Native window decorations: when resizing a window to the right or to the bottom, then first fill the new space with the window background color (instead of black) before the layout is updated (issue #339)

CHANGELOG.md

@@ -9,8 +9,11 @@ FlatLaf Change Log
   honor maximum size of internal frame. (issue #362)
 - Popup: Fixed incorrectly placed drop shadow for medium-weight popups in
   maximized windows. (issue #358)
-- Native window decorations: Fixed occasional application crash on Windows 10 in
+- Native window decorations (Windows 10 only):
-  `flatlaf-windows.dll`. (issue #357)
+  - Fixed occasional application crash in `flatlaf-windows.dll`. (issue #357)
+  - When resizing a window to the right or to the bottom, then first fill the
+    new space with the window background color (instead of black) before the
+    layout is updated.
 
 
 ## 1.4
@@ -25,7 +28,7 @@ FlatLaf Change Log
 - Table and PopupFactory: Use `StackWalker` in Java 9+ for better performance.
   (issue #334)
 - ToolBar: Paint focus indicator for focused button in toolbar. (issue #346)
-- ToolBar: Support focusable buttons in toolbar (set UI values
+- ToolBar: Support focusable buttons in toolbar (set UI value
   `ToolBar.focusableButtons` to `true`). (issue #346)
 
 #### Fixed bugs

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatWindowsNativeWindowBorder.java

@@ -25,6 +25,8 @@ import java.awt.Point;
 import java.awt.Rectangle;
 import java.awt.Window;
 import java.awt.geom.AffineTransform;
+import java.beans.PropertyChangeEvent;
+import java.beans.PropertyChangeListener;
 import java.util.Collections;
 import java.util.IdentityHashMap;
 import java.util.List;
@@ -289,6 +291,7 @@ class FlatWindowsNativeWindowBorder
 	//---- class WndProc ------------------------------------------------------
 
 	private class WndProc
+		implements PropertyChangeListener
 	{
 		// WM_NCHITTEST mouse position codes
 		private static final int
@@ -313,18 +316,36 @@ class FlatWindowsNativeWindowBorder
 
 			// remove the OS window title bar
 			updateFrame( hwnd, (window instanceof JFrame) ? ((JFrame)window).getExtendedState() : 0 );
+
+			// set window background (used when resizing window)
+			updateWindowBackground();
+			window.addPropertyChangeListener( "background", this );
 		}
 
 		void uninstall() {
+			window.removePropertyChangeListener( "background", this );
+
 			uninstallImpl( hwnd );
 
 			// cleanup
 			window = null;
 		}
 
+		@Override
+		public void propertyChange( PropertyChangeEvent e ) {
+			updateWindowBackground();
+		}
+
+		private void updateWindowBackground() {
+			Color bg = window.getBackground();
+			if( bg != null )
+				setWindowBackground( hwnd, bg.getRed(), bg.getGreen(), bg.getBlue() );
+		}
+
 		private native long installImpl( Window window );
 		private native void uninstallImpl( long hwnd );
 		private native void updateFrame( long hwnd, int state );
+		private native void setWindowBackground( long hwnd, int r, int g, int b );
 		private native void showWindow( long hwnd, int cmd );
 
 		// invoked from native code

flatlaf-natives/flatlaf-natives-jna/src/main/java/com/formdev/flatlaf/natives/jna/windows/FlatWindowsNativeWindowBorder.java

@@ -28,6 +28,8 @@ import java.awt.Point;
 import java.awt.Rectangle;
 import java.awt.Window;
 import java.awt.geom.AffineTransform;
+import java.beans.PropertyChangeEvent;
+import java.beans.PropertyChangeListener;
 import java.util.Collections;
 import java.util.IdentityHashMap;
 import java.util.List;
@@ -47,6 +49,7 @@ import com.sun.jna.Structure.FieldOrder;
 import com.sun.jna.platform.win32.Advapi32Util;
 import com.sun.jna.platform.win32.BaseTSD;
 import com.sun.jna.platform.win32.BaseTSD.ULONG_PTR;
+import com.sun.jna.platform.win32.GDI32;
 import com.sun.jna.platform.win32.Shell32;
 import com.sun.jna.platform.win32.User32;
 import com.sun.jna.platform.win32.WTypes.LPWSTR;
@@ -57,6 +60,7 @@ import com.sun.jna.platform.win32.WinDef.LRESULT;
 import com.sun.jna.platform.win32.WinDef.RECT;
 import com.sun.jna.platform.win32.WinDef.UINT_PTR;
 import com.sun.jna.platform.win32.WinDef.WPARAM;
+import com.sun.jna.platform.win32.WinNT.HANDLE;
 import com.sun.jna.platform.win32.WinUser.HMONITOR;
 import com.sun.jna.platform.win32.WinUser.WindowProc;
 import com.sun.jna.win32.W32APIOptions;
@@ -282,7 +286,7 @@ public class FlatWindowsNativeWindowBorder
 	//---- class WndProc ------------------------------------------------------
 
 	private class WndProc
-		implements WindowProc
+		implements WindowProc, PropertyChangeListener
 	{
 		private static final int GWLP_WNDPROC = -4;
 
