如何阴影添加到一个ListView？ [英] How to add a drop shadow to a ListView?

问题描述

有没有一种方法，我可以在C＃中（查看= LargeIcon 模式），而无需使用第三方组件添加阴影到ListView项目？

Is there's a way I can add a drop shadow to a ListView item in C# (view = LargeIcon mode) without using a third party component?

我能想到的唯一方法是通过绘制的图像本身的阴影，但这样一来，当我点击图像，投影也将得到强调（因为它是图像的一部分！）。因此，也许有一种方法，使ListView控件只突出了图像的特定区域，当我点击一个项目？

The only way I can think of is by drawing the drop shadow on the image itself, but this way when I click on the image, the drop shadow will also be highlighted (because it is part of the image!). So maybe there is a way to make the ListView only highlight a specific area of the image when I click on an item?

推荐答案

最简单的方法是创建一个合适的阴影效果的位图，并使用 OwnerDrawing 的 ListView控件的项目。

The simplest way is to create a suitable dropshadow bitmap and use OwnerDrawing the ListView items.

下面是一个例子：

public Form1()
{
    InitializeComponent();

    shadow = (Bitmap)Image.FromFile(aDropShadowBitmap);
    overlay = new Bitmap(64, 64);
    using (Graphics G = Graphics.FromImage(overlay))
            G.Clear(Color.FromArgb(127, 31, 191, 255));
}

Bitmap shadow;
Bitmap overlay;

private void listView1_DrawItem(object sender, DrawListViewItemEventArgs e)
{
    ListViewItem item = e.Item;
    Point bLoc = new Point(e.Bounds.X + 35, e.Bounds.Y + 10);
    Size imgS = imageList1.ImageSize;

    e.Graphics.DrawImage(shadow, bLoc);
    e.Graphics.DrawImage(imageList1.Images[e.ItemIndex], bLoc);

    if ((e.State & ListViewItemStates.Selected) == ListViewItemStates.Selected)
    {
        e.Graphics.DrawImage(overlay, bLoc);
    }
    else  {  }

    e.Graphics.DrawString(item.Text, listView1.Font, Brushes.Black,
                bLoc.X, bLoc.Y + imgS.Height + 10);
}

它使用图片在 64×64的ImageList 和适当的80×80位图阴影（在Photoshop中创建）

It uses Images in a 64x64 ImageList and a suitable 80x80 bitmap with a drop shadow (created in Photoshop) :

要想像我覆盖在图像与半透明选择位图覆盖。下面是结果：

To visualize the selection I overlay the image with a semitransparent Bitmap overlay. Here is the result:

注意：原样，结果有一个微妙的错误：点击文本将不会选择该项目。补救的办法是一个简单的解决方法..：

Note: As is, the result has a subtle bug: Clicking on the texts won't select the items. The remedy is a simple workaround..:

在 ItemHeight 不能直接设置。相反，它是从最大高度得到的分配和适用图像列表：这里 LargeImageList 和 StateImageList 。

The ItemHeight can't be set directly. Instead it is derived from the maximum heights of the assigned and applicable ImageLists: Here LargeImageList and StateImageList.

除非我们要添加额外的透明像素为我们所有的图像，我们可以通过添加第二个的ImageList 与 IMAGESIZE 1×，并将其指定为 StateImageList 。氖需要添加实际图片！现在，该项目文本也将选择的项目..！

Unless we want to add extra transparent pixels to all our images, we can enlarge the active height of the items by adding a second ImageList with an ImageSize 1x100 and assign it as the StateImageList. Ne need to add actual Images! Now the item texts will also select the items..!

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