ui/cocoa: add zoom-interpolation display option

Provides a new display option, zoom-interpolation, that enables
interpolation of the scaled display when zoom-to-fit is enabled.

Also provides a corresponding view menu item to allow this to be toggled
as required.

Signed-off-by: Carwyn Ellis <carwynellis@gmail.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-ID: <20231110161729.36822-2-carwynellis@gmail.com>
[PMD: QAPI @zoom-interpolation since 9.0]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

qapi/ui.json

@@ -1428,14 +1428,18 @@
 #     turned off the host window will be resized instead. Defaults to
 #     "off". (Since 8.2)
 #
+# @zoom-interpolation: Apply interpolation to smooth output when
+#     zoom-to-fit is enabled. Defaults to "off". (Since 9.0)
+#
 # Since: 7.0
 ##
 { 'struct': 'DisplayCocoa',
   'data': {
       '*left-command-key': 'bool',
       '*full-grab': 'bool',
       '*swap-opt-cmd': 'bool',
-      '*zoom-to-fit': 'bool'
+      '*zoom-to-fit': 'bool',
+      '*zoom-interpolation': 'bool'
   } }
 
 ##

ui/cocoa.m

@@ -105,6 +105,7 @@ static void cocoa_switch(DisplayChangeListener *dcl,
 static bool swap_opt_cmd;
 
 static bool stretch_video;
+static CGInterpolationQuality zoom_interpolation = kCGInterpolationNone;
 static NSTextField *pauseLabel;
 
 static bool allow_events;
@@ -455,7 +456,7 @@ - (void) drawRect:(NSRect) rect
     // get CoreGraphic context
     CGContextRef viewContextRef = [[NSGraphicsContext currentContext] CGContext];
 
-    CGContextSetInterpolationQuality (viewContextRef, kCGInterpolationNone);
+    CGContextSetInterpolationQuality (viewContextRef, zoom_interpolation);
     CGContextSetShouldAntialias (viewContextRef, NO);
 
     // draw screen bitmap directly to Core Graphics context
@@ -1411,6 +1412,17 @@ - (void)zoomToFit:(id) sender
     }
 }
 
+- (void)toggleZoomInterpolation:(id) sender
+{
+    if (zoom_interpolation == kCGInterpolationNone) {
+        zoom_interpolation = kCGInterpolationLow;
+        [sender setState: NSControlStateValueOn];
+    } else {
+        zoom_interpolation = kCGInterpolationNone;
+        [sender setState: NSControlStateValueOff];
+    }
+}
+
 /* Displays the console on the screen */
 - (void)displayConsole:(id)sender
 {
@@ -1673,6 +1685,9 @@ static void create_initial_menus(void)
     menuItem = [[[NSMenuItem alloc] initWithTitle:@"Zoom To Fit" action:@selector(zoomToFit:) keyEquivalent:@""] autorelease];
     [menuItem setState: stretch_video ? NSControlStateValueOn : NSControlStateValueOff];
     [menu addItem: menuItem];
+    menuItem = [[[NSMenuItem alloc] initWithTitle:@"Zoom Interpolation" action:@selector(toggleZoomInterpolation:) keyEquivalent:@""] autorelease];
+    [menuItem setState: zoom_interpolation == kCGInterpolationLow ? NSControlStateValueOn : NSControlStateValueOff];
+    [menu addItem: menuItem];
     menuItem = [[[NSMenuItem alloc] initWithTitle:@"View" action:nil keyEquivalent:@""] autorelease];
     [menuItem setSubmenu:menu];
     [[NSApp mainMenu] addItem:menuItem];
@@ -2070,6 +2085,10 @@ static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
         stretch_video = true;
     }
 
+    if (opts->u.cocoa.has_zoom_interpolation && opts->u.cocoa.zoom_interpolation) {
+        zoom_interpolation = kCGInterpolationLow;
+    }
+
     create_initial_menus();
     /*
      * Create the menu entries which depend on QEMU state (for consoles