C＃如何检查PictureBox是否在指定的图像列表中包含图像？

Question

I need to know whether the PictureBox contains an Image in a specified imageList . Because if ImageList is long, it will take a lot to say in an if-statement if each image in imageList is in the PictureBox. and when I type

foreach (var image in imageList1)
        {
            if (pictureBox1.Image = image)
            {
                //Code
            }
        }

It doesn't work :/

Answer 1

Try the following:

//using System.Linq;

bool isinside = /*yourImageList*/.Images.Any(x => x == /*yourPictureBox*/.Image);

if (isinside)
{
    //is in yourImageList
    MessageBox.Show("image is from imagelist!");
    //or do what you want here!
}

Answer 2

ImageList is a special thing and it may or may not be the right object to use..

One good thing about it is that it stores the images not as type Image ; this is good because it doesn't need a GDI handle for each image it stores, even if you add a large number of images.

One problem with this is that you simply can't compare its images to an image you have assigned to a PictureBox.Image .

So even after correcting your syntax this will not work:

// assign an image
pictureBox1.Image = imageList1.Images[2];
// now look for it:
foreach (var  img in imageList1.Images)
{
    if (pictureBox1.Image  == img )
    {
        Console.WriteLine("Found the Image!");  // won't happen
    }
}

Instead you should store the Key to the image in the ImageList :

pictureBox1.Image = imageList1.Images[2];
pictureBox1.Tag = imageList1.Images.Keys[2];

Now you can easily look for the key:

foreach (var  imgKey in imageList1.Images.Keys)
{
    if (pictureBox1.Tag.ToString() == imgKey )
    {
        Console.WriteLine("Found the Image-Key!");  // will happen quite quickly!
    }
}

Of course the question if using an ImageList is a good idea in the first place is quite another matter..

It is really meant to be used with ListViews , TreeViews and other Controls that can display small iconic images.

It is limited to 256x256 pixels for instance; also: all its images must have the same size!

But if that is OK, stay with it.

Otherwise a List<Image> , as Hans suggested would be a natural and flexible alternative..