Add way to get back from a Com4jObject to an IUknown

And add example showing how to use that the get the cached object at a
specific cell.

Author: tonyroberts

examples/jinx-com4j-examples.xlsx

@@ -33,7 +33,7 @@
         <dependency>
             <groupId>com.exceljava</groupId>
             <artifactId>jinx</artifactId>
-            <version>2.0.0-beta1</version>
+            <version>2.0.0-beta2</version>
         </dependency>
     </dependencies>
 </project>

examples/pom.xml

@@ -5,7 +5,11 @@
 
 import com.exceljava.com4j.JinxBridge;
 import com.exceljava.com4j.excel.*;
-import com4j.Com4jObject;
+import com.exceljava.jinx.ExcelReference;
+import com.exceljava.jinx.IUnknown;
+
+import javax.swing.*;
+import java.awt.*;
 
 /**
  * Example macros that use com4j to call back into Excel
@@ -76,4 +80,32 @@ public void scrollbarExample() {
         // Set the cell value from the scrollbar value
         range.setValue(scrollbar.getValue());
     }
+
+    @ExcelMacro(
+            value = "jinx.show_object_example",
+            shortcut = "Ctrl+Shift+I"
+    )
+    public void showObject() throws HeadlessException {
+        // Get the current selection
+        _Application app = JinxBridge.getApplication(xl);
+        Range selection = app.getSelection().queryInterface(Range.class);
+
+        // Ensure the cell is calculated
+        selection.setFormula(selection.getFormula());
+        selection.calculate();
+
+        // Get an ExcelReference corresponding to the selection
+        IUnknown unk = JinxBridge.getIUnknown(selection);
+        ExcelReference cell = xl.getReference(unk);
+
+        // Find the cached object for this cell
+        Object cachedObject = xl.getCachedObject(cell);
+
+        // Popup a non-modal dialog with the string representation of the object
+        String message = cachedObject != null ? cachedObject.toString() : "NULL";
+        JOptionPane pane = new JOptionPane(message, JOptionPane.INFORMATION_MESSAGE);
+        JDialog dialog = pane.createDialog("Java Object");
+        dialog.setModal(false);
+        dialog.setVisible(true);
+    }
 }

examples/src/main/java/com/exceljava/com4j/examples/MacroFunctions.java

@@ -26,7 +26,7 @@
         <dependency>
             <groupId>com.exceljava</groupId>
             <artifactId>jinx</artifactId>
-            <version>2.0.0-beta1</version>
+            <version>2.0.0-beta2</version>
         </dependency>
         <!-- com4j -->
         <dependency>

jinx-com4j/pom.xml

@@ -0,0 +1,48 @@
+package com.exceljava.com4j;
+
+import com.exceljava.jinx.IUnknown;
+import com4j.Com4jObject;
+
+/**
+ * Adaptor class that implements the IUnknown interface
+ * wrapping a Com4jObject instance.
+ */
+class IUnknownAdaptor implements IUnknown {
+    private Com4jObject obj;
+
+    public IUnknownAdaptor(Com4jObject obj) {
+        this.obj = obj;
+    }
+
+    private static <T extends Com4jObject> Class<T> adaptClass(Class<?> cls) {
+        return (Class<T>)cls;
+    }
+
+    @Override
+    public <T> T queryInterface(Class<T> cls) {
+        Com4jObject obj = this.obj;
+        if (null != obj && cls.isAssignableFrom(Com4jObject.class)) {
+            return obj.queryInterface(adaptClass(cls));
+        }
+        return null;
+    }
+
+    @Override
+    public long getPointer(boolean addRef) {
+        if (addRef) {
+            throw new UnsupportedOperationException();
+        }
+
+        Com4jObject obj = this.obj;
+        if (null != obj) {
+            return obj.getIUnknownPointer();
+        }
+
+        return 0;
+    }
+
+    @Override
+    public void close() {
+        this.obj = null;
+    }
+}

jinx-com4j/src/main/java/com/exceljava/com4j/IUnknownAdaptor.java

@@ -31,6 +31,19 @@ public static _Application getApplication(ExcelAddIn xl) {
         return xl.getExcelApplication(_Application.class);
     }
 
+    /**
+     * Return an IUnknown instance that wraps a Com4jObject.
+     *
+     * This can be used for passing Com4jObjects back to Jinx
+     * methods requiring an IUnknown instance.
+     *
+     * @param object COM object to be wrapped as an IUnknown.
+     * @return Instance implementing IUnknown.
+     */
+    public static IUnknown getIUnknown(Com4jObject object) {
+        return new IUnknownAdaptor(object);
+    }
+
     /**
      * Converts IUnknown to any Com4jObject type.
      *