MediaQuickview: add recenter

src/platform/MediaQuickview.css

@@ -47,8 +47,6 @@
       max-width: 100vw;
       max-height: 100vh;
       contain: strict;
-      display: grid;
-      place-items: center;
 
       cursor: grab;
 

src/platform/MediaQuickview.tsx

@@ -56,19 +56,39 @@ export function createMediaQuickview() {
   return createCallback(renderIsolateMediaQuickview);
 }
 
+type VisualMediaMeta = {
+  width: number;
+  height: number;
+};
+
 function ImagePage(props: {
   src: string;
   alt?: string;
   scale: number;
   offsetX: number;
   offsetY: number;
+
+  onMetadata?(metadata: VisualMediaMeta): void;
 }) {
+  const [loaded, setLoaded] = createSignal(false);
+
   return (
     <img
+      onLoad={({ currentTarget }) => {
+        const { naturalHeight, naturalWidth } = currentTarget;
+
+        props.onMetadata?.({
+          width: naturalWidth,
+          height: naturalHeight,
+        });
+
+        setLoaded(true);
+      }}
       src={props.src}
       alt={props.alt}
       style={{
         transform: `scale(${props.scale}) translateX(${-props.offsetX}px) translateY(${-props.offsetY}px)`,
+        opacity: loaded() ? 1 : 0,
       }}
     ></img>
   );
@@ -88,10 +108,6 @@ export type MediaQuickviewProps = {
   onClose?(): void;
 };
 
-function clamp<T extends number>(value: T, min: T, max: T) {
-  return Math.max(Math.min(value, max), min);
-}
-
 const MediaQuickview: Component<MediaQuickviewProps> = (props) => {
   let root: HTMLDialogElement;
 
@@ -126,6 +142,11 @@ const MediaQuickview: Component<MediaQuickviewProps> = (props) => {
        * positive = the top edge move towards top
        */
       offsetY: number;
+
+      size?: {
+        width: number;
+        height: number;
+      };
     }[],
   );
 
@@ -202,6 +223,40 @@ const MediaQuickview: Component<MediaQuickviewProps> = (props) => {
     setIsMoving(false);
   };
 
+  const recenter = (index: number) => {
+    const sz = transformations[index].size;
+    if (!sz) return;
+    const { width, height } = sz;
+
+    const xscale = Math.min(window.innerWidth / width, 1);
+    const yscale = Math.min(window.innerHeight / height, 1);
+
+    const finalScale = Math.min(xscale, yscale);
+
+    const nheight = height * finalScale;
+    const top = (window.innerHeight - nheight) / 2;
+
+    const nwidth = width * finalScale;
+    const left = (window.innerWidth - nwidth) / 2;
+
+    setTransformations(index, {
+      scale: finalScale,
+      offsetX: -left,
+      offsetY: -top,
+    });
+  };
+
+  const onMetadata = (index: number, { width, height }: VisualMediaMeta) => {
+    setTransformations(index, {
+      size: {
+        width,
+        height,
+      },
+    });
+
+    recenter(index);
+  };
+
   return (
     <dialog
       ref={(e) => {
@@ -254,6 +309,7 @@ const MediaQuickview: Component<MediaQuickviewProps> = (props) => {
                   <Switch>
                     <Match when={item().cat === "image"}>
                       <ImagePage
+                        onMetadata={(m) => onMetadata(index, m)}
                         src={item().src}
                         alt={item().alt}
                         scale={transformationGetOrSetDefault(index).scale}