How to enable resize handles on a simple MacOS window? - objective-c

Question

I have a very simple MacOS window, single compilation file, compiled with the clang compiler (e.g. clang -framework AppKit -o simple-mac-window osx_main.mm). It can be run from the command line.
//OSX Main - Entry point for the OSX platform.
#include <stdio.h>
#include <AppKit/AppKit.h>
static float GlobalRenderWidth = 1024;
static float GlobalRenderHeight = 768;
static bool Running = true;
//Declare an interface that inherits from NSObject and implements NSWindowDelegate.
#interface SimpleMainWindowDelegate: NSObject<NSWindowDelegate>
#end
#implementation SimpleMainWindowDelegate
- (void)windowWillClose:(id)sender {
Running = false;
}
#end
int main(int argc, const char * argv[]) {
SimpleMainWindowDelegate *mainWindowDelegate = [[SimpleMainWindowDelegate alloc] init];
NSRect screenRect = [[NSScreen mainScreen] frame];
NSRect initialFrame = NSMakeRect((screenRect.size.width - GlobalRenderWidth) * 0.5,
(screenRect.size.height - GlobalRenderHeight) * 0.5,
GlobalRenderWidth,
GlobalRenderHeight);
NSWindow *window = [[NSWindow alloc] initWithContentRect: initialFrame
styleMask: NSWindowStyleMaskTitled |
NSWindowStyleMaskClosable |
NSWindowStyleMaskMiniaturizable |
NSWindowStyleMaskResizable
backing:NSBackingStoreBuffered
defer:NO];
[window setBackgroundColor: NSColor.redColor];
[window setTitle:#"simple-mac-window"];
[window makeKeyAndOrderFront: nil];
[window setDelegate: mainWindowDelegate];
while(Running) {
NSEvent* event;
do {
event = [NSApp nextEventMatchingMask: NSEventMaskAny
untilDate: nil
inMode: NSDefaultRunLoopMode
dequeue: YES];
switch([event type]) {
default:
[NSApp sendEvent: event];
}
} while (event != nil);
}
printf("Finished running simple-mac-window.");
}
I have set the NSWindowStyleMaskResizable flag on the styleMask when initialising the window. This allows me to drag and resize the window when selecting the edges of the screen. However I do not get the handles to resize the window when I move my cursor to edge of the window. What are the minimum code elements I need to add in order to support this?
I have tried checking out the NSWindow Apple documentation but it seems that all is required is the flag. Perhaps I need to set some values on the window object or update the window delegate to include something? Or is this because of the minimal approach taken to get a window running?

Answer 1

There are two issues (at least). First, passing nil for the untilDate: parameter means your event loop spins, handling a nil event all the time. You should pass [NSDate distantFuture].
Second, standalone executables — that is, those that are not in an app bundle — start life with an activation policy of NSApplicationActivationPolicyProhibited. You need to do [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular] before your event loop.