fix top scrollbar freezing after card drag: re-resolve #board-container on rebuild, sync on parent; v1.4.2

Asset/css/shrink-vertically.css

@@ -26,47 +26,54 @@
  * (BoardDragAndDrop.js: css("min-height", parent().height())). In CSS, min-height
  * beats max-height, so that inline value keeps tall columns from shrinking and our
  * max-height alone does nothing. A stylesheet !important overrides the inline
- * (non-important) min-height, so we reset it to 0 and let max-height win.
+ * (non-important) min-height so max-height can win.
+ *
+ * We override it to a small NON-ZERO value, not 0: Kanboard relies on that same inline
+ * min-height to keep EMPTY columns tall enough to be a drop target, so zeroing it makes
+ * you unable to drop a card into an empty collapsed column. 100px clears Kanboard's 70px
+ * drag placeholder (.draggable-placeholder) with margin, and stays well below max-height
+ * so tall columns still shrink; non-empty columns are unaffected (their content is taller).
  */
 #board td .board-task-list.board-task-list-compact {
     max-height: calc(100vh - var(--sv-shrink-offset, 240px)) !important;
-    min-height: 0 !important;
+    min-height: 100px !important;
 }
 
 /*
- * Optional top horizontal scrollbar (added by Asset/js/top-scrollbar.js when the
+ * Optional custom top horizontal scrollbar (built by Asset/js/top-scrollbar.js when the
- * "Add a top horizontal scrollbar" setting is enabled). The inner element is given a
+ * "Add a top horizontal scrollbar" setting is enabled). It is a track + draggable thumb,
- * width equal to the board's scrollable width by the script; overflow-x: auto then
+ * not a native scrollbar, so it renders and can be sized identically in every browser
- * produces a scrollbar whose range mirrors the board's own bottom scrollbar. The 1px
+ * (Chrome, Firefox, Safari) and on touch. Thickness follows the --sv-bar-size variable
- * inner height keeps the bar to just the scrollbar itself.
+ * (Settings -> Shrink Vertically), injected in the page head; falls back to 25px.
+ * touch-action: none lets a finger drag the thumb without scrolling the page.
  */
 .sv-top-scroll {
-    overflow-x: auto;
+    position: relative;
-    overflow-y: hidden;
+    width: 100%;
-}
-
-.sv-top-scroll-inner {
-    height: 1px;
-}
-
-/*
- * Make the top scrollbar thick enough to grab easily (touch / big fingers).
- * WebKit/Blink (most desktop browsers and mobile Chrome/Safari) let us size the
- * scrollbar; styling the thumb/track is needed for it to stay visible once customised.
- * Thickness comes from the --sv-bar-size variable (Settings -> Shrink Vertically),
- * injected in the page head; falls back to 25px. Chromium/WebKit only (Chrome/Edge/
- * Safari, mobile Chrome/Safari); Firefox ignores ::-webkit-scrollbar and keeps its
- * default thin bar -- accepted for now.
- */
-.sv-top-scroll::-webkit-scrollbar {
     height: var(--sv-bar-size, 25px);
+    background: rgba(0, 0, 0, 0.06);
+    border-radius: 4px;
+    overflow: hidden;
+    touch-action: none;
 }
 
-.sv-top-scroll::-webkit-scrollbar-track {
+.sv-top-scroll-thumb {
-    background: rgba(0, 0, 0, 0.05);
+    position: absolute;
-}
+    top: 0;
-
+    left: 0;
-.sv-top-scroll::-webkit-scrollbar-thumb {
+    width: 0;
+    height: 100%;
     background: rgba(0, 0, 0, 0.35);
-    border-radius: 6px;
+    border-radius: 4px;
+    cursor: grab;
+    touch-action: none;
+}
+
+.sv-top-scroll.sv-dragging .sv-top-scroll-thumb {
+    cursor: grabbing;
+    background: rgba(0, 0, 0, 0.5);
+}
+
+.sv-dragging {
+    user-select: none;
 }

Asset/js/top-scrollbar.js

@@ -1,63 +1,186 @@
 /*
- * ShrinkVertically -- optional horizontal scrollbar above the board.
+ * ShrinkVertically -- optional custom horizontal scrollbar above the board.
  *
- * Kanboard's board scrolls horizontally inside #board-container (overflow-x: auto),
+ * Kanboard's board scrolls horizontally inside #board-container (overflow-x: auto), so the
- * so the only horizontal scrollbar sits at the very bottom of the board. On a wide
+ * only native horizontal scrollbar sits at the very bottom of the board. On a wide board
- * board you have to scroll all the way down to reach it. This adds a second, mirrored
+ * you have to scroll all the way down to reach it. This adds a second scrollbar just above
- * scrollbar just above the columns and keeps the two scroll positions in sync.
+ * the columns and keeps it in sync with the board.
+ *
+ * Unlike a native scrollbar (whose thickness cannot be sized in Firefox), this is a custom
+ * track + thumb widget: it renders and behaves the same in every browser (Chrome, Firefox,
+ * Safari) and on touch, and its thickness follows the --sv-bar-size setting.
+ *
+ * Resilience note: after a card drag Kanboard rebuilds the board with
+ * `$("#board-container").replaceWith(data)` (BoardDragAndDrop.refresh), so the element we
+ * started with is destroyed and replaced. We therefore never cache the container: we
+ * re-resolve it on every use, listen for its scroll on `document` in the capture phase (so
+ * the listener survives the swap), and observe the STABLE parent (which is not replaced) so
+ * the widget keeps working -- previously the observer and scroll listener died with the old
+ * element, which froze the bar and lost sync after each move.
  *
  * Loaded only when the "Add a top horizontal scrollbar" setting is enabled.
  */
 (function () {
     "use strict";
 
