1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
/*
GoToSocial
Copyright (C) GoToSocial Authors admin@gotosocial.org
SPDX-License-Identifier: AGPL-3.0-or-later
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import { decode } from "blurhash";
// Generate a blurhash canvas for each image for
// each blurhash container and put it in the summary.
Array.from(document.getElementsByClassName('blurhash-container')).forEach(blurhashContainer => {
const hash = blurhashContainer.dataset.blurhashHash;
const thumbHeight = blurhashContainer.dataset.blurhashHeight;
const thumbWidth = blurhashContainer.dataset.blurhashWidth;
const thumbAspect = blurhashContainer.dataset.blurhashAspect;
/*
It's very expensive to draw big canvases
with blurhashes, so use tiny ones, keeping
aspect ratio of the original thumbnail.
*/
var useWidth = 32;
var useHeight = 32;
switch (true) {
case thumbWidth > thumbHeight:
useHeight = Math.round(useWidth / thumbAspect);
break;
case thumbHeight > thumbWidth:
useWidth = Math.round(useHeight * thumbAspect);
break;
}
const pixels = decode(
hash,
useWidth,
useHeight,
);
// Create canvas of appropriate size.
const canvas = document.createElement("canvas");
canvas.width = useWidth;
canvas.height = useHeight;
// Draw the image data into the canvas.
const ctx = canvas.getContext("2d");
const imageData = ctx.createImageData(
useWidth,
useHeight,
);
imageData.data.set(pixels);
ctx.putImageData(imageData, 0, 0);
// Put the canvas inside the container.
blurhashContainer.appendChild(canvas);
});
// Add a smooth transition from blurhash
// to image for each sensitive image.
Array.from(document.getElementsByTagName('img')).forEach(img => {
if (!img.dataset.blurhashHash) {
// Has no blurhash,
// can't transition smoothly.
return;
}
if (img.dataset.sensitive !== "true") {
// Not sensitive, smooth
// transition doesn't matter.
return;
}
if (img.complete) {
// Image already loaded,
// don't stub it with anything.
return;
}
const parentSlide = img.closest(".photoswipe-slide");
if (!parentSlide) {
// Parent slide was nil,
// can't do anything.
return;
}
const blurhashContainer = document.querySelector("div[data-blurhash-hash=\"" + img.dataset.blurhashHash + "\"]");
if (!blurhashContainer) {
// Blurhash div was nil,
// can't do anything.
return;
}
const canvas = blurhashContainer.children[0];
if (!canvas) {
// Canvas was nil,
// can't do anything.
return;
}
// "Replace" the hidden img with a canvas
// that will show initially when it's clicked.
const clone = canvas.cloneNode(true);
clone.getContext("2d").drawImage(canvas, 0, 0);
parentSlide.prepend(clone);
img.className = img.className + " hidden";
// Add a listener so that when the spoiler
// is opened, loading of the image begins.
const parentSummary = img.closest(".media-spoiler");
parentSummary.addEventListener("toggle", (_) => {
if (parentSummary.hasAttribute("open") && !img.complete) {
img.loading = "eager";
}
});
// Add a callback that triggers
// when image loading is complete.
img.addEventListener("load", () => {
// Show the image now that it's loaded.
img.className = img.className.replace(" hidden", "");
// Reset the lazy loading tag to its initial
// value. This doesn't matter too much since
// it's already loaded but it feels neater.
img.loading = "lazy";
// Remove the temporary blurhash
// canvas so only the image shows.
const canvas = parentSlide.getElementsByTagName("canvas")[0];
if (canvas) {
canvas.remove();
}
});
});
|
