Changes:

• Add string split expression function.
• Add View data update listeners. (#1383)
• Add tickFormat method to bin-ordinal scale. (#1395)
• Add separation flag for tree layout. (#1399)
• Add require parameter to LinkPath transform.
• Add support for aggregate to sum strings as numbers.
• Fix pickArea method to support arbitrary orders (#1390).
• Fix extent transform to return [undefined, undefined] for empty data. (#1401)
• Fix scaleFraction method to protect from infinite spans. (#1401)
• Fix aggregate measures to standardize outputs for invalid data. (#1404)
• Fix path scaling bug. (#1408)
• Fix width/height calc for empty legend. (#1415)
• Fix react flag for operator parameter initialization. (#1428)
• Fix bootstrapCI method with empty data check.
• Allow signal-only transform parameters in schema.
• Update selection methods for Vega-Lite.
• Update test specifications.
• Update dependencies.

Changes:

• Add dynamic data loading: data url and format now accept signal values.
• Add title align property. (#1362)
• Add schemeDiscretized function to API. (Thanks @benib!)
• Update nest and stratify transforms to handle empty data.
• Update sequence transform to accept as parameter.
• Update dataflow request changeset to remove existing data.
• Update dataflow request to return a Promise that resolves to a status code: 0 for success, -1 for load fail, -2 for parse fail.
• Fix gradient labels when two or fewer are produced. (#1364)
• Fix View autosize logic for dynamic data loading.
• Fix AxisTicks to omit extra tick for empty data.
• Fix unterminated rule chain with null else value. (#1366)
• Fix dataflow operator pulse assignment bug.
• Fix dataflow run to return the dataflow instance.
• Fix dataflow runAsync and request to handle chained load requests.

Changes:

• Add axis opacity parameters: domainOpacity, labelOpacity, tickOpacity, titleOpacity
• Add legend opacity parameters: gradientOpacity, labelOpacity, symbolOpacity, titleOpacity
• Add signal support for axis label flush and overlap parameters.
• Fix Overlap transform propagation bug, support disabled settings.
• Update schema, fix schema bugs.

Vega 4.0.0

This major version includes a few breaking changes for both specification validation and the JavaScript API. All Vega 3 specifications should be successfully parsed and rendered by Vega 4. However, a small number of Vega 3 specifications may fail JSON schema validation.

Overview of Changes

Breaking Changes:

• We now use fetch rather than XMLHttpRequest to load remote files. While similar, fetch has different default behavior and parameters. As a result, some of the parameters to vega.loader have also changed.
• The deprecated view.tooltipHandler method has been removed. Instead, use view.tooltip to register a customized tooltip handler.
• The key parameter for both the nest and treelinks transforms is no longer needed. If included in a spec, the parser will simply ignore it. However, such specs will fail JSON schema validation.
• Generated data objects for symbol legends no longer include a total data property.
• Some config options have changed. The legend entryPadding option has been removed. The legend symbolFillColor and symbolStrokeColor options are now always applied; the prior selective behavior for these options is now provided using the new symbolBaseFillColor and symbolBaseStrokeColor options.

Major Additions:

• Support for discrete gradient legends. (See county unemployment example.)
• Support for both horizontal and vertical legend directions.
• Gradient legends now default to a vertical direction.
• Multi-column layout and symbol clipping support for symbol legends. (See Dorling cartogram example.)
• Legend types, if not explicitly specified, are now automatically determined based on the scales used. Previously, all legends defaulted to symbol legends.
• Tooltip support for individual points in area, line, and trail marks.
• Add timer event type, can be used to drive frame-by-frame animation. (docs)
• Add merge expression function to merge objects into a new output object. (docs)
• Add boolean domainImplicit parameter to enable implicit domain construction for ordinal scales. (docs)
• Add naturalEarth1 geographic projection. (docs)
• Add as property to set output field name for {"field": ...} and {"expr": ...} transform parameters.
• Anchor positioning for title layout is now by default performed relative to the full calculated bounding box, rather than the group width or height. The new frame title property explicitly sets which reference frame to use. (docs)
• Multiple new configuration options, and comprehensive support for configuration options within axis, legend, and title specifications. (docs)

