Reduce dynamic tile drag jitter

kwin/effects/shift-tile-preview/contents/ui/main.qml

@@ -16,6 +16,7 @@ KWinComponents.SceneEffect {
     readonly property int floatEscapeMargin: 32
     readonly property int previewAnimationDuration: 180
     readonly property int previewFadeDuration: 110
+    readonly property real insertIntentDeadZone: 0.18
 
     property var dragConnectedWindows: ({})
     property var draggingWindow: null
@@ -101,26 +102,25 @@ KWinComponents.SceneEffect {
     }
 
     function insertDirection(cursor, geometry) {
-        const leftDistance = Math.abs(cursor.x - geometry.x);
+        const relativeX = (cursor.x - geometry.x) / geometry.width;
-        const rightDistance = Math.abs((geometry.x + geometry.width) - cursor.x);
+        const relativeY = (cursor.y - geometry.y) / geometry.height;
-        const topDistance = Math.abs(cursor.y - geometry.y);
+        const fromCenterX = relativeX - 0.5;
-        const bottomDistance = Math.abs((geometry.y + geometry.height) - cursor.y);
+        const fromCenterY = relativeY - 0.5;
-        const nearestDistance = Math.min(leftDistance, rightDistance, topDistance, bottomDistance);
+        if (Math.abs(fromCenterX) < insertIntentDeadZone && Math.abs(fromCenterY) < insertIntentDeadZone) {
+            return "";
+        }
 
-        if (nearestDistance === leftDistance) {
+        if (Math.abs(fromCenterX) >= Math.abs(fromCenterY)) {
-            return "left";
+            return fromCenterX < 0 ? "left" : "right";
         }
-        if (nearestDistance === rightDistance) {
+        return fromCenterY < 0 ? "up" : "down";
-            return "right";
-        }
-        if (nearestDistance === topDistance) {
-            return "up";
-        }
-        return "down";
     }
 
     function previewRectFor(cursor, targetGeometry) {
         const direction = insertDirection(cursor, targetGeometry);
+        if (direction === "") {
+            return null;
+        }
         const orientation = direction === "left" || direction === "right" ? "vertical" : "horizontal";
         const splitGeometries = splitRect(targetGeometry, orientation);
         if (direction === "left" || direction === "up") {
@@ -208,8 +208,11 @@ KWinComponents.SceneEffect {
         const cursor = KWinComponents.Workspace.cursorPos;
         const targetGeometry = findTileAtCursor(cursor, window);
         if (targetGeometry) {
-            showPreview("insert", previewRectFor(cursor, targetGeometry), window.output.name);
+            const insertGeometry = previewRectFor(cursor, targetGeometry);
-            return;
+            if (validRect(insertGeometry)) {
+                showPreview("insert", insertGeometry, window.output.name);
+                return;
+            }
         }
 
         if (outsideWorkArea(window, cursor)) {

kwin/scripts/shift-tiling/contents/ui/main.qml

@@ -27,6 +27,7 @@ Item {
     readonly property int outerGap: 8
     readonly property int innerGap: 8    // half applied to each edge → 4px per tile
     readonly property real stablePrimaryRatio: 0.58
+    readonly property real insertIntentDeadZone: 0.18
 
     // ── State ───────────────────────────────────────────────────────────────
 
@@ -540,6 +541,7 @@ Item {
 
         if (win.maximizable) win.setMaximize(false, false);
         win.noBorder = false;
+        retileScreen(targetName);
         scheduleRetile(targetName);
     }
 
@@ -569,6 +571,7 @@ Item {
         // (Same pattern as convergentwindows constrainAfterRestoreTimer.)
         if (win.maximizable) win.setMaximize(false, false);
         win.noBorder = false;
+        retileScreen(name);
         scheduleRetile(name);
     }
 
@@ -801,16 +804,18 @@ Item {
     function tileInsertDirection(cursor, rect) {
         if (!validRect(rect)) return "";
 
-        const left = Math.abs(cursor.x - rect.x);
+        const relativeX = (cursor.x - rect.x) / rect.width;
-        const right = Math.abs((rect.x + rect.width) - cursor.x);
+        const relativeY = (cursor.y - rect.y) / rect.height;
-        const top = Math.abs(cursor.y - rect.y);
+        const fromCenterX = relativeX - 0.5;
-        const bottom = Math.abs((rect.y + rect.height) - cursor.y);
+        const fromCenterY = relativeY - 0.5;
-        const nearest = Math.min(left, right, top, bottom);
+        if (Math.abs(fromCenterX) < insertIntentDeadZone && Math.abs(fromCenterY) < insertIntentDeadZone) {
+            return "";
+        }
 
-        if (nearest === left) return "left";
+        if (Math.abs(fromCenterX) >= Math.abs(fromCenterY)) {
-        if (nearest === right) return "right";
+            return fromCenterX < 0 ? "left" : "right";
-        if (nearest === top) return "up";
+        }
-        return "down";
+        return fromCenterY < 0 ? "up" : "down";
     }
 
     function previewInsertRect(win, target, position) {

tests/check-dynamic-tiles-motion.sh

@@ -53,14 +53,20 @@ require_line "$effect_qml" "Behavior on height"
 require_line "$effect_qml" "showPreview(\"insert\""
 require_line "$effect_qml" "showPreview(\"float\""
 require_line "$effect_qml" "showPreview(\"restore\""
+require_line "$effect_qml" "readonly property real insertIntentDeadZone: 0.18"
+require_line "$effect_qml" "if (Math.abs(fromCenterX) < insertIntentDeadZone && Math.abs(fromCenterY) < insertIntentDeadZone)"
 
 require_line "$tiling_script" "readonly property real stablePrimaryRatio: 0.58"
+require_line "$tiling_script" "readonly property real insertIntentDeadZone: 0.18"
 require_line "$tiling_script" "function orderedWindowsForScreen(outputName)"
 require_line "$tiling_script" "function buildStableStack(windows, startIndex)"
 require_line "$tiling_script" "function buildStableLayout(windows)"
 require_line "$tiling_script" "function setStableLayout(outputName, windows)"
 require_line "$tiling_script" "setStableLayout(outputName, windows)"
 require_line "$tiling_script" "setStableLayout(outputName, remaining)"
+require_line "$tiling_script" "retileScreen(name)"
+require_line "$tiling_script" "retileScreen(targetName)"
+require_line "$tiling_script" "if (Math.abs(fromCenterX) < insertIntentDeadZone && Math.abs(fromCenterY) < insertIntentDeadZone)"
 
 reject_line "$tiling_script" "targetKey = lastLeafKey(rootNode)"
 reject_line "$tiling_script" "setScreenLayout(outputName, splitLeaf(rootNode, targetKey"