In order to take full advantage of the new plugin hooks called before and after a dataset is drawn, all drawing operations must happen on stable meta data, so make sure that transitions are performed before.
Chart data can now be entirely replaced using `chart.data = {...}` thanks to the new property setter (instead of using `chart.config.data = {}`). Also update the documentation, as suggested by @ldaguise and @kennethkalmer, with a note about versions prior 2.6.
Make all `before` hooks cancellable (except `beforeInit`), meaning that if any plugin return explicitly `false`, the current action is not performed. Ensure that `init` hooks are called before `update` hooks and add associated calling order unit tests. Deprecate `Chart.PluginBase` in favor of `IPlugin` (no more an inheritable class) and document plugin hooks (also rename `extension` by `hook`).
Move base platform definition and logic in src/platform/platform.js and simplify the browser -> Chart.js event mapping by listing only different naming then fallback to the native type.
Replace `createEvent` by `add/removeEventListener` methods which dispatch Chart.js IEvent objects instead of native events. Move `add/removeResizeListener` implementation into the DOM platform which is now accessible via `platform.add/removeEventListener(chart, 'resize', listener)`.
Finally, remove `bindEvent` and `unbindEvent` from the helpers since the implementation is specific to the chart controller (and should be private).
Refactoring to put browser specific code in a new class, BrowserPlatform.
BrowserPlatform implements IPlatform. Chart.Platform is the constructor for the platform object that is attached to the chart instance.
Plugins are notified about the event using the `onEvent` call. The legend plugin was converted to use onEvent instead of the older private `handleEvent` method.
Wrote test to check that plugins are notified about events
Plugins can now be declared in the chart `config.plugins` array and will only be applied to the associated chart(s), after the globally registered plugins. Plugin specific options are now scoped under the `config.options.plugins` options. Hooks now receive the chart instance as first argument and the plugin options as last argument.
Pass the hover event to the onHover event handler
This makes the behavior of the `onHover` handler consistent with the `onClick` handler:
```
function(event, activeElements) {
var chartInstance = this;
}
```
Prevent the resize method from notifying plugins if it is a silent resize. A silent resize occurs during startup and we do not want plugins to do anything here because the chart is not set up.
The retinaScale helper now enforces the display size to the correct values because if no style has been set on the canvas, the render size is used as display size, making the chart bigger (or smaller) when deviceAspectRatio is different of 1.
In many cases, the canvas render size is changed by the lib, causing the state stack to be discarded, meaning that we can't use save() and restore() to release the context with its initial state (i.e. before creating the chart). Since we don't need (want) to manually save / restore the context initial state, simply make sure to reset it to the default state to give a fresh context back to the user. That also means we don't need to revert the scale when the pixel device ratio is not 1.
When legend is disabled (i.e. {options: {legend: false}}), me.legend is null. Add the same test on me.tooltip even if the tooltip object is always created in case of {options: {tooltips: false}}.
Add support for creating a chart from the canvas id and prevent exceptions, at construction time, when the given item doesn't provide a valid CanvasRenderingContext2D or when the getContext API is not accessible (e.g. undefined by add-ons to prevent fingerprinting). New jasmine matcher to verify chart validity.
Solve weird animation issues with the tooltip. The optimization in Chart.Element.transition when the animation finishes to set `_view = _model` caused problems during update because we were using `helpers.extend` all over the place.
I changed to code so that we regenerate the model variable rather than continuously extending the old version. I also removed unnecessary tooltip reinitializations from the controller which should improve overall performance during interaction.
In order to simulate real-time chart updates (i.e. horizontal animation), it's necessary to distinguish a removed or added value from a simple update. The dataset controller now hooks array methods that alter the data array length to synchronize metadata accordingly. Also remove the duplicate calls of updateBezierControlPoints() for line and radar charts.
Responsiveness is currently based on the use of an iframe, however this method causes performance issues and could be troublesome when used with ad blockers. So make sure that the user is still able to create a chart without iframe when responsive is false.
When responsive is false and no canvas height explicitly set, the aspectRatio option wasn't applied because of the canvas default height. Prevent the retinaScale method to change the canvas display size since this method is called for none responsive charts, but instead make the resize() responsible of these changes. Also, as discussed some time ago, moved most of the core.js logic into core.controller.js. Clean up the destroy process and make sure that initial canvas values are properly saved and restored.
Add "onHover" to the legend options that will hold a user defined function (default is null) and called when a "mousemove" event is registered on top of a label item, with same parameters as the "onClick" option.
Also introduced logic that determines if the type of event passed to the legend "handleEvent" function is one we can handle. Currently allowing "click" and "mousemove" events. If the event is not one of those we stop the function execution (this is for the sake of reusing the legend hitbox calculations).
Add `beforeDatasetsUpdate` and `afterDatasetsUpdate` plugin notifications during the chart update. Plugins are able to cancel the datasets update by explicitly returning false to `beforeDatasetsUpdate`. For consistency, rename `(before|after)DatasetDraw` to `(before|after)DatasetsDraw`.
Rename `Chart.pluginService` to `Chart.plugins` (so move the old Chart.plugins array as a private member of the service), and rename `notifyPlugins` to `notify` for consistency with other service methods.
This change allows for smaller minified code in the final version, resulting in a smaller file size. Some files had previously used _this, but that has been changed to me to keep consistency throughout the project.