Detailed Change Log

vega-loader

• Use fetch to service requests, drop use of d3-request and XMLHttpRequest (XHR). Note that, while similar in many respects, fetch has a different default behavior than XHR. For example, fetch is more secure by default and does not share cookies or credentials unless configured to do so.
• Change loader options format. Clients should use the options.http object property to provide fetch parameters. The options.headers property is no longer supported, instead use options.http.headers.
• The loader http method now directly accepts an http parameter object rather than the top-level loader options. The loader's options.http property is used as the base set of parameters, which may then be overridden by the options argument to the http method.
• Fix data loader type inference to avoid splicing the test function array.

vega-scenegraph

• Add tooltip support for area, line, and trail marks. Perform lookup of individual data points along a path, rather than just the first data point.
• Add tooltip handler updates for mousemove events, rather than mouseover events.
• Add getItemBoundingClientRect method to Handler.
• Add standardized canvas getter method to Renderer and Handler to access underlying Canvas/SVG element.
• Add fontFamily and fontSize scenegraph utility methods.
• Update SVG renderers to use separate font style properties (font-family, font-size, etc.) rather than the shorthand font property. This change provides better compatibility with downstream SVG tools, including librsvg. (#1315)
• Update Handler origin method to be getter/setter; previously it was a setter only.
• Fix group item x, y coordinate lookup in resolveItem method.

vega-dataflow

• Fix operator evaluation skip bug upon signal update.
• Fix changeset by adding safeguards for input data: ensure existing tuples are not inserted multiple times and ignore tuples that are both added and removed in the same set. (#1318)

vega-transforms

• Add expression transform for management of expression-typed transform parameters.

vega-geo

• Add weight parameter for contour transform.

vega-hierarchy

• Refactor nest, stratify, and treelinks data object generation.
• Remove nest transform key parameter, which is no longer needed.
• Remove treelinks transform key parameter, which is no longer needed.
• Fix transform as parameter schemas. (#1342)

vega-encode

• Add support for generating discrete gradient legend entries.
• Add schemeDiscretized method to get/set discretized color schemes, defined using an array of color arrays, each of which corresponds to a color scheme to use for a specific value count.
• Add boolean domainImplicit parameter to enable implicit domain construction for ordinal scales. (#1189).
• Add warning for log scale domain containing zero. (#1334)
• Modify colormap quantization for better balance.
• Remove total property from generated symbol legend entries.
• Fix to use provided number format specifier even when scale.tickFormat is undefined.

vega-projection

• Add naturalEarth1 geographic projection.

vega-parser

• Legend type, if unspecified, is now automatically determined based on the encoding channels and scale types used. Previously, the behavior was to always default to a symbol legend.
• Add legend direction property for specifying horizontal or vertical legends. Gradient legends now use a vertical orientation by default. The configuration options gradientDirection and symbolDirection can be used to separately set default directions.
• Add gradientLength and gradientThickness properties to specify gradient dimensions regardless of horizontal or vertical direction. The previous gradientWidth and gradientHeight properties are now deprecated, and used as the default settings of gradientLength and gradientThickness, respectively, if the new properties are not defined.
• Add multi-column layouts for symbol legends, set via the columns property and configured using the rowPadding, columnPadding, and gridAlign properties.
• Add clipping of symbol legend entries using the legend clipHeight property. For example, a legend can indicate size by showing just the horizontal extent of a vertically clipped circle, rather than a full, large circle.
• Add discrete gradient legends for discretizing scales (quantize, quantile, etc.).
• Add label overlap removal support for gradient legend labels, using the legend labelOverlap property.
• Add legend entries encoding block to customize the group items containing symbol/label pairs.
• Add symbolBaseFillColor and symbolBaseStrokeColor configuration properties for legends to determine symbol legend defaults that are selectively applied based on the encoding channels (e.g., fill, stroke, size, etc) used by the legend. The symbolFillColor and symbolStrokeColor configuration options are now always applied, regardless of the encoding channels used by the legend.
• Add labelAlign and labelBaseline axis configuration properties. These will override the default align and baseline values chosen based on the axis orientation.
• Add new frame title property explicitly sets which reference frame to use.
• Add as property to set output field name for {"field": ...} and {"expr": ...} transform parameters.
• Add configuration properties (previously only available as config options) to specifications for axis, legend, and title guides.
• Add merge expression function to merge objects into a new output object.
• Add extent expression function to get min/max values from an array. (vega/vega-parser#81)
• Remove legend entryPadding property, replace with rowPadding and columnPadding.
• Fix flush axis label alignment. (#1278)
• Fix expression dependency handling for {"expr": ...} parameters.
• Fix clampRange calculation bug. (vega/vega-parser#80)
• Update Vega JSON schema.

