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Pass along the ability to measure and cache text width

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This commit is contained in:
Tim Schaub
2018-11-19 15:34:48 -07:00
parent e058eb3164
commit 8b50c3c6cb
4 changed files with 44 additions and 35 deletions
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16
src/ol/render/canvas.js
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@@ -324,6 +324,22 @@ export function measureTextWidth(font, text) {
}
/**
* Measure text width using a cache.
* @param {string} font The font.
* @param {string} text The text to measure.
* @param {Object<string, number>} cache A lookup of cached widths by text.
* @returns {number} The text width.
*/
export function measureAndCacheTextWidth(font, text, cache) {
if (text in cache) {
return cache[text];
}
const width = cache[text] = measureTextWidth(font, text);
return width;
}
/**
* @param {string} font Font to use for measuring.
* @param {Array<string>} lines Lines to measure.

27
src/ol/render/canvas/Executor.js
View File

@@ -19,10 +19,8 @@ import {
apply as applyTransform,
setFromArray as transformSetFromArray
} from '../../transform.js';
import {createCanvasContext2D} from '../../dom.js';
import {labelCache, defaultTextAlign, measureTextHeight, measureTextWidth, measureTextWidths} from '../canvas.js';
import {labelCache, defaultTextAlign, measureTextHeight, measureAndCacheTextWidth, measureTextWidths} from '../canvas.js';
/**
@@ -736,29 +734,22 @@ class CanvasExecutor {
const textState = this.textStates[textKey];
const font = textState.font;
const textScale = textState.scale;
const textScale = textState.scale * measurePixelRatio;
let widths = this.widths_[font];
if (!widths) {
this.widths_[font] = widths = {};
let cachedWidths;
if (font in this.widths_) {
cachedWidths = this.widths_[font];
} else {
cachedWidths = this.widths_[font] = {};
}
//FIXME Do not create this function on every call
const measure = function(text) {
let width = widths[text];
if (!width) {
width = widths[text] = measureTextWidth(font, text);
}
return width * textScale * measurePixelRatio;
};
const pathLength = lineStringLength(pixelCoordinates, begin, end, 2);
const textLength = measure(text);
const textLength = textScale * measureAndCacheTextWidth(font, text, cachedWidths);
if (overflow || textLength <= pathLength) {
const textAlign = this.textStates[textKey].textAlign;
const startM = (pathLength - textLength) * TEXT_ALIGN[textAlign];
const parts = drawTextOnPath(
pixelCoordinates, begin, end, 2, text, measure, startM, maxAngle);
pixelCoordinates, begin, end, 2, text, startM, maxAngle, textScale, measureAndCacheTextWidth, font, cachedWidths);
if (parts) {
let c, cc, chars, label, part;
if (strokeKey) {