将旧式视图(音频单元视图)合并到自动布局中

Question

我想将音频单元创建的自定义视图嵌入到使用自动布局的窗口中。在尝试了几十种组合后，我仍然没有找到一种方法来处理大量的音频单元。

目标是创建一个以音频单元视图作为子视图的容器NSView对象，并以容器的大小与AU视图的大小匹配的方式设置约束，包括当AU视图调整自身大小时。容器应该将translatesAutoresizingMaskIntoConstraints设置为NO，这样它就可以很好地处理窗口的其余部分。

我的第一个尝试是创建两个约束，简单地强制两个视图(容器和AU)的大小相等。这会失败，因为AU视图随后会折叠到非常小的尺寸。

另一种尝试是为容器视图创建固定大小约束，这些约束被初始化为与AU视图匹配，侦听AU视图的NSViewFrameDidChangeNotification，并根据需要调整固定大小。只要AU视图想要调整自己的大小，它就会崩溃。原因是，当我增加容器的大小以匹配AU视图时，自动调整掩码约束指示AU视图再次增加其大小，从而导致无限循环。

到目前为止，最有效的方法是关闭AU视图的translatesAutoresizingMaskIntoConstraints，并通过监听帧更改通知来设置容器的大小。这似乎适用于所有的AUv2音频单元，但对于AUv3音频单元(特别是苹果的演示AUv3)，我总是得到(1,1)的视图大小，这显然是无用的。我将非常感谢任何关于如何使其工作的见解……

Answer 1

基于您提供的示例项目，这应该是可行的：

@interface MyViewController ()
{
    NSLayoutConstraint *widthConstraint, *heightConstraint;
}
@end

@implementation MyViewController


-(void)setFormatForBus:(AUAudioUnitBus*)bus
{
    AudioStreamBasicDescription fmt = {44100, kAudioFormatLinearPCM, kAudioFormatFlagIsNonInterleaved | kAudioFormatFlagIsFloat | kAudioFormatFlagIsPacked, 4, 1, 4, 2, 32, 0};  // Stereo audio on each bus
    AVAudioFormat* format = [[AVAudioFormat alloc] initWithStreamDescription:&fmt];
    NSError* error = nil;
    if (![bus setFormat:format error:&error]) {
        NSLog(@"Couldn't set the format for bus... %@", error);
        return;
    }
    
    bus.enabled = YES;
}

-(void)doLoad:(AVAudioUnit*)node controller:(NSViewController*)viewController
{
    NSView* auView = nil;
    if (viewController == nil) {
        auView = [[AUGenericView alloc] initWithAudioUnit:node.audioUnit displayFlags:(AUViewPropertiesDisplayFlag | AUViewParametersDisplayFlag)];
        auView.frame = self.view.frame;
        [self.view addSubview:auView];
    }
    else {
        self.auViewController = viewController;
        auView = self.auViewController.view;
        auView.translatesAutoresizingMaskIntoConstraints = NO;
        [self.view addSubview:auView];
    }

    NSSize size = _auViewController.view.frame.size;

    widthConstraint = [NSLayoutConstraint constraintWithItem:self.view attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:size.width];
    heightConstraint = [NSLayoutConstraint constraintWithItem:self.view attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:size.height];

    [self.view addConstraints:@[widthConstraint, heightConstraint]];

    NSLayoutConstraint* top = [NSLayoutConstraint constraintWithItem:self.view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:auView
                                                           attribute:NSLayoutAttributeTop multiplier:1.0 constant:0];
    NSLayoutConstraint* bottom = [NSLayoutConstraint constraintWithItem:self.view attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:auView
                                                              attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0];
    NSLayoutConstraint* left = [NSLayoutConstraint constraintWithItem:self.view attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual toItem:auView
                                                            attribute:NSLayoutAttributeLeft multiplier:1.0 constant:0];
    NSLayoutConstraint* right = [NSLayoutConstraint constraintWithItem:self.view attribute:NSLayoutAttributeRight relatedBy:NSLayoutRelationEqual toItem:auView
                                                             attribute:NSLayoutAttributeRight multiplier:1.0 constant:0];

    [self.view addConstraints:@[top, bottom, left, right]];
}

- (void)viewDidLoad {
    [super viewDidLoad];

    NSArray* list = [[AVAudioUnitComponentManager sharedAudioUnitComponentManager] componentsPassingTest: ^BOOL(AVAudioUnitComponent *comp, BOOL *stop) {
        return [comp.typeName containsString:@"Effect"];
    }];
    
    AVAudioUnitComponent* component = nil;
    for (AVAudioUnitComponent* comp in list) {
        if ([comp.name containsString:@"MultibandCompressor"])  // That allows itself to be squashed. Also, it doesn't resize itself when "details" is toggled
//        if ([comp.name containsString:@"FilterDemo"]) // That one is squashed both vertically and horizontally... (Apple's sample AUv3 Audio Unit, needs to be installed first.)
//        if ([comp.name containsString:@"GraphicEQ"])  // That one is squashed vertically
//                    if ([comp.name containsString:@"AUDelay"])
            component = comp;
    }
    
    [AVAudioUnit instantiateWithComponentDescription:component.audioComponentDescription options:0
                                   completionHandler:^(__kindof AVAudioUnit *audioUnit, NSError *error) {
        if (error) {
            NSLog(@"Error instantiating AU: %@", error);
            return;
        }
        
        self.audioUnit = audioUnit;
        AUAudioUnitBusArray* inputBusses = audioUnit.AUAudioUnit.inputBusses;
        AUAudioUnitBusArray* outputBusses = audioUnit.AUAudioUnit.outputBusses;
        
        if (!inputBusses.count || !outputBusses.count) {
            NSLog(@"No busses...");
            return;
        }
        
        [self setFormatForBus:[inputBusses objectAtIndexedSubscript:0]];
        [self setFormatForBus:[outputBusses objectAtIndexedSubscript:0]];
        
        NSError* AUerror = nil;
        if (![audioUnit.AUAudioUnit allocateRenderResourcesAndReturnError:&AUerror]){
            NSLog(@"Error allocating resources: %@", AUerror);
            return;
        }
        [audioUnit.AUAudioUnit requestViewControllerWithCompletionHandler:^(NSViewController* viewController) {
            dispatch_async(dispatch_get_main_queue(), ^{
                [self doLoad:audioUnit controller:viewController];
            });
        }];
    }];
}

- (void)viewWillLayout
{
    [super viewWillLayout];
    if(_auViewController != nil) {
        [self.view removeConstraints:@[widthConstraint, heightConstraint]];
        NSSize size = _auViewController.view.frame.size;
        widthConstraint.constant = size.width;
        heightConstraint.constant = size.height;
        [self.view addConstraints:@[widthConstraint, heightConstraint]];
    }
}

@end