Empty HandlerBox name instead of "libavif"

CHANGELOG.md

@@ -22,6 +22,7 @@ The changes are relative to the previous release, unless the baseline is specifi
  error.
  The `gainMapPresent` field is now only populated if enableParsingGainMapMetadata
  is true.
+* Write an empty HandlerBox name field instead of "libavif" (saves 7 bytes).
 
 ## [1.1.1] - 2024-07-30
 

src/write.c

@@ -771,6 +771,18 @@ static avifResult avifEncoderWriteExtendedColorProperties(avifRWStream * dedupSt
  return AVIF_RESULT_OK;
 }
 
+static avifResult avifRWStreamWriteHandlerBox(avifRWStream * s, const char handlerType[4])
+{
+ avifBoxMarker hdlr;
+ AVIF_CHECKRES(avifRWStreamWriteFullBox(s, "hdlr", AVIF_BOX_SIZE_TBD, 0, 0, &hdlr));
+ AVIF_CHECKRES(avifRWStreamWriteU32(s, 0)); // unsigned int(32) pre_defined = 0;
+ AVIF_CHECKRES(avifRWStreamWriteChars(s, handlerType, 4)); // unsigned int(32) handler_type;
+ AVIF_CHECKRES(avifRWStreamWriteZeros(s, 12)); // const unsigned int(32)[3] reserved = 0;
+ AVIF_CHECKRES(avifRWStreamWriteChars(s, "", 1)); // string name; (writing null terminator)
+ avifRWStreamFinishBox(s, hdlr);
+ return AVIF_RESULT_OK;
+}
+
 // Write unassociated metadata items (EXIF, XMP) to a small meta box inside of a trak box.
 // These items are implicitly associated with the track they are contained within.
 static avifResult avifEncoderWriteTrackMetaBox(avifEncoder * encoder, avifRWStream * s)
@@ -791,13 +803,7 @@ static avifResult avifEncoderWriteTrackMetaBox(avifEncoder * encoder, avifRWStre
  avifBoxMarker meta;
  AVIF_CHECKRES(avifRWStreamWriteFullBox(s, "meta", AVIF_BOX_SIZE_TBD, 0, 0, &meta));
 
- avifBoxMarker hdlr;
- AVIF_CHECKRES(avifRWStreamWriteFullBox(s, "hdlr", AVIF_BOX_SIZE_TBD, 0, 0, &hdlr));
- AVIF_CHECKRES(avifRWStreamWriteU32(s, 0)); // unsigned int(32) pre_defined = 0;
- AVIF_CHECKRES(avifRWStreamWriteChars(s, "pict", 4)); // unsigned int(32) handler_type;
- AVIF_CHECKRES(avifRWStreamWriteZeros(s, 12)); // const unsigned int(32)[3] reserved = 0;
- AVIF_CHECKRES(avifRWStreamWriteChars(s, "libavif", 8)); // string name; (writing null terminator)
- avifRWStreamFinishBox(s, hdlr);
+ AVIF_CHECKRES(avifRWStreamWriteHandlerBox(s, "pict"));
 
  avifBoxMarker iloc;
  AVIF_CHECKRES(avifRWStreamWriteFullBox(s, "iloc", AVIF_BOX_SIZE_TBD, 0, 0, &iloc));
@@ -3095,13 +3101,7 @@ avifResult avifEncoderFinish(avifEncoder * encoder, avifRWData * output)
  // -----------------------------------------------------------------------
  // Write hdlr
 
- avifBoxMarker hdlr;
- AVIF_CHECKRES(avifRWStreamWriteFullBox(&s, "hdlr", AVIF_BOX_SIZE_TBD, 0, 0, &hdlr));
- AVIF_CHECKRES(avifRWStreamWriteU32(&s, 0)); // unsigned int(32) pre_defined = 0;
- AVIF_CHECKRES(avifRWStreamWriteChars(&s, "pict", 4)); // unsigned int(32) handler_type;
- AVIF_CHECKRES(avifRWStreamWriteZeros(&s, 12)); // const unsigned int(32)[3] reserved = 0;
- AVIF_CHECKRES(avifRWStreamWriteChars(&s, "libavif", 8)); // string name; (writing null terminator)
- avifRWStreamFinishBox(&s, hdlr);
+ AVIF_CHECKRES(avifRWStreamWriteHandlerBox(&s, "pict"));
 
