如何围绕给定的矩形在屏幕上绘制轮廓？

Question

我的目标是在另一个应用程序的窗口周围画一个轮廓。类似于 Microsoft Teams 在桌面共享期间绘制轮廓的方式。

例如，如图所示，Safari 窗口周围的轮廓。

使用 macOS 的 Quartz Window Services 和辅助功能 API，我能够获取 Safari 的坐标（x、y、宽度、高度），并且我订阅了窗口发生的事件，例如调整大小或窗口改变其位置.

// How I get window coordinates

- (CGRect)selectedAppCoordinates:(long)windowId {
  NSLog(@"selectedAppCoordinates - IN");
  CGRect rect;
  CGWindowID windowid[1];
  windowid[0] = windowId;
  CFArrayRef windowArray =
      CFArrayCreate(nullptr, (const void **)windowid, 1, nullptr);
  CFArrayRef windowsdescription =
      CGWindowListCreateDescriptionFromArray(windowArray);
  CFDictionaryRef windowdescription = (CFDictionaryRef)CFArrayGetValueAtIndex(
      (CFArrayRef)windowsdescription, 0);
  if (CFDictionaryContainsKey(windowdescription, kCGWindowBounds)) {
    CFDictionaryRef bounds = (CFDictionaryRef)CFDictionaryGetValue(
        windowdescription, kCGWindowBounds);
    if (bounds) {
      if (CGRectMakeWithDictionaryRepresentation(bounds, &rect)) {

        NSLog(@"x: %f, y: %f, width: %f, height: %f", rect.origin.x,
              rect.origin.y, rect.size.width, rect.size.height);
      }
    }
  }
  CFRelease(windowArray);
  NSLog(@"selectedAppCoordinates - OUT");

  return rect;
}

对我来说，问题是绘制轮廓。我对原生 macOS 开发经验很少，如果有任何帮助，我将不胜感激。

我应该如何绘制这个轮廓，在需要时更新和隐藏它？

Answer 1

根据 bhaller 之前给出的建议，下面的演示使用第二个底层窗口，其中包含一个彩色填充视图，并且比主窗口略大，因此它的边缘是可见的。底层窗口通过窗口代理绑定到主窗口，以同步更改位置/大小，并且可以显示或隐藏。该演示可以在 Xcode 中运行，只需将主文件替换为以下代码并另外删除 Apple 提供的 AppDelegate 文件（以避免重复符号错误）：

#import <Cocoa/Cocoa.h>

@interface CustomView : NSView
@end

@implementation CustomView
 
- (id)initWithFrame:(NSRect)frameRect{
 if ((self = [super initWithFrame:frameRect]) != nil) {
 // Add initialization code here
 }
 return self;
}
 
- (void)drawRect:(NSRect)rect {
 // ****** Background ***** //
 [[NSColor redColor] set];
 [NSBezierPath fillRect:rect];
}
 
 // ----- Use this if you want 0,0 (origin) to be top, left ---- //
 // ----- Otherwise origin will be at bottom, left (Unflipped) ----- //
 -(BOOL)isFlipped
 {
 return YES;
 }
@end

@interface WindowDelegate : NSObject <NSWindowDelegate>
 @property(strong) NSWindow *underlayWnd;
@end

@implementation WindowDelegate
 
- (void)windowDidResize:(NSNotification *)notification {
NSRect frameR = NSMakeRect([notification.object frame].origin.x - 10, [notification.object frame].origin.y - 10, [notification.object frame].size.width + 20, [notification.object frame].size.height + 20);
[_underlayWnd setFrame:frameR display:YES];
}
 
- (void)windowDidEndLiveResize:(NSNotification *)notification {
 NSRect frameR = NSMakeRect([notification.object frame].origin.x - 10, [notification.object frame].origin.y - 10, [notification.object frame].size.width + 20, [notification.object frame].size.height + 20);
[_underlayWnd setFrame:frameR display:YES];
}
 
- (void)windowDidMove:(NSNotification *)notification {
 NSRect frameR = NSMakeRect([notification.object frame].origin.x - 10, [notification.object frame].origin.y - 10, [notification.object frame].size.width + 20, [notification.object frame].size.height + 20);
 [_underlayWnd setFrame:frameR display:YES];
}
 
