Add _render.Texture.scale_mode

[damusss]

Should be straight forward. It's one of the texture properties you can freely get or set with SDL (both 2 and 3). Keeping it a constructor only argument makes no sense. That constructor only argument is also not conformed to SDL3. If this gets in I will make a follow up pull request that removes that argument (no deprecation needed since the module isn't public).
Currently to change the scale mode of a texture made from a surface your only option is create the texture and then use Texture.update, but when you do that the alpha of the surface isn't ported properly. One could say that's a bug of its own, but even if, doesn't make this property less useful.

SDL2 scale mode: https://wiki.libsdl.org/SDL2/SDL_ScaleMode
SDL3 scale mode: https://wiki.libsdl.org/SDL3/SDL_ScaleMode

I added SCALEMODE_PIXELART even if SDL2 doesn't have it, as it can just fall back to SCALEMODE_NEAREST, given the similarities between them.

Since the module isn't public and doesn't have a dedicated docs page I'm forced to add the docs to the stubs, which is what would have happened anyways when the docs were added to it.

Also, the C code for the scale mode isn't SDL3 compatible yet (the error macros have to branch for sdl3), a future pull request will make the whole module SDL3 compatible.

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• buildconfig/stubs/pygame/_render.pyi

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• buildconfig/stubs/pygame/_render.pyi

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📝 Walkthrough

Walkthrough

Adds texture scale-mode support: three new constants (SCALEMODE_LINEAR, SCALEMODE_NEAREST, SCALEMODE_PIXELART) and a Texture.scale_mode property implemented in C, exposed in type stubs, and covered by a unit test.

Changes

Cohort / File(s)	Summary
Type Stubs - Constants buildconfig/stubs/pygame/constants.pyi, buildconfig/stubs/pygame/locals.pyi	Added int constants SCALEMODE_LINEAR, SCALEMODE_NEAREST, SCALEMODE_PIXELART and updated __all__.
Type Stubs - Module Exports buildconfig/stubs/pygame/__init__.pyi	Exported the three new scale mode constants from the public API.
Type Stubs - Texture Property buildconfig/stubs/pygame/_render.pyi	Added Texture.scale_mode property (getter -> int, setter -> int) with docstring and version note.
C Implementation - Constants src_c/constants.c	Introduced SDL-version-gated constants for SCALEMODE_NEAREST, SCALEMODE_LINEAR, SCALEMODE_PIXELART (native on SDL3, mapped on older SDL).
C Implementation - Texture Property src_c/render.c	Added texture_get_scale_mode and texture_set_scale_mode and registered scale_mode in texture_getset to get/set SDL texture scale mode.
Tests test/render_test.py	Added test_scale_mode to assert default is SCALEMODE_NEAREST and that setting to SCALEMODE_LINEAR updates the property.

Sequence Diagram(s)

sequenceDiagram
    participant Py as Python (Texture)
    participant C as C Extension (render.c)
    participant SDL as SDL Library

    Py->>C: getattr(Texture.scale_mode)
    C->>SDL: SDL_GetTextureScaleMode(texture)
    SDL-->>C: scale_mode (int)
    C-->>Py: return int

    Py->>C: setattr(Texture.scale_mode = value)
    C->>SDL: SDL_SetTextureScaleMode(texture, value)
    SDL-->>C: success / error
    C-->>Py: None or raise error

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 7.69% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: adding a scale_mode property to _render.Texture, which is the core purpose of this PR.
Description check	✅ Passed	The description is clearly related to the changeset, explaining the rationale for adding the scale_mode property, SDL compatibility details, and implementation notes.

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@test/render_test.py`:
- Around line 276-279: The test uses a no-op comparison instead of setting the
property: replace the comparison expression "self.texture.scale_mode ==
pygame.SCALEMODE_LINEAR" with an assignment to set the scale mode (i.e., assign
pygame.SCALEMODE_LINEAR to self.texture.scale_mode) so that the subsequent
assertion in test_scale_mode actually verifies the setter behavior for the
texture.scale_mode property.

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Configuration used: Path: .coderabbit.yaml

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📥 Commits

Reviewing files that changed from the base of the PR and between bda4eae and 38a27f6.

📒 Files selected for processing (7)

• buildconfig/stubs/pygame/__init__.pyi
• buildconfig/stubs/pygame/_render.pyi
• buildconfig/stubs/pygame/constants.pyi
• buildconfig/stubs/pygame/locals.pyi
• src_c/constants.c
• src_c/render.c
• test/render_test.py