Allow creating images with a different grid for the gain map.

The main image can have a different number of cols/rows than
the gain map, or one can be a grid and the other be a single image.
Also allow setting differnet values for gain map metadata version
fields.
Add code in gainmaptest.cc to generate test images. These images
are used in tests and as seeds by the fuzzer.

Author: maryla-uc

include/avif/internal.h

@@ -774,7 +774,7 @@ typedef struct avifSequenceHeader
 AVIF_NODISCARD avifBool avifSequenceHeaderParse(avifSequenceHeader * header, const avifROData * sample, avifCodecType codecType);
 
 // ---------------------------------------------------------------------------
-// gain maps
+// Gain maps
 
 #if defined(AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP)
 
@@ -786,6 +786,37 @@ avifResult avifFindMinMaxWithoutOutliers(const float * gainMapF, int numPixels,
 
 #endif // AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP
 
+// ---------------------------------------------------------------------------
+// Internal encode
+//
+// These functions/options give extra flexibility to create non standard images for use in testing.
+
+typedef struct avifEncoderInternalOptions
+{
+#if defined(AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP)
+    // Options related to the 'tmap' (tone mapped image) box.
+    uint8_t tmapVersion;         // Value that should be written for the 'version' field (use default if 0)
+    uint16_t tmapMinimumVersion; // Value that should be written for the 'minimum_version' field (use default if 0)
+    uint16_t tmapWriterVersion;  // Value that should be written for the 'writerVersion' field (use default if 0)
+    avifBool tmapAddExtraBytes;  // Add arbitrary bytes at the end of the box
+#endif
+    char dummy; // Avoid emptry struct error when AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP is off
+} avifEncoderInternalOptions;
+
+// Sets extra encoding options.
+void avifEncoderSetInternalOptions(avifEncoder * encoder, const avifEncoderInternalOptions * internalOptions);
+
+// Variant of avifEncoderAddImageGrid() that allows creating images where 'gridCols' and 'gridRows' differ for
+// the base image and the gain map image.
+avifResult avifEncoderAddImageGridInternal(avifEncoder * encoder,
+                                           uint32_t gridCols,
+                                           uint32_t gridRows,
+                                           const avifImage * const * cellImages,
+                                           uint32_t gainMapGridCols,
+                                           uint32_t gainMapGridRows,
+                                           const avifImage * const * gainMapCellImages,
+                                           avifAddImageFlags addImageFlags);
+
 #define AVIF_INDEFINITE_DURATION64 UINT64_MAX
 #define AVIF_INDEFINITE_DURATION32 UINT32_MAX
 

src/write.c

@@ -500,8 +500,9 @@ exiftool "-icc_profile<=p3.icc" paris_exif_xmp_icc_gainmap_bigendian.jpg
 
 License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
 
-Source: generated with a modified libavif at https://github.com/maryla-uc/libavif/tree/weirdgainmaps
-by running `./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateGainMapImages ../tests/data/` 
+Source: generated by `avifgainmaptest.cc`. To update, set `kUpdateTestImages` to true
+in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 Contains a 4x3 color grid, a 4x3 alpha grid, and a 2x2 gain map grid.
 
@@ -511,8 +512,9 @@ Contains a 4x3 color grid, a 4x3 alpha grid, and a 2x2 gain map grid.
 
 License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
 
-Source: generated with a modified libavif at https://github.com/maryla-uc/libavif/tree/weirdgainmaps
-by running `./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateGainMapImages ../tests/data/` 
+Source: generated by `avifgainmaptest.cc`. To update, set `kUpdateTestImages` to true
+in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 Contains a single color image, single alpha image, and a 2x2 gain map grid.
 
@@ -522,8 +524,9 @@ Contains a single color image, single alpha image, and a 2x2 gain map grid.
 
 License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
 
-Source: generated with a modified libavif at https://github.com/maryla-uc/libavif/tree/weirdgainmaps
-by running `./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateGainMapImages ../tests/data/` 
+Source: generated by `avifgainmaptest.cc`. To update, set `kUpdateTestImages` to true
+in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 Contains a 4x3 color grid, a 4x3 alpha grid, and a single gain map image.
 
