Initial implementation of ComponentRenderer for Grid (#8743)

Fixes #8622 
Fixes #8623 

2 files changed, 103 insertions, 0 deletions

diff --git a/server/src/main/java/com/vaadin/ui/Grid.java b/server/src/main/java/com/vaadin/ui/Grid.java
index 5d03825c6f..d0b908a956 100644
--- a/server/src/main/java/com/vaadin/ui/Grid.java
+++ b/server/src/main/java/com/vaadin/ui/Grid.java
@@ -115,6 +115,7 @@ import com.vaadin.ui.declarative.DesignContext;
 import com.vaadin.ui.declarative.DesignException;
 import com.vaadin.ui.declarative.DesignFormatter;
 import com.vaadin.ui.renderers.AbstractRenderer;
+import com.vaadin.ui.renderers.ComponentRenderer;
 import com.vaadin.ui.renderers.HtmlRenderer;
 import com.vaadin.ui.renderers.Renderer;
 import com.vaadin.ui.renderers.TextRenderer;
@@ -831,6 +832,7 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
         private DescriptionGenerator<T> descriptionGenerator;
 
         private Binding<T, ?> editorBinding;
+        private Map<T, Component> activeComponents = new HashMap<>();
 
         private String userId;
 
@@ -961,6 +963,11 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
 
             V providerValue = valueProvider.apply(data);
 
+            // Make Grid track components.
+            if (renderer instanceof ComponentRenderer
+                    && providerValue instanceof Component) {
+                addComponent(data, (Component) providerValue);
+            }
             JsonValue rendererValue = renderer.encode(providerValue);
 
             obj.put(communicationId, rendererValue);
@@ -981,6 +988,38 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
             }
         }
 
+        private void addComponent(T data, Component component) {
+            if (activeComponents.containsKey(data)) {
+                if (activeComponents.get(data).equals(component)) {
+                    // Reusing old component
+                    return;
+                }
+                removeComponent(data);
+            }
+            activeComponents.put(data, component);
+            addComponentToGrid(component);
+        }
+
+        @Override
+        public void destroyData(T item) {
+            removeComponent(item);
+        }
+
+        private void removeComponent(T item) {
+            Component component = activeComponents.remove(item);
+            if (component != null) {
+                removeComponentFromGrid(component);
+            }
+        }
+
+        @Override
+        public void destroyAllData() {
+            // Make a defensive copy of keys, as the map gets cleared when
+            // removing components.
+            new HashSet<>(activeComponents.keySet())
+                    .forEach(this::removeComponent);
+        }
+
         /**
          * Gets a data object with the given key from the given JsonObject. If
          * there is no object with the key, this method creates a new
diff --git a/server/src/main/java/com/vaadin/ui/renderers/ComponentRenderer.java b/server/src/main/java/com/vaadin/ui/renderers/ComponentRenderer.java
new file mode 100644
index 0000000000..1053907723
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/renderers/ComponentRenderer.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.ui.renderers;
+
+import com.vaadin.shared.ui.grid.renderers.ComponentRendererState;
+import com.vaadin.ui.Component;
+
+import elemental.json.Json;
+import elemental.json.JsonValue;
+
+/**
+ * A renderer for presenting Components.
+ * <p>
+ * <strong>Note:</strong> The use of ComponentRenderer causes the Grid to
+ * generate components for all items currently available in the client-side.
+ * This means that a number of components is always generated and sent to the
+ * client. Using complex structures of many nested components might be heavy to
+ * generate and store, which will lead to performance problems.
+ * <p>
+ * <strong>Note:</strong> Components will occasionally be generated again during
+ * runtime e.g. when selection changes. If your component has an internal state
+ * that is not stored into the object, you should reuse the same component
+ * instances.
+ *
+ * @author Vaadin Ltd
+ * @since 8.1
+ */
+public class ComponentRenderer extends AbstractRenderer<Object, Component> {
+
+    /**
+     * Constructor for ComponentRenderer.
+     */
+    public ComponentRenderer() {
+        super(Component.class);
+    }
+
+    @Override
+    public JsonValue encode(Component value) {
+        return Json.create(value.getConnectorId());
+    }
+
+    @Override
+    protected ComponentRendererState getState(boolean markAsDirty) {
+        return (ComponentRendererState) super.getState(markAsDirty);
+    }
+
+    @Override
+    protected ComponentRendererState getState() {
+        return (ComponentRendererState) super.getState();
+    }
+}