add paneSize getter to IChartApi

[SlicedSilver]

Type of PR: enhancement

PR checklist:

• N/A Addresses an existing issue
• Includes tests
• Documentation update

Overview of change:

Adds a paneSize method to the IChartApi which returns the dimensions of the chart pane (the area excluding the time and price scales) where the actual series rendering takes place.

This is useful for Plugin development because there isn't an easy way to determine the pane height from the API, and you typically need to either use some getBoundingClientRect call, or get the height within the renderer scope.

[edew]

The d.ts changes are expected

+/**
+ * Dimensions of the Chart Pane
+ * (the main chart area which excludes the time and price scales).
+ */
+export interface PaneSize {
+       /** Height of the Chart Pane (pixels) */
+       height: number;
+       /** Width of the Chart Pane (pixels) */
+       width: number;
+}

[ghost]

Any updates on this merging? This is a pre req to closing #1407 I think

[SlicedSilver]

Any updates on this merging? This is a pre req to closing #1407 I think

@skdillon This is unrelated. This PR just adds a method for reading the paneSize. This isn't useful for any existing use cases and we are adding it for one of our upcoming features. (plugins support)

We do plan on merging this but it wouldn't solve your existing issue.