qr_code_generator: support alphanumeric mode.

If the input to a QR code only uses certain values (A-Z, 0-9, plus a
handful of punctuation) then it can be encoded with 11 bits per pair of
symbols.

This change adds support for that mode in order to better support eSIM
QR codes, which can make use of this.

Change-Id: Id3164dada8c45606e6dfa92dd30f6eb213d9b19f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2623841
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Auto-Submit: Adam Langley <agl@chromium.org>
Reviewed-by: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#843045}

components/qr_code_generator/qr_code_generator_unittest.cc

@@ -12,44 +12,44 @@ TEST(QRCodeGenerator, Generate) {
   // that no DCHECKs are hit and that the output has the correct structure. When
   // run under ASan, this will also check that every byte of the output has been
   // written to.
+
+  constexpr size_t kMaxInputLen = 210;
+  uint8_t input[kMaxInputLen];
   QRCodeGenerator qr;
-  uint8_t input[QRCodeGenerator::V5::kInputBytes];
-  memset(input, 'a', sizeof(input));
-  base::Optional<QRCodeGenerator::GeneratedCode> qr_code = qr.Generate(input);
-  ASSERT_NE(qr_code, base::nullopt);
-  auto& qr_data = qr_code->data;
-
-  int index = 0;
-  ASSERT_EQ(qr_data.size(),
-            static_cast<size_t>(QRCodeGenerator::V5::kTotalSize));
-  for (int y = 0; y < QRCodeGenerator::V5::kSize; y++) {
-    for (int x = 0; x < QRCodeGenerator::V5::kSize; x++) {
-      ASSERT_EQ(0, qr_data[index++] & 0b11111100);
+  base::Optional<int> smallest_size;
+  base::Optional<int> largest_size;
+
+  for (const bool use_alphanum : {false, true}) {
+    SCOPED_TRACE(use_alphanum);
+    // 'A' is in the alphanumeric set, but 'a' is not.
+    memset(input, use_alphanum ? 'A' : 'a', sizeof(input));
+
+    for (size_t input_len = 30; input_len < kMaxInputLen; input_len += 10) {
+      SCOPED_TRACE(input_len);
+
+      base::Optional<QRCodeGenerator::GeneratedCode> qr_code =
+          qr.Generate(base::span<const uint8_t>(input, input_len));
+      ASSERT_NE(qr_code, base::nullopt);
+      auto& qr_data = qr_code->data;
+
+      if (!smallest_size || qr_code->qr_size < *smallest_size) {
+        smallest_size = qr_code->qr_size;
+      }
+      if (!largest_size || qr_code->qr_size > *largest_size) {
+        largest_size = qr_code->qr_size;
+      }
+
+      int index = 0;
+      for (int y = 0; y < qr_code->qr_size; y++) {
+        for (int x = 0; x < qr_code->qr_size; x++) {
+          ASSERT_EQ(0, qr_data[index++] & 0b11111100);
+        }
+      }
     }
   }
-}
-
-TEST(QRCodeGenerator, GenerateVersionSelection) {
-  // Ensure that dynamic version selection works,
-  // even when reusing the same QR Generator object.
-  // Longer inputs produce longer codes.
-  QRCodeGenerator qr;
 
-  uint8_t input_small[10];
-  memset(input_small, 'a', sizeof(input_small));
-  base::Optional<QRCodeGenerator::GeneratedCode> qr_code_small(
-      qr.Generate(input_small));
-  ASSERT_NE(qr_code_small, base::nullopt);
-  int size_small = qr_code_small->data.size();
-
-  uint8_t input_large[100];
-  memset(input_large, 'a', sizeof(input_large));
-  base::Optional<QRCodeGenerator::GeneratedCode> qr_code_large(
-      qr.Generate(input_large));
-  ASSERT_NE(qr_code_large, base::nullopt);
-  int size_large = qr_code_large->data.size();
-
-  ASSERT_GT(size_small, 0);
-  ASSERT_GT(size_large, 0);
-  ASSERT_GT(size_large, size_small);
+  // The generator should generate a variety of QR sizes.
+  ASSERT_TRUE(smallest_size);
+  ASSERT_TRUE(largest_size);
+  ASSERT_LT(*smallest_size, *largest_size);
 }