Expose some selection control to the api

* add_selection_change_handler: allows to handle selection change events;
* select_cells: allows to programmatically change the selection;

qmxgraph/api.py

@@ -209,6 +209,22 @@ def set_visible(self, cell_id, visible):
         """
         return self.call_api('setVisible', cell_id, visible)
 
+    def set_selected_cells(self, cell_ids):
+        """
+        Select the cells with the given ids.
+
+        :param list[str] cell_ids:
+        """
+        return self.call_api('setSelectedCells', cell_ids)
+
+    def get_selected_cells(self):
+        """
+        Get the selected cells ids.
+
+        :rtype: list[str]
+        """
+        return self.call_api('getSelectedCells')
+
     def remove_cells(self, cell_ids):
         """
         Remove cells from graph.
@@ -293,6 +309,17 @@ def on_cells_removed(self, handler):
         """
         return self.call_api('onCellsRemoved', qmxgraph.js.Variable(handler))
 
+    def on_selection_changed(self, handler):
+        """
+        Add function to handle selection change events in the graph.
+
+        :param handler: Name of signal bound to JavaScript by a bridge object
+            that is going to be used as callback to event. Receives an list of
+            str with selected cells ids as only argument.
+        """
+        return self.call_api(
+            'onSelectionChanged', qmxgraph.js.Variable(handler))
+
     def resize_container(self, width, height):
         """
         Resizes the container of graph drawing widget.

qmxgraph/page/api.js

@@ -368,6 +368,41 @@ graphs.Api.prototype.setVisible = function setVisible (cellId, visible) {
     }
 };
 
+/**
+ * Select the cells with the given ids.
+ *
+ * @param {number[]} cellIds An array with the ids of the cells to select.
+ */
+graphs.Api.prototype.setSelectedCells = function setSelectedCells (cellIds) {
+    "use strict";
+
+    var cellsToSelect = [];
+    var model = api._graphEditor.graph.getModel();
+    var cell = null;
+    for (var i = cellIds.length; i--;) {
+        cell = model.getCell(cellIds[i]);
+        cellsToSelect.push(cell)
+    }
+
+    var selectionModel = this._graphEditor.graph.getSelectionModel();
+    selectionModel.setCells(cellsToSelect);
+};
+
+/**
+ * Get the ids of the selected cells.
+ */
+graphs.Api.prototype.getSelectedCells = function getSelectedCells () {
+    "use strict";
+
+    var selectionModel = this._graphEditor.graph.getSelectionModel();
+    var cells = selectionModel.cells;
+    var cellIds = [];
+    for (var i = cells.length; i--;) {
+        cellIds.push(cells[i].getId())
+    }
+    return cellIds;
+};
+
 /**
  * Groups the currently selected cells in graph.
  */
@@ -515,6 +550,28 @@ graphs.Api.prototype.onCellsAdded = function onCellsAdded (handler) {
     graph.addListener(mxEvent.ADD_CELLS, addHandler);
 };
 
+/**
+ * Add function to handle selection change events in the graph.
+ *
+ * @param {function} handler Callback that handles event. Receives an array with the id of cells
+ * that are selected as only argument.
+ */
+graphs.Api.prototype.onSelectionChanged = function onSelectionChanged (handler) {
+    "use strict";
+
+    var selectionHandler = function(source, event) {
+        var selectedCells = source.cells;
+        var selectedCellsIds = [];
+        for (var i = selectedCells.length; i--;) {
+            selectedCellsIds.push(selectedCells[i].getId());
+        }
+        handler(selectedCellsIds);
+    };
+
+    var selectionModel = this._graphEditor.graph.getSelectionModel();
+    selectionModel.addListener(mxEvent.CHANGE, selectionHandler);
+};
+
 
 /**
  * Register a handler to event when cells have their label changed.

