# GSLayer Metrics *API Collection* Side bearings, baseline offsets, layer box, and metrics keys. ## Overview Side bearings describe the distance between layer content and the layer advance. Horizontal layout uses left and right side bearings with [`GSLayer.width`](/Core/GlyphsCore/GSLayer/width). Vertical layout uses top and bottom side bearings with [`GSLayer.vertWidth`](/Core/GlyphsCore/GSLayer/vertWidth) and [`GSLayer.vertOrigin`](/Core/GlyphsCore/GSLayer/vertOrigin). Metrics keys link a metric to another glyph, layer, side, or fixed value. Layer metrics keys override glyph metrics keys when present. ## Topics ### Horizontal Metrics - [`GSLayer.width`](/Core/GlyphsCore/GSLayer/width) — Advance width for horizontal text layout. - [`GSLayer.LSB`](/Core/GlyphsCore/GSLayer/LSB) — Horizontal distance from the origin to the left outline edge. - [`GSLayer.LSBFast`](/Core/GlyphsCore/GSLayer/LSBFast) — Cached left side bearing without updating metrics. - [`GSLayer LSBPlain`](/Core/GlyphsCore/GSLayer/LSBPlain) — Left side bearing without normalizing the no-outline value. - [`GSLayer.RSB`](/Core/GlyphsCore/GSLayer/RSB) — Horizontal distance from the right outline edge to the advance width. - [`GSLayer.RSBFast`](/Core/GlyphsCore/GSLayer/RSBFast) — Cached right side bearing without updating metrics. - [`GSLayer RSBPlain`](/Core/GlyphsCore/GSLayer/RSBPlain) — Right side bearing without normalizing the no-outline value. - [`GSLayer lsbAtHeight:`](/Core/GlyphsCore/GSLayer/lsbAtHeight:) — Left side bearing measured at a y coordinate. - [`GSLayer setLsb:atHeight:`](/Core/GlyphsCore/GSLayer/setLsb:atHeight:) — Sets the left side bearing measured at a y coordinate. - [`GSLayer rsbAtHeight:`](/Core/GlyphsCore/GSLayer/rsbAtHeight:) — Right side bearing measured at a y coordinate. - [`GSLayer setRsb:atHeight:`](/Core/GlyphsCore/GSLayer/setRsb:atHeight:) — Sets the right side bearing measured at a y coordinate. ### Vertical Metrics - [`GSLayer.TSB`](/Core/GlyphsCore/GSLayer/TSB) — Distance from the top metric to the top outline edge. - [`GSLayer.TSBFast`](/Core/GlyphsCore/GSLayer/TSBFast) — Cached top side bearing without updating metrics. - [`GSLayer TSBPlain`](/Core/GlyphsCore/GSLayer/TSBPlain) — Top side bearing without normalizing the no-outline value. - [`GSLayer.BSB`](/Core/GlyphsCore/GSLayer/BSB) — Distance from the bottom outline edge to the vertical advance. - [`GSLayer.BSBFast`](/Core/GlyphsCore/GSLayer/BSBFast) — Cached bottom side bearing without updating metrics. - [`GSLayer BSBPlain`](/Core/GlyphsCore/GSLayer/BSBPlain) — Bottom side bearing without normalizing the no-outline value. - [`GSLayer.vertWidth`](/Core/GlyphsCore/GSLayer/vertWidth) — Advance width for vertical text layout. - [`GSLayer.vertOrigin`](/Core/GlyphsCore/GSLayer/vertOrigin) — Vertical origin offset for vertical text layout. - [`GSLayer tsbAtHeight:`](/Core/GlyphsCore/GSLayer/tsbAtHeight:) — Top side bearing measured at an x coordinate. - [`GSLayer setTsb:atHeight:`](/Core/GlyphsCore/GSLayer/setTsb:atHeight:) — Sets the top side bearing measured at an x coordinate. - [`GSLayer bsbAtHeight:`](/Core/GlyphsCore/GSLayer/bsbAtHeight:) — Bottom side bearing measured at an x coordinate. - [`GSLayer setBsb:atHeight:`](/Core/GlyphsCore/GSLayer/setBsb:atHeight:) — Sets the bottom side bearing measured at an x coordinate. ### Master