instance
If a multi frame series starts loading using wadouri all frame promises will be added to the requestPoolManager but all threads will waiting for the same dataset. If you open Chrome DevTools and try to prefetch a different series (we developed a StudyPrefetcher on OHIF) you will see that only the first one will be in progress. The second series will be downloaded only when the first one is done and all its promises are resolved.

Abort a download when its promise is rejected.
When a 100MB series is being loaded and user clicks on another series he/she will have to wait for the first one to be loaded before starting loading the second one what can result in a delay on UI impacting the user experience.

General Issues

ES6 transition should start soon so that new code is cleaner
- https://groups.google.com/forum/?nomobile=true#!searchin/cornerstone-platform/es6%7Csort:relevance/cornerstone-platform/lCTBrKDt-Fo/p1uSn3lTCAAJ
- https://docs.google.com/document/d/1hIH1H0jyOz62q2KW9X6ONCZYCtfsHwcKgFc-Y7FSTkQ/edit
- https://github.com/OHIF/dicom-parser/pull/1
- Chris: Does the ES6 change change the API at all?
- Move 1.x to a 1.x branch where patches can be applied
- Master works off of the 2.0 branch
- Erik Ziegler Put this on OHIF roadmap: Start with dicomParser
- Axe the Meteor package, move towards NPM
- Get rid of bower and use NPM for everything
- Chris Hafey (Unlicensed) Move repo from /chafey/ to /OHIF/
- Check naming conventions for NPM

Viewers / Cornerstone should use requestAnimationFrame loop to display images
Multi-layer composition work is ongoing

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