  // -----------------------------------------------------------------------
  // Write pitm
@@ -3447,13 +3447,7 @@ avifResult avifEncoderFinish(avifEncoder * encoder, avifRWData * output)
  AVIF_CHECKRES(avifRWStreamWriteU16(&s, 0)); // unsigned int(16) pre_defined = 0;
  avifRWStreamFinishBox(&s, mdhd);
 
- avifBoxMarker hdlrTrak;
- AVIF_CHECKRES(avifRWStreamWriteFullBox(&s, "hdlr", AVIF_BOX_SIZE_TBD, 0, 0, &hdlrTrak));
- AVIF_CHECKRES(avifRWStreamWriteU32(&s, 0)); // unsigned int(32) pre_defined = 0;
- AVIF_CHECKRES(avifRWStreamWriteChars(&s, (item->itemCategory == AVIF_ITEM_ALPHA) ? "auxv" : "pict", 4)); // unsigned int(32) handler_type;
- AVIF_CHECKRES(avifRWStreamWriteZeros(&s, 12)); // const unsigned int(32)[3] reserved = 0;
- AVIF_CHECKRES(avifRWStreamWriteChars(&s, "libavif", 8)); // string name; (writing null terminator)
- avifRWStreamFinishBox(&s, hdlrTrak);
+ AVIF_CHECKRES(avifRWStreamWriteHandlerBox(&s, (item->itemCategory == AVIF_ITEM_ALPHA) ? "auxv" : "pict"));
 
  avifBoxMarker minf;
  AVIF_CHECKRES(avifRWStreamWriteBox(&s, "minf", AVIF_BOX_SIZE_TBD, &minf));

tests/CMakeLists.txt

@@ -130,6 +130,7 @@ if(AVIF_ENABLE_GTEST)
  endif()
 
  add_avif_gtest(avifgridapitest)
+ add_avif_gtest(avifheadertest)
  add_avif_gtest_with_data(avifilocextenttest)
  add_avif_gtest(avifimagetest)
  add_avif_gtest_with_data(avifincrtest avifincrtest_helpers)
@@ -356,6 +357,7 @@ if(AVIF_CODEC_AVM_ENABLED)
  avifdimgtest
  avifencodetest
  avifgridapitest
+ avifheadertest
  avifincrtest
  avifiostatstest
  avifmetadatatest

tests/data/goldens/circle-trns-after-plte.png.avif.xml

@@ -8,8 +8,8 @@
 <BrandEntry AlternateBrand="miaf"/>
 <BrandEntry AlternateBrand="MA1A"/>
 </FileTypeBox>
-<MetaBox Size="397" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="390" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>

tests/data/goldens/dog_exif_extended_xmp_icc.jpg.avif.xml

@@ -8,8 +8,8 @@
 <BrandEntry AlternateBrand="miaf"/>
 <BrandEntry AlternateBrand="MA1B"/>
 </FileTypeBox>
-<MetaBox Size="495" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="488" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>

