objective-c - cocoa 中的自定义主应用程序循环

Question

我一直在关注 Handmade Hero 项目，Casey Muratori 在该项目中从头开始创建了一个完整的游戏引擎，而不使用库。该引擎具有高度可移植性，因为它呈现自己的位图，然后平台特定的代码将其绘制到屏幕上。

在 Windows 下，通常有一个主应用程序循环，您可以在其中放置应重复执行的代码，直到应用程序终止。然而Cocoa中没有这样的东西。一旦 [NSApp run]; 被调用，int main() 就变得毫无用处，你必须将代码放入委托(delegate)方法中才能执行。但这不是我想要的方式。我在网上找到了一些代码，其中有人已经完全按照我的要求做了，但代码有一些缺陷，或者可以说我只是不知道如何处理它。

#import <Cocoa/Cocoa.h>
#import <CoreGraphics/CoreGraphics.h>
#include <stdint.h>


#define internal static
#define local_persist static
#define global_variable static

typedef uint8_t uint8;

global_variable bool running = false;

global_variable void *BitmapMemory;
global_variable int BitmapWidth = 1024;
global_variable int BitmapHeight = 768;
global_variable int BytesPerPixel = 4;

global_variable int XOffset = 0;
global_variable int YOffset = 0;


@class View;
@class AppDelegate;
@class WindowDelegate;


global_variable AppDelegate *appDelegate;
global_variable NSWindow *window;
global_variable View *view;
global_variable WindowDelegate *windowDelegate;


@interface AppDelegate: NSObject <NSApplicationDelegate> {
}
@end

@implementation AppDelegate

- (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender {
    // Cocoa will kill your app on the spot if you don't stop it
    // So if you want to do anything beyond your main loop then include this method.
    running = false;
    return NSTerminateCancel;
}

@end


@interface WindowDelegate : NSObject <NSWindowDelegate> {
}
@end
@implementation WindowDelegate

- (BOOL)windowShouldClose:(id)sender {
    running = false;
    return YES;
}

-(void)windowWillClose:(NSNotification *)notification {
    if (running) {
        running = false;
        [NSApp terminate:self];
    }
}

@end




@interface View : NSView <NSWindowDelegate> {
@public
    CGContextRef backBuffer_;
}
- (instancetype)initWithFrame:(NSRect)frameRect;
- (void)drawRect:(NSRect)dirtyRect;
@end

@implementation View
// Initialize
- (id)initWithFrame:(NSRect)frameRect {
    self = [super initWithFrame:frameRect];
    if (self) {
        int bitmapByteCount;
        int bitmapBytesPerRow;

        bitmapBytesPerRow = (BitmapWidth * 4);
        bitmapByteCount = (bitmapBytesPerRow * BitmapHeight);
        BitmapMemory = mmap(0,
                            bitmapByteCount,
                            PROT_WRITE |
                            PROT_READ,
                            MAP_ANON |
                            MAP_PRIVATE,
                            -1,
                            0);
        //CMProfileRef prof;
        //CMGetSystemProfile(&prof);
        CGColorSpaceRef colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
        backBuffer_ = CGBitmapContextCreate(BitmapMemory, BitmapWidth, BitmapHeight, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast);
        CGColorSpaceRelease(colorSpace);
        //CMCloseProfile(prof);
    }
    return self;
}



- (void)drawRect:(NSRect)dirtyRect {
    CGContextRef gctx = [[NSGraphicsContext currentContext] graphicsPort];
    CGRect myBoundingBox;
    myBoundingBox = CGRectMake(0, 0, 1024, 768);
    //RenderWeirdGradient(XOffset, YOffset);
    CGImageRef backImage = CGBitmapContextCreateImage(backBuffer_);
    CGContextDrawImage(gctx, myBoundingBox, backImage);
    CGImageRelease(backImage);
}


internal void RenderWeirdGradient(int BlueOffset, int GreenOffset) {
    int Width = BitmapWidth;
    int Height = BitmapHeight;

    int Pitch = Width*BytesPerPixel;
    uint8 *Row = (uint8 *)BitmapMemory;
    for(int Y = 0;
        Y < BitmapHeight;
        ++Y)
    {
        uint8 *Pixel = (uint8 *)Row;
        for(int X = 0;
            X < BitmapWidth;
            ++X)
        {
            *Pixel = 0;
            ++Pixel;

            *Pixel = (uint8)Y + XOffset;
            ++Pixel;

            *Pixel = (uint8)X + YOffset;
            ++Pixel;

            *Pixel = 255;
            ++Pixel;