Metrics - [`GSMetricStore`](/Core/GlyphsCore/GSMetricStore) - [`GSLayer metrics`](/Core/GlyphsCore/GSLayer/metrics) — Vertical metrics for the associated master. - [`GSLayer metricsForMaster:`](/Core/GlyphsCore/GSLayer/metricsForMaster:) — Vertical metrics for a master. - [`GSLayer metricForType:`](/Core/GlyphsCore/GSLayer/metricForType:) — Master metric value for a metrics type. - [`GSLayer metricForName:`](/Core/GlyphsCore/GSLayer/metricForName:) — Master metric value for a metric name. - [`GSLayer isSecondaryMetric:`](/Core/GlyphsCore/GSLayer/isSecondaryMetric:) — Whether a metric is secondary for the layer’s glyph case. - [`GSValueStore`](/Core/GlyphsCore/GSValueStore) - [`GSLayer stemsForMaster:`](/Core/GlyphsCore/GSLayer/stemsForMaster:) — Stem values for a master. ### Common Master Metrics - [`GSLayer.ascender`](/Core/GlyphsCore/GSLayer/ascender) — Ascender value from the associated master. - [`GSLayer.descender`](/Core/GlyphsCore/GSLayer/descender) — Descender value from the associated master. - [`GSLayer.italicAngle`](/Core/GlyphsCore/GSLayer/italicAngle) — Italic angle from the associated master. - [`GSLayer.slantHeight`](/Core/GlyphsCore/GSLayer/slantHeight) — Slant height from the associated master. - [`GSLayer.topHeight`](/Core/GlyphsCore/GSLayer/topHeight) — Top height from the associated master. ### Glyph Metrics - [`GSGlyphMetrics`](/Core/GlyphsCore/GSGlyphMetrics) - [`GSLayer glyphMetrics`](/Core/GlyphsCore/GSLayer/glyphMetrics) — Glyph metrics for left-to-right layout. - [`GSLayer glyphMetricsForDirection:`](/Core/GlyphsCore/GSLayer/glyphMetricsForDirection:) — Glyph metrics for a writing direction. ### Metric Values - [`GSMetricNumbers`](/Core/GlyphsCore/GSMetricNumbers) - [`GSLayer metricsValue:atHeight:`](/Core/GlyphsCore/GSLayer/metricsValue:atHeight:) — Metric value for a side at a measurement height. - [`GSLayer metricsValue:forKey:`](/Core/GlyphsCore/GSLayer/metricsValue:forKey:) — Value described by a metrics key for a metric side. - [`GSLayer metricsValue:forKey:value:atHeight:`](/Core/GlyphsCore/GSLayer/metricsValue:forKey:value:atHeight:) — Evaluates a metrics key for a metric side. ### Metrics Keys - [`GSLayer.widthMetricsKey`](/Core/GlyphsCore/GSLayer/widthMetricsKey) — Layer-specific metrics key for the advance width. - [`GSLayer.leftMetricsKey`](/Core/GlyphsCore/GSLayer/leftMetricsKey) — Layer-specific metrics key for the left side bearing. - [`GSLayer.rightMetricsKey`](/Core/GlyphsCore/GSLayer/rightMetricsKey) — Layer-specific metrics key for the right side bearing. - [`GSLayer.topMetricsKey`](/Core/GlyphsCore/GSLayer/topMetricsKey) — Layer-specific metrics key for the top side bearing. - [`GSLayer.bottomMetricsKey`](/Core/GlyphsCore/GSLayer/bottomMetricsKey) — Layer-specific metrics key for the bottom side bearing. - [`GSLayer.vertWidthMetricsKey`](/Core/GlyphsCore/GSLayer/vertWidthMetricsKey) — Layer-specific metrics key for the vertical advance width. - [`GSLayer.vertOriginMetricsKey`](/Core/GlyphsCore/GSLayer/vertOriginMetricsKey) — Layer-specific metrics key for the vertical origin. - [`GSLayer metricsKey:name:operator:value:oppositeSite:atHeight:master:`](/Core/GlyphsCore/GSLayer/metricsKey:name:operator:value:oppositeSite:atHeight:master:) — Parses a metrics key into its referenced glyph, operator, numeric value, opposite