fix: Instance TSUID is needed to decode images

Author: wayfarer3130

.github/workflows/publish-package.yml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   publish-package:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     environment: publish
 
     steps:

.github/workflows/tests.yml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
 
     steps:
       - name: Checkout repository

src/api.js

@@ -1,6 +1,4 @@
-import { multipartEncode, multipartDecode } from './message.js';
-
-
+import { multipartEncode, multipartDecode, addHeaders } from './message.js';
 
 function isObject(obj) {
   return typeof obj === 'object' && obj !== null;
@@ -256,12 +254,16 @@ class DICOMwebClient {
       requestInstance.onreadystatechange = () => {
         if (requestInstance.readyState === 4) {
           if (requestInstance.status === 200) {
-            const contentType = requestInstance.getResponseHeader('Content-Type');
+            const contentType = requestInstance.getResponseHeader(
+              'Content-Type',
+            );
+            const headers = requestInstance.getAllResponseHeaders();
             // Automatically distinguishes between multipart and singlepart in an array buffer, and
             // converts them into a consistent type.
             if (contentType && contentType.indexOf('multipart') !== -1) {
               resolve(multipartDecode(requestInstance.response));
             } else if (requestInstance.responseType === 'arraybuffer') {
+              addHeaders(requestInstance.response, headers);
               resolve([requestInstance.response]);
             } else {
               resolve(requestInstance.response);

src/message.js

@@ -38,7 +38,7 @@ function identifyBoundary(header) {
   const parts = header.split('\r\n');
 
   for (let i = 0; i < parts.length; i++) {
-    if (parts[i].substr(0, 2) === '--') {
+    if (parts[i].substring(0, 2) === '--') {
       return parts[i];
     }
   }
@@ -179,16 +179,72 @@ function multipartEncode(
   };
 }
 
+/**
+ * Splits the header string into  parts and extracts the simple contentType
+ * and transferSyntaxUID, assigning them, plus the headers map into the destination object.
+ *
+ * @param {*} destination
+ * @param {string} headerString
+ */
+function addHeaders(destination, headerString) {
+  if (!headerString) {
+    return;
+  }
+  const headerLines = headerString.split('\r\n').filter(Boolean);
+  const headers = new Map();
+  let transferSyntaxUID = null,
+    contentType = null;
+
+  for (const line of headerLines) {
+    const colon = line.indexOf(':');
+    if (colon === -1) {
+      continue;
+    }
+    const name = line.substring(0, colon).toLowerCase();
+    const value = line.substring(colon + 1).trim();
+    if (headers.has(name)) {
+      headers.get(name).push(value);
+    } else {
+      headers.set(name, [value]);
+    }
+    if (name === 'content-type') {
+      const endSimpleType = value.indexOf(';');
+      contentType ||= value.substring(
+        0,
+        endSimpleType === -1 ? value.length : endSimpleType,
+      );
+      const transferSyntaxStart = value.indexOf('transfer-syntax=');
+      if (transferSyntaxStart !== -1) {
+        const endTsuid = value.indexOf(';', transferSyntaxStart);
+        transferSyntaxUID = value.substring(
+          transferSyntaxStart + 16,
+          endTsuid === -1 ? value.length : endTsuid,
+        );
+      }
+    }
+  }
+
+  Object.defineProperty(destination, 'headers', { value: headers });
+  Object.defineProperty(destination, 'contentType', { value: contentType });
+  Object.defineProperty(destination, 'transferSyntaxUID', {
+    value: transferSyntaxUID,
+  });
+}
+
 /**
  * Decode a Multipart encoded ArrayBuffer and return the components as an Array.
  *
  * @param {ArrayBuffer} response Data encoded as a 'multipart/related' message
- * @returns {Array} The content
+ * @returns {Uint8Array[]} The content as an array of Uint8Array
+ *    Each item shall have a contentType value, and a transferSyntaxUID if available,
+ *    as well as the headers Map.  See parseHeaders for output.
+ *
  */
 function multipartDecode(response) {
   // Use the raw data if it is provided in an appropriate format
-  const message = ArrayBuffer.isView(response) ? response : new Uint8Array(response);
-
+  const message = ArrayBuffer.isView(response)
+    ? response
+    : new Uint8Array(response);
   /* Set a maximum length to search for the header boundaries, otherwise
        findToken can run for a long time
     */
@@ -211,6 +267,8 @@ function multipartDecode(response) {
   const boundaryLength = boundary.length;
   const components = [];
 
+  const headers = header.substring(boundary.length + 2);
+
   let offset = boundaryLength;
 
   // Loop until we cannot find any more boundaries
@@ -240,6 +298,8 @@ function multipartDecode(response) {
     // Extract data from response message, excluding "\r\n"
     const spacingLength = 2;
     const data = response.slice(offset, boundaryIndex - spacingLength);
+    // TODO - extract header data on a per frame basis.
+    addHeaders(data, headers);
 
     // Add the data to the array of results
     components.push(data);
@@ -261,4 +321,5 @@ export {
   multipartEncode,
   multipartDecode,
   guid,
+  addHeaders,
 };