        }

        Row += Pitch;
    }
}



@end


static void createWindow() {
    NSUInteger windowStyle = NSTitledWindowMask  | NSClosableWindowMask | NSResizableWindowMask | NSMiniaturizableWindowMask;

    NSRect screenRect = [[NSScreen mainScreen] frame];
    NSRect viewRect = NSMakeRect(0, 0, 1024, 768);
    NSRect windowRect = NSMakeRect(NSMidX(screenRect) - NSMidX(viewRect),
                                   NSMidY(screenRect) - NSMidY(viewRect),
                                   viewRect.size.width,
                                   viewRect.size.height);

    window = [[NSWindow alloc] initWithContentRect:windowRect
                                                    styleMask:windowStyle
                                                      backing:NSBackingStoreBuffered
                                                        defer:NO];

    [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];

    id menubar = [[NSMenu new] autorelease];
    id appMenuItem = [[NSMenuItem new] autorelease];
    [menubar addItem:appMenuItem];
    [NSApp setMainMenu:menubar];

    // Then we add the quit item to the menu. Fortunately the action is simple since terminate: is
    // already implemented in NSApplication and the NSApplication is always in the responder chain.
    id appMenu = [[NSMenu new] autorelease];
    id appName = [[NSProcessInfo processInfo] processName];
    id quitTitle = [@"Quit " stringByAppendingString:appName];
    id quitMenuItem = [[[NSMenuItem alloc] initWithTitle:quitTitle
                                                  action:@selector(terminate:) keyEquivalent:@"q"] autorelease];
    [appMenu addItem:quitMenuItem];
    [appMenuItem setSubmenu:appMenu];

    NSWindowController * windowController = [[NSWindowController alloc] initWithWindow:window];
    [windowController autorelease];

    //View
    view = [[[View alloc] initWithFrame:viewRect] autorelease];
    [window setContentView:view];

    //Window Delegate
    windowDelegate = [[WindowDelegate alloc] init];
    [window setDelegate:windowDelegate];

    [window setAcceptsMouseMovedEvents:YES];
    [window setDelegate:view];

    // Set app title
    [window setTitle:appName];

    // Add fullscreen button
    [window setCollectionBehavior: NSWindowCollectionBehaviorFullScreenPrimary];
    [window makeKeyAndOrderFront:nil];
}

void initApp() {
    [NSApplication sharedApplication];

    appDelegate = [[AppDelegate alloc] init];
    [NSApp setDelegate:appDelegate];

    running = true;

    [NSApp finishLaunching];
}

void frame() {
    @autoreleasepool {
        NSEvent* ev;
        do {
            ev = [NSApp nextEventMatchingMask: NSAnyEventMask
                                    untilDate: nil
                                       inMode: NSDefaultRunLoopMode
                                      dequeue: YES];
            if (ev) {
                // handle events here
                [NSApp sendEvent: ev];
            }
        } while (ev);
    }
}

int main(int argc, const char * argv[])  {
    initApp();
    createWindow();
    while (running) {
        frame();
        RenderWeirdGradient(XOffset, YOffset);
        [view setNeedsDisplay:YES];
        XOffset++;
        YOffset++;
    }

    return (0);
}

这是应用程序到目前为止需要运行的所有代码。只需将其复制并粘贴到空的 Xcode 命令行项目中即可运行。

但是，当您在应用程序运行时检查硬件时，您会发现 CPU 几乎以 100% 的速度运行。我读到这个问题的原因是由于自定义运行循环，应用程序必须一直搜索新事件。

此外，由于循环不会将控制权移交给委托(delegate)对象，因此 - (BOOL)windowShouldClose:(id)sender 等方法不再起作用。

问题:

1. 是否有一种更好的方法来实现具有以下样式的自定义主应用程序循环，并且不会像我正在使用的那样浪费 CPU 时间？

   同时(运行){//做东西}

2. 由于应用程序委托(delegate)和窗口委托(delegate)方法不再响应，如何通过按窗口的关闭按钮来终止应用程序？

我现在花了几个小时在网上搜索 Cocoa 中的自定义主运行循环，但刚刚遇到了多线程和对我没有帮助的东西。

您能推荐一些对我的情况有帮助的在线资源/书籍吗？我真的很想获得一些处理不寻常事物(例如自定义运行循环)的资源。

Answer 1

我知道这已经晚了两年，但我在 Cocoa With Love 上发现了一篇文章，您可能会觉得有用。

https://www.cocoawithlove.com/2009/01/demystifying-nsapplication-by.html

我尝试以这种方式实现主事件循环，查看了 CPU 使用情况，它比我之前得到的更合理。我不完全知道为什么，但我会对此做更多研究。