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* Bump MicroCOM to 0.11.4, add workaround for WinRT bug * menu.h - use ComPtr for COM stored references * Replaced raw COM pointers with smart ones * fixes * Use weak com ref from AvnMenuItem * Better smart pointer handling * Avalonia native readme update * review * missing dif * Just call the ctor like a normal personrelease/12.0.0-rc2
Nikita Tsukanov
6 months ago
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GitHub
GitHub
30 changed files with 305 additions and 115 deletions
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When running code review, please refer to the following documents if they are relevant to the changed parts of the codebase: |
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- `native/Avalonia.Native/**` -> `native/Avalonia.Native/README.md` |
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<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003"> |
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<PropertyGroup> |
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<!-- Uncomment to use local MicroCOM build --> |
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<!--<UseLocalMicroComBuild>true</UseLocalMicroComBuild>--> |
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<LocalMicroComPath Condition="'$(LocalMicroComPath)' == ''">$(MSBuildThisFileDirectory)/../../MicroCom</LocalMicroComPath> |
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</PropertyGroup> |
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<!-- Local build: delegate to MicroCom's own targets --> |
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<Import Condition="'$(UseLocalMicroComBuild)' == 'true'" |
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Project="$(LocalMicroComPath)/UseLocalBuild.targets" /> |
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<!-- NuGet packages: include based on property flags --> |
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<ItemGroup Condition="'$(UseLocalMicroComBuild)' != 'true'"> |
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<PackageReference Condition="'$(UseMicroCom)' == 'true'" |
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Include="MicroCom.Runtime" /> |
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<PackageReference Condition="'$(UseMicroComGenerator)' == 'true'" |
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Include="MicroCom.CodeGenerator" /> |
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<PackageReference Condition="'$(UseMicroComGeneratorMSBuild)' == 'true'" |
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Include="MicroCom.CodeGenerator.MSBuild" |
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PrivateAssets="all" /> |
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<PackageReference Condition="'$(UseMicroComGeneratorRoslyn)' == 'true'" |
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Include="MicroCom.CodeGenerator.Roslyn" |
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PrivateAssets="all" /> |
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</ItemGroup> |
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</Project> |
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# Avalonia.Native |
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This project implements the macOS native platform backend for Avalonia using Objective-C++ and COM (Component Object Model) interfaces. |
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## COM Reference Management |
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This codebase uses COM for cross-boundary object lifetime management. COM types are typically prefixed with `IAvn` (interfaces) or `Avn` (implementations). All COM objects ultimately derive from `IUnknown` and use reference counting (`AddRef`/`Release`). |
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**No raw COM pointer should ever be stored in class fields, instance variables, closures, or containers.** Raw COM pointers are only acceptable as function parameters and local variables with the lifetime of the current function call. |
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### COM Return Value Convention |
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By convention, any COM interface reference returned from a COM call has its reference counter incremented — it is the caller's responsibility to release it. With the `IFoo* GetFoo()` pattern it is hard to track this correctly, so all methods in `avn.idl` should use the out-parameter pattern instead: |
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```cpp |
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// WRONG — easy to leak or forget Release: |
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IFoo* GetFoo(); |
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// CORRECT — use HRESULT + out-parameter: |
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HRESULT GetFoo(IFoo** ppv); |
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``` |
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# Smart pointer types |
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### Objective-C Objects |
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For Objective-C objects, reference counting is provided by the compiler. Objective-C pointers _look_ like raw pointers, however every `NSObject*` reference is properly ref-counted by ARC (Automatic Reference Counting). No manual wrapping is needed for `NSObject*` fields. |
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### COM Smart Pointer Types |
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All retained COM references must use one of the following wrappers defined in `inc/comimpl.h`: |
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#### `ComPtr<T>` — Owning Reference |
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Use for any COM pointer that the holder needs to keep alive. |
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```cpp |
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ComPtr<IAvnWindow> _window; // correct |
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IAvnWindow* _window; // WRONG — raw COM pointer in a field |
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``` |
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#### `ComObjectWeakPtr<T>` — Non-Owning Weak Reference |
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Use for intentional non-owning references to `ComObject`-derived objects (internal implementations). Allows safely referencing COM objects without extending their lifetime. |
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```cpp |
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ComObjectWeakPtr<WindowBaseImpl> _parent; // correct |
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WindowBaseImpl* _parent; // WRONG |
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``` |
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Access weak references with `tryGet()`, which returns a `ComPtr<T>` (null if the object was destroyed): |
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```cpp |
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auto parent = _parent.tryGet(); |
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if (parent) { |
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parent->DoSomething(); |
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} |
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``` |
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#### `ComStaticPtr<T>` — Process-Lifetime Static Reference |
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Use for static/global COM singletons that must live for the entire process lifetime. Intentionally does **not** Release in its destructor to avoid crashes during app teardown. |
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```cpp |
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static ComStaticPtr<IAvnGlDisplay> GlDisplay; // correct |
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static IAvnGlDisplay* GlDisplay; // WRONG |
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``` |
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Assign via `set()`: |
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```cpp |
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GlDisplay.set(comnew<AvnGlDisplay>()); |
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``` |
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### `comnew<T>(args...)` — COM Object Factory |
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A convenience template similar to `std::make_shared`. Creates a new COM object and returns it wrapped in a `ComPtr<T>` with correct ownership (no double-AddRef): |
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```cpp |
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// Instead of: |
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ComPtr<Cursor> cursor(new Cursor(nsCursor), true); |
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// Write: |
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ComPtr<Cursor> cursor = comnew<Cursor>(nsCursor); |
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``` |
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This works because `new T()` on a `ComObject`-derived type starts with refcount=1, and `comnew` wraps it in a `ComPtr` that takes ownership without an additional `AddRef`. |
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