+    // Keep the thumb wide enough to grab, even on a very wide board.
+    var MIN_THUMB = 24;
+
+    function getContainer() {
+        return document.getElementById("board-container");
+    }
+
     function init() {
-        var container = document.getElementById("board-container");
+        var container = getContainer();
 
         // Only on the board, and never add it twice.
         if (!container || document.querySelector(".sv-top-scroll")) {
             return;
         }
 
-        var bar = document.createElement("div");
+        // The parent survives the board refresh (only #board-container is replaced).
-        bar.className = "sv-top-scroll";
+        var boardParent = container.parentNode;
 
-        var inner = document.createElement("div");
+        var track = document.createElement("div");
-        inner.className = "sv-top-scroll-inner";
+        track.className = "sv-top-scroll";
-        bar.appendChild(inner);
 
-        container.parentNode.insertBefore(bar, container);
+        var thumb = document.createElement("div");
+        thumb.className = "sv-top-scroll-thumb";
+        track.appendChild(thumb);
 
-        function sync() {
+        boardParent.insertBefore(track, container);
-            // Match the dummy bar's content width to the board's scrollable width
+
-            // so its scrollbar has the same range as the board's own scrollbar.
+        var dragging = false;
-            inner.style.width = container.scrollWidth + "px";
+        var dragStartX = 0;
+        var dragStartScrollLeft = 0;
+
+        function metrics() {
+            var c = getContainer();
+            if (!c) {
+                return null;
+            }
+            return {
+                c: c,
+                viewport: c.clientWidth,
+                content: c.scrollWidth,
+                trackW: track.clientWidth
+            };
         }
 
-        var lock = false;
+        function positionThumb(m, thumbW) {
+            var maxScroll = m.content - m.viewport;
+            var maxThumb = m.trackW - thumbW;
+            var left = maxScroll > 0 ? (m.c.scrollLeft / maxScroll) * maxThumb : 0;
+            thumb.style.transform = "translateX(" + Math.round(left) + "px)";
+        }
 
-        bar.addEventListener("scroll", function () {
+        // Recompute thumb width/position; hide the whole bar when nothing to scroll.
-            if (lock) { return; }
+        function layout() {
-            lock = true;
+            var m = metrics();
-            container.scrollLeft = bar.scrollLeft;
+
-            lock = false;
+            if (!m || m.content <= m.viewport || m.trackW <= 0) {
+                track.style.display = "none";
+                return;
+            }
+
+            track.style.display = "";
+
+            var thumbW = Math.round(m.trackW * m.viewport / m.content);
+            if (thumbW < MIN_THUMB) { thumbW = MIN_THUMB; }
+            if (thumbW > m.trackW) { thumbW = m.trackW; }
+
+            thumb.style.width = thumbW + "px";
+            positionThumb(m, thumbW);
+        }
+
+        // Keep the track directly before the (current) container after a board refresh.
+        function reattachTrack() {
+            var c = getContainer();
+            if (c && c.parentNode && track.nextSibling !== c) {
+                c.parentNode.insertBefore(track, c);
+            }
+        }
+
+        // Board scrolled by any other means -> keep the thumb in sync. Capture-phase on
+        // document catches #board-container's (non-bubbling) scroll and survives the swap.
+        document.addEventListener("scroll", function (e) {
+            if (dragging) { return; }
+            if (e.target !== getContainer()) { return; }
+            var m = metrics();
+            if (!m || m.content <= m.viewport) { return; }
+            positionThumb(m, thumb.offsetWidth);
+        }, true);
+
+        // Drag the thumb (mouse + touch via Pointer Events).
+        thumb.addEventListener("pointerdown", function (e) {
+            var c = getContainer();
+            if (!c) { return; }
+            e.preventDefault();
+            e.stopPropagation();
+            dragging = true;
+            dragStartX = e.clientX;
+            dragStartScrollLeft = c.scrollLeft;
+            track.classList.add("sv-dragging");
+            if (thumb.setPointerCapture) {
+                thumb.setPointerCapture(e.pointerId);
+            }
         });
 
-        container.addEventListener("scroll", function () {
+        thumb.addEventListener("pointermove", function (e) {
-            if (lock) { return; }
+            if (!dragging) { return; }
-            lock = true;
+            var m = metrics();
-            bar.scrollLeft = container.scrollLeft;
+            if (!m) { return; }
-            lock = false;
+            var maxThumb = m.trackW - thumb.offsetWidth;
+            var maxScroll = m.content - m.viewport;
+            if (maxThumb <= 0) { return; }
+            m.c.scrollLeft = dragStartScrollLeft + (e.clientX - dragStartX) * (maxScroll / maxThumb);
+            positionThumb(m, thumb.offsetWidth);
         });
 
