Make Button component draggable (#9038)

* Make Button component draggable (#9037)

* Add own state to button drag source

client/src/main/java/com/vaadin/client/extensions/ButtonDragSourceConnector.java

@@ -0,0 +1,58 @@
+/*
+ * 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.client.extensions;
+
+import com.vaadin.client.ServerConnector;
+import com.vaadin.client.ui.VButton;
+import com.vaadin.client.ui.button.ButtonConnector;
+import com.vaadin.event.dnd.ButtonDragSource;
+import com.vaadin.shared.ui.Connect;
+import com.vaadin.shared.ui.dnd.ButtonDragSourceState;
+
+/**
+ * Extension to make Button a drag source for HTML5 drag and drop functionality.
+ *
+ * @author Vaadin Ltd.
+ * @since 8.1
+ */
+@Connect(ButtonDragSource.class)
+public class ButtonDragSourceConnector extends DragSourceExtensionConnector {
+
+    private VButton buttonWidget;
+
+    @Override
+    protected void extend(ServerConnector target) {
+        super.extend(target);
+
+        buttonWidget = ((ButtonConnector) target).getWidget();
+
+        // Disable mouse event capturing to make the widget draggable
+        buttonWidget.setCapturingEnabled(false);
+    }
+
+    @Override
+    public void onUnregister() {
+        super.onUnregister();
+
+        // Reset mouse event capturing
+        buttonWidget.setCapturingEnabled(true);
+    }
+
+    @Override
+    public ButtonDragSourceState getState() {
+        return (ButtonDragSourceState) super.getState();
+    }
+}

client/src/main/java/com/vaadin/client/ui/VButton.java

@@ -67,6 +67,13 @@ public class VButton extends FocusWidget implements ClickHandler {
 
     private int tabIndex = 0;
 
+    /**
+     * Switch for disabling mouse capturing.
+     *
+     * @see #isCapturing
+     */
+    private boolean capturingEnabled = true;
+
     /*
      * BELOW PRIVATE MEMBERS COPY-PASTED FROM GWT CustomButton
      */
@@ -199,7 +206,7 @@ public class VButton extends FocusWidget implements ClickHandler {
                 clickPending = true;
                 setFocus(true);
                 DOM.setCapture(getElement());
-                isCapturing = true;
+                isCapturing = isCapturingEnabled();
                 addStyleName(CLASSNAME_PRESSED);
             }
             break;
@@ -412,6 +419,27 @@ public class VButton extends FocusWidget implements ClickHandler {
         }
     }
 
+    /**
+     * Enables or disables the widget's capturing of mouse events with the mouse
+     * held down.
+     *
+     * @param enabled
+     *         {@literal true} if capturing enabled, {@literal false} otherwise
+     */
+    public void setCapturingEnabled(boolean enabled) {
+        capturingEnabled = enabled;
+    }
+
+    /**
+     * Returns if the widget's capturing of mouse events are enabled.
+     *
+     * @return {@literal true} if mouse capturing is enabled, {@literal false}
+     * otherwise
+     */
+    public boolean isCapturingEnabled() {
+        return capturingEnabled;
+    }
+
     private static native int getHorizontalBorderAndPaddingWidth(Element elem)
     /*-{
         // THIS METHOD IS ONLY USED FOR INTERNET EXPLORER, IT DOESN'T WORK WITH OTHERS

server/src/main/java/com/vaadin/event/dnd/ButtonDragSource.java

@@ -0,0 +1,42 @@
+/*
+ * 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.event.dnd;
+
+import com.vaadin.shared.ui.dnd.ButtonDragSourceState;
+import com.vaadin.ui.Button;
+
+/**
+ * Extension to make Button a drag source for HTML5 drag and drop functionality.
+ *
+ * @author Vaadin Ltd.
+ * @since 8.1
+ */
+public class ButtonDragSource extends DragSourceExtension<Button> {
+
+    public ButtonDragSource(Button target) {
+        super(target);
+    }
+
+    @Override
+    protected ButtonDragSourceState getState() {
+        return (ButtonDragSourceState) super.getState();
+    }
+
+    @Override
+    protected ButtonDragSourceState getState(boolean markAsDirty) {
+        return (ButtonDragSourceState) super.getState(markAsDirty);
+    }
+}

shared/src/main/java/com/vaadin/shared/ui/dnd/ButtonDragSourceState.java

@@ -0,0 +1,26 @@
+/*
+ * 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.shared.ui.dnd;
+
+/**
+ * State class containing parameters for ButtonDragSourceExtension.
+ *
+ * @author Vaadin Ltd
+ * @since 8.1
+ */
+public class ButtonDragSourceState extends DragSourceState {
+
+}

uitest/src/main/java/com/vaadin/tests/dnd/DraggableButton.java

@@ -0,0 +1,73 @@
+/*
+ * 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.tests.dnd;
+
+import com.vaadin.event.dnd.ButtonDragSource;
+import com.vaadin.event.dnd.DropTargetExtension;
+import com.vaadin.server.Page;
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.tests.components.AbstractTestUIWithLog;
+import com.vaadin.ui.Button;
+import com.vaadin.ui.HorizontalLayout;
+import com.vaadin.ui.Label;
+import com.vaadin.ui.Layout;
+
+public class DraggableButton extends AbstractTestUIWithLog {
+
+    @Override
+    protected void setup(VaadinRequest request) {
+
+        Button draggableButton = new Button("Draggable Button");
+        ButtonDragSource dragSourceExtension = new ButtonDragSource(
+                draggableButton);
+        dragSourceExtension.setDataTransferText(
+                "If you see this, the drop was successful");
+
+        Label dropTarget = new Label("Drop Here");
+        dropTarget.addStyleName("drop-target");
+        DropTargetExtension<Label> dropTargetExtension = new DropTargetExtension<>(
+                dropTarget);
+        dropTargetExtension
+                .addDropListener(event -> log(event.getDataTransferText()));
+
+        Layout layout = new HorizontalLayout();
+        layout.addComponents(draggableButton, dropTarget);
+        addComponent(layout);
+
+        // Add styling
+        setStyle();
+    }
+
+    private void setStyle() {
+        Page.Styles styles = Page.getCurrent().getStyles();
+
+        styles.add(".drop-target {"
+                + "width: 150px;"
+                + "height: 100px;"
+                + "border: 1px solid black;"
+                + "border-radius: 4px;"
+                + "text-align: center;"
+                + "}");
+        styles.add(".v-drag-over {"
+                + "border-style: dashed;"
+                + "}");
+    }
+
+    @Override
+    protected String getTestDescription() {
+        return "Test if Button is draggable";
+    }
+}