workspace: Confine caption width to workspace area

When we started to only show a single caption at a time, we allowed
title captions to be wider than their corresponding window preview.
But while overlapping neighboring previews is fine, we shouldn't
allow the captions to leak outside the workspace area itself and
overlap unrelated elements like workspace switcher or dash.

This partly reverts commit b3b30f239d.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/214

diff --git a/js/ui/workspace.js b/js/ui/workspace.js
index ddf343e77d49a33e470c29e95d21ee5094bf2b54..97c2d3a58400669588cfa91dc39348763d0aafbb 100644 (file)
--- a/js/ui/workspace.js
+++ b/js/ui/workspace.js
@@ -465,6 +465,8 @@ var WindowOverlay = new Lang.Class({
         title.clutter_text.ellipsize = Pango.EllipsizeMode.END;
         windowClone.actor.label_actor = title;
 
+        this._maxTitleWidth = -1;
+
         this._updateCaptionId = metaWindow.connect('notify::title', w => {
             this.title.text = this._getCaption();
             this.relayout(false);
@@ -527,6 +529,13 @@ var WindowOverlay = new Lang.Class({
                 Math.max(this.borderSize, this.closeButton.width - this.closeButton._overlap)];
     },
 
+    setMaxChromeWidth(max) {
+        if (this._maxTitleWidth == max)
+            return;
+
+        this._maxTitleWidth = max;
+    },
+
     relayout(animate) {
         let button = this.closeButton;
         let title = this.title;
@@ -553,13 +562,26 @@ var WindowOverlay = new Lang.Class({
         else
             button.set_position(Math.floor(buttonX), Math.floor(buttonY));
 
-        let titleX = cloneX + (cloneWidth - title.width) / 2;
+        // Clutter.Actor.get_preferred_width() will return the fixed width if
+        // one is set, so we need to reset the width by calling set_width(-1),
+        // to forward the call down to StLabel.
+        // We also need to save and restore the current width, otherwise the
+        // animation starts from the wrong point.
+        let prevTitleWidth = title.width;
+        title.set_width(-1);
+
+        let [titleMinWidth, titleNatWidth] = title.get_preferred_width(-1);
+        let titleWidth = Math.max(titleMinWidth,
+                                  Math.min(titleNatWidth, this._maxTitleWidth));
+        title.width = prevTitleWidth;
+
+        let titleX = cloneX + (cloneWidth - titleWidth) / 2;
         let titleY = cloneY + cloneHeight - (title.height - this.borderSize) / 2;
 
         if (animate) {
-            this._animateOverlayActor(title, Math.floor(titleX), Math.floor(titleY), title.width);
+            this._animateOverlayActor(title, Math.floor(titleX), Math.floor(titleY), titleWidth);
         } else {
-            title.width = title.width;
+            title.width = titleWidth;
             title.set_position(Math.floor(titleX), Math.floor(titleY));
         }
 
@@ -1305,6 +1327,12 @@ var Workspace = new Lang.Class({
             let cloneHeight = clone.actor.height * scale;
             clone.slot = [x, y, cloneWidth, cloneHeight];
 
+            let cloneCenter = x + cloneWidth / 2;
+            let maxChromeWidth = 2 * Math.min(
+                cloneCenter - area.x,
+                area.x + area.width - cloneCenter);
+            overlay.setMaxChromeWidth(Math.round(maxChromeWidth));
+
             if (overlay && (initialPositioning || !clone.positioned))
                 overlay.hide();