Allow parsing png files to fail if thumbnailing is successful

src/ContentMessages.ts

@@ -96,17 +96,22 @@ async function loadImageElement(imageFile: File): Promise<{
         // Thus we could slice the file down to only sniff the first 0x1000
         // bytes (but this makes extractPngChunks choke on the corrupt file)
         const headers = imageFile; //.slice(0, 0x1000);
-        parsePromise = readFileAsArrayBuffer(headers).then((arrayBuffer) => {
-            const buffer = new Uint8Array(arrayBuffer);
-            const chunks = extractPngChunks(buffer);
-            for (const chunk of chunks) {
-                if (chunk.name === "pHYs") {
-                    if (chunk.data.byteLength !== PHYS_HIDPI.length) return false;
-                    return chunk.data.every((val, i) => val === PHYS_HIDPI[i]);
+        parsePromise = readFileAsArrayBuffer(headers)
+            .then((arrayBuffer) => {
+                const buffer = new Uint8Array(arrayBuffer);
+                const chunks = extractPngChunks(buffer);
+                for (const chunk of chunks) {
+                    if (chunk.name === "pHYs") {
+                        if (chunk.data.byteLength !== PHYS_HIDPI.length) return false;
+                        return chunk.data.every((val, i) => val === PHYS_HIDPI[i]);
+                    }
                 }
-            }
-            return false;
-        });
+                return false;
+            })
+            .catch((e) => {
+                console.error("Failed to parse PNG", e);
+                return false;
+            });
     }
 
     const [hidpi] = await Promise.all([parsePromise, imgPromise]);

test/ContentMessages-test.ts

@@ -115,10 +115,25 @@ describe("ContentMessages", () => {
             );
         });
 
-        it("should fall back to m.file for invalid image files", async () => {
+        it("should use m.image for PNG files which cannot be parsed but successfully thumbnail", async () => {
             mocked(client.uploadContent).mockResolvedValue({ content_uri: "mxc://server/file" });
             const file = new File([], "fileName", { type: "image/png" });
             await contentMessages.sendContentToRoom(file, roomId, undefined, client, undefined);
+            expect(client.sendMessage).toHaveBeenCalledWith(
+                roomId,
+                null,
+                expect.objectContaining({
+                    url: "mxc://server/file",
+                    msgtype: "m.image",
+                }),
+            );
+        });
+
+        it("should fall back to m.file for invalid image files", async () => {
+            mocked(client.uploadContent).mockResolvedValue({ content_uri: "mxc://server/file" });
+            const file = new File([], "fileName", { type: "image/jpeg" });
+            mocked(BlurhashEncoder.instance.getBlurhash).mockRejectedValue("NOT_AN_IMAGE");
+            await contentMessages.sendContentToRoom(file, roomId, undefined, client, undefined);
             expect(client.sendMessage).toHaveBeenCalledWith(
                 roomId,
                 null,