Move in the poster list with h,j,k,l

frontend/js/components/list/posters.js

@@ -1,4 +1,4 @@
-import React, { useState, useEffect } from "react"
+import React, { useState, useEffect, useCallback } from "react"
 import PropTypes from "prop-types"
 import { OrderedMap, Map } from "immutable"
 import fuzzy from "fuzzy";
@@ -81,6 +81,99 @@ ListPosters.propTypes = {
 export default ListPosters;
 
 const Posters = (props) => {
+  const addMoreCount = 20;
+  const [size, setSize] = useState(0);
+  const [postersPerRow, setPostersPerRow] = useState(0);
+  const [posterHeight, setPosterHeight] = useState(0);
+
+  const loadMore = () => {
+    if ((size === props.elmts.size)) { return }
+
+    const newSize = (((size + addMoreCount) >= props.elmts.size)
+      ? props.elmts.size
+      : size + addMoreCount);
+
+    setSize(newSize);
+  }
+
+  useEffect(() => {
+    loadMore()
+  }, [props.elmts.size]);
+
+  const move = (event) => {
+    // Only run the function if nothing else if actively focused
+    if (document.activeElement.tagName.toLowerCase() !== "body") { return }
+
+    let diff = 0;
+    let moveFocus = 0;
+    switch (event.key) {
+      case "Enter":
+        props.onKeyEnter(props.selectedImdbId);
+        return;
+      case "l":
+        diff = 1;
+        break;
+      case "h":
+        diff = -1;
+        break;
+      case "k":
+        diff =  -1*postersPerRow;
+        moveFocus = -1*posterHeight;
+        break;
+      case "j":
+        diff =  postersPerRow;
+        moveFocus = posterHeight;
+        break;
+      default:
+        return;
+    }
+
+    // Get the index of the currently selected item
+    const idx = props.elmts.keySeq().findIndex(k => k === props.selectedImdbId);
+
+    var newIdx = idx + diff;
+
+    // Handle edge cases
+    if (newIdx > props.elmts.size -1) {
+      newIdx = props.elmts.size -1;
+    } else if (newIdx < 0) {
+      newIdx = 0;
+    }
+
+    // Get the imdbID of the newly selected item
+    var selectedImdb = Object.keys(props.elmts.toJS())[newIdx];
+
+    // Select the movie
+    props.selectPoster(selectedImdb);
+    if (moveFocus !== 0) {
+      window.scrollBy(0, moveFocus);
+    }
+  }
+
+  const posterCount = useCallback(node => {
+    if (node === null) { return }
+    const parentWidth = node.getBoundingClientRect().width;
+    const childContainer = node.getElementsByClassName("img-thumbnail");
+    let childWidth = 0;
+    let posterHeight = 0;
+    if ((childContainer !== null) && (childContainer.item(0) !== null)) {
+      const child = childContainer.item(0);
+      childWidth = child.getBoundingClientRect().width + child.getBoundingClientRect().left;
+      posterHeight = child.getBoundingClientRect().height;
+    }
+
+    let numberPerRow = (childWidth >= parentWidth) ? 1 : Math.floor(parentWidth/childWidth);
+    setPostersPerRow(numberPerRow);
+    setPosterHeight(posterHeight);
+  })
+
+  useEffect(() => {
+    document.onkeypress = move;
+    return () => {
+      document.onkeypress = null;
+    }
+  }, [move])
+
   if (props.loading) {
     return (<Loader />);
   }
@@ -93,46 +186,31 @@ const Posters = (props) => {
     );
   }
 
-  const addMoreCount = 20;
-  const [size, setSize] = useState(0);
-  useEffect(() => {
-    loadMore()
-  }, [props.elmts.size]);
-  const hasMore = () => (size !== props.elmts.size);
-
-  const loadMore = () => {
-    if (!hasMore()) { return }
-
-    const newSize = (((size + addMoreCount) >= props.elmts.size)
-      ? props.elmts.size
-      : size + addMoreCount);
-
-    setSize(newSize);
-  }
-
   return (
-    <InfiniteScroll
-      className="poster-list d-flex flex-column flex-sm-row flex-sm-wrap justify-content-around"
-      dataLength={size}
-      next={loadMore}
-      hasMore={hasMore()}
-      loader={<Loader />}
-    >
-      {props.elmts.slice(0, size).toIndexedSeq().map(function(el, index) {
-        const imdbId = el.get("imdb_id");
-        const selected = (imdbId === props.selectedImdbId) ? true : false;
+    <div ref={posterCount}>
+      <InfiniteScroll
+        className="poster-list d-flex flex-column flex-sm-row flex-sm-wrap justify-content-around"
+        dataLength={size}
+        next={loadMore}
+        hasMore={(size !== props.elmts.size)}
+        loader={<Loader />}
+      >
+        {props.elmts.slice(0, size).toIndexedSeq().map(function(el, index) {
+          const imdbId = el.get("imdb_id");
+          const selected = (imdbId === props.selectedImdbId) ? true : false;
 
-        return (
-          <Poster
-            data={el}
-            key={`poster-${imdbId}-${index}`}
-            selected={selected}
-            onClick={() => props.selectPoster(imdbId)}
-            onDoubleClick={() => props.onDoubleClick(imdbId)}
-          />
-        )
-      } ,this)}
-    </InfiniteScroll>
+          return (
+            <Poster
+              data={el}
+              key={`poster-${imdbId}-${index}`}
+              selected={selected}
+              onClick={() => props.selectPoster(imdbId)}
+              onDoubleClick={() => props.onDoubleClick(imdbId)}
+            />
+          )
+        } ,this)}
+      </InfiniteScroll>
+    </div>
   );
 }
 Posters.propTypes = {