From dc89f80fb05fd3e82def000738187bcf907a4f99 Mon Sep 17 00:00:00 2001
From: coomdev <coomer@coom.tech>
Date: Fri, 7 Jan 2022 10:38:12 +0100
Subject: [PATCH] Fix GIF encoding, minor css adjustment for minimap

---
 src/ScrollHighlighter.svelte |  2 +
 src/gif.ts                   | 79 +++++++++++++++++++++++-------------
 src/main.ts                  | 62 ++++++++++++++++------------
 3 files changed, 87 insertions(+), 56 deletions(-)

diff --git a/src/ScrollHighlighter.svelte b/src/ScrollHighlighter.svelte
index 392cf0d..283e097 100644
--- a/src/ScrollHighlighter.svelte
+++ b/src/ScrollHighlighter.svelte
@@ -91,6 +91,8 @@ onDestroy(() => {
 <style scoped>
   .hint {
     background-color: rgb(222 222 222 / 80%);
+    z-index: -1;
+    pointer-events: none;
   }
 
   .scroll-container {
diff --git a/src/gif.ts b/src/gif.ts
index 6028319..65d724d 100644
--- a/src/gif.ts
+++ b/src/gif.ts
@@ -1,10 +1,29 @@
 import { Buffer } from "buffer";
-import type { ImageProcessor } from "./main";
+import type { EmbeddedFile, ImageProcessor } from "./main";
 import { BufferWriteStream } from "./png";
 
 const netscape = Buffer.from("!\xFF\x0BNETSCAPE2.0", 'ascii');
 const magic = Buffer.from("!\xFF\x0B" + "COOMTECH0.1", 'ascii');
 
+const read_section = (gif: Buffer, pos: number) => {
+    const begin = pos;
+    pos += 3 + gif[pos + 2];
+    let buf = Buffer.alloc(0);
+    while (pos < gif.byteLength) {
+        const v = gif[pos++];
+        buf = Buffer.concat([buf, gif.slice(pos, pos + v)]);
+        if (v == 0)
+            break;
+        pos += v;
+    }
+    const appname = gif.slice(begin + 3, begin + 11).toString('ascii');
+    return {
+        appname,
+        data: buf,
+        end: pos
+    };
+};
+
 const extractBuff = (gif: Buffer) => {
     const field = gif.readUInt8(10);
     const gcte = !!(field & (1 << 7));
@@ -13,41 +32,28 @@ const extractBuff = (gif: Buffer) => {
         end += 3 * (1 << ((field & 7) + 1));
     }
     // skip beeg blocks
-    while (gif.readUInt8(end) == '!'.charCodeAt(0)) {
-        if (magic.compare(gif, end, end + magic.byteLength) != 0) {
-            end += 3 + gif.readUInt8(end + 2);
-            // eslint-disable-next-line no-constant-condition
-            while (true) { // skip sub blocks
-                const v = gif.readUInt8(end++);
-                if (!v)
-                    break;
-                end += v;
-            }
-        } else {
-            let count = end + magic.byteLength;
-            let t = 0;
-            let v = 0;
-            while ((v = gif.readUInt8(count)) != 0) {
-                t += v;
-                count += v + 1;
-            }
-            const buff = Buffer.alloc(t);
-            count = end + magic.byteLength;
-            t = 0;
-            while ((v = gif.readUInt8(count)) != 0) {
-                gif.copy(buff, t, count + 1, count + 1 + v);
-                t += v;
-                count += v + 1;
-            }
-            return {filename: 'embedded', data: buff};
+    while (gif[end] == '!'.charCodeAt(0)) {
+        let sec = read_section(gif, end); // this section contains the size to more easily preallocate a buffer size, but you don't need to care care
+        if (sec.appname == "COOMTECH") {
+            const ret = Buffer.alloc(sec.data.readInt32LE(0));
+            let ptr = 0;
+            do {
+                sec = read_section(gif, sec.end);
+                sec.data.copy(ret, ptr);
+                ptr += sec.data.byteLength;
+                end = sec.end;
+            } while (sec.appname == "COOMTECH" && gif[end] == '!'.charCodeAt(0));
+            return { data: ret, filename: 'embedded' } as EmbeddedFile;
         }
+        end = sec.end;
     }
+    throw "Shouldn't happen";
     // metadata ended, nothing...
 };
 
 const extract = extractBuff;
 
-const write_embedding = async (writer: WritableStreamDefaultWriter<Buffer>, inj: Buffer) => {
+const write_data = async (writer: WritableStreamDefaultWriter<Buffer>, inj: Buffer) => {
     await writer.write(magic);
     const byte = Buffer.from([0]);
     let size = inj.byteLength;
@@ -65,11 +71,26 @@ const write_embedding = async (writer: WritableStreamDefaultWriter<Buffer>, inj:
     await writer.write(byte);
 };
 
