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Remove custom measure text #11747

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Remove custom measure text #11747

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333db30
Replace custom measureText function
javagl Jan 7, 2024
d24f2e1
Add comments about dimension in LabelCollection
javagl Jan 7, 2024
c6af94c
Merge branch 'main' into remove-custom-measure-text
ggetz Jan 23, 2024
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102 changes: 9 additions & 93 deletions packages/engine/Source/Core/writeTextToCanvas.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,98 +3,6 @@ import defaultValue from "./defaultValue.js";
import defined from "./defined.js";
import DeveloperError from "./DeveloperError.js";

function measureText(context2D, textString, font, stroke, fill) {
const metrics = context2D.measureText(textString);
const isSpace = !/\S/.test(textString);

if (!isSpace) {
const fontSize = document.defaultView
.getComputedStyle(context2D.canvas)
.getPropertyValue("font-size")
.replace("px", "");
const canvas = document.createElement("canvas");
const padding = 100;
const width = (metrics.width + padding) | 0;
const height = 3 * fontSize;
const baseline = height / 2;
canvas.width = width;
canvas.height = height;

const ctx = canvas.getContext("2d");
ctx.font = font;
ctx.fillStyle = "white";
ctx.fillRect(0, 0, canvas.width + 1, canvas.height + 1);

if (stroke) {
ctx.strokeStyle = "black";
ctx.lineWidth = context2D.lineWidth;
ctx.strokeText(textString, padding / 2, baseline);
}

if (fill) {
ctx.fillStyle = "black";
ctx.fillText(textString, padding / 2, baseline);
}

// Context image data has width * height * 4 elements, because
// each pixel's R, G, B and A are consecutive values in the array.
const pixelData = ctx.getImageData(0, 0, width, height).data;
const length = pixelData.length;
const width4 = width * 4;
let i, j;

let ascent, descent;
// Find the number of rows (from the top) until the first non-white pixel
for (i = 0; i < length; ++i) {
if (pixelData[i] !== 255) {
ascent = (i / width4) | 0;
break;
}
}

// Find the number of rows (from the bottom) until the first non-white pixel
for (i = length - 1; i >= 0; --i) {
if (pixelData[i] !== 255) {
descent = (i / width4) | 0;
break;
}
}

let minx = -1;
// For each column, for each row, check for first non-white pixel
for (i = 0; i < width && minx === -1; ++i) {
for (j = 0; j < height; ++j) {
const pixelIndex = i * 4 + j * width4;
if (
pixelData[pixelIndex] !== 255 ||
pixelData[pixelIndex + 1] !== 255 ||
pixelData[pixelIndex + 2] !== 255 ||
pixelData[pixelIndex + 3] !== 255
) {
minx = i;
break;
}
}
}

return {
width: metrics.width,
height: descent - ascent,
ascent: baseline - ascent,
descent: descent - baseline,
minx: minx - padding / 2,
};
}

return {
width: metrics.width,
height: 0,
ascent: 0,
descent: 0,
minx: 0,
};
}

let imageSmoothingEnabledName;

/**
Expand Down Expand Up @@ -168,7 +76,15 @@ function writeTextToCanvas(text, options) {
canvas.style.visibility = "hidden";
document.body.appendChild(canvas);

const dimensions = measureText(context2D, text, font, stroke, fill);
const metrics = context2D.measureText(text);
const dimensions = {
width: metrics.width,
height: metrics.actualBoundingBoxDescent + metrics.actualBoundingBoxAscent,
ascent: metrics.actualBoundingBoxAscent,
descent: metrics.actualBoundingBoxDescent,
minx: metrics.actualBoundingBoxLeft,
};

// Set canvas.dimensions to be accessed in LabelCollection
canvas.dimensions = dimensions;

Expand Down
15 changes: 15 additions & 0 deletions packages/engine/Source/Scene/LabelCollection.js
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,20 @@ import GraphemeSplitter from "grapheme-splitter";
// not have a billboard, depending on whether the texture info has an index into
// the the label collection's texture atlas. Invisible characters have no texture, and
// no billboard. However, it always has a valid dimensions object.
//
// A valid 'dimensions' object is an object that has the properties that are
// derived from a https://developer.mozilla.org/en-US/docs/Web/API/TextMetrics
// object (in pixels)
// - width: The width of the glyph, as given by TextMetrics.width
// - ascent: The the distance from the 'textBaseline' attribute to
// the top of the bounding rectangle of the glyph, as given by
// TextMetrics.actualBoundingBoxAscent
// - descent: The the distance from the 'textBaseline' attribute to
// the bottom of the bounding rectangle of the glyph, as given by
// TextMetrics.actualBoundingBoxDescent
// - minx: The distance of the alignment point given by the 'textAlign'
// property to the left side of the bounding rectangle of the glyph,
// as given by TextMetrics.actualBoundingBoxLeft
function Glyph() {
this.textureInfo = undefined;
this.dimensions = undefined;
Expand All @@ -33,6 +47,7 @@ function Glyph() {
// shared and reference counted across all labels. It may or may not have an
// index into the label collection's texture atlas, depending on whether the character
// has both width and height, but it always has a valid dimensions object.
// (See notes above about what that means)
function GlyphTextureInfo(labelCollection, index, dimensions) {
this.labelCollection = labelCollection;
this.index = index;
Expand Down