@@ -533,8 +536,9 @@ Contains a 4x3 color grid, a 4x3 alpha grid, and a single gain map image.
 
 License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
 
-Source: generated with a modified libavif at https://github.com/maryla-uc/libavif/tree/weirdgainmaps
-by running `./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateGainMapImages ../tests/data/` 
+Source: generated by `avifgainmaptest.cc`. To update, set `kUpdateTestImages` to true
+in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 Contains a gain map with the `version` field set to 99 in the tmap box.
 `minimum_version` and `writer_version` are 0.
@@ -545,8 +549,9 @@ Contains a gain map with the `version` field set to 99 in the tmap box.
 
 License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
 
-Source: generated with a modified libavif at https://github.com/maryla-uc/libavif/tree/weirdgainmaps
-by running `./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateGainMapImages ../tests/data/` 
+Source: generated by `avifgainmaptest.cc`. To update, set `kUpdateTestImages` to true
+in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 Contains a gain map with the `minimum_version` field set to 99 in the tmap box.
 `version` and `writer_version` are 0.
@@ -557,8 +562,9 @@ Contains a gain map with the `minimum_version` field set to 99 in the tmap box.
 
 License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
 
-Source: generated with a modified libavif at https://github.com/maryla-uc/libavif/tree/weirdgainmaps
-by running `./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateGainMapImages ../tests/data/` 
+Source: generated by `avifgainmaptest.cc`. To update, set `kUpdateTestImages` to true
+in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 Contains a gain map with the `writer_version` field set to 99 in the tmap box,
 and some extra unexpected bytes at the end of the gain map metadata.
@@ -570,8 +576,9 @@ and some extra unexpected bytes at the end of the gain map metadata.
 
 License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
 
-Source: generated with a modified libavif at https://github.com/maryla-uc/libavif/tree/weirdgainmaps
-by running `./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateGainMapImages ../tests/data/` 
+Source: generated by `avifgainmaptest.cc`. To update, set `kUpdateTestImages` to true
+in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 Contains a gain map with some extra unexpected bytes at the end of the gain map metadata.
 Contains `version`, `minimum_version` and `writer_version` are 0.
@@ -631,7 +638,8 @@ SDR image with a gain map to allow tone mapping to HDR.
 ![](seine_sdr_gainmap_big_srgb.avif)
 
 Source : modified version of `seine_sdr_gainmap_srgb.avif` with an upscaled gain map, generated using libavif's API.
-See `CreateTestImages` in `avifgainmaptest.cc` (set kUpdateTestImages to update images).
+To update, set `kUpdateTestImages` to true in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 SDR image with a gain map to allow tone mapping to HDR. The gain map's width and height are doubled compared to the base image.
 This is an atypical image just for testing. Typically, the gain map would be either the same size or smaller as the base image.
@@ -643,7 +651,8 @@ This is an atypical image just for testing. Typically, the gain map would be eit
 License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
 
 Source : created from `seine_hdr_srgb.avif` (for the base image) and `seine_sdr_gainmap_srgb.avif` (for the gain map) with libavif's API.
-See `CreateTestImages` in `avifgainmaptest.cc` (set kUpdateTestImages to update images).
+To update, set `kUpdateTestImages` to true in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 HDR image with a gain map to allow tone mapping to SDR.
 
@@ -654,7 +663,8 @@ HDR image with a gain map to allow tone mapping to SDR.
 License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
 
 Source : modified version of `seine_hdr_gainmap_srgb.avif` with a downscaled gain map, generated using libavif's API.
-See `CreateTestImages` in `avifgainmaptest.cc` (set kUpdateTestImages to update images).
+To update, set `kUpdateTestImages` to true in `avifgainmaptest.cc` and run the test:
+`./tests/avifgainmaptest --gtest_filter=GainMapTest.CreateTestImages ../tests/data/`
 
 SDR image with a gain map to allow tone mapping to HDR. The gain map's width and height are halved compared to the base image.