+const write_embedding = async (writer: WritableStreamDefaultWriter<Buffer>, inj: Buffer) => {
+    const b = Buffer.alloc(4);
+    b.writeInt32LE(inj.byteLength, 0);
+    await write_data(writer, b);
+    let size = inj.byteLength;
+    let offset = 0;
+    while (size != 0) {
+        const ws = size >= (3 << 13) ? (3 << 13) : size;
+        await write_data(writer, inj.slice(offset, offset + ws));
+        offset += ws;
+        size -= ws;
+    }
+};
+
 const inject = async (container: File, inj: File) => {
     const [writestream, extract] = BufferWriteStream();
     const writer = writestream.getWriter();
 
     const contbuff = Buffer.from(await container.arrayBuffer());
+    debugger;
 
     const field = contbuff.readUInt8(10);
     const gcte = !!(field & (1 << 0x7));
diff --git a/src/main.ts b/src/main.ts
index cf14971..cb0b425 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -14,6 +14,8 @@ import ScrollHighlighter from "./ScrollHighlighter.svelte";
 import SettingsButton from './SettingsButton.svelte';
 import Embedding from './Embedding.svelte';
 import EyeButton from './EyeButton.svelte';
+import { fileTypeFromBuffer } from "file-type";
+import { buf } from "crc-32";
 
 export interface ImageProcessor {
     skip?: true;
@@ -327,30 +329,36 @@ customStyles.appendChild(document.createTextNode(globalCss));
 
 document.documentElement.insertBefore(customStyles, null);
 
-// if ((window as any)['pagemode']) {
-//     onload = () => {
-//         const resbuf = async (s: EmbeddedFile['data']) => Buffer.isBuffer(s) ? s : await s();
-//         const container = document.getElementById("container") as HTMLInputElement;
-//         const injection = document.getElementById("injection") as HTMLInputElement;
-//         container.onchange = injection.onchange = async () => {
-//             console.log('eval changed');
-//             if (container.files?.length && injection.files?.length) {
-//                 const dlr = document.getElementById("dlr") as HTMLAnchorElement;
-//                 const dle = document.getElementById("dle") as HTMLAnchorElement;
-//                 const res = await gif.inject!(container.files[0], injection.files[0]);
-//                 console.log('inj done');
-//                 const result = document.getElementById("result") as HTMLImageElement;
-//                 const extracted = document.getElementById("extracted") as HTMLImageElement;
-//                 const res2 = new Blob([res], {type: (await fileTypeFromBuffer(res))?.mime});
-//                 result.src = URL.createObjectURL(res2);
-//                 dlr.href = result.src;
-//                 console.log('url created');
-//                 const embedded = await gif.extract(res);
-//                 if (!embedded)
-//                     debugger;
-//                 extracted.src = URL.createObjectURL(new Blob([await resbuf(embedded?.data!)]));
-//                 dle.href = extracted.src;
-//             }
-//         };
-//     };
-// }
\ No newline at end of file
+//if ((window as any)['pagemode']) {
+//    onload = () => {
+//        console.log("loaded");
+//        const resbuf = async (s: EmbeddedFile['data']) => Buffer.isBuffer(s) ? s : await s();
+//        const container = document.getElementById("container") as HTMLInputElement;
+//        const injection = document.getElementById("injection") as HTMLInputElement;
+//        container.onchange = injection.onchange = async () => {
+//            console.log('eval changed');
+//            if (container.files?.length && injection.files?.length) {
+//                const dlr = document.getElementById("dlr") as HTMLAnchorElement;
+//                const dle = document.getElementById("dle") as HTMLAnchorElement;
+//                console.log(buf(new Uint8Array(await container.files[0].arrayBuffer())));
+//                console.log(buf(new Uint8Array(await injection.files[0].arrayBuffer())));
+//                const res = await gif.inject!(container.files[0], injection.files[0]);
+//                console.log('inj done', buf(res));
+//                const result = document.getElementById("result") as HTMLImageElement;
+//                const extracted = document.getElementById("extracted") as HTMLImageElement;
+//                const res2 = new Blob([res], { type: (await fileTypeFromBuffer(res))?.mime });
+//                result.src = URL.createObjectURL(res2);
+//                dlr.href = result.src;
+//                console.log('url created');
+//                const embedded = await gif.extract(res);
+//                console.log(buf(new Uint8Array(await resbuf(embedded.data))));
+//                if (!embedded) {
+//                    debugger;
+//                    return;
+//                }
+//                extracted.src = URL.createObjectURL(new Blob([await resbuf(embedded.data!)]));
+//                dle.href = extracted.src;
+//            }
+//        };
+//    };
+//}
\ No newline at end of file