cocoa - 如何在 NSImageView 中设置内容切换动画？

Question

我想切换 NSImageView 中显示的图像，但我想为该更改设置动画。我尝试了各种方法来做到这一点。希望你们中的一位能够推荐一种可能真正有效的方法。我正在使用 Cocoa for Mac。

Answer 1

据我所知，NSImageView不支持动画图像更改。但是，您可以将第二个 NSImageView 放置在第一个 NSImageView 之上，并以动画方式隐藏旧的并显示新的。例如:

NSImageView *newImageView = [[NSImageView alloc] initWithFrame: [imageView frame]];
[newImageView setImageFrameStyle: [imageView imageFrameStyle]];
// anything else you need to copy properties from the old image view
// ...or unarchive it from a nib

[newImageView setImage: [NSImage imageNamed: @"NSAdvanced"]];
[[imageView superview] addSubview: newImageView
                       positioned: NSWindowAbove relativeTo: imageView];
[newImageView release];

NSDictionary *fadeIn = [NSDictionary dictionaryWithObjectsAndKeys:
             newImageView, NSViewAnimationTargetKey,
             NSViewAnimationFadeInEffect, NSViewAnimationEffectKey,
             nil];
NSDictionary *fadeOut = [NSDictionary dictionaryWithObjectsAndKeys:
             imageView, NSViewAnimationTargetKey,
             NSViewAnimationFadeOutEffect, NSViewAnimationEffectKey,
             nil];
NSViewAnimation *animation = [[NSViewAnimation alloc] initWithViewAnimations:
              [NSArray arrayWithObjects: fadeOut, fadeIn, nil]];
[animation setAnimationBlockingMode: NSAnimationBlocking];
[animation setDuration: 2.0];
[animation setAnimationCurve: NSAnimationEaseInOut];
[animation startAnimation];
[imageView removeFromSuperview];
imageView = newImageView;
[animation release];

如果您的 View 很大并且可能需要 10.5+，那么您可以使用 Core Animation 做同样的事情，它将进行硬件加速并使用更少的 CPU。

创建 newImageView 后，执行以下操作:

[newImageView setAlphaValue: 0];
[newImageView setWantsLayer: YES];
// ...
[self performSelector: @selector(animateNewImageView:) withObject: newImageView afterDelay: 0];

- (void)animateNewImageView:(NSImageView *)newImageView;
{
    [NSAnimationContext beginGrouping];
    [[NSAnimationContext currentContext] setDuration: 2];
    [[newImageView animator] setAlphaValue: 1];
    [[imageView animator] setAlphaValue: 0];
    [NSAnimationContext endGrouping];
}

您需要修改上面的内容才能中止，但我不会为您编写所有代码:-)