bar from scratch Assets

Asset/css/shrink-vertically.css

@@ -34,39 +34,40 @@
 }
 
 /*
- * 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

@@ -1,16 +1,23 @@
 /*
- * 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.
  *
  * 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 init() {
         var container = document.getElementById("board-container");
 
@@ -19,45 +26,124 @@
             return;
         }
 
-        var bar = document.createElement("div");
+        var track = document.createElement("div");
-        bar.className = "sv-top-scroll";
+        track.className = "sv-top-scroll";
 
-        var inner = document.createElement("div");
+        var thumb = document.createElement("div");
-        inner.className = "sv-top-scroll-inner";
+        thumb.className = "sv-top-scroll-thumb";
-        bar.appendChild(inner);
+        track.appendChild(thumb);
 
-        container.parentNode.insertBefore(bar, container);
+        container.parentNode.insertBefore(track, container);
 
-        function sync() {
+        var dragging = false;
-            // Match the dummy bar's content width to the board's scrollable width
+        var dragStartX = 0;
-            // so its scrollbar has the same range as the board's own scrollbar.
+        var dragStartScrollLeft = 0;
-            inner.style.width = container.scrollWidth + "px";
+
+        function metrics() {
+            return {
+                viewport: container.clientWidth,
+                content: container.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 ? (container.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.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);
+        }
+
+        // Board scrolled by any other means -> keep the thumb in sync.
         container.addEventListener("scroll", function () {
-            if (lock) { return; }
+            if (dragging) { return; }
-            lock = true;
+            var m = metrics();
-            bar.scrollLeft = container.scrollLeft;
+            if (m.content <= m.viewport) { return; }
-            lock = false;
+            positionThumb(m, thumb.offsetWidth);
         });
 
-        window.addEventListener("resize", sync);
+        // Drag the thumb (mouse + touch via Pointer Events).
+        thumb.addEventListener("pointerdown", function (e) {
+            e.preventDefault();
+            e.stopPropagation();
+            dragging = true;
+            dragStartX = e.clientX;
+            dragStartScrollLeft = container.scrollLeft;
+            track.classList.add("sv-dragging");
+            if (thumb.setPointerCapture) {
+                thumb.setPointerCapture(e.pointerId);
+            }
+        });
 
-        // The board can be redrawn by the AJAX polling/refresh; keep the width current.
+        thumb.addEventListener("pointermove", function (e) {
-        if (window.MutationObserver) {
+            if (!dragging) { return; }
-            new MutationObserver(sync).observe(container, { childList: true, subtree: true });
+            var m = metrics();
+            var maxThumb = m.trackW - thumb.offsetWidth;
+            var maxScroll = m.content - m.viewport;
+            if (maxThumb <= 0) { return; }
+            container.scrollLeft = dragStartScrollLeft + (e.clientX - dragStartX) * (maxScroll / maxThumb);
+            positionThumb(m, thumb.offsetWidth);
+        });
+
+        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 */ }
+            }
         }
 
-        sync();
+        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.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; }
+
+            container.scrollLeft = (targetLeft / maxThumb) * maxScroll;
+            positionThumb(m, thumbW);
+        });
+
+        window.addEventListener("resize", layout);
+
+        // The board can be redrawn by AJAX polling / drag-and-drop; keep sizes current.
+        if (window.MutationObserver) {
+            new MutationObserver(layout).observe(container, { childList: true, subtree: true });
+        }
+
+        layout();
     }
 
     if (document.readyState === "loading") {