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Enable use in browsers with limited measureText properties #57

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Enable use in browsers with limited measureText properties #57

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9 changes: 5 additions & 4 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ export default class TinySDF {
this.buffer = buffer;
this.cutoff = cutoff;
this.radius = radius;
this.fontSize = fontSize;

// make the canvas size big enough to both have the specified buffer around the glyph
// for "halo", and account for some glyphs possibly being larger than their font size
Expand Down Expand Up @@ -51,20 +52,20 @@ export default class TinySDF {

// The integer/pixel part of the top alignment is encoded in metrics.glyphTop
// The remainder is implicitly encoded in the rasterization
const glyphTop = Math.ceil(actualBoundingBoxAscent);
const glyphTop = Math.ceil(actualBoundingBoxAscent) || this.fontSize;
const glyphLeft = 0;

// If the glyph overflows the canvas size, it will be clipped at the bottom/right
const glyphWidth = Math.max(0, Math.min(this.size - this.buffer, Math.ceil(actualBoundingBoxRight - actualBoundingBoxLeft)));
const glyphHeight = Math.min(this.size - this.buffer, glyphTop + Math.ceil(actualBoundingBoxDescent));
const glyphWidth = Math.max(0, Math.min(this.size - this.buffer, Math.ceil(actualBoundingBoxRight - actualBoundingBoxLeft))) || this.size - this.buffer;
const glyphHeight = Math.min(this.size - this.buffer, glyphTop + Math.ceil(actualBoundingBoxDescent)) || this.size - this.buffer;

const width = glyphWidth + 2 * this.buffer;
const height = glyphHeight + 2 * this.buffer;

const len = Math.max(width * height, 0);
const data = new Uint8ClampedArray(len);
const glyph = {data, width, height, glyphWidth, glyphHeight, glyphTop, glyphLeft, glyphAdvance};
if (glyphWidth === 0 || glyphHeight === 0) return glyph;
if (glyphWidth === 0 || isNaN(glyphWidth) || glyphHeight === 0 || isNaN(glyphHeight)) return glyph;

const {ctx, buffer, gridInner, gridOuter} = this;
ctx.clearRect(buffer, buffer, glyphWidth, glyphHeight);
Expand Down