mirror of
https://github.com/mozilla/pdf.js.git
synced 2026-07-30 19:07:22 +02:00
79 lines
2.9 KiB
JavaScript
79 lines
2.9 KiB
JavaScript
/* Copyright 2025 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.
|
|
*/
|
|
|
|
// Alpha lives in the high byte of a pixel on a little-endian host and in the
|
|
// low byte on a big-endian one.
|
|
const ALPHA_MASK =
|
|
new Uint8Array(new Uint32Array([1]).buffer)[0] === 1 ? 0xff000000 : 0x000000ff;
|
|
const RGB_MASK = ~ALPHA_MASK;
|
|
|
|
class QCMS {
|
|
static #memoryArray = null;
|
|
|
|
static _memory = null;
|
|
|
|
// Where the next `qcms_convert_array` result should land.
|
|
static _destBuffer = null;
|
|
|
|
static _destOffset = 0;
|
|
|
|
// Set when the destination is RGBA and its alpha channel already holds
|
|
// something worth keeping, which is the case whenever the image has an
|
|
// /SMask: `fillOpacity` has run by then. The Wasm side does not know about
|
|
// that, so it always fills alpha in, and the bytes are merged here instead of
|
|
// copied wholesale.
|
|
static _keepAlpha = false;
|
|
|
|
static get _memoryArray() {
|
|
const array = this.#memoryArray;
|
|
if (array?.byteLength) {
|
|
return array;
|
|
}
|
|
return (this.#memoryArray = new Uint8Array(this._memory.buffer));
|
|
}
|
|
}
|
|
|
|
function copy_result(ptr, len) {
|
|
// This function is called from the wasm module (it's an external
|
|
// "C" function). Its goal is to copy the result from the wasm memory
|
|
// to the destination buffer without any intermediate copies. The wasm side
|
|
// has already laid the result out the way the caller asked for it, so this is
|
|
// one bulk copy unless the destination's alpha has to survive.
|
|
const { _destBuffer, _destOffset, _keepAlpha, _memoryArray } = QCMS;
|
|
if (!_keepAlpha) {
|
|
_destBuffer.set(_memoryArray.subarray(ptr, ptr + len), _destOffset);
|
|
return;
|
|
}
|
|
const count = len >> 2;
|
|
const destStart = _destBuffer.byteOffset + _destOffset;
|
|
if (((destStart | ptr) & 3) === 0) {
|
|
// Both sides are pixel-aligned, so RGB can be merged a whole pixel at a
|
|
// time. `len` is a multiple of 4 here: the wasm side wrote RGBA.
|
|
const dest32 = new Uint32Array(_destBuffer.buffer, destStart, count);
|
|
const src32 = new Uint32Array(QCMS._memory.buffer, ptr, count);
|
|
for (let i = 0; i < count; i++) {
|
|
dest32[i] = (dest32[i] & ALPHA_MASK) | (src32[i] & RGB_MASK);
|
|
}
|
|
return;
|
|
}
|
|
for (let i = ptr, ii = ptr + len, j = _destOffset; i < ii; i += 4, j += 4) {
|
|
_destBuffer[j] = _memoryArray[i];
|
|
_destBuffer[j + 1] = _memoryArray[i + 1];
|
|
_destBuffer[j + 2] = _memoryArray[i + 2];
|
|
}
|
|
}
|
|
|
|
export { copy_result, QCMS };
|