side, height, and master. ### Metrics Key Alignment - [`GSLayer.hasAlignedWidth`](/Core/GlyphsCore/GSLayer/hasAlignedWidth) — Whether automatic alignment controls the layer width. - [`GSLayer hasAlignedSideBearings`](/Core/GlyphsCore/GSLayer/hasAlignedSideBearings) — Whether automatic alignment controls side bearings. - [`GSLayer.isAligned`](/Core/GlyphsCore/GSLayer/isAligned) — Whether components are currently aligned by automatic alignment. - [`GSLayer.isAligning`](/Core/GlyphsCore/GSLayer/isAligning) — Whether an automatic alignment operation is in progress. - [`GSLayer checkIfAlign`](/Core/GlyphsCore/GSLayer/checkIfAlign) — Whether automatic component alignment can be applied to the layer. - [`GSLayer doAlignWidth`](/Core/GlyphsCore/GSLayer/doAlignWidth) — Applies automatic width alignment. - [`GSLayer metricKeyOffsetLeft:right:width:`](/Core/GlyphsCore/GSLayer/metricKeyOffsetLeft:right:width:) — Metrics key offsets used by automatic component alignment. ### Metrics Sync - [`GSLayer syncMetricsThreshold:`](/Core/GlyphsCore/GSLayer/syncMetricsThreshold:) — Tolerance used when deciding whether metrics need synchronization. - [`GSLayer syncMetrics`](/Core/GlyphsCore/GSLayer/syncMetrics) — Applies all available metrics keys. - [`GSLayer syncLeftMetrics`](/Core/GlyphsCore/GSLayer/syncLeftMetrics) — Applies the left side-bearing metrics key. - [`GSLayer syncWidthMetrics`](/Core/GlyphsCore/GSLayer/syncWidthMetrics) — Applies the advance-width metrics key. - [`GSLayer syncRightMetrics`](/Core/GlyphsCore/GSLayer/syncRightMetrics) — Applies the right side-bearing metrics key. - [`GSLayer syncTopMetrics`](/Core/GlyphsCore/GSLayer/syncTopMetrics) — Applies the top side-bearing metrics key. - [`GSLayer syncBottomMetrics`](/Core/GlyphsCore/GSLayer/syncBottomMetrics) — Applies the bottom side-bearing metrics key. - [`GSLayer syncVertWidthMetrics`](/Core/GlyphsCore/GSLayer/syncVertWidthMetrics) — Applies the vertical advance-width metrics key. - [`GSLayer reinterpolateMetrics:`](/Core/GlyphsCore/GSLayer/reinterpolateMetrics:) — Reinterpolates the horizontal metrics of an Alternative layer or interpolated layer. - [`GSLayer updateMetrics`](/Core/GlyphsCore/GSLayer/updateMetrics) — Recalculates side bearings from the layer contents. ### Horizontal Metrics Keys UI - [`GSLayer.leftMetricsKeyUI`](/Core/GlyphsCore/GSLayer/leftMetricsKeyUI) — Display and editing string for the left metrics key. - [`GSLayer leftMetricsKeyState`](/Core/GlyphsCore/GSLayer/leftMetricsKeyState) — State flags for the left metrics key. - [`GSLayer leftMetricsKeyState:`](/Core/GlyphsCore/GSLayer/leftMetricsKeyState:) — Display string for the left metrics key and its state. - [`GSLayer leftPlainMetricsKey`](/Core/GlyphsCore/GSLayer/leftPlainMetricsKey) — Plain effective metrics key for the left side bearing. - [`GSLayer.widthMetricsKeyUI`](/Core/GlyphsCore/GSLayer/widthMetricsKeyUI) — Display and editing string for the width metrics key. - [`GSLayer widthMetricsKeyUIFast`](/Core/GlyphsCore/GSLayer/widthMetricsKeyUIFast) — Fast display string for the width metrics key. - [`GSLayer widthMetricsKeyState`](/Core/GlyphsCore/GSLayer/widthMetricsKeyState) — State flags for the width metrics key. - [`GSLayer widthMetricsKeyState:`](/Core/GlyphsCore/GSLayer/widthMetricsKeyState:) — Display string for the width metrics key and its