chore: clean recommit

Examples/Web/scaleUtils.js

@@ -0,0 +1,67 @@
+export const CANVAS_WIDTH = 800;
+export const CANVAS_HEIGHT = 450;
+export const SCALE_MODES = new Set(['integer', 'native', 'fit']);
+export const DEFAULT_SCALE_MODE = 'native';
+
+export function normalizeScaleMode(mode) {
+    if (!mode) {
+        return DEFAULT_SCALE_MODE;
+    }
+
+    const normalized = String(mode).toLowerCase();
+    return SCALE_MODES.has(normalized) ? normalized : DEFAULT_SCALE_MODE;
+}
+
+export function computeDisplaySize(mode, viewportWidth, viewportHeight, dpr = 1) {
+    const safeDpr = Number.isFinite(dpr) && dpr > 0 ? dpr : 1;
+
+    if (viewportWidth <= 0 || viewportHeight <= 0) {
+        return {
+            cssWidth: CANVAS_WIDTH / safeDpr,
+            cssHeight: CANVAS_HEIGHT / safeDpr,
+            deviceWidth: CANVAS_WIDTH,
+            deviceHeight: CANVAS_HEIGHT,
+            scale: 1,
+            dpr: safeDpr
+        };
+    }
+
+    // Convert viewport from CSS pixels to device pixels first so scaling is DPI/zoom aware.
+    const viewportDeviceWidth = Math.max(1, Math.floor(viewportWidth * safeDpr));
+    const viewportDeviceHeight = Math.max(1, Math.floor(viewportHeight * safeDpr));
+
+    let deviceWidth;
+    let deviceHeight;
+    let scale;
+
+    if (mode === 'native') {
+        // 1 source pixel -> 1 physical device pixel.
+        scale = 1;
+        deviceWidth = CANVAS_WIDTH;
+        deviceHeight = CANVAS_HEIGHT;
+    } else if (mode === 'fit') {
+        const fitRatio = Math.min(viewportDeviceWidth / CANVAS_WIDTH, viewportDeviceHeight / CANVAS_HEIGHT);
+        const safeRatio = Number.isFinite(fitRatio) && fitRatio > 0 ? fitRatio : 1;
+        scale = safeRatio;
+        deviceWidth = Math.max(1, Math.floor(CANVAS_WIDTH * safeRatio));
+        deviceHeight = Math.max(1, Math.floor(CANVAS_HEIGHT * safeRatio));
+    } else {
+        // integer mode
+        const integerScale = Math.max(1, Math.floor(Math.min(
+            viewportDeviceWidth / CANVAS_WIDTH,
+            viewportDeviceHeight / CANVAS_HEIGHT
+        )));
+        scale = integerScale;
+        deviceWidth = CANVAS_WIDTH * integerScale;
+        deviceHeight = CANVAS_HEIGHT * integerScale;
+    }
+
+    return {
+        cssWidth: deviceWidth / safeDpr,
+        cssHeight: deviceHeight / safeDpr,
+        deviceWidth,
+        deviceHeight,
+        scale,
+        dpr: safeDpr
+    };
+}