ashatora/openlayers
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Avoid try/catch, DOM and workers

Browse Source
This commit is contained in:
Andreas Hocevar
2020-03-21 15:49:01 +01:00
parent 6dcc54bfb8
commit 3f7f999db0
6 changed files with 85 additions and 100 deletions
Download Patch File Download Diff File Expand all files Collapse all files

72
src/ol/render/canvas.js
View File

@@ -6,7 +6,7 @@ import {createCanvasContext2D} from '../dom.js';
import {clear} from '../obj.js';
import BaseObject from '../Object.js';
import EventTarget from '../events/Target.js';
import {WINDOW} from '../has.js';
import {WORKER_OFFSCREEN_CANVAS} from '../has.js';
import {toString} from '../transform.js';
@@ -266,7 +266,8 @@ export const registerFont = (function() {
}
}
function fontCallback(font) {
return function(fontSpec) {
const font = getFontParameters(fontSpec);
if (!font) {
return;
}
@@ -284,31 +285,6 @@ export const registerFont = (function() {
}
}
}
}
return function(fontSpec) {
if (WINDOW) {
getFontParameters(fontSpec, fontCallback);
} else if (self.postMessage) {
/** @type {any} */
const worker = self;
worker.postMessage({
action: 'getFontParameters',
font: fontSpec
});
worker.addEventListener('message', function handler(event) {
if (event.data.action === 'getFontParameters') {
worker.removeEventListener('message', handler);
const font = event.data.font;
fontCallback(font);
if (!textHeights[fontSpec]) {
const metrics = measureText(fontSpec, 'Žg');
const lineHeight = isNaN(font.lineHeight) ? 1.2 : Number(font.lineHeight);
textHeights[fontSpec] = lineHeight * (metrics.actualBoundingBoxAscent + metrics.actualBoundingBoxDescent);
}
}
});
}
};
})();
@@ -323,22 +299,29 @@ export const measureTextHeight = (function() {
*/
let div;
const heights = textHeights;
return function(font) {
let height = heights[font];
return function(fontSpec) {
let height = heights[fontSpec];
if (height == undefined) {
if (!div) {
div = document.createElement('div');
div.innerHTML = 'M';
div.style.margin = '0 !important';
div.style.padding = '0 !important';
div.style.position = 'absolute !important';
div.style.left = '-99999px !important';
if (WORKER_OFFSCREEN_CANVAS) {
const font = getFontParameters(fontSpec);
const metrics = measureText(fontSpec, 'Žg');
const lineHeight = isNaN(Number(font.lineHeight)) ? 1.2 : Number(font.lineHeight);
textHeights[fontSpec] = lineHeight * (metrics.actualBoundingBoxAscent + metrics.actualBoundingBoxDescent);
} else {
if (!div) {
div = document.createElement('div');
div.innerHTML = 'M';
div.style.margin = '0 !important';
div.style.padding = '0 !important';
div.style.position = 'absolute !important';
div.style.left = '-99999px !important';
}
div.style.font = fontSpec;
document.body.appendChild(div);
height = div.offsetHeight;
heights[fontSpec] = height;
document.body.removeChild(div);
}
div.style.font = font;
document.body.appendChild(div);
height = div.offsetHeight;
heights[font] = height;
document.body.removeChild(div);
}
return height;
};
@@ -369,7 +352,6 @@ export function measureTextWidth(font, text) {
return measureText(font, text).width;
}
/**
* Measure text width using a cache.
* @param {string} font The font.
@@ -484,13 +466,13 @@ let createTransformStringCanvas = null;
* @return {string} CSS transform.
*/
export function createTransformString(transform) {
if (WINDOW) {
if (WORKER_OFFSCREEN_CANVAS) {
return toString(transform);
} else {
if (!createTransformStringCanvas) {
createTransformStringCanvas = createCanvasContext2D(1, 1).canvas;
}
createTransformStringCanvas.style.transform = toString(transform);
return createTransformStringCanvas.style.transform;
} else {
return toString(transform);
}
}