Adding PNG drag point.

Author: phase1geo

src/CanvasToolbar.vala

@@ -69,6 +69,8 @@ public class CanvasToolbar : Box {
     create_color();
     create_stroke();
     create_fonts();
+    create_separator();
+    create_drag_label();
 
     /* If the selection changes, update the toolbar */
     _canvas.items.selection_changed.connect( selection_changed );
@@ -724,6 +726,33 @@ public class CanvasToolbar : Box {
 
   }
 
+  //-------------------------------------------------------------
+  // Creates a label that we can drag an image from. 
+  private void create_drag_label() {
+
+    var drag_label = new Label( "PNG" ) {
+      tooltip_text = _( "Drag PNG Image" ),
+      margin_start = 20
+    };
+
+    var drag = new DragSource() {
+      actions = Gdk.DragAction.MOVE
+    };
+    drag_label.add_controller( drag );
+
+    drag.prepare.connect((d) => {
+      var val = Value( typeof(GLib.File) );
+      var fname = Utils.create_temp_filename( "png" );
+      _canvas.win.editor.canvas.image.export_image( "png", fname );
+      val = File.new_for_path( fname );
+      var cp = new Gdk.ContentProvider.for_value( val );
+      return( cp );
+    });
+
+    append( drag_label );
+
+  }
+
   private Image make_color_icon() {
 
     var snapshot = new Snapshot();

src/Utils.vala

@@ -274,4 +274,16 @@ public class Utils {
     return( str );
   }
 
+  //-------------------------------------------------------------
+  // Creates a temporary filename.
+  public static string? create_temp_filename( string extension ) {
+    try {
+      string filename = "";
+      var fd = FileUtils.open_tmp( "annotator_XXXXXX.%s".printf( extension ), out filename );
+      FileUtils.close( fd );
+      return( filename );
+    } catch( FileError e ) {}
+    return( null );
+  }
+
 }