0045116606
AAPT Container Format (.apc) is a simple container that enumerates the various intermediate files that AAPT2 generates during the compile phase. The format is defined in formats.md. For now, continue using the .flat extension for the container file, and keep making use of the .flata zip for storing multiple files. This will allow easier integration with existing build systems and allow the evolution of the APC format to better handle arbitrarily large files. Test: make aapt2_tests Change-Id: Id7216e5b76316bdd683f0fa4eaf2d2da273ba815
45 lines
3.2 KiB
Markdown
45 lines
3.2 KiB
Markdown
# AAPT2 On-Disk Formats
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- AAPT2 Container Format (extension `.apc`)
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- AAPT2 Static Library Format (extension `.sapk`)
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## AAPT2 Container Format (extension `.apc`)
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The APC format (AAPT2 Container Format) is generated by AAPT2 during the compile phase and
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consumed by the AAPT2 link phase. It is a simple container format for storing compiled PNGs,
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binary and protobuf XML, and intermediate protobuf resource tables. It also stores all associated
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meta-data from the compile phase.
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### Format
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The file starts with a simple header. All multi-byte fields are little-endian.
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| Size (in bytes) | Field | Description |
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|:----------------|:--------------|:-----------------------------------------------------|
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| `4` | `magic` | The magic bytes must equal `'AAPT'` or `0x54504141`. |
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| `4` | `version` | The version of the container format. |
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| `4` | `entry_count` | The number of entries in this container. |
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This is followed by `entry_count` of the following data structure. It must be aligned on a 32-bit
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boundary, so if a previous entry ends unaligned, padding must be inserted.
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| Size (in bytes) | Field | Description |
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|:----------------|:---------------|:----------------------------------------------------------------------------------------------------------|
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| `4` | `entry_type` | The type of the entry. This can be one of two types: `RES_TABLE (0x00000000)` or `RES_FILE (0x00000001)`. |
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| `8` | `entry_length` | The length of the data that follows. |
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| `entry_length` | `data` | The payload. The contents of this varies based on the `entry_type`. |
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If the `entry_type` is equal to `RES_TABLE (0x00000000)`, the `data` field contains a serialized
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[aapt.pb.ResourceTable](Resources.proto).
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If the `entry_type` is equal to `RES_FILE (0x00000001)`, the `data` field contains the following:
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| Size (in bytes) | Field | Description |
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|:----------------|:---------------|:----------------------------------------------------------------------------------------------------------|
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| `4` | `header_size` | The size of the `header` field. |
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| `8` | `data_size` | The size of the `data` field. |
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| `header_size` | `header` | The serialized Protobuf message [aapt.pb.internal.CompiledFile](ResourcesInternal.proto). |
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| `x` | `padding` | Up to 4 bytes of zeros, if padding is necessary to align the `data` field on a 32-bit boundary. |
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| `data_size` | `data` | The payload, which is determined by the `type` field in the `aapt.pb.internal.CompiledFile`. This can be a PNG file, binary XML, or [aapt.pb.XmlNode](Resources.proto). |
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## AAPT2 Static Library Format (extension `.sapk`)
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