qmxgraph/widget.py

@@ -182,6 +182,8 @@ def set_events_bridge(self, bridge):
             self.api.on_cells_added('bridge_events_handler.on_cells_added')
             self.api.on_cells_removed('bridge_events_handler.on_cells_removed')
             self.api.on_label_changed('bridge_events_handler.on_label_changed')
+            self.api.on_selection_changed(
+                'bridge_events_handler.on_selection_changed')
 
     def set_double_click_handler(self, handler):
         """
@@ -511,6 +513,12 @@ class EventsBridge(QObject):
     # old_label: str
     on_label_changed = pyqtSignal(
         str, str, str, name='on_label_changed')
+    # JavaScript client code emits this signal when the current selection
+    # change.
+    # Arguments:
+    # cell_ids: str
+    on_selection_changed = pyqtSignal(
+        'QVariantList', name='on_selection_changed')
 
 
 class _DoubleClickBridge(QObject):

tests/test_js_graph.py

@@ -1032,6 +1032,60 @@ def test_set_double_click_handler(graph_cases):
         [vertex_id]
 
 
+def test_add_selection_change_handler(graph_cases):
+    """
+    :type graph_cases: qmxgraph.tests.conftest.GraphCaseFactory
+    """
+
+    graph = graph_cases('2v_1e')
+    source, target = graph.get_vertices()
+    edge = graph.get_edge(source, target)
+
+    graph.selenium.execute_script(
+        'callback = function(cellIds) {'
+        '    if (!window.__selectionChange__) {'
+        '        window.__selectionChange__ = [];'
+        '    }'
+        '    window.__selectionChange__.push(cellIds);'
+        '}')
+    graph.eval_js_function(
+        'api.onSelectionChanged', qmxgraph.js.Variable('callback'))
+
+    # Select all cells.
+    actions = ActionChains(graph.selenium)
+    actions.key_down(Keys.CONTROL)
+    actions.click(source)
+    actions.click(target)
+    actions.click(edge)
+    actions.key_up(Keys.CONTROL)
+    actions.perform()
+
+    fired_selection_events = graph.selenium.execute_script(
+        'return window.__selectionChange__')
+    assert fired_selection_events == [
+        ['2'],
+        ['3', '2'],
+        ['4', '3', '2'],
+    ]
+
+    assert graph.eval_js_function('api.getSelectedCells') == ['4', '3', '2']
+
+    # Programmatically select one cell.
+    graph.eval_js_function('api.setSelectedCells', ['3'])
+    # Clear selection.
+    graph.eval_js_function('api.setSelectedCells', [])
+
+    fired_selection_events = graph.selenium.execute_script(
+        'return window.__selectionChange__')
+    assert fired_selection_events == [
+        ['2'],
+        ['3', '2'],
+        ['4', '3', '2'],
+        ['3'],
+        [],
+    ]
+
+
 def test_set_popup_menu_handler(graph_cases):
     """
     :type graph_cases: qmxgraph.tests.conftest.GraphCaseFactory

tests/test_qt_js_integration.py

@@ -52,6 +52,7 @@ def test_events_bridge(graph, qtbot):
     added = []
     removed = []
     labels = []
+    selections = []
 
     def on_cells_added(cell_ids):
         added.extend(cell_ids)
@@ -68,11 +69,20 @@ def on_label_changed(a, b, c):
 
     events.on_label_changed.connect(on_label_changed)
 
+    def on_selection_changed(cells_ids):
+        selections.extend(cells_ids)
+
+    events.on_selection_changed.connect(on_selection_changed)
+
     wait_until_loaded(graph, qtbot)
 
     vertex_id = graph.api.insert_vertex(10, 10, 20, 20, 'test')
     assert added == [vertex_id]
 
+    assert selections == []
+    eval_js(graph, "graphEditor.execute('selectVertices')")
+    assert selections == [vertex_id]
+
     graph.api.set_label(vertex_id, 'TOTALLY NEW LABEL')
     assert labels == [vertex_id, 'TOTALLY NEW LABEL', 'test']