vega-view-transforms

• Add centering options to grid layout.
• Add width/height adjustment for symbol legend groups.
• Add reference frame parameter (full bounds or group dimensions) to title layout. Anchor positioning is now by default performed relative to the full calculated bounding box, rather than the group width or height.
• Adjust title layout to be outside legend and grid bounds.
• Fix view layout to include grid layout row/column title bounds.
• Fix left-oriented legend layout to incorporate legend widths to align along left edge.
• Fix legend title to respond to legen...

Vega 4.0.0, Release Candidate 3

Changes from v4.0.0-rc.2:

• Add boolean domainImplicit parameter for implicit domain construction for ordinal scales. (#1189).
• Add naturalEarth1 geographic projection.
• Add labelAlign and labelBaseline axis configuration properties.
• Add fontFamily and fontSize scenegraph API utility methods.
• Add schemeDiscretized API method to get/set discretized color schemes, defined using an array of color arrays, each of which corresponds to a color scheme to use for a specific value count.
• Update SVG renderers to use separate font style properties (font-family, font-size, etc.) rather than the shorthand font property. This change provides better compatibility with downstream SVG tools, including librsvg. (#1315)
• Fix changeset by adding safeguards for input data: ensure existing tuples are not inserted multiple times and ignore tuples that are both added and removed in the same set. (#1318)
• Fix color scheme quantization denominator bug.
• Fix data loader type inference to avoid splicing the test function array.
• Fix legend title to respond to legend padding changes.
• Fix legend bounds calculation to prevent content clipping.

Vega 4.0.0, Release Candidate 2

Changes from v4.0.0-rc.1:

• Add timer event type, can be used to drive frame-by-frame animation.
• Add merge expression function to merge objects into a new output object.
• Add new example test specifications.
• Add runtime description $ref object support for event update sources.
• Add cyclical color schemes rainbow and sinebow.
• Fix standard input (stdin) handling by vg2png and vg2svg.
• Fix container element check in default tooltip handler, preventing errors for headless displays.
• Fix value equality check in bind input update to suppress unnecessary updates.
• Fix flush axis label alignment. (#1278)
• Fix dataflow bug where operator evaluation might skip upon signal update.
• Update dependencies.
• Update documentation.

Vega 4.0.0, Release Candidate 1

This major version includes a few breaking changes for both specification validation and the JavaScript API. All Vega 3 specifications should be successfully parsed and rendered by Vega 4. However, a small number of Vega 3 specifications may fail JSON schema validation.

For details, see the v4.0.0-rc.1 pull request changelog.

Changes:

• Add error trap for tooltip handler, route errors to view.error.
• Fix order of operations in scenegraph CanvasHandler. Set vegaType property on event object prior to invoking all handlers, including href and tooltip handlers.

Changes:

• Add customizable tooltip support. (#1198)
• Add origin accessor to View API. (#1221)
• Add resolution scale parameter to vg2png. (Thanks to Robin Linacre!)
• Add random seed paramter to vg2png and vg2svg.
• Add default event stream scoping. Uses event source type "scope" (instead of "view") for event strems defined in nested groups. (#1231)
• Add schema validation and documentation of signal bind name property for customizing the visible label for bound input elements.
• Add identity geographic projection.
• Update SVG renderer to streamline processing and minimize z-index DOM churn.
• Fix axis title layout and bounds calculation. (resolves #1232)
• Fix pixel ratio adjustment of picking coordinates. (#1220)
• Fix autosize calculation to skip width/height update functions. (#1213)
• Fix internal legend parameterization, improving signal support. (#1228)
• Fix dataflow transform metadata (vega/vega-transforms#6).
• Fix pulse handling and metadata for Nest and Stratify transforms. (#1239)
• Fix contour transform parameters and metadata.
• Fix Canvas hit testing for group backgrounds.
• Fix hover encode directives issued from view mouseover/mouseout listeners.
• Fix hover encode propagation. Prevent group events from triggering hover updates on contained marks.

Changes:

• Fix projection fit parameter parsing to allow direct use of GeoJSON objects.