tests/data/goldens/kodim03_23_animation.avif.xml

@@ -11,8 +11,8 @@
 <BrandEntry AlternateBrand="miaf"/>
 <BrandEntry AlternateBrand="MA1B"/>
 </FileTypeBox>
-<MetaBox Size="242" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="235" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>
@@ -51,10 +51,10 @@
 </ItemPropertyAssociationBox>
 </ItemPropertiesBox>
 </MetaBox>
-<MovieBox Size="717" Type="moov" Specification="p12" Container="file cmvd" >
+<MovieBox Size="710" Type="moov" Specification="p12" Container="file cmvd" >
 <MovieHeaderBox Size="120" Type="mvhd" Version="1" Flags="0" Specification="p12" Container="moov" CreationTime="REDACTED" ModificationTime="REDACTED" TimeScale="25" Duration="-1" NextTrackID="1">
 </MovieHeaderBox>
-<TrackBox Size="589" Type="trak" Specification="p12" Container="moov" >
+<TrackBox Size="582" Type="trak" Specification="p12" Container="moov" >
 <TrackHeaderBox Size="104" Type="tkhd" Version="1" Flags="1" Specification="p12" Container="trak" CreationTime="REDACTED" ModificationTime="REDACTED" TrackID="1" Duration="-1" Width="768.00" Height="512.00">
 <Matrix m11="0x00010000" m12="0x00000000" m13="0x00000000" m21="0x00000000" m22="0x00010000" m23="0x00000000" m31="0x00000000" m32="0x00000000" m33="0x40000000"/>
 </TrackHeaderBox>
@@ -63,10 +63,10 @@
 <EditListEntry Duration="2" MediaTime="0" MediaRate="1"/>
 </EditListBox>
 </EditBox>
-<MediaBox Size="433" Type="mdia" Specification="p12" Container="trak" >
+<MediaBox Size="426" Type="mdia" Specification="p12" Container="trak" >
 <MediaHeaderBox Size="44" Type="mdhd" Version="1" Flags="0" Specification="p12" Container="mdia" CreationTime="REDACTED" ModificationTime="REDACTED" TimeScale="25" Duration="2" LanguageCode="und">
 </MediaHeaderBox>
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <MediaInformationBox Size="341" Type="minf" Specification="p12" Container="mdia" >
 <VideoMediaHeaderBox Size="20" Type="vmhd" Version="0" Flags="1" Specification="p12" Container="minf" >
@@ -105,7 +105,7 @@
 <SampleSizeEntry Size="REDACTED"/>
 </SampleSizeBox>
 <ChunkOffsetBox Size="20" Type="stco" Version="0" Flags="0" Specification="p12" Container="stbl" EntryCount="1">
-<ChunkEntry offset="1011"/>
+<ChunkEntry offset="997"/>
 </ChunkOffsetBox>
 <SyncSampleBox Size="20" Type="stss" Version="0" Flags="0" Specification="p12" Container="stbl" EntryCount="1">
 <SyncSampleEntry sampleNumber="1"/>

tests/data/goldens/kodim03_23_animation_keyframes.avif.xml

@@ -12,8 +12,8 @@
 <BrandEntry AlternateBrand="miaf"/>
 <BrandEntry AlternateBrand="MA1B"/>
 </FileTypeBox>
-<MetaBox Size="242" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="235" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>
@@ -52,10 +52,10 @@
 </ItemPropertyAssociationBox>
 </ItemPropertiesBox>
 </MetaBox>
-<MovieBox Size="697" Type="moov" Specification="p12" Container="file cmvd" >
+<MovieBox Size="690" Type="moov" Specification="p12" Container="file cmvd" >
 <MovieHeaderBox Size="120" Type="mvhd" Version="1" Flags="0" Specification="p12" Container="moov" CreationTime="REDACTED" ModificationTime="REDACTED" TimeScale="25" Duration="-1" NextTrackID="1">
 </MovieHeaderBox>
-<TrackBox Size="569" Type="trak" Specification="p12" Container="moov" >
+<TrackBox Size="562" Type="trak" Specification="p12" Container="moov" >
 <TrackHeaderBox Size="104" Type="tkhd" Version="1" Flags="1" Specification="p12" Container="trak" CreationTime="REDACTED" ModificationTime="REDACTED" TrackID="1" Duration="-1" Width="768.00" Height="512.00">
 <Matrix m11="0x00010000" m12="0x00000000" m13="0x00000000" m21="0x00000000" m22="0x00010000" m23="0x00000000" m31="0x00000000" m32="0x00000000" m33="0x40000000"/>
 </TrackHeaderBox>
@@ -64,10 +64,10 @@
 <EditListEntry Duration="2" MediaTime="0" MediaRate="1"/>
 </EditListBox>
 </EditBox>
-<MediaBox Size="413" Type="mdia" Specification="p12" Container="trak" >
+<MediaBox Size="406" Type="mdia" Specification="p12" Container="trak" >
 <MediaHeaderBox Size="44" Type="mdhd" Version="1" Flags="0" Specification="p12" Container="mdia" CreationTime="REDACTED" ModificationTime="REDACTED" TimeScale="25" Duration="2" LanguageCode="und">
 </MediaHeaderBox>
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <MediaInformationBox Size="321" Type="minf" Specification="p12" Container="mdia" >
 <VideoMediaHeaderBox Size="20" Type="vmhd" Version="0" Flags="1" Specification="p12" Container="minf" >
@@ -106,7 +106,7 @@
 <SampleSizeEntry Size="REDACTED"/>
 </SampleSizeBox>
 <ChunkOffsetBox Size="20" Type="stco" Version="0" Flags="0" Specification="p12" Container="stbl" EntryCount="1">
-<ChunkEntry offset="995"/>
+<ChunkEntry offset="981"/>
 </ChunkOffsetBox>
 </SampleTableBox>
 </MediaInformationBox>

