[gnome-shell/wip/fmuellner/confine-title-captions: 104/104] workspace: Confine caption width to workspace area

[Florian Müllner <fmuellner src gnome org>]

commit 775fb774c6741467635ca285513b456fa13d3d6d
Author: Florian Müllner <fmuellner gnome org>
Date:   Sat Sep 1 18:57:59 2018 +0200

    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

 js/ui/workspace.js | 34 +++++++++++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 3 deletions(-)
---
diff --git a/js/ui/workspace.js b/js/ui/workspace.js
index ddf343e77..ff9f112af 100644
--- 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 - this._actualGeometry.x,
+                this._actualGeometry.x + this._actualGeometry.width - cloneCenter);
+            overlay.setMaxChromeWidth(Math.round(maxChromeWidth));
+
             if (overlay && (initialPositioning || !clone.positioned))
                 overlay.hide();