Return 0 dec rows when contentToDecode is gainmap (AOMediaCodec#3000)

Author: y-guyon

src/read.c

@@ -7125,6 +7125,14 @@ static uint32_t avifGetDecodedRowCount(const avifDecoder * decoder, const avifTi
 
 uint32_t avifDecoderDecodedRowCount(const avifDecoder * decoder)
 {
+    if (decoder->data->tileInfos[AVIF_ITEM_COLOR].tileCount == 0) {
+        // decoder->imageContentToDecode & AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA
+        // was likely 0 when avifDecoderNextImage() was called.
+        // avifDecoderDecodedRowCount() only describes decoder->image->yuvPlanes[0].
+        // There is no available luma plane, so return 0 decoded rows.
+        return 0;
+    }
+
     uint32_t minRowCount = decoder->image->height;
     for (int c = 0; c < AVIF_ITEM_CATEGORY_COUNT; ++c) {
         if (c == AVIF_ITEM_GAIN_MAP) {

tests/gtest/avifincrtest.cc

@@ -126,6 +126,34 @@ INSTANTIATE_TEST_SUITE_P(SinglePixel, IncrementalTest,
 
 //------------------------------------------------------------------------------
 
+// Check that avifDecoderDecodedRowCount() returns 0 unless
+// decoder->imageContentToDecode is set to at least
+// AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA.
+// Regression test for b/481550106.
+TEST(IncrementalTest, DecodeGainMapOnly) {
+  const testutil::AvifRwData encoded_avif = testutil::ReadFile(
+      std::string(data_path) + "seine_sdr_gainmap_srgb.avif");
+  ASSERT_NE(encoded_avif.size, 0u);
+  ImagePtr reference(avifImageCreateEmpty());
+  ASSERT_NE(reference, nullptr);
+  DecoderPtr decoder(avifDecoderCreate());
+  ASSERT_NE(decoder, nullptr);
+  ASSERT_EQ(avifDecoderReadMemory(decoder.get(), reference.get(),
+                                  encoded_avif.data, encoded_avif.size),
+            AVIF_RESULT_OK);
+  ASSERT_NE(reference->gainMap, nullptr);
+
+  decoder->imageContentToDecode = AVIF_IMAGE_CONTENT_GAIN_MAP;
+  ASSERT_EQ(
+      testutil::DecodeIncrementally(
+          encoded_avif, decoder.get(), /*is_persistent=*/true,
+          /*give_size_hint=*/true, /*use_nth_image_api=*/false, *reference,
+          /*cell_height=*/154, /*enable_fine_incremental_check=*/true),
+      AVIF_RESULT_OK);
+}
+
+//------------------------------------------------------------------------------
+
 }  // namespace
 }  // namespace avif
 

tests/gtest/avifincrtest_helpers.cc

@@ -333,7 +333,8 @@ avifResult DecodeIncrementally(const avifRWData& encoded_avif,
     data.available.size = std::min(data.available.size + step, data.full_size);
     parse_result = avifDecoderParse(decoder);
   }
-  if (data.available.size == data.full_size &&
+  if ((decoder->imageContentToDecode & AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA) &&
+      data.available.size == data.full_size &&
       expect_parse_success_from_partial_file) {
     // Can happen if the data is in 'idat', or if some metadata is at the end of
     // the file. But ideally this should be avoided.
@@ -362,15 +363,23 @@ avifResult DecodeIncrementally(const avifRWData& encoded_avif,
              previously_decoded_row_count, decoded_row_count);
       AVIF_CHECKERR(false, AVIF_RESULT_INVALID_ARGUMENT);
     }
-    const uint32_t min_decoded_row_count = GetMinDecodedRowCount(
-        reference.height, cell_height, reference.alphaPlane != nullptr,
-        reference.gainMap != nullptr, data.available.size, data.full_size,
-        enable_fine_incremental_check);
-    if (decoded_row_count < min_decoded_row_count) {
+    if (decoder->imageContentToDecode & AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA) {
+      const uint32_t min_decoded_row_count = GetMinDecodedRowCount(
+          reference.height, cell_height, reference.alphaPlane != nullptr,
+          reference.gainMap != nullptr, data.available.size, data.full_size,
+          enable_fine_incremental_check);
+      if (decoded_row_count < min_decoded_row_count) {
+        printf(
+            "ERROR: expected to have decoded at least %d rows with %zu "
+            "available bytes, but only %d were decoded\n",
+            min_decoded_row_count, data.available.size, decoded_row_count);
+        AVIF_CHECKERR(false, AVIF_RESULT_INVALID_ARGUMENT);
+      }
+    } else if (decoded_row_count != 0) {
+      // avifDecoderDecodedRowCount() is only for decoder->image->yuvPlanes[0].
       printf(
-          "ERROR: expected to have decoded at least %d rows with %zu available "
-          "bytes, but only %d were decoded\n",
-          min_decoded_row_count, data.available.size, decoded_row_count);
+          "ERROR: decoded row count shall be 0 unless "
+          "decoder->imageContentToDecode&AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA\n");
       AVIF_CHECKERR(false, AVIF_RESULT_INVALID_ARGUMENT);
     }
     ComparePartialYuva(reference, *decoder->image, decoded_row_count);
@@ -385,10 +394,18 @@ avifResult DecodeIncrementally(const avifRWData& encoded_avif,
     AVIF_CHECKERR(data.available.size == data.full_size,
                   AVIF_RESULT_INVALID_ARGUMENT);
   }
-  AVIF_CHECKERR(avifDecoderDecodedRowCount(decoder) == decoder->image->height,
-                AVIF_RESULT_INVALID_ARGUMENT);
-
-  ComparePartialYuva(reference, *decoder->image, reference.height);
+  const uint32_t decoded_row_count = avifDecoderDecodedRowCount(decoder);
+  if (decoder->imageContentToDecode & AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA) {
+    AVIF_CHECKERR(decoded_row_count == decoder->image->height,
+                  AVIF_RESULT_INVALID_ARGUMENT);
+    ComparePartialYuva(reference, *decoder->image, reference.height);
+  } else if (decoded_row_count != 0) {
+    // avifDecoderDecodedRowCount() is only for decoder->image->yuvPlanes[0].
+    printf(
+        "ERROR: decoded row count shall be 0 unless "
+        "decoder->imageContentToDecode&AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA\n");
+    AVIF_CHECKERR(false, AVIF_RESULT_INVALID_ARGUMENT);
+  }
   return AVIF_RESULT_OK;
 }