[ui] Added selectionLine and delegate variant to allow drawing an edge

The drawn edge is checked for intersection with individual node edges and any edge found interesecting is emitted when the selection ends

meshroom/ui/qml/Controls/SelectionLine.qml

@@ -0,0 +1,77 @@
+import QtQuick
+import QtQuick.Shapes
+
+/*
+Simple selection line that can be used by a MouseArea.
+
+Usage:
+1. Create a MouseArea and a selectionShape.
+2. Bind the selectionShape to the MouseArea by setting the `mouseArea` property.
+3. Call startSelection() with coordinates when the selection starts.
+4. Call endSelection() when the selection ends.
+5. Listen to the selectionEnded signal to get the rectangle whose Diagonal is the selection line.
+*/
+
+Item {
+    id: root
+
+    property MouseArea mouseArea
+
+    readonly property bool active: mouseArea.drag.target == dragTarget
+
+    signal selectionEnded(rect selectionRect, int modifiers)
+
+    function startSelection(mouse) {
+        dragTarget.startPos.x = dragTarget.x = mouse.x;
+        dragTarget.startPos.y = dragTarget.y = mouse.y;
+        dragTarget.modifiers = mouse.modifiers;
+        mouseArea.drag.target = dragTarget;
+    }
+
+    function endSelection() {
+        if (!active) {
+            return;
+        }
+        mouseArea.drag.target = null;
+        const rect = Qt.rect(selectionShape.x, selectionShape.y, selectionShape.width, selectionShape.height)
+        selectionEnded(rect, dragTarget.modifiers);
+    }
+
+    visible: active
+
+    Item {
+        id: selectionShape
+        x: dragTarget.startPos.x
+        y: dragTarget.startPos.y
+        width: dragTarget.x - dragTarget.startPos.x
+        height: dragTarget.y - dragTarget.startPos.y
+
+        Shape {
+            id: dynamicLine;
+            width: selectionShape.width;
+            height: selectionShape.height;
+            anchors.fill: parent;
+
+            ShapePath {
+                strokeWidth: 2;
+                strokeStyle: ShapePath.DashLine;
+                strokeColor: "#FF0000";
+                dashPattern: [3, 2];
+
+                startX: 0;
+                startY: 0;
+
+                PathLine {
+                    x: selectionShape.width;
+                    y: selectionShape.height;
+                }
+            }
+        }
+    }
+
+    Item {
+        id: dragTarget
+        property point startPos
+        property var modifiers
+    }
+}