Implement selection across multiple MessageDelegates

BUG: 457669

src/qml/Component/Timeline/MessageDelegate.qml

@@ -13,6 +13,13 @@ import org.kde.neochat 1.0
 TimelineContainer {
     id: messageDelegate
 
+    function positionAt(x, y) {
+        let point = label.mapFromItem(messageDelegate, x, y)
+        return label.positionAt(point.x, point.y)
+    }
+
+    property alias selectedText: label.selectedText
+
     property bool isEmote: false
     onOpenContextMenu: openMessageContext(model, label.selectedText, Controller.plainText(label.textDocument))
 
@@ -22,6 +29,7 @@ TimelineContainer {
             id: label
             Layout.fillWidth: true
             isEmote: messageDelegate.isEmote
+            isDelegate: true
         }
         Loader {
             id: linkPreviewLoader

src/qml/Component/Timeline/RichLabel.qml

@@ -16,6 +16,8 @@ TextEdit {
 
     property bool isEmote: false
 
+    property bool isDelegate: false
+
     readonly property var linkRegex: /(href=["'])?(\b(https?):\/\/[^\s\<\>\"\'\\]+)/g
     property string textMessage: model.display.includes("http")
         ? model.display.replace(linkRegex, function() {
@@ -41,8 +43,11 @@ TextEdit {
     persistentSelection: true
 
     // Work around QTBUG 93281
-    Component.onCompleted: if (text.includes("<img")) {
-        Controller.forceRefreshTextDocument(contentLabel.textDocument, contentLabel)
+    Component.onCompleted: {
+        updateSelection();
+        if (text.includes("<img")) {
+            Controller.forceRefreshTextDocument(contentLabel.textDocument, contentLabel)
+        }
     }
 
     text: "<style>
@@ -103,4 +108,26 @@ a{
         enabled: !parent.hoveredLink && !spoilerRevealed
         onTapped: spoilerRevealed = true
     }
+
+    Connections {
+        target: selectionArea
+        enabled: contentLabel.isDelegate
+        function onSelectionChanged() {
+            updateSelection();
+        }
+    }
+
+    function updateSelection() {
+        if (index < selectionArea.lowerIndex || index > selectionArea.upperIndex) {
+            contentLabel.select(0, 0);
+        } else if (index > selectionArea.lowerIndex && index < selectionArea.upperIndex) {
+            contentLabel.selectAll();
+        } else if (index === selectionArea.selectionStartIndex && index === selectionArea.selectionEndIndex) {
+            contentLabel.select(selectionArea.upperPos, selectionArea.lowerPos);
+        } else if (index === selectionArea.upperIndex) {
+            contentLabel.select(selectionArea.upperPos, contentLabel.length);
+        } else if (index === selectionArea.lowerIndex) {
+            contentLabel.select(0, selectionArea.lowerPos);
+        }
+    }
 }

src/qml/Page/RoomPage.qml

@@ -549,8 +549,66 @@ Kirigami.ScrollablePage {
                 }
             }
         }
-    }
 
+        function indexAtRelative(x, y) {
+            return indexAt(x + contentX, y + contentY)
+        }
+
+        MouseArea {
+            id: selectionArea
+            property int selectionStartIndex
+            property int selectionEndIndex
+            property int selectionStartPos
+            property int selectionEndPos
+
+            property int upperIndex: selectionStartIndex > selectionEndIndex ? selectionStartIndex : selectionEndIndex
+            property int upperPos: selectionStartIndex > selectionEndIndex ? selectionStartPos : (selectionStartIndex == selectionEndIndex ? (selectionStartPos > selectionEndPos ? selectionEndPos : selectionStartPos) : selectionEndPos)
+            property int lowerIndex: selectionStartIndex > selectionEndIndex ? selectionEndIndex : selectionStartIndex
+            property int lowerPos: selectionStartIndex > selectionEndIndex ? selectionEndPos : (selectionStartIndex == selectionEndIndex ? (selectionStartPos > selectionEndPos ? selectionStartPos : selectionEndPos) : selectionStartPos)
+
+            signal selectionChanged
+
+            anchors.fill: parent
+
+            function indexAndPos(x, y) {
+                const index = messageListView.indexAtRelative(x, y);
+                if (index == -1) {
+                    return;
+                }
+                const item = messageListView.itemAtIndex(index);
+                const relItemY = item.y - messageListView.contentY;
+                const pos = item.positionAt(x, y - relItemY);
+
+                return [index, pos]
+            }
+
+            onPressed: {
+                [selectionEndIndex, selectionEndPos] = indexAndPos(mouse.x, mouse.y);
+                [selectionStartIndex, selectionStartPos] = indexAndPos(mouse.x, mouse.y);
+                selectionChanged();
+            }
+            onPositionChanged: {
+                if (!pressed) {
+                    return
+                }
+                [selectionEndIndex, selectionEndPos] = indexAndPos(mouse.x, mouse.y);
+                selectionChanged();
+            }
+        }
+        Kirigami.Action {
+            onTriggered: {
+                var text = ""
+                for (let i = selectionArea.upperIndex; i >= selectionArea.lowerIndex; i--) {
+                    text += messageListView.itemAtIndex(i).selectedText
+                    if (i > selectionArea.lowerIndex) {
+                        text += " "
+                    }
+                }
+                Clipboard.saveText(text)
+            }
+            shortcut: "Ctrl+C"
+        }
+    }
 
     footer: ChatBox {
         id: chatBox