state. - [`GSLayer widthPlainMetricsKey`](/Core/GlyphsCore/GSLayer/widthPlainMetricsKey) — Plain effective metrics key for the advance width. - [`GSLayer.rightMetricsKeyUI`](/Core/GlyphsCore/GSLayer/rightMetricsKeyUI) — Display and editing string for the right metrics key. - [`GSLayer rightMetricsKeyState`](/Core/GlyphsCore/GSLayer/rightMetricsKeyState) — State flags for the right metrics key. - [`GSLayer rightMetricsKeyState:`](/Core/GlyphsCore/GSLayer/rightMetricsKeyState:) — Display string for the right metrics key and its state. - [`GSLayer rightPlainMetricsKey`](/Core/GlyphsCore/GSLayer/rightPlainMetricsKey) — Plain effective metrics key for the right side bearing. ### Vertical Metrics Keys UI - [`GSLayer.topMetricsKeyUI`](/Core/GlyphsCore/GSLayer/topMetricsKeyUI) — Display and editing string for the top metrics key. - [`GSLayer topMetricsKeyState`](/Core/GlyphsCore/GSLayer/topMetricsKeyState) — State flags for the top metrics key. - [`GSLayer topMetricsKeyState:`](/Core/GlyphsCore/GSLayer/topMetricsKeyState:) — Display string for the top metrics key and its state. - [`GSLayer topPlainMetricsKey`](/Core/GlyphsCore/GSLayer/topPlainMetricsKey) — Plain effective metrics key for the top side bearing. - [`GSLayer.bottomMetricsKeyUI`](/Core/GlyphsCore/GSLayer/bottomMetricsKeyUI) — Display and editing string for the bottom metrics key. - [`GSLayer bottomMetricsKeyState`](/Core/GlyphsCore/GSLayer/bottomMetricsKeyState) — State flags for the bottom metrics key. - [`GSLayer bottomMetricsKeyState:`](/Core/GlyphsCore/GSLayer/bottomMetricsKeyState:) — Display string for the bottom metrics key and its state. - [`GSLayer bottomPlainMetricsKey`](/Core/GlyphsCore/GSLayer/bottomPlainMetricsKey) — Plain effective metrics key for the bottom side bearing. - [`GSLayer vertWidthUI`](/Core/GlyphsCore/GSLayer/vertWidthUI) — Vertical advance width for display. - [`GSLayer.vertWidthMetricsKeyUI`](/Core/GlyphsCore/GSLayer/vertWidthMetricsKeyUI) — Display and editing string for the vertical width metrics key. - [`GSLayer vertWidthMetricsKeyState`](/Core/GlyphsCore/GSLayer/vertWidthMetricsKeyState) — State flags for the vertical width metrics key. - [`GSLayer vertWidthMetricsKeyState:defaultKey:`](/Core/GlyphsCore/GSLayer/vertWidthMetricsKeyState:defaultKey:) — Display string for the vertical width metrics key and its state. - [`GSLayer vertWidthPlainMetricsKey`](/Core/GlyphsCore/GSLayer/vertWidthPlainMetricsKey) — Plain effective metrics key for the vertical advance width. - [`GSLayer.vertOriginMetricsKeyUI`](/Core/GlyphsCore/GSLayer/vertOriginMetricsKeyUI) — Display and editing string for the vertical origin metrics key. - [`GSLayer vertOriginMetricsKeyState`](/Core/GlyphsCore/GSLayer/vertOriginMetricsKeyState) — State flags for the vertical origin metrics key. - [`GSLayer vertOriginMetricsKeyState:`](/Core/GlyphsCore/GSLayer/vertOriginMetricsKeyState:) — Display string for the vertical origin metrics key and its state. - [`GSLayer vertOriginPlainMetricsKey`](/Core/GlyphsCore/GSLayer/vertOriginPlainMetricsKey) — Plain effective metrics key for the vertical origin. ### Metrics Keys Utilities - [`GSLayer plainMetricsKeyUI:`](/Core/GlyphsCore/GSLayer/plainMetricsKeyUI:) — Plain metrics key for display and editing. - [`GSLayer attributedMetricsKey:fontSize:state:`](/Core/GlyphsCore/GSLayer/attributedMetricsKey:fontSize:state:) — Attributed