Add source

src/Resolution.swift

@@ -0,0 +1,40 @@
+import Foundation
+
+struct VDConfig: Equatable {
+    let pixelWidth: Int
+    let pixelHeight: Int
+    let logicalWidth: Int
+    let logicalHeight: Int
+    let refreshRate: Int
+}
+
+let scalePercents: [Int] = [100, 125, 133, 150, 166, 175, 200]
+
+let maxFramebufferPixelWidth  = 6144
+let maxFramebufferPixelHeight = 3456
+
+func vdConfig(physicalPixelWidth pw: Int,
+              physicalPixelHeight ph: Int,
+              refreshRate: Int,
+              scalePercent s: Int) -> VDConfig {
+    let lw = max(1, Int((Double(pw) * 100.0 / Double(s)).rounded()))
+    let lh = max(1, Int((Double(ph) * 100.0 / Double(s)).rounded()))
+    return VDConfig(
+        pixelWidth:  lw * 2,
+        pixelHeight: lh * 2,
+        logicalWidth:  lw,
+        logicalHeight: lh,
+        refreshRate: refreshRate
+    )
+}
+
+func availableScales(physicalPixelWidth pw: Int, physicalPixelHeight ph: Int) -> [Int] {
+    return scalePercents.filter { s in
+        let cfg = vdConfig(physicalPixelWidth: pw,
+                           physicalPixelHeight: ph,
+                           refreshRate: 60,
+                           scalePercent: s)
+        return cfg.pixelWidth  <= maxFramebufferPixelWidth
+            && cfg.pixelHeight <= maxFramebufferPixelHeight
+    }
+}