ios - 如何在不加载图像文件的情况下获取图像文件的图像大小？

Question

如何在不加载内存的情况下获取图像文件的图像大小？

我尝试使用 MonoTouch.ImageIO 命名空间中的 CGImageSource，如 Apple 文档和此博客文章中所述:

oleb.net

但是这段代码不起作用:

public Size GetImageSizeFromImageFile (string image_file_path)
    {

        CGImageSource imageSource = CGImageSource.FromUrl (NSUrl.FromFilename (image_file_path));

        if (imageSource == null) {
            // Error loading image
            Console.WriteLine ("Error loading image info for file: " + image_file_path);
            return Size.Empty;
        }

        NSDictionary imageProperties = new NSDictionary ();
        imageSource.CopyProperties (imageProperties, 0);

        int width = (int)imageProperties.ValueForKey (new NSString ("kCGImagePropertyPixelWidth"));
        int height = (int)imageProperties.ValueForKey (new NSString ("kCGImagePropertyPixelHeight"));


        Console.WriteLine (@"Image " + image_file_path + " dimensions: " + width + " x " + height+" px");

        imageProperties.Dispose ();

        return new Size(width, height);
    }

转换为字符串没有任何区别，该字段返回空。

感谢任何帮助，谢谢!

Answer 1

最新的 MonoTouch 版本使得使用新的 GetProperties 方法获取图像属性变得更加容易。例如

using (var src = CGImageSource.FromUrl (NSUrl.FromFilename (filename))) {
    CGImageOptions options = new CGImageOptions () { ShouldCache = false };
    // do not forget the '0' image index or you won't get what you're looking for!
    using (var p = src.GetProperties (options, 0)) {
        Console.WriteLine ("{0}x{1}", p.PixelWidth, p.PixelHeight);
    }
}