display string for a metrics key. - [`GSLayer alignedMetricsValueForKey:`](/Core/GlyphsCore/GSLayer/alignedMetricsValueForKey:) — Numeric offset encoded in an aligned metrics key. - [`GSLayer metricsKeysOutOfSync`](/Core/GlyphsCore/GSLayer/metricsKeysOutOfSync) — Whether any horizontal metrics key is out of sync. - [`GSLayer metricsKeysInvalid`](/Core/GlyphsCore/GSLayer/metricsKeysInvalid) — Whether any horizontal metrics key is invalid. - [`GSLayer metricsLabelForSide:`](/Core/GlyphsCore/GSLayer/metricsLabelForSide:) — Localized label for a metric side. - [`GSLayer colorForMetricsState:`](/Core/GlyphsCore/GSLayer/colorForMetricsState:) — Display color for metrics key state flags. ### Metrics Locks - [`GSLayer lockReadMetrics`](/Core/GlyphsCore/GSLayer/lockReadMetrics) — Acquires the read lock for metrics. - [`GSLayer unlockReadMetrics`](/Core/GlyphsCore/GSLayer/unlockReadMetrics) — Releases the read lock for metrics. - [`GSLayer lockWriteMetrics`](/Core/GlyphsCore/GSLayer/lockWriteMetrics) — Acquires the write lock for metrics. - [`GSLayer unlockWriteMetrics`](/Core/GlyphsCore/GSLayer/unlockWriteMetrics) — Releases the write lock for metrics. ### Alignment Locks - [`GSLayer lockReadAlignInfo`](/Core/GlyphsCore/GSLayer/lockReadAlignInfo) — Acquires the read lock for alignment information. - [`GSLayer unlockReadAlignInfo`](/Core/GlyphsCore/GSLayer/unlockReadAlignInfo) — Releases the read lock for alignment information. - [`GSLayer lockWriteAlignInfo`](/Core/GlyphsCore/GSLayer/lockWriteAlignInfo) — Acquires the write lock for alignment information. - [`GSLayer unlockWriteAlignInfo`](/Core/GlyphsCore/GSLayer/unlockWriteAlignInfo) — Releases the write lock for alignment information. ## See Also - [GSLayer Kind](/Core/GlyphsCore/GSLayer-Kind) — The different roles that a layer can serve. - [GSLayer Shapes](/Core/GlyphsCore/GSLayer-Shapes) — The paths and components that form the outline of a layer. - [GSLayer Bounds](/Core/GlyphsCore/GSLayer-Bounds) — Bounding rectangles of outlines, selections, and metrics. - [GSLayer Grid](/Core/GlyphsCore/GSLayer-Grid) — Setting for rounding coordinates on a layer. - [GSLayer Background](/Core/GlyphsCore/GSLayer-Background) — Background content and reference images associated with a layer. - [GSLayer Anchors](/Core/GlyphsCore/GSLayer-Anchors) — Named attachment points on a layer. - [GSLayer Hints](/Core/GlyphsCore/GSLayer-Hints) — Manual and generated hint data on a layer. - [GSLayer Guides](/Core/GlyphsCore/GSLayer-Guides) — Layer-local guides used while editing outlines. - [GSLayer Kerning](/Core/GlyphsCore/GSLayer-Kerning) — Spacing adjustment between specific layers. - [GSLayer Annotations](/Core/GlyphsCore/GSLayer-Annotations) — Layer-local notes displayed with a glyph. - [GSLayer Interpolation](/Core/GlyphsCore/GSLayer-Interpolation) — Axis coordinates and rules that place layers in a design space. - [GSLayer Color](/Core/GlyphsCore/GSLayer-Color) — Colors used to draw a layer. - [GSLayer Attributes](/Core/GlyphsCore/GSLayer-Attributes) — Additional values stored for a layer. - [GSLayer Inspection](/Core/GlyphsCore/GSLayer-Inspection) — Intersections between layer outlines and line segments. - [GSLayer Editing](/Core/GlyphsCore/GSLayer-Editing) — Operations for modifying outlines and other layer content.