MacApp.m

#import "MacApp.h"

@import AppKit;

@implementation MacApp

static CGFloat regularWidth = 960;
static CGFloat compressedWidth = 320;
static CGFloat height = 640;

+ (void)configureApp
{
  static dispatch_once_t once;
  static MacApp *windowDelegate;
  dispatch_once(&once, ^{
    windowDelegate = [MacApp new];
  });

  for (NSWindow *window in NSApplication.sharedApplication.windows) {
    [self configureWindow:window withDelegate:windowDelegate];
  }
}

+(void)configureWindow:(NSWindow *)window
          withDelegate:(NSObject<NSWindowDelegate> *)delegate
{
  // Titlebar appearance
  [window setTitlebarAppearsTransparent:YES];
  [window setTitleVisibility:NSWindowTitleHidden];

  // Change fullscreen button to + zoom button
  [window setCollectionBehavior:NSWindowCollectionBehaviorFullScreenAuxiliary];
  [window setShowsResizeIndicator:YES];

  // Optimise resizing
  CGFloat widthIncrement = regularWidth - compressedWidth;
  [window setContentResizeIncrements:CGSizeMake(widthIncrement, 1)];

  // Initial size
  CGSize size = [MacApp sizeForExpanded:YES];
  CGRect frame = CGRectMake(0, 0, size.width, size.height);
  [window setFrame:frame display:YES];
  [window center];

  // Blur (whole) background for sidebar
  NSVisualEffectView *view = [[NSVisualEffectView alloc] initWithFrame:window.screen.frame];
  view.blendingMode = NSVisualEffectBlendingModeBehindWindow;
  view.state = NSVisualEffectStateActive;
  view.material = NSVisualEffectMaterialSidebar;
  view.wantsLayer = true;
  [window.contentView addSubview:view positioned:NSWindowBelow relativeTo:window.contentView.subviews[0]];
  window.backgroundColor = [NSColor clearColor];

  window.delegate = delegate;
}

+ (BOOL)isExandedForWidth:(CGFloat)currentWidth
{
  return currentWidth > (compressedWidth + regularWidth) / 2;
}

+ (CGSize)sizeForExpanded:(BOOL)expanded
{
  CGFloat width = expanded ? regularWidth : compressedWidth;
  return CGSizeMake(width, height);
}

- (NSSize)windowWillResize:(NSWindow *)sender toSize:(NSSize)frameSize
{
  BOOL isExpanded = [MacApp isExandedForWidth:frameSize.width];
  return [MacApp sizeForExpanded:isExpanded];
}

- (BOOL)windowShouldZoom:(NSWindow *)window toFrame:(NSRect)newFrame
{
  CGPoint origin = window.frame.origin;
  BOOL wasExpanded = [MacApp isExandedForWidth:CGRectGetWidth(window.frame)];
  CGSize size = [MacApp sizeForExpanded:!wasExpanded];
  CGRect frame = CGRectMake(origin.x, origin.y, size.width, size.height);
  [window setFrame:frame display:YES animate:NO];
  return NO;
}

@end