Rewrite for macOS 10.15 Catalina

Another way to support what occurs under macOS 10.15 where the bitmap graphics context
prepared by the system when drawRect: runs sometimes changes its number of bytes/row
even if the width and height are unchanged.
This is expected to perform better when the number of bytes/row alternates between
two values.

1 files changed, 7 insertions, 2 deletions

diff --git a/src/Fl_cocoa.mm b/src/Fl_cocoa.mm
index 5d5596042..e2ddb8cc9 100644
--- a/src/Fl_cocoa.mm
+++ b/src/Fl_cocoa.mm
@@ -2277,9 +2277,14 @@ static FLTextInputContext* fltextinputcontext_instance = nil;
   if (!through_Fl_X_flush) window->clear_damage();
 #if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_14
   if (gc) {
-    if (aux_bitmap && CGBitmapContextGetBytesPerRow(gc) != CGBitmapContextGetBytesPerRow(aux_bitmap)) [self reset_aux_bitmap];
     if (!aux_bitmap) [self create_aux_bitmap:gc retina:d->mapped_to_retina()];
-    memcpy(CGBitmapContextGetData(aux_bitmap), CGBitmapContextGetData(gc), CGBitmapContextGetHeight(gc) * CGBitmapContextGetBytesPerRow(gc));
+    if (CGBitmapContextGetBytesPerRow(gc) != CGBitmapContextGetBytesPerRow(aux_bitmap)) {
+      CGImageRef img = CGBitmapContextCreateImage(gc);
+      CGContextDrawImage(aux_bitmap, [self frame], img);
+      CGImageRelease(img);
+    } else {
+      memcpy(CGBitmapContextGetData(aux_bitmap), CGBitmapContextGetData(gc), CGBitmapContextGetHeight(gc) * CGBitmapContextGetBytesPerRow(gc));
+    }
     Fl_Cocoa_Window_Driver::q_release_context();
     direct_draw = NO;
   }