C＃如何在没有OutOfMemoryException的情况下批量加载listview上的图像？ [英] C# How to bulk load images on a listview without getting OutOfMemoryException?

问题描述

Hello Winforms社区，



我正在尝试在listview中加载超过一千个图像，但我得到了OutOfMemoryException。作为解决方案，我阅读了有关按需加载或启用VirtualMode及其处理程序的信息。我不知道如何将我的代码转换到那个级别...但是我怎么能成功实现
？b

 

 private void btnAddImg_Click（object sender，EventArgs e）
 {
 OpenFileDialog ofd = new OpenFileDialog（）; 
 ofd.Multiselect = true; 
 DialogResult dr = ofd.ShowDialog（）; 
 if（dr == DialogResult.OK）
 {
 
 
 foreach（ofd.FileNames中的字符串文件名）
 {
 Image img = Image.FromFile（filename）; 
 string a = c.ToString（）; 
 
 
 imageList1.Images.Add（a，img）; 
 
 var listViewItem = listView1.Items.Add（""）; 
 
 listViewItem.ImageKey = a; 
 
 c ++; 
} 
 
} 
} 

$

解决方案

嗨尼克，

>>我不知道如何改造我的代码虽然...

请参阅以下有关使用带有ListView的VirtualMode的演示：

1，定义一个列表以保存需要加载的数据：

 protected List< ListViewItem> CurrentCacheItemsSource 
 {
 get; 
私人套装; 
} 

2，通过VirtualMode加载数据：

 private void LoadListViewItems（List< ListViewItem> item）
 {
 listView.Items.Clear（）; 
 if（items == null）
 {
 stripStatusInfo.Text =" Current Record：0" ;; 
返回; 
} 
 
 listView.GridLines = true; 
 listView.FullRowSelect = true; 
 listView.View = View.Details; 
 listView.Scrollable = true; 
 listView.MultiSelect = false; 
 listView.HeaderStyle = ColumnHeaderStyle.Clickable; 
 listView.Visible = true; 
 
 listView.VirtualListSize = items.Count; //设置虚拟列表容量大小
 listView.VirtualMode = true; //设置虚拟模式
 listView.RetrieveVirtualItem + = new RetrieveVirtualItemEventHandler（listView_RetrieveVirtualItem）; //绑定虚拟操作
 
 stripStatusInfo.Text =" Current Record：" + items.Count; 
} 

3， 在RetrieveVirtualItem方法中加载相关数据：

 void listView_RetrieveVirtualItem （对象发送者，RetrieveVirtualItemEventArgs e）
 {
 if（this.CurrentCacheItemsSource == null || this.CurrentCacheItemsSource.Count == 0）
 {
 return; 
} 
 
 e.Item = this.CurrentCacheItemsSource [e.ItemIndex]; 
 if（e.ItemIndex == this.CurrentCacheItemsSource.Count）
 {
 this.CurrentCacheItemsSource = null; 
} 
} 

有关VirtualMode的更多详情，请参阅以下文件：

ListView.VirtualMode Property。

虚拟模式ListView。

希望这会有所帮助！

最好的问候，

Stanly

Hello Winforms Community,

I am trying to load more than a thousand images in my listview but Im getting the OutOfMemoryException. As a solution I read about load on demand or enabling VirtualMode and its handlers. I dont know how to transform my code to that level though... how can I achieve that successfully?

 

private void btnAddImg_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Multiselect = true;
            DialogResult dr = ofd.ShowDialog();
            if(dr == DialogResult.OK)
            {
                

                    foreach (string filename in ofd.FileNames)
                    {
                        Image img = Image.FromFile(filename);
                        string a = c.ToString();


                        imageList1.Images.Add(a, img);

                        var listViewItem = listView1.Items.Add("");
                     
                        listViewItem.ImageKey = a;
                       
                        c++;
                    }
                
            }
        }

解决方案

Hi Nick,

>>I dont know how to transform my code to that level though...

Please refer to the following demo about use VirtualMode with ListView:

1, Define a list to save data what need to loaded:

        protected List<ListViewItem> CurrentCacheItemsSource  
        {
            get;
            private set;
        }

2, Load data through VirtualMode:

        private void LoadListViewItems(List<ListViewItem> items)
        {
            listView.Items.Clear();   
            if (items == null)
            {
                stripStatusInfo.Text = "Current Record: 0";  
                return;
            }
              
            listView.GridLines = true;
            listView.FullRowSelect = true;
            listView.View = View.Details;
            listView.Scrollable = true;
            listView.MultiSelect = false;
            listView.HeaderStyle = ColumnHeaderStyle.Clickable;
            listView.Visible = true;
            
            listView.VirtualListSize = items.Count; //Set the virtual list capacity size
            listView.VirtualMode = true; //set virtual mode
            listView.RetrieveVirtualItem += new RetrieveVirtualItemEventHandler(listView_RetrieveVirtualItem); //Bind the virtual operation

            stripStatusInfo.Text = "Current Record：" + items.Count;          
        }

3, Load the relevant data in the RetrieveVirtualItem method:

       void listView_RetrieveVirtualItem(object sender, RetrieveVirtualItemEventArgs e)
        {
            if (this.CurrentCacheItemsSource == null || this.CurrentCacheItemsSource.Count == 0)
            {
                return;
            }

            e.Item = this.CurrentCacheItemsSource[e.ItemIndex];
            if (e.ItemIndex == this.CurrentCacheItemsSource.Count)
            {
                this.CurrentCacheItemsSource = null ;
            }
        }

More details about VirtualMode, please refer to the following documents:

ListView.VirtualMode Property.

Virtual Mode ListView.

Hope this helps!

Best Regards,

Stanly

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