More cautious image creation

src/dorkbox/jna/windows/HBITMAPWrap.java

@@ -34,6 +34,8 @@ import com.sun.jna.ptr.PointerByReference;
 
 public class HBITMAPWrap extends HBITMAP {
 
+    private static final Object lockObject = new Object();
+
     // NOTE: This is a field (instead of private) so that GC does not try to collect this object
     private HBITMAP bitmap;
 
@@ -42,6 +44,9 @@ public class HBITMAPWrap extends HBITMAP {
     HBITMAP createBitmap(BufferedImage image) {
         int w = image.getWidth(null);
         int h = image.getHeight(null);
+
+        // all sorts of issues occur if this is called quickly from different threads!
+        synchronized(lockObject) {
             HDC screenDC = User32.GetDC(null);
             HDC memDC = GDI32.CreateCompatibleDC(screenDC);
             HBITMAP hBitmap = null;
@@ -92,6 +97,7 @@ public class HBITMAPWrap extends HBITMAP {
                 GDI32.DeleteDC(memDC);
             }
         }
+    }
 
     BufferedImage img;
 

src/dorkbox/jna/windows/HICONWrap.java

@@ -27,6 +27,7 @@ import dorkbox.jna.windows.structs.ICONINFO;
  * http://www.pinvoke.net/default.aspx/user32.createiconindirect
  */
 public class HICONWrap extends HICON {
+    private static final Object lockObject = new Object();
 
     static HICON createIconIndirect(HBITMAP bm) {
         ICONINFO info = new ICONINFO();
@@ -35,9 +36,16 @@ public class HICONWrap extends HICON {
         info.ColorBitmap = bm;
 
         HICON hicon = User32.CreateIconIndirect(info);
+        if (hicon == null) {
+            // something weird is going on! Try again but more carefully!
+            synchronized(lockObject) {
+                hicon = User32.CreateIconIndirect(info);
+            }
+
             if (hicon == null) {
                 throw new GetLastErrorException();
             }
+        }
 
         return hicon;
     }