Hi, I would like feedback on a patch to enable changing the text and
non-text mouse pointer colors on MacOS, via "set-mouse-color". I'm new
to Emacs development and objective-C, so I expect I have a sub-optimal
and potentially leaky implementation.

I chose to only modify those pointers, as my implementation is a bit
heavy handed and changes the entire cursor image to the requested
color. On the I-beam (text) cursor this is ok, but the (nontext) arrow
pointer loses its thin white outline. The other cursors (the modeline
and resize pointers) don't suffer the visibility problems the
text/nontext pointers do when using a dark frame background, and are
left alone.

Thanks,
Joe

--------------

diff --git a/src/nsfns.m b/src/nsfns.m
index ca8f492..266ae5b 100644
--- a/src/nsfns.m
+++ b/src/nsfns.m
@@ -61,11 +61,15 @@ int fns_trace_num = 1;

 #ifdef HAVE_NS

+// Required for set-mouse-color
+#import <QuartzCore/CoreImage.h>
+
 extern NSArray *ns_send_types, *ns_return_types, *ns_drag_types;

 extern Lisp_Object Qforeground_color;
 extern Lisp_Object Qbackground_color;
 extern Lisp_Object Qcursor_color;
+extern Lisp_Object Qmouse_color;
 extern Lisp_Object Qinternal_border_width;
 extern Lisp_Object Qvisibility;
 extern Lisp_Object Qcursor_type;
@@ -878,15 +882,90 @@ x_set_cursor_type (struct frame *f, Lisp_Object arg,
Lisp_Object oldval)
   set_frame_cursor_types (f, arg);
 }

+
+#undef Z
+static void
+changeMouseColor(NSCursor **crs, NSColor *col)
+{
+
+  NSPoint hs    = [*crs hotSpot];
+  NSImage *img  = [*crs image];
+
+  CGContextRef myContext = [[NSGraphicsContext currentContext]
graphicsPort];
+  CIContext *context     = [CIContext contextWithCGContext:myContext
options:nil];
+
+  // Convert to CIImage input
+  NSRect  rect;
+  rect.origin = NSMakePoint(0.0, 0.0);
+  rect.size   = [img size];
+
+  CGImageRef cgImage = [img CGImageForProposedRect:&rect
+                                           context:[NSGraphicsContext
currentContext]
+                                             hints:nil];
+  CIImage *inputImage = [CIImage imageWithCGImage:cgImage];
+
+
+  // Set up the filter path
+  CIFilter *constColor = [CIFilter filterWithName:@
"CIConstantColorGenerator"];
+  CIColor  *newColor   = [CIColor colorWithCGColor:[col CGColor]];
+  [constColor setValue:newColor forKey: kCIInputColorKey];
+
+  // Needs crop to be usable
+  constColor = [CIFilter filterWithName:@"CICrop" keysAndValues:
+                           kCIInputImageKey, [constColor valueForKey:
kCIOutputImageKey],
+                         @"inputRectangle", [CIVector vectorWithX:0.0f
Y:0.0f Z:2.0f W:2.0f],
+                         nil];
+
+  // Apply a constant color map to change all colors in the image
+  CIFilter *colorMap   = [CIFilter filterWithName:@"CIColorMap"];
+  [colorMap setValue:inputImage forKey:kCIInputImageKey];
+  [colorMap setValue:[constColor valueForKey: kCIOutputImageKey]
+              forKey:kCIInputGradientImageKey];
+
+
+  // Render the output image
+  CIImage      *render = [colorMap valueForKey: kCIOutputImageKey];
+  CGRect        extent = [render extent];
+  CGImageRef  finalImg = [context createCGImage:render fromRect:extent];
+
+  NSImage *resultImage = [[NSImage alloc] initWithCGImage:finalImg
size:extent.size];
+
+  if (resultImage)
+    {
+      *crs = [[NSCursor alloc] initWithImage:resultImage hotSpot:hs];
+      [resultImage release];
+    }
+  else {
+    error("Could not change cursor");
+  }
+}
+
+
+
 /* called to set mouse pointer color, but all other terms use it to
    initialize pointer types (and don't set the color ;) */
 static void
 x_set_mouse_color (struct frame *f, Lisp_Object arg, Lisp_Object oldval)
 {
-  /* don't think we can do this on Nextstep */
+  NSColor *col;
+  if (ns_lisp_to_color (arg, &col))
+    {
+      store_frame_param (f, Qmouse_color, oldval);
+      error ("Unknown color");
+    }
+
+  // Only change text and non-text cursor colors. The pointy hand and
resize
+  // cursors should be okay (ie. easily visible) in their appropriate
window
+  // locations.
+  if (FRAME_CURSOR(f, text))    changeMouseColor(&FRAME_CURSOR(f, text),
col);
+  if (FRAME_CURSOR(f, nontext)) changeMouseColor(&FRAME_CURSOR(f,
nontext), col);
+
+  store_frame_param(f, Qmouse_color, arg);
 }


+
+
 #define Str(x) #x
 #define Xstr(x) Str(x)

diff --git a/src/nsterm.h b/src/nsterm.h
index 00a0b54..7c26259 100644
--- a/src/nsterm.h
+++ b/src/nsterm.h
@@ -736,9 +736,10 @@ struct x_output

 #define FRAME_DEFAULT_FACE(f) FACE_FROM_ID (f, DEFAULT_FACE_ID)

-#define FRAME_NS_VIEW(f) ((f)->output_data.ns->view)
+#define FRAME_NS_VIEW(f)      ((f)->output_data.ns->view)
 #define FRAME_CURSOR_COLOR(f) ((f)->output_data.ns->cursor_color)
 #define FRAME_POINTER_TYPE(f) ((f)->output_data.ns->current_pointer)
+#define FRAME_CURSOR(f, t)    ((f)->output_data.ns->t##_cursor)

 #define FRAME_FONT(f) ((f)->output_data.ns->font)