CanvasRenderingContext2D.textBaseline

The CanvasRenderingContext2D.textBaseline property of the Canvas 2D API specifies the current text baseline used when drawing text.

Value

Possible values:

"top"

The text baseline is the top of the em square.

"hanging"

The text baseline is the hanging baseline. (Used by Tibetan and other Indic scripts.)

"middle"

The text baseline is the middle of the em square.

"alphabetic"

The text baseline is the normal alphabetic baseline. Default value.

"ideographic"

The text baseline is the ideographic baseline; this is the bottom of the body of the characters, if the main body of characters protrudes beneath the alphabetic baseline. (Used by Chinese, Japanese, and Korean scripts.)

"bottom"

The text baseline is the bottom of the bounding box. This differs from the ideographic baseline in that the ideographic baseline doesn't consider descenders.

The default value is "alphabetic".

Examples

Comparison of property values

This example demonstrates the various textBaseline property values.

HTML

<canvas id="canvas" width="550" height="500"></canvas>

JavaScript

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');

const baselines = ['top', 'hanging', 'middle', 'alphabetic', 'ideographic', 'bottom'];
ctx.font = '36px serif';
ctx.strokeStyle = 'red';

baselines.forEach((baseline, index) => {
  ctx.textBaseline = baseline;
  const y = 75 + index * 75;
  ctx.beginPath();
  ctx.moveTo(0, y + 0.5);
  ctx.lineTo(550, y + 0.5);
  ctx.stroke();
  ctx.fillText(`Abcdefghijklmnop (${baseline})`, 0, y);
});

Result

Comparison of property values on the same line

As with the previous example, this example demonstrates the various textBaseline property values, but in this case with all of them lined up horizontally along the same line — to make it easier to see how they differ from each other.

HTML

<canvas id="canvas" width="724" height="160"></canvas>

JavaScript

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');

const baselines = ['top', 'hanging', 'middle', 'alphabetic', 'ideographic', 'bottom'];
ctx.font = '20px serif';
ctx.strokeStyle = 'red';

ctx.beginPath();
ctx.moveTo(0, 100);
ctx.lineTo(840, 100);
ctx.moveTo(0, 55);
ctx.stroke();

baselines.forEach((baseline, index) => {
  ctx.save();
  ctx.textBaseline = baseline;
  let x = index * 120 + 10;
  ctx.fillText('Abcdefghijk', x, 100);
  ctx.restore();
  ctx.fillText(baseline, x + 5, 50);
});

Result

Specifications

Specification
HTML Standard
# dom-context-2d-textbaseline-dev

Browser compatibility

BCD tables only load in the browser

See also