-        window.addEventListener("resize", sync);
+        function endDrag(e) {
+            if (!dragging) { return; }
+            dragging = false;
+            track.classList.remove("sv-dragging");
+            if (thumb.releasePointerCapture && e && e.pointerId != null) {
+                try { thumb.releasePointerCapture(e.pointerId); } catch (err) { /* ignore */ }
+            }
+        }
 
-        // The board can be redrawn by the AJAX polling/refresh; keep the width current.
+        thumb.addEventListener("pointerup", endDrag);
+        thumb.addEventListener("pointercancel", endDrag);
+
+        // Click on the empty track -> jump so the thumb centers under the pointer.
+        track.addEventListener("pointerdown", function (e) {
+            if (e.target === thumb || dragging) { return; }
+            var m = metrics();
+            if (!m || m.content <= m.viewport) { return; }
+
+            var thumbW = thumb.offsetWidth;
+            var maxThumb = m.trackW - thumbW;
+            var maxScroll = m.content - m.viewport;
+            if (maxThumb <= 0) { return; }
+
+            var clickX = e.clientX - track.getBoundingClientRect().left;
+            var targetLeft = clickX - thumbW / 2;
+            if (targetLeft < 0) { targetLeft = 0; }
+            if (targetLeft > maxThumb) { targetLeft = maxThumb; }
+
+            m.c.scrollLeft = (targetLeft / maxThumb) * maxScroll;
+            positionThumb(m, thumbW);
+        });
+
+        window.addEventListener("resize", layout);
+
+        // Observe the STABLE parent so we keep working after #board-container is replaced by
+        // a card move / AJAX polling; re-seat the track and recompute sizes on any change.
         if (window.MutationObserver) {
-            new MutationObserver(sync).observe(container, { childList: true, subtree: true });
+            new MutationObserver(function () {
+                reattachTrack();
+                layout();
+            }).observe(boardParent, { childList: true, subtree: true });
         }
 
-        sync();
+        layout();
     }
 
     if (document.readyState === "loading") {

Plugin.php

@@ -51,7 +51,7 @@ class Plugin extends Base
 
     public function getPluginVersion()
     {
-        return '1.3.1';
+        return '1.4.2';
     }
 
     public function getPluginHomepage()

README.md

@@ -69,10 +69,13 @@ from the folder name). Reload the board; no build step, no configuration.
 Kanboard's board scrolls horizontally inside `#board-container`, so its only horizontal
 scrollbar is at the very bottom of the board -- on a wide board you must scroll all the
 way down to move sideways. Enable "Add a top horizontal scrollbar" in the settings to get
-a second, mirrored scrollbar just above the columns. A small script
+a second scrollbar just above the columns.
-(`Asset/js/top-scrollbar.js`, loaded only when the option is on) inserts a dummy scroll
+
-strip above `#board-container` and keeps its scroll position in sync with the board both
+It is a custom track + draggable thumb (`Asset/js/top-scrollbar.js`, loaded only when the
-ways.
+option is on), not a native scrollbar, so it renders and can be sized the same in every
+browser (Chrome, Firefox, Safari) and on touch. Drag the thumb or click the track to move
+the board; the thumb tracks the board when you scroll it by other means. Its thickness
+follows the "Top Horizontal Scrollbar thickness" setting.
 
 ## Settings
 
@@ -83,8 +86,8 @@ These settings are global (per Kanboard instance) and admin-only. Go to
   in the page head as the `--sv-shrink-offset` CSS variable. Increase it if the scrollbar
   is still clipped (for example with a taller theme header); decrease it to make the
   collapsed columns taller. Default: 240.
-- **Top Horizontal Scrollbar thickness in pixels** -- thickness of the top scrollbar
+- **Top Horizontal Scrollbar thickness in pixels** -- thickness of the custom top
-  (Chromium/WebKit only). Injected as the `--sv-bar-size` CSS variable. Default: 25.
+  scrollbar (all browsers). Injected as the `--sv-bar-size` CSS variable. Default: 25.
 - **Add a top horizontal scrollbar to the board** -- toggles the mirrored top scrollbar
   described above. Default: on.
 

Template/config/show.php

@@ -17,7 +17,7 @@
         <?= $this->form->label(t('Top Horizontal Scrollbar thickness in pixels'), 'shrink_vertically_bar_size') ?>
         <?= $this->form->number('shrink_vertically_bar_size', $values, $errors) ?>
         <p class="form-help">
-            <?= t('Thickness of the top horizontal scrollbar (Chromium/WebKit browsers only). Default: 25.') ?>
+            <?= t('Thickness of the top horizontal scrollbar. Default: 25.') ?>
         </p>
     </fieldset>
 

VERSION

@@ -1 +1 @@
-ShrinkVertically v1.3.1
+ShrinkVertically v1.4.2