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[TextLayer] Avoid unnecessary font updates in _layoutText (PR 11097 follow-up)

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*This should obviously have been done in PR 11097, but for some reason I completely overlooked it; sorry about that.*

There's no good reason to update the font unless you're actually going to measure the width of the textContent. This can reduce unnecessary font switching a fair bit, even for documents which are somewhat simple/short (in e.g. the `tracemonkey.pdf` file this cuts the amount of font switches almost in half).
This commit is contained in:
Jonas Jenwald 2019-08-28 16:08:06 +02:00
parent 184d416639
commit 106b239c5d
1 changed files with 12 additions and 13 deletions
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25
src/display/text_layer.js
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@ -525,26 +525,25 @@ var renderTextLayer = (function renderTextLayerClosure() {
},
_layoutText(textDiv) {
let textLayerFrag = this._container;
let textDivProperties = this._textDivProperties.get(textDiv);
const textDivProperties = this._textDivProperties.get(textDiv);
if (textDivProperties.isWhitespace) {
return;
}
const { fontSize, fontFamily, } = textDiv.style;
// Only build font string and set to context if different from last.
if (fontSize !== this._layoutTextLastFontSize ||
fontFamily !== this._layoutTextLastFontFamily) {
this._layoutTextCtx.font = `${fontSize} ${fontFamily}`;
this._layoutTextLastFontSize = fontSize;
this._layoutTextLastFontFamily = fontFamily;
}
let transform = '';
if (textDivProperties.canvasWidth !== 0) {
const { fontSize, fontFamily, } = textDiv.style;
// Only build font string and set to context if different from last.
if (fontSize !== this._layoutTextLastFontSize ||
fontFamily !== this._layoutTextLastFontFamily) {
this._layoutTextCtx.font = `${fontSize} ${fontFamily}`;
this._layoutTextLastFontSize = fontSize;
this._layoutTextLastFontFamily = fontFamily;
}
// Only measure the width for multi-char text divs, see `appendText`.
const { width, } = this._layoutTextCtx.measureText(textDiv.textContent);
if (width > 0) {
textDivProperties.scale = textDivProperties.canvasWidth / width;
transform = `scaleX(${textDivProperties.scale})`;
@ -560,7 +559,7 @@ var renderTextLayer = (function renderTextLayerClosure() {
textDiv.style.transform = transform;
}
this._textDivProperties.set(textDiv, textDivProperties);
textLayerFrag.appendChild(textDiv);
this._container.appendChild(textDiv);
},
_render: function TextLayer_render(timeout) {