feat(qt): Library Explorer columns select a run with Shift

A facet column already took Ctrl as "add or remove one" and a plain click
as "only this". Shift now picks the run from the last clicked value and
Ctrl+Shift adds that run, the file-list rule (SelectionModel.nextExclusive),
each column over its values as listed. A column whose values are rebuilt by
a change upstream starts without an anchor.

cc

crates/qbz-qt/qml/controls/SelectionModel.qml

@@ -118,4 +118,39 @@ QtObject {
         root.anchorId = key
         return out
     }
+
+    /// The spreadsheet / file-manager rule, for lists where a plain click
+    /// REPLACES the selection (the Library Explorer facets):
+    ///
+    ///   plain click    only this row; it becomes the anchor
+    ///   Ctrl / Cmd     toggle this row, keep the rest; it becomes the anchor
+    ///   Shift          only the range anchor..row; the anchor stays
+    ///   Ctrl+Shift     add the range anchor..row to the selection
+    ///
+    /// Without a visible anchor Shift behaves like the same click without it.
+    function nextExclusive(current, id, rows, modifiers) {
+        var mods = modifiers || 0
+        var shift = (mods & Qt.ShiftModifier) !== 0
+        var additive = (mods & (Qt.ControlModifier | Qt.MetaModifier)) !== 0
+        var key = String(id)
+        var anchorAt = root.anchorId !== "" ? root._indexOf(rows, root.anchorId) : -1
+
+        if (shift && anchorAt >= 0) {
+            var here = root._indexOf(rows, id)
+            if (here >= 0)
+                return root._fillRange(additive ? Object.assign({}, current) : {},
+                                       rows, anchorAt, here)
+        }
+
+        root.anchorId = key
+        if (!additive) {
+            var only = {}
+            only[key] = true
+            return only
+        }
+        var out = Object.assign({}, current)
+        if (out[key] === true) delete out[key]
+        else out[key] = true
+        return out
+    }
 }

crates/qbz-qt/qml/views/LocalLibraryView.qml

@@ -1187,23 +1187,42 @@ Rectangle {
         return sortRows(rows, genresSort)
     }
 
+    // The Explorer facets follow the spreadsheet rule — a plain click picks
+    // one value, Ctrl adds or removes one, Shift picks the run from the last
+    // click, Ctrl+Shift adds that run (SelectionModel.nextExclusive) — each
+    // column over its values AS LISTED (sorted, and filtered by its own
+    // search box). One anchor per column; a column whose values are rebuilt
+    // by a change upstream starts without one.
+    SelectionModel { id: genreFacetSel; idKey: "key" }
+    SelectionModel { id: yearFacetSel; idKey: "key" }
+    SelectionModel { id: artistFacetSel; idKey: "key" }
+    SelectionModel { id: albumFacetSel; idKey: "key" }
     function toggleGenre(key, modifiers) {
-        selectedGenres = nextFacetSelection(selectedGenres, key, modifiers)
+        selectedGenres = nextFacetSelection(genreFacetSel, selectedGenres, key, modifiers, genreNames)
         selectedGenreYears = ({})
         selectedGenreArtists = ({})
         selectedGenreAlbums = ({})
+        yearFacetSel.anchorId = ""
+        artistFacetSel.anchorId = ""
+        albumFacetSel.anchorId = ""
     }
     function toggleGenreYear(key, modifiers) {
-        selectedGenreYears = nextFacetSelection(selectedGenreYears, key, modifiers)
+        selectedGenreYears = nextFacetSelection(yearFacetSel, selectedGenreYears, key, modifiers,
+                                                genreYearOptions)
         selectedGenreArtists = ({})
         selectedGenreAlbums = ({})
+        artistFacetSel.anchorId = ""
+        albumFacetSel.anchorId = ""
     }
     function toggleGenreArtist(key, modifiers) {
-        selectedGenreArtists = nextFacetSelection(selectedGenreArtists, key, modifiers)
+        selectedGenreArtists = nextFacetSelection(artistFacetSel, selectedGenreArtists, key,
+                                                  modifiers, genreArtistOptions)
         selectedGenreAlbums = ({})
+        albumFacetSel.anchorId = ""
     }
     function toggleGenreAlbum(key, modifiers) {
-        selectedGenreAlbums = nextFacetSelection(selectedGenreAlbums, key, modifiers)
+        selectedGenreAlbums = nextFacetSelection(albumFacetSel, selectedGenreAlbums, key, modifiers,
+                                                 genreAlbumOptions)
     }
     function setExplorerColumns(mode) {
         if (["genre", "year", "both"].indexOf(mode) < 0 || mode === explorerColumns)
@@ -1219,17 +1238,14 @@ Rectangle {
     readonly property int explorerFacetCount: explorerColumns === "both" ? 4 : 3
     readonly property int explorerLeadingCount: explorerColumns === "year"
         ? genreYearOptions.length : genreNames.length
-    function nextFacetSelection(current, key, modifiers) {
-        if (key === "") return ({})
-        var additive = (modifiers & Qt.ControlModifier) !== 0
-            || (modifiers & Qt.MetaModifier) !== 0
-        if (!additive) {
-            var only = {}; only[key] = true; return only
+    /// `key` "" is the column's "All" row: it clears the column.
+    function nextFacetSelection(rule, current, key, modifiers, options) {
+        if (key === "") {
+            rule.anchorId = ""
+            return ({})
         }
-        var out = Object.assign({}, current)
-        if (out[key]) delete out[key]
-        else out[key] = true
-        return out
+        return rule.nextExclusive(current, key, options || [],
+                                  modifiers === undefined ? Qt.NoModifier : modifiers)
     }
 
     // The selected artist's albums.

scripts/qml-tests/tst_multi_select.qml

@@ -432,5 +432,24 @@ Item {
             m = keyedRule.next(m, 7, rows, Qt.ShiftModifier)
             compare(Object.keys(m).sort().join(","), "7,8,9")
         }
+
+        function test_exclusive_rule() {
+            var rows = [{ "id": "g1" }, { "id": "g2" }, { "id": "g3" }, { "id": "g4" }, { "id": "g5" }]
+            var m = rule.nextExclusive({}, "g2", rows, Qt.NoModifier)
+            compare(Object.keys(m).sort().join(","), "g2", "a plain click selects only that row")
+            m = rule.nextExclusive(m, "g4", rows, Qt.ShiftModifier)
+            compare(Object.keys(m).sort().join(","), "g2,g3,g4", "Shift selects the range")
+            m = rule.nextExclusive(m, "g1", rows, Qt.ShiftModifier)
+            compare(Object.keys(m).sort().join(","), "g1,g2", "the anchor stays, Shift replaces the range")
+            m = rule.nextExclusive(m, "g5", rows, Qt.ControlModifier)
+            compare(Object.keys(m).sort().join(","), "g1,g2,g5", "Ctrl adds one")
+            m = rule.nextExclusive(m, "g5", rows, Qt.ControlModifier)
+            compare(Object.keys(m).sort().join(","), "g1,g2", "Ctrl on a selected row removes it")
+            m = rule.nextExclusive(m, "g3", rows, Qt.ControlModifier)
+            m = rule.nextExclusive(m, "g5", rows, Qt.ControlModifier | Qt.ShiftModifier)
+            compare(Object.keys(m).sort().join(","), "g1,g2,g3,g4,g5", "Ctrl+Shift adds a range")
+            m = rule.nextExclusive(m, "g4", rows, Qt.NoModifier)
+            compare(Object.keys(m).sort().join(","), "g4", "a plain click starts over")
+        }
     }
 }