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node_modules/motion-dom/dist/es/frameloop/render-step.mjs

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+import { statsBuffer } from '../stats/buffer.mjs';
+
+function createRenderStep(runNextFrame, stepName) {
+    /**
+     * We create and reuse two queues, one to queue jobs for the current frame
+     * and one for the next. We reuse to avoid triggering GC after x frames.
+     */
+    let thisFrame = new Set();
+    let nextFrame = new Set();
+    /**
+     * Track whether we're currently processing jobs in this step. This way
+     * we can decide whether to schedule new jobs for this frame or next.
+     */
+    let isProcessing = false;
+    let flushNextFrame = false;
+    /**
+     * A set of processes which were marked keepAlive when scheduled.
+     */
+    const toKeepAlive = new WeakSet();
+    let latestFrameData = {
+        delta: 0.0,
+        timestamp: 0.0,
+        isProcessing: false,
+    };
+    let numCalls = 0;
+    function triggerCallback(callback) {
+        if (toKeepAlive.has(callback)) {
+            step.schedule(callback);
+            runNextFrame();
+        }
+        numCalls++;
+        callback(latestFrameData);
+    }
+    const step = {
+        /**
+         * Schedule a process to run on the next frame.
+         */
+        schedule: (callback, keepAlive = false, immediate = false) => {
+            const addToCurrentFrame = immediate && isProcessing;
+            const queue = addToCurrentFrame ? thisFrame : nextFrame;
+            if (keepAlive)
+                toKeepAlive.add(callback);
+            if (!queue.has(callback))
+                queue.add(callback);
+            return callback;
+        },
+        /**
+         * Cancel the provided callback from running on the next frame.
+         */
+        cancel: (callback) => {
+            nextFrame.delete(callback);
+            toKeepAlive.delete(callback);
+        },
+        /**
+         * Execute all schedule callbacks.
+         */
+        process: (frameData) => {
+            latestFrameData = frameData;
+            /**
+             * If we're already processing we've probably been triggered by a flushSync
+             * inside an existing process. Instead of executing, mark flushNextFrame
+             * as true and ensure we flush the following frame at the end of this one.
+             */
+            if (isProcessing) {
+                flushNextFrame = true;
+                return;
+            }
+            isProcessing = true;
+            [thisFrame, nextFrame] = [nextFrame, thisFrame];
+            // Execute this frame
+            thisFrame.forEach(triggerCallback);
+            /**
+             * If we're recording stats then
+             */
+            if (stepName && statsBuffer.value) {
+                statsBuffer.value.frameloop[stepName].push(numCalls);
+            }
+            numCalls = 0;
+            // Clear the frame so no callbacks remain. This is to avoid
+            // memory leaks should this render step not run for a while.
+            thisFrame.clear();
+            isProcessing = false;
+            if (flushNextFrame) {
+                flushNextFrame = false;
+                step.process(frameData);
+            }
+        },
+    };
+    return step;
+}
+
+export { createRenderStep };