@@ -345,9 +349,15 @@ public class FlatWindowsNativeWindowBorder
 
 			// remove the OS window title bar
 			updateFrame( (window instanceof JFrame) ? ((JFrame)window).getExtendedState() : 0 );
+
+			// set window background (used when resizing window)
+			updateWindowBackground();
+			window.addPropertyChangeListener( "background", this );
 		}
 
 		void uninstall() {
+			window.removePropertyChangeListener( "background", this );
+
 			// restore original window procedure
 			if( SystemInfo.isX86_64 )
 				User32Ex.INSTANCE.SetWindowLongPtr( hwnd, GWLP_WNDPROC, defaultWndProc );
@@ -382,6 +392,28 @@ public class FlatWindowsNativeWindowBorder
 			wmSizeWParam = -1;
 		}
 
+		@Override
+		public void propertyChange( PropertyChangeEvent evt ) {
+			updateWindowBackground();
+		}
+
+		private void updateWindowBackground() {
+			Color bg = window.getBackground();
+			if( bg != null )
+				setWindowBackground( bg.getRed(), bg.getGreen(), bg.getBlue() );
+		}
+
+		private void setWindowBackground( int r, int g, int b ) {
+			// delete old background brush
+			ULONG_PTR oldBrush = User32.INSTANCE.GetClassLongPtr( hwnd, GCLP_HBRBACKGROUND );
+			if( oldBrush != null && oldBrush.longValue() != 0 )
+				GDI32.INSTANCE.DeleteObject( new HANDLE( oldBrush.toPointer() ) );
+
+			// create new background brush
+			HBRUSH brush = GDI32Ex.INSTANCE.CreateSolidBrush( RGB( r, g, b ) );
+			User32Ex.INSTANCE.SetClassLongPtr( hwnd, GCLP_HBRBACKGROUND, brush );
+		}
+
 		/**
 		 * NOTE: This method is invoked on the AWT-Windows thread (not the AWT-EventQueue thread).
 		 */
@@ -637,6 +669,13 @@ public class FlatWindowsNativeWindowBorder
 			return (short) ((lParam.longValue() >> 16) & 0xffff);
 		}
 
+		/**
+		 * Same implementation as RGB(r,g,b) macro in wingdi.h.
+		 */
+		private DWORD RGB( int r, int g, int b ) {
+			return new DWORD( (r & 0xff) | ((g & 0xff) << 8) | ((b & 0xff) << 16) );
+		}
+
 		/**
 		 * Opens the window's system menu.
 		 * The system menu is the menu that opens when the user presses Alt+Space or
@@ -690,6 +729,8 @@ public class FlatWindowsNativeWindowBorder
 		LONG_PTR SetWindowLong( HWND hWnd, int nIndex, LONG_PTR wndProc );
 		LRESULT CallWindowProc( LONG_PTR lpPrevWndFunc, HWND hWnd, int uMsg, WPARAM wParam, LPARAM lParam );
 
+		LONG_PTR SetClassLongPtr( HWND hWnd, int nIndex, HANDLE wndProc );
+
 		int GetDpiForWindow( HWND hwnd );
 		int GetSystemMetricsForDpi( int nIndex, int dpi );
 
@@ -702,6 +743,16 @@ public class FlatWindowsNativeWindowBorder
 		BOOL TrackPopupMenu( HMENU hMenu, int uFlags, int x, int y, int nReserved, HWND hWnd, RECT prcRect );
 	}
 
+	//---- interface GDI32Ex --------------------------------------------------
+
+	private interface GDI32Ex
+		extends GDI32
+	{
+		GDI32Ex INSTANCE = Native.load( "gdi32", GDI32Ex.class, W32APIOptions.DEFAULT_OPTIONS );
+
+		HBRUSH CreateSolidBrush( DWORD color );
+	}
+
 	//---- class NCCALCSIZE_PARAMS --------------------------------------------
 