tests/data/goldens/kodim03_yuv420_8bpc.y4m.avif.xml

@@ -8,8 +8,8 @@
 <BrandEntry AlternateBrand="miaf"/>
 <BrandEntry AlternateBrand="MA1B"/>
 </FileTypeBox>
-<MetaBox Size="242" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="235" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>

tests/data/goldens/paris_exif_xmp_gainmap_bigendian.jpg.avif.xml

@@ -9,8 +9,8 @@
 <BrandEntry AlternateBrand="MA1B"/>
 <BrandEntry AlternateBrand="tmap"/>
 </FileTypeBox>
-<MetaBox Size="606" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="599" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>

tests/data/goldens/paris_exif_xmp_gainmap_bigendian_ignore.jpg.avif.xml

@@ -8,8 +8,8 @@
 <BrandEntry AlternateBrand="miaf"/>
 <BrandEntry AlternateBrand="MA1B"/>
 </FileTypeBox>
-<MetaBox Size="379" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="372" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>

tests/data/goldens/paris_exif_xmp_gainmap_littleendian.jpg.avif.xml

@@ -9,8 +9,8 @@
 <BrandEntry AlternateBrand="MA1B"/>
 <BrandEntry AlternateBrand="tmap"/>
 </FileTypeBox>
-<MetaBox Size="606" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="599" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>

tests/data/goldens/paris_exif_xmp_icc_gainmap_bigendian.jpg.avif.xml

@@ -9,8 +9,8 @@
 <BrandEntry AlternateBrand="MA1B"/>
 <BrandEntry AlternateBrand="tmap"/>
 </FileTypeBox>
-<MetaBox Size="1121" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="1114" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>

tests/data/goldens/paris_icc_exif_xmp.png.avif.xml

@@ -8,8 +8,8 @@
 <BrandEntry AlternateBrand="miaf"/>
 <BrandEntry AlternateBrand="MA1A"/>
 </FileTypeBox>
-<MetaBox Size="988" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
-<HandlerBox Size="40" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="libavif" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
+<MetaBox Size="981" Type="meta" Version="0" Flags="0" Specification="p12" Container="file moov trak moof traf udta" >
+<HandlerBox Size="33" Type="hdlr" Version="0" Flags="0" Specification="p12" Container="mdia meta minf" hdlrType="pict" Name="" reserved1="0" reserved2="data:application/octet-string,000000000000000000000000">
 </HandlerBox>
 <PrimaryItemBox Size="14" Type="pitm" Version="0" Flags="0" Specification="p12" Container="meta" item_ID="1">
 </PrimaryItemBox>

tests/gtest/avifheadertest.cc

@@ -0,0 +1,39 @@
+// Copyright 2024 Google LLC
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <algorithm>
+
+#include "avif/avif.h"
+#include "aviftest_helpers.h"
+#include "gtest/gtest.h"
+
+namespace avif {
+namespace {
+
+TEST(BasicTest, EncodeDecode) {
+ ImagePtr image = testutil::CreateImage(12, 34, 8, AVIF_PIXEL_FORMAT_YUV420,
+ AVIF_PLANES_ALL);
+ ASSERT_NE(image, nullptr);
+ testutil::FillImageGradient(image.get());
+ const testutil::AvifRwData avif = testutil::Encode(image.get());
+ ASSERT_NE(avif.data, nullptr);
+
+ // Make sure the HandlerBox is as small as possible, meaning its name field is
+ // empty.
+ const uint8_t kHdlr[] = {'h', 'd', 'l', 'r'};
+ const uint8_t* hdlr_position =
+ std::search(avif.data, avif.data + avif.size, kHdlr, kHdlr + 4);
+ ASSERT_NE(hdlr_position, avif.data + avif.size);
+ // The previous four bytes represent the size of the box as a big endian
+ // unsigned integer.
+ constexpr uint8_t kExpectedHdlrSize =
+ /*size field*/ 4 + /*"hdlr"*/ 4 + /*version*/ 3 + /*flags*/ 1 +
+ /*pre_defined*/ 4 + /*handler_type*/ 4 + /*reserved*/ 4 * 3 + /*name*/ 1;
+ ASSERT_EQ(hdlr_position[-4], 0);
+ ASSERT_EQ(hdlr_position[-3], 0);
+ ASSERT_EQ(hdlr_position[-2], 0);
+ ASSERT_EQ(hdlr_position[-1], kExpectedHdlrSize);
+}
+
+} // namespace
+} // namespace avif