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The TextMetrics interface represents the dimension of a text in the canvas, as created by the CanvasRenderingContext2D.measureText() method.

Properties

TextMetrics.width Read only
Is a double giving the calculated width of a segment of inline text in CSS pixels. It takes into account the current font of the context.
TextMetrics.actualBoundingBoxLeft Read only
Is a double giving the distance parallel to the baseline from the alignment point given by the CanvasRenderingContext2D.textAlign property to the left side of the bounding rectangle of the given text, in CSS pixels.
TextMetrics.actualBoundingBoxRight Read only
Is a double giving the distance parallel to the baseline from the alignment point given by the CanvasRenderingContext2D.textAlign property to the right side of the bounding rectangle of the given text, in CSS pixels.
TextMetrics.fontBoundingBoxAscent Read only
Is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline attribute to the top of the highest bounding rectangle of all the fonts used to render the text, in CSS pixels.
TextMetrics.fontBoundingBoxDescent Read only
Is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline attribute to the top of the bounding rectangle of all the fonts used to render the text, in CSS pixels.
TextMetrics.actualBoundingBoxAscent Read only
Is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline attribute to the top of the bounding rectangle used to render the text, in CSS pixels.
TextMetrics.actualBoundingBoxDescent Read only
Is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline attribute to the bottom of the bounding rectangle used to render the text, in CSS pixels.
TextMetrics.emHeightAscent Read only
Is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline property to the top of the em square in the line box, in CSS pixels.
TextMetrics.emHeightDescent Read only
Is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline property to the bottom of the em square in the line box, in CSS pixels.
TextMetrics.hangingBaseline Read only
Is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline property to the hanging baseline of the line box, in CSS pixels.
TextMetrics.alphabeticBaseline Read only
Is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline property to the alphabetic baseline of the line box, in CSS pixels.
TextMetrics.ideographicBaseline Read only
Is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline property to the ideographic baseline of the line box, in CSS pixels.

Specifications

Specification Status Comment
WHATWG HTML Living Standard
The definition of 'TextMetrics' in that specification.
Living Standard Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 4.0 1.5 (1.8) 9.0 9.0 3.1
width 4.0 1.5 (1.8) 9.0 9.0 3.1
actualBoundingBoxLeft,
actualBoundingBoxRight,
fontBoundingBoxAscent,
fontBoundingBoxDescent,
actualBoundingBoxAscent,
actualBoundingBoxDescent,
emHeightAscent,
emHeightDescent,
hangingBaseline,
alphabeticBaseline,
ideographicBaseline
(Yes)[1] Not supported[2] ? ? ?
Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 2.1 1.0 (1.8) ? 10.0 3.2
width 2.1 1.0 (1.8) ? 10.0 3.2
actualBoundingBoxLeft,
actualBoundingBoxRight,
fontBoundingBoxAscent,
fontBoundingBoxDescent,
actualBoundingBoxAscent,
actualBoundingBoxDescent,
emHeightAscent,
emHeightDescent,
hangingBaseline,
alphabeticBaseline,
ideographicBaseline
? Not supported[2] ? ? ?

[1] To turn on advanced text metrics, set the flag ExperimentalCanvasFeatures to true.

[2] Gecko does not implement this feature yet. See the related bug 1102584.

See also

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