AppDimens.Net 3.6.0

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📐 AppDimens.Net

Responsive dimensions for .NET MAUI — scaled dp/sp with snapshot caching and allocation-free fast lanes.

The principal module: core engine, Scaled strategy (Sdp/Sdpa/Hdp/Wdp), inverters, facilitators, builder, ambient context and cache.

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✨ Why AppDimens?

Fixed dp values don't scale across phones, foldables, tablets and desktops. AppDimens scales your dimensions from a screen qualifier (smallest-width, height or width), with bit-a-bit parity to the Kotlin appdimens-kmp library, an event-driven resize watcher, and a snapshot-partitioned cache that makes hot-path lookups allocation-free.

float pad = 16.Sdp();   // scales with smallest-width — the classic SDP lane
float h   = 48.Hdp();   // scales with height axis
float w   = 24.Wdp();   // scales with width axis
float sp  = 16.Ssp();   // text size, font-scale aware

📦 Installation

dotnet add package AppDimens.Net

🚀 Getting started

Attach a window once (MAUI) — before creating any page:

using AppDimens.Net.Maui.Platform;

protected override Window CreateWindow(IActivationState? state)
{
    var window = new Window();
    AppDimensMaui.AttachWindow(window);          // ambient context + cache + resize watcher
    window.Page = new NavigationPage(new MainPage());
    return window;
}

Parameterless extensions resolve through AppDimensAmbient.Require(). Outside MAUI (unit tests, design time, Blazor), pass an IAppDimensContext explicitly or use FakeAppDimensContext.

🧭 The Scaled strategy

scaled = value × screenDp(qualifier) ÷ 300            (base design width: 300 dp)

Inverters — axis-swap rules for rotation

Facilitators — conditional values without if-chains

16.SdpRotate(24, Orientation.Landscape);      // 24 when landscape, else scaled 16
16.SdpMode(20, UiModeType.Foldable);          // UI-mode aware
16.SdpQualifier(DpQualifier.SmallWidth, 600f, 28);  // ≥600 sw → 28
16.SdpScreen(UiModeType.Normal, DpQualifier.SmallWidth, 700f, 32);
// …and *Plain variants that take pre-scaled branches (no re-scaling).

Builder — declarative screens

float size = 18.ScaledDp()
    .AspectRatio()
    .Screen(DpQualifier.SmallWidth, 600f, 26f)     // tablet
    .Screen(Orientation.Landscape, 22f)            // landscape override
    .Screen(UiModeType.Foldable, 30f)
    .Sdp();

Priority: qualifier+orientation → mode-only → qualifier-only → orientation-only.

Generic kernel

Full control in a single entry point (also used by every satellite module):

float v = baseValue.ToDynamicScaledDp(ctx, qualifier, inverter, ignoreMultiWindows, applyAspectRatio, k);

⚡ Performance

• Fast lanes (DimenCache.ResolveSdpDp/Hdp/Wdp(+Px)): allocation-free, bitwise-equal to the full cached path.
• Snapshot-partitioned cache: configuration changes invalidate automatically via the event watcher — no manual clearing.
• Custom sensitivity k values bypass caching by design.

🧪 Testing support

FakeAppDimensContext ships in this package: mutable configuration + NotifyChange() to drive watchers deterministically.

📚 Full package family

Apache-2.0 — © Jean Bodenberg · Repository · Documentation · Formulas are bit-a-bit ports of appdimens-kmp