From a357a83860aaac90b37832de066e5a5a016910ea Mon Sep 17 00:00:00 2001
From: memdmp <memdmp@estrogen.zone>
Date: Wed, 25 Mar 2026 12:22:23 +0100
Subject: feat: figured i'd revisit this code i wrote as a shitpost, it seems
 quite decent actually

---
 src/lib/test/canvas/CanvasCopy.svelte | 148 ++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 src/lib/test/canvas/CanvasCopy.svelte

(limited to 'src/lib/test/canvas/CanvasCopy.svelte')

diff --git a/src/lib/test/canvas/CanvasCopy.svelte b/src/lib/test/canvas/CanvasCopy.svelte
new file mode 100644
index 0000000..7795116
--- /dev/null
+++ b/src/lib/test/canvas/CanvasCopy.svelte
@@ -0,0 +1,148 @@
+<!-- Small test for making copy-pasting images harder (without putting any major technical restrictions in there, and keeping the site itself working if it errors) -->
+
+<script lang="ts">
+  import { onDestroy, tick } from 'svelte';
+  import { canvascopy, shuffleInPlace } from './CanvasCopyLib';
+
+  let {
+    src,
+    alt,
+    loading = 'lazy',
+    width,
+    height,
+    artifacts = 'fix',
+    useBg = false,
+  }: {
+    src: string;
+    alt: string;
+    width?: number;
+    height?: number;
+    loading?: 'eager' | 'lazy' | undefined | null;
+    artifacts?: 'fix' | 'keep';
+    useBg?: boolean;
+  } = $props();
+  let blobUrl = $state(undefined as undefined | string);
+  let additionalOverlayedBlobs = $state([] as string[]);
+  let additionalOverlayedBlobsDone = $state(false);
+  // svelte-ignore state_referenced_locally
+  let lastLoadedSrc = $state(src);
+
+  const blobify = (
+    image: HTMLImageElement,
+    artifacts: 'fix' | 'keep' = 'fix',
+  ) => {
+    firstLoad = false;
+    if (image.src.startsWith('blob:') || image.src === blobUrl) {
+      // The image is likely a partial of the image. Tell the browser to reload the original
+      lastLoadedSrc = '';
+    } else {
+      console.debug('[blobify] Entering blobify');
+      if (blobUrl) URL.revokeObjectURL(blobUrl);
+      if (additionalOverlayedBlobs.length) {
+        for (const blobUrl of additionalOverlayedBlobs)
+          URL.revokeObjectURL(blobUrl);
+        additionalOverlayedBlobs.length = 0;
+      }
+      additionalOverlayedBlobsDone = false;
+
+      // Need to update lastLoaded to prevent unneeded refreshes
+      console.debug('[blobify] Set lastload to', src);
+      const lastLoad = lastLoadedSrc;
+      lastLoadedSrc = src;
+
+      let nextPerf = 0;
+      canvascopy(
+        image,
+        artifacts,
+        () => blobUrl,
+        (blob) => (blobUrl = blob),
+        tick,
+        (blob) => additionalOverlayedBlobs.push(blob),
+        () => shuffleInPlace(additionalOverlayedBlobs).shift()!,
+        () => {
+          const p = performance.now();
+          if (p >= nextPerf) {
+            nextPerf = p + 10;
+            return new Promise((rs) => requestAnimationFrame(() => rs(void 0)));
+          }
+        },
+      )
+        .then(() => {
+          additionalOverlayedBlobsDone = true;
+        })
+        .catch((e) => {
+          lastLoadedSrc = lastLoad;
+          throw e;
+        });
+    }
+  };
+
+  let imgloaded = $state(false);
+  let image = $state(null as null | HTMLImageElement);
+
+  $effect(() => {
+    if (lastLoadedSrc !== src && blobUrl) {
+      URL.revokeObjectURL(blobUrl);
+      blobUrl = undefined;
+      imgloaded = false;
+      console.debug('[effect] Revoking blobURL due to src change');
+    }
+  });
+  let firstLoad = true;
+  $effect(() => {
+    if (imgloaded && image) {
+      console.debug('[effect][imgload] Calling blobify. State:', {
+        imgloaded,
+        image,
+        artifacts,
+      });
+      if (firstLoad) {
+        requestIdleCallback(() => blobify(image!, artifacts));
+        firstLoad = false;
+      } else requestAnimationFrame(() => blobify(image!, artifacts));
+    }
+  });
+
+  onDestroy(() => {
+    if (blobUrl) URL.revokeObjectURL(blobUrl);
+  });
+</script>
+
+<div
+  class="relative max-w-max max-h-max block"
+  aria-label={additionalOverlayedBlobsDone ? alt : undefined}
+  role={additionalOverlayedBlobsDone ? 'img' : undefined}
+>
+  <img
+    class="select-none"
+    {loading}
+    src={blobUrl ?? src}
+    alt={additionalOverlayedBlobsDone ? undefined : alt}
+    {width}
+    {height}
+    onload={() => (blobUrl !== undefined ? void 0 : (imgloaded = true))}
+    onloadstart={() => (blobUrl !== undefined ? void 0 : (imgloaded = false))}
+    bind:this={image}
+  />
+  {#if additionalOverlayedBlobsDone}
+    {#each additionalOverlayedBlobs
+      .map( (v, i, a) => (useBg ? (i % 2 === 0 ? ([v, a[i + 1]] as [string, string | undefined]) : undefined!) : ([v] as const)), )
+      .filter((v) => v !== undefined) as [blob1, blob2]}
+      <img
+        src={blob1}
+        {loading}
+        alt=""
+        class="blob-img"
+        style={blob2 ? `background-image: url(${JSON.stringify(blob2)});}` : ''}
+      />
+    {/each}
+  {/if}
+</div>
+
+<style lang="postcss">
+  @reference "tailwindcss";
+
+  .blob-img {
+    @apply absolute top-0 left-0 h-full w-full bg-contain select-none;
+  }
+</style>
-- 
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