fix image preview and add option for automatically stop auto screenshoting when idle

shared/ui/src/main/java/dev/photosync/ui/image/ThumbnailCache.java

@@ -55,12 +55,19 @@ public final class ThumbnailCache implements AutoCloseable {
         this.textures = textures;
         this.loader = loader;
         this.size = size;
-        this.capacity = Math.max(8, capacity);
+        this.capacity = Math.max(1, capacity);
     }
 
-    /** Follows the player's setting without discarding what is already loaded. */
+    /**
+     * Follows the player's setting without discarding what is already loaded.
+     *
+     * <p>Only one is imposed here, because the caller is the one who knows what
+     * it is caching: the grid's floor comes from its config setting, and the
+     * detail view genuinely wants a capacity of two. Nothing thrashes at a small
+     * capacity anyway -- {@link #endFrame()} refuses to evict what was drawn.
+     */
     public void capacity(int value) {
-        this.capacity = Math.max(8, value);
+        this.capacity = Math.max(1, value);
     }
 
     /** Call once at the top of a frame, before any {@link #of} in that frame. */

shared/ui/src/main/java/dev/photosync/ui/screen/SettingsScreen.java

@@ -215,6 +215,9 @@ public final class SettingsScreen extends PhotoSyncScreen {
         toggle("photosync.settings.skip_when_screen_open", "",
                 () -> draft().autoCapture().skipWhenScreenOpen(),
                 value -> autoCapture(settings -> settings.toBuilder().skipWhenScreenOpen(value).build()));
+        toggle("photosync.settings.skip_when_still", "photosync.settings.skip_when_still.detail",
+                () -> draft().autoCapture().skipWhenStill(),
+                value -> autoCapture(settings -> settings.toBuilder().skipWhenStill(value).build()));
     }
 
     private void buildNotifications() {

shared/ui/src/main/java/dev/photosync/ui/screen/TimelineScreen.java

@@ -77,8 +77,10 @@ public final class TimelineScreen extends PhotoSyncScreen {
         BrowserSettings settings = ui.core().config().current().browser();
         this.tiles = new ThumbnailCache(ui.bridge().textures(), ui.core().thumbnails(),
                 ThumbnailSize.GRID, settings.thumbnailCacheEntries());
-        // Three is enough for the one open photo and the two either side of it.
-        this.detail = new ThumbnailCache(ui.bridge().textures(), ui.core().thumbnails(), ThumbnailSize.DETAIL, 3);
+        // Only one photo is ever open, and these are full-resolution textures --
+        // a 4K screenshot is 33MB on the GPU. Two, so re-opening the last one is
+        // instant, and no more than that.
+        this.detail = new ThumbnailCache(ui.bridge().textures(), ui.core().thumbnails(), ThumbnailSize.DETAIL, 2);
     }
 
     @Override
@@ -297,17 +299,40 @@ public final class TimelineScreen extends PhotoSyncScreen {
                 half - uHalf, half - vHalf, half + uHalf, half + vHalf);
     }
 
+    /**
+     * The opened photo, at whatever resolution has arrived so far.
+     *
+     * <p>What arrives first is the ThumbHash: a blurred 32x32 that is right for a
+     * tile and nowhere near enough for a full-screen view. It is still worth
+     * drawing, because it says which photo is opening, but it is dimmed and
+     * labelled while it stands in -- an unannotated blur is indistinguishable
+     * from a mod that fetched the wrong size.
+     */
     private void renderOpened(RenderBridge render, int mouseX, int mouseY) {
         detail.beginFrame();
         Rect area = body();
         render.fill(area.x(), area.y(), area.width(), area.height(), theme().overlay());
         Rect frame = area.inset(6);
         Optional<ThumbnailCache.Thumbnail> image = detail.of(opened);
-        if (image.isPresent()) {
-            drawContained(render, image.get().texture(), frame);
-        } else {
+
+        if (detail.failed(opened.id())) {
+            chrome.notice(render, frame, chrome.translate("photosync.browse.open_failed"),
+                    chrome.translate("photosync.browse.open_failed.hint"));
+        } else if (image.isEmpty()) {
             chrome.notice(render, frame, chrome.translate("photosync.browse.opening"), "");
+        } else {
+            drawContained(render, image.get().texture(), frame);
+            if (image.get().placeholder()) {
+                render.fill(frame.x(), frame.y(), frame.width(), frame.height(),
+                        theme().fade(theme().overlay(), 0.6f));
+                chrome.centered(render, chrome.translate("photosync.browse.opening"),
+                        new Rect(frame.x(), frame.centerY() - render.lineHeight(), frame.width(), render.lineHeight()),
+                        theme().text());
+                chrome.busyBar(render, new Rect(frame.centerX() - 60, frame.centerY() + 6, 120, 3),
+                        System.currentTimeMillis(), theme().accent());
+            }
         }
+
         chrome.centered(render, chrome.translate("photosync.browse.close_hint"),
                 area.bottom(render.lineHeight() + 2), theme().textFaint());
         detail.endFrame();
@@ -367,7 +392,7 @@ public final class TimelineScreen extends PhotoSyncScreen {
     @Override
     public boolean mouseClicked(double mouseX, double mouseY, int button) {
         if (opened != null) {
-            opened = null;
+            closeOpened();
             return true;
         }
         if (scroll.mouseClicked(mouseX, mouseY, button)) {
@@ -401,7 +426,7 @@ public final class TimelineScreen extends PhotoSyncScreen {
     @Override
     public boolean keyPressed(int key, int scanCode, int modifiers) {
         if (opened != null && key == Keys.ESCAPE) {
-            opened = null;
+            closeOpened();
             return true;
         }
         return switch (key) {
@@ -425,6 +450,19 @@ public final class TimelineScreen extends PhotoSyncScreen {
         };
     }
 
+    /**
+     * A cache entry that failed stays failed, which is right for a grid tile the
+     * player is scrolling past and wrong for the one photo they chose to open. It
+     * holds three entries, so dropping them all is the cheapest way to let a
+     * second click try again.
+     */
+    private void closeOpened() {
+        if (detail.failed(opened.id())) {
+            detail.clear();
+        }
+        opened = null;
+    }
+
     /** Escape dismisses the open photo before it dismisses the screen. */
     @Override
     public boolean closeOnEscape() {