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54 lines
2.4 KiB
54 lines
2.4 KiB
7 months ago
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# View Compiler
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This directory contains an experimental compiler for layout files.
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It will take a layout XML file and produce a CompiledLayout.java file with a
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specialized layout inflation function.
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To use it, let's assume you had a layout in `my_layout.xml` and your app was in
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the Java language package `com.example.myapp`. Run the following command:
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viewcompiler my_layout.xml --package com.example.myapp --out CompiledView.java
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This will produce a `CompiledView.java`, which can then be compiled into your
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Android app. Then to use it, in places where you would have inflated
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`R.layouts.my_layout`, instead call `CompiledView.inflate`.
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Precompiling views like this generally improves the time needed to inflate them.
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This tool is still in its early stages and has a number of limitations.
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* Currently only one layout can be compiled at a time.
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* `merge` and `include` nodes are not supported.
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* View compilation is a manual process that requires code changes in the
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application.
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* This only works for apps that do not use a custom layout inflater.
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* Other limitations yet to be discovered.
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## DexBuilder Tests
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The DexBuilder has several low-level end to end tests to verify generated DEX
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code validates, runs, and has the correct behavior. There are, unfortunately, a
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number of pieces that must be added to generate new tests. Here are the
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components:
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* `dex_testcase_generator` - Written in C++ using `DexBuilder`. This runs as a
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build step produce the DEX files that will be tested on device. See the
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`genrule` named `generate_dex_testcases` in `Android.bp`. These files are then
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copied over to the device by TradeFed when running tests.
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* `DexBuilderTest` - This is a Java Language test harness that loads the
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generated DEX files and exercises methods in the file.
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To add a new DEX file test, follow these steps:
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1. Modify `dex_testcase_generator` to produce the DEX file.
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2. Add the filename to the `out` list of the `generate_dex_testcases` rule in
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`Android.bp`.
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3. Add a new `push` option to `AndroidTest.xml` to copy the DEX file to the
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device.
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4. Modify `DexBuilderTest.java` to load and exercise the new test.
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In each case, you should be able to cargo-cult the existing test cases.
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In general, you can probably get by without adding a new generated DEX file, and
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instead add more methods to the files that are already generated. In this case,
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you can skip all of steps 2 and 3 above, and simplify steps 1 and 4.
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