- (void)windowDidMiniaturize:(NSNotification *)notification {
NSRect frameR = NSMakeRect([notification.object frame].origin.x - 10, [notification.object frame].origin.y - 10, [notification.object frame].size.width + 20, [notification.object frame].size.height + 20);
 [_underlayWnd setFrame:frameR display:YES];
}
  
@end
 
@interface AppDelegate : NSObject <NSApplicationDelegate>
{
 NSWindow *window;
 NSWindow *underlayWnd;
 WindowDelegate *windowDelegate;
 CustomView *view;
}
- (void) myShowAction;
- (void) myHideAction;
- (void) buildMenu;
- (void) buildWindow;
@end

@implementation AppDelegate

-(void) myHideAction {
 [underlayWnd orderOut:nil];
 }

-(void) myShowAction {
 [underlayWnd orderFront:nil];
 [window makeKeyAndOrderFront: nil];
}

- (void) buildMenu {
NSMenu *menubar = [NSMenu new];
NSMenuItem *menuBarItem = [NSMenuItem new];
[menubar addItem:menuBarItem];
[NSApp setMainMenu:menubar];
NSMenu *appMenu = [NSMenu new];
NSMenuItem *quitMenuItem = [[NSMenuItem alloc] initWithTitle:@"Quit"
action:@selector(terminate:) keyEquivalent:@"q"];
[appMenu addItem:quitMenuItem];
[menuBarItem setSubmenu:appMenu];
}

- (void) buildWindow {

windowDelegate = [[WindowDelegate alloc]init];

#define _wndW  700
#define _wndH  550

window = [[NSWindow alloc] initWithContentRect: NSMakeRect( 0, 0, _wndW, _wndH )
styleMask: NSWindowStyleMaskTitled | NSWindowStyleMaskMiniaturizable | NSWindowStyleMaskClosable | NSWindowStyleMaskResizable
backing: NSBackingStoreBuffered defer: NO];

[window center];
[window setTitle: @"Test window"];
[window setDelegate: windowDelegate];
[window makeKeyAndOrderFront: nil];

NSRect frameR = NSMakeRect([window frame].origin.x - 10, [window frame].origin.y - 10, [window frame].size.width + 20, [window frame].size.height + 20);
underlayWnd = [[NSWindow alloc] initWithContentRect:frameR styleMask: NSWindowStyleMaskBorderless backing: NSBackingStoreBuffered defer: NO];
[underlayWnd setIgnoresMouseEvents:true];
[underlayWnd orderWindow:NSWindowBelow relativeTo:0];

// **** Custom View **** //
view = [[CustomView alloc]initWithFrame:NSMakeRect(0,0,frameR.size.width, frameR.size.height)];
[view setAutoresizingMask: NSViewWidthSizable | NSViewHeightSizable ];
[[underlayWnd contentView] addSubview:view]
[windowDelegate setUnderlayWnd:underlayWnd];

// **** Hide Button **** //
NSButton *hideBtn =[[NSButton alloc]initWithFrame:NSMakeRect( 30, 30, 165, 30 )];
[hideBtn setBezelStyle:NSBezelStyleRounded ];
[hideBtn setTitle: @"Hide underlay window"];
[hideBtn setAction: @selector (myHideAction)];
[[window contentView] addSubview: hideBtn];

// **** Show Button **** //
NSButton *showBtn =[[NSButton alloc]initWithFrame:NSMakeRect( 210, 30, 165, 30 )];
[showBtn setBezelStyle:NSBezelStyleRounded ];
[showBtn setTitle: @"Show underlay window"];
[showBtn setAction: @selector (myShowAction)];
[[window contentView] addSubview: showBtn];

// **** Quit btn **** //
NSButton *quitBtn = [[NSButton alloc]initWithFrame:NSMakeRect( _wndW - 50, 5, 40, 40 )];
[quitBtn setBezelStyle:NSBezelStyleCircular ];
[quitBtn setTitle: @"Q" ];
[quitBtn setAutoresizingMask: NSViewMinXMargin];
[quitBtn setAction:@selector(terminate:)];
[[window contentView] addSubview: quitBtn];
}

- (void) applicationWillFinishLaunching: (NSNotification *)notification
{
[self buildMenu];
[self buildWindow];
}

- (void) applicationDidFinishLaunching: (NSNotification *)notification
{
}
@end

int main (){
NSApplication *application = [NSApplication sharedApplication];
AppDelegate *appDelegate = [[AppDelegate alloc] init];
[application setDelegate:appDelegate];
[application run];
return 0;
}