pdf.js.mirror/web/draw_layer_builder.js
Titus Wormer 957e004e38
Make text selection more visible (bug 1879559)
References <https://bugzilla.mozilla.org/show_bug.cgi?id=1879559>
(“In HCM, the text selection is barely visible”).

Continues work from @calixteman who had a partial patch.

This PR improves viewer text-selection highlighting by rendering
selection shapes in the draw layer.

* add selection overlay rendering in the draw layer
  * significant code relates to selections spanning multiple text
    layers/pages, and edges/end-of-content boundaries
* clear selection on rotate/scale/scroll/spread changes

My main question is: how should it appear?
I don’t have access to the Figma file linked on bugzilla.

In the CSS (`draw_layer-builder.css`) there are 3 blocks:

* default
* `@supports` for browsers supporting `backdrop-filter`
* `forced-colors` mode

So it’s possible to design for those (or more).
Personally, the `backdrop-filter: invert(1)` is the most contrast,
so perhaps it’s better to use something else as the default,
and to use `invert(1)` if high contrast mode is used (maybe with a
`prefers-contrast` media query instead)?
2026-05-19 21:10:12 +02:00

88 lines
2.3 KiB
JavaScript

/* Copyright 2022 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { DrawLayer } from "pdfjs-lib";
/**
* @typedef DrawLayerBuilderOptions
* Configuration for {@linkcode DrawLayerBuilder}.
* @property {number} pageIndex
* Zero-based page index.
* @property {Element | null} [textLayer]
* Text layer element (optional).
* @property {Object | null} [filterFactory]
* Filter factory used to style selections (optional).
* @property {Object | null} [pageColors]
* Page foreground/background colors for HCM (optional).
*/
/**
* @typedef {Object} DrawLayerBuilderRenderOptions
* @property {string} [intent] - The default value is "display".
*/
class DrawLayerBuilder {
#drawLayer = null;
/**
* @param {DrawLayerBuilderOptions} options
* Configuration.
* @returns
* Instance.
*/
constructor(options) {
this.pageIndex = options.pageIndex;
this.textLayer = options.textLayer || null;
this.filterFactory = options.filterFactory || null;
this.pageColors = options.pageColors || null;
}
/**
* @param {DrawLayerBuilderRenderOptions} options
* @returns {Promise<void>}
*/
async render({ intent = "display" }) {
if (intent !== "display" || this.#drawLayer || this._cancelled) {
return;
}
this.#drawLayer = new DrawLayer({
pageIndex: this.pageIndex,
textLayer: this.textLayer,
filterFactory: this.filterFactory,
pageColors: this.pageColors,
});
}
cancel() {
this._cancelled = true;
if (!this.#drawLayer) {
return;
}
this.#drawLayer.destroy();
this.#drawLayer = null;
}
setParent(parent) {
this.#drawLayer?.setParent(parent);
}
getDrawLayer() {
return this.#drawLayer;
}
}
export { DrawLayerBuilder };