 	@FieldOrder( { "rgrc" } )

flatlaf-natives/flatlaf-natives-windows/build.gradle.kts

@@ -73,8 +73,8 @@ library {
 
 				linkerArgs.addAll( toolChain.map {
 					when( it ) {
-						is Gcc, is Clang -> listOf( "-l${jawt}", "-lUser32", "-lshell32", "-lAdvAPI32", "-lKernel32" )
+						is Gcc, is Clang -> listOf( "-l${jawt}", "-lUser32", "-lGdi32", "-lshell32", "-lAdvAPI32", "-lKernel32" )
-						is VisualCpp -> listOf( "${jawt}.lib", "User32.lib", "shell32.lib", "AdvAPI32.lib", "Kernel32.lib", "/NODEFAULTLIB" )
+						is VisualCpp -> listOf( "${jawt}.lib", "User32.lib", "Gdi32.lib", "shell32.lib", "AdvAPI32.lib", "Kernel32.lib", "/NODEFAULTLIB" )
 						else -> emptyList()
 					}
 				} )

flatlaf-natives/flatlaf-natives-windows/src/main/cpp/FlatWndProc.cpp

@@ -52,6 +52,13 @@ JNIEXPORT void JNICALL Java_com_formdev_flatlaf_ui_FlatWindowsNativeWindowBorder
 	FlatWndProc::updateFrame( reinterpret_cast<HWND>( hwnd ), state );
 }
 
+extern "C"
+JNIEXPORT void JNICALL Java_com_formdev_flatlaf_ui_FlatWindowsNativeWindowBorder_00024WndProc_setWindowBackground
+	( JNIEnv* env, jobject obj, jlong hwnd, jint r, jint g, jint b )
+{
+	FlatWndProc::setWindowBackground( reinterpret_cast<HWND>( hwnd ), r, g, b );
+}
+
 extern "C"
 JNIEXPORT void JNICALL Java_com_formdev_flatlaf_ui_FlatWindowsNativeWindowBorder_00024WndProc_showWindow
 	( JNIEnv* env, jobject obj, jlong hwnd, jint cmd )
@@ -174,6 +181,17 @@ void FlatWndProc::updateFrame( HWND hwnd, int state ) {
 		fwp->wmSizeWParam = -1;
 }
 
+void FlatWndProc::setWindowBackground( HWND hwnd, int r, int g, int b ) {
+	// delete old background brush
+	HBRUSH oldBrush = (HBRUSH) ::GetClassLongPtr( hwnd, GCLP_HBRBACKGROUND );
+	if( oldBrush != NULL )
+		::DeleteObject( oldBrush );
+
+	// create new background brush
+	HBRUSH brush = ::CreateSolidBrush( RGB( r, g, b ) );
+	::SetClassLongPtr( hwnd, GCLP_HBRBACKGROUND, (LONG_PTR) brush );
+}
+
 LRESULT CALLBACK FlatWndProc::StaticWindowProc( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam ) {
 	FlatWndProc* fwp = (FlatWndProc*) hwndMap->get( hwnd );
 	if( fwp == NULL )

flatlaf-natives/flatlaf-natives-windows/src/main/cpp/FlatWndProc.h

@@ -26,6 +26,7 @@ public:
 	static HWND install( JNIEnv *env, jobject obj, jobject window );
 	static void uninstall( JNIEnv *env, jobject obj, HWND hwnd );
 	static void updateFrame( HWND hwnd, int state );
+	static void setWindowBackground( HWND hwnd, int r, int g, int b );
 
 private:
 	static int initialized;

flatlaf-natives/flatlaf-natives-windows/src/main/headers/com_formdev_flatlaf_ui_FlatWindowsNativeWindowBorder_WndProc.h

@@ -39,6 +39,14 @@ JNIEXPORT void JNICALL Java_com_formdev_flatlaf_ui_FlatWindowsNativeWindowBorder
 JNIEXPORT void JNICALL Java_com_formdev_flatlaf_ui_FlatWindowsNativeWindowBorder_00024WndProc_updateFrame
   (JNIEnv *, jobject, jlong, jint);
 
+/*
+ * Class:     com_formdev_flatlaf_ui_FlatWindowsNativeWindowBorder_WndProc
+ * Method:    setWindowBackground
+ * Signature: (JIII)V
+ */
+JNIEXPORT void JNICALL Java_com_formdev_flatlaf_ui_FlatWindowsNativeWindowBorder_00024WndProc_setWindowBackground
+  (JNIEnv *, jobject, jlong, jint, jint, jint);
+
 /*
  * Class:     com_formdev_flatlaf_ui_FlatWindowsNativeWindowBorder_WndProc
  * Method:    showWindow