[PATCH v2 2/2] ui/cocoa: Adds NSCursor absolute pointer support

[Phil Dennis-Jordan <phil@philjordan.eu>]

When pointer input is absolute, use the native macOS host’s Cocoa
NSCursor to render the guest’s cursor. The rendered cursor is no longer
cropped to the guest viewport, and the correct cursor image is passed to
anything tapping into the host system’s native cursor. (such as remote
access)

The CALayer is retained for rendering the cursor in relative pointer
input mode. Cropping the cursor here gives a visual indication of the
captured pointer (the mouse must be explicitly ungrabbed before allowing
the cursor to leave the Qemu window), and teleporting the host cursor
when its position is changed by the guest causes a feedback loop in
input events.

Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
---
 ui/cocoa.m | 82 +++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 65 insertions(+), 17 deletions(-)

diff --git a/ui/cocoa.m b/ui/cocoa.m
index cca987eac7..131c442e16 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -314,6 +314,7 @@ @interface QemuCocoaView : NSView
     CFMachPortRef eventsTap;
     CALayer *cursorLayer;
     QEMUCursor *cursor;
+    NSCursor *cocoaCursor;
     int mouseX;
     int mouseY;
     int mouseOn;
@@ -402,6 +403,9 @@ - (void) dealloc
 
     [cursorLayer release];
     cursorLayer = nil;
+    [cocoaCursor release];
+    cocoaCursor = nil;
+
     [super dealloc];
 }
 
@@ -460,27 +464,14 @@ - (void)setMouseX:(int)x y:(int)y on:(int)on
     [CATransaction begin];
     [CATransaction setDisableActions:YES];
     [cursorLayer setPosition:position];
-    [cursorLayer setHidden:!mouseOn];
+    [cursorLayer setHidden:!mouseOn || isAbsoluteEnabled];
     [CATransaction commit];
 }
 
-- (void)setCursor:(QEMUCursor *)given_cursor
+static CGImageRef cursor_cgimage_create(QEMUCursor *cursor)
 {
     CGDataProviderRef provider;
     CGImageRef image;
-    CGRect bounds = CGRectZero;
-
-    cursor_unref(cursor);
-    cursor = given_cursor;
-
-    if (!cursor) {
-        return;
-    }
-
-    cursor_ref(cursor);
-
-    bounds.size.width = cursor->width;
-    bounds.size.height = cursor->height;
     CGColorSpaceRef color_space = CGColorSpaceCreateWithName(kCGColorSpaceSRGB);
 
     provider = CGDataProviderCreateWithData(
@@ -506,6 +497,43 @@ - (void)setCursor:(QEMUCursor *)given_cursor
 
     CGDataProviderRelease(provider);
     CGColorSpaceRelease(color_space);
+    return image;
+}
+
+static NSCursor *cocoa_cursor_create(QEMUCursor *cursor, CGImageRef image)
+{
+    NSPoint hotspot = { cursor->hot_x, cursor->hot_y };
+    NSSize size = NSMakeSize(cursor->width, cursor->height);
+    NSImage *cursor_image = [[NSImage alloc] initWithCGImage:image size:size];
+    NSCursor *cocoa_cursor =
+        [[NSCursor alloc] initWithImage:cursor_image hotSpot:hotspot];
+    [cursor_image release];
+    return cocoa_cursor;
+}
+
+- (void)setCursor:(QEMUCursor *)given_cursor
+{
+    CGImageRef image;
+    NSImage *cursor_nsimage = nil;
+    CGRect bounds = CGRectZero;
+
+    cursor_unref(cursor);
+    cursor = given_cursor;
+
+    if (!cursor) {
+        return;
+    }
+
+    cursor_ref(cursor);
+
+    bounds.size.width = cursor->width;
+    bounds.size.height = cursor->height;
+
+    image = cursor_cgimage_create(cursor);
+    [cocoaCursor release];
+    cocoaCursor = cocoa_cursor_create(cursor, image);
+    [self.window invalidateCursorRectsForView:self];
+
     [CATransaction begin];
     [CATransaction setDisableActions:YES];
     [cursorLayer setBounds:bounds];
@@ -514,6 +542,16 @@ - (void)setCursor:(QEMUCursor *)given_cursor
     CGImageRelease(image);
 }
 
+- (void) resetCursorRects
+{
+    if (self->cocoaCursor == nil) {
+        [super resetCursorRects];
+    } else {
+        NSRect guest_area = {{ 0.0, 0.0 }, { screen.width, screen.height }};
+        [self addCursorRect:guest_area cursor:cocoaCursor];
+    }
+}
+
 - (void) drawRect:(NSRect) rect
 {
     COCOA_DEBUG("QemuCocoaView: drawRect\n");
@@ -1181,7 +1219,12 @@ - (void) grabMouse
         [[self window] setTitle:[NSString stringWithFormat:@"QEMU %s - (Press  " UC_CTRL_KEY " " UC_ALT_KEY " G  to release Mouse)", qemu_name]];
     else
         [[self window] setTitle:@"QEMU - (Press  " UC_CTRL_KEY " " UC_ALT_KEY " G  to release Mouse)"];
-    [self hideCursor];
+
+    [cursorLayer setHidden:!mouseOn || isAbsoluteEnabled];
+    if (!isAbsoluteEnabled) {
+        [self hideCursor];
+    }
+
     CGAssociateMouseAndMouseCursorPosition(isAbsoluteEnabled);
     isMouseGrabbed = TRUE; // while isMouseGrabbed = TRUE, QemuCocoaApp sends all events to [cocoaView handleEvent:]
 }
@@ -1194,7 +1237,11 @@ - (void) ungrabMouse
         [[self window] setTitle:[NSString stringWithFormat:@"QEMU %s", qemu_name]];
     else
         [[self window] setTitle:@"QEMU"];
-    [self unhideCursor];
+
+    [cursorLayer setHidden:!mouseOn || isAbsoluteEnabled];
+    if (!isAbsoluteEnabled) {
+        [self unhideCursor];
+    }
     CGAssociateMouseAndMouseCursorPosition(TRUE);
     isMouseGrabbed = FALSE;
     [self raiseAllButtons];
@@ -1216,6 +1263,7 @@ - (void) notifyMouseModeChange {
             [self ungrabMouse];
         } else {
             CGAssociateMouseAndMouseCursorPosition(isAbsoluteEnabled);
+            [self hideCursor];
         }
     }
 }
-- 
2.39.3 (Apple Git-146)