Question

如何动态创建固定大小的缩略图，并在listview中调整图像大小最适合缩略图的大小。

private void Treeview1_AfterSelect(System.Object sender, System.Windows.Forms.TreeViewEventArgs e)
{
    if (folder != null && System.IO.Directory.Exists(folder))
                {
                    try
                    {

                        DirectoryInfo dir = new DirectoryInfo(@folder);
                        foreach (FileInfo file in dir.GetFiles())
                        {
                            try
                            {
                                imageList.ImageSize = new Size(136, 136);
                                imageList.ColorDepth = ColorDepth.Depth32Bit;
                                Image img = new Bitmap(Image.FromFile(file.FullName));                                    
                                Graphics g = Graphics.FromImage(img);

                                g.DrawRectangle(Pens.Red, 0, 0, img.Width - 21, img.Height - 21);
                                //g.DrawRectangle(Pens.Red, 0, 0, img.Width, img.Height);                                                                                                                                                
                                imageList.Images.Add(img);
                            }
                            catch
                            {
                                Console.WriteLine("This is not an image file");
                            }     
                        }


                        for (int j = 0; j < imageList.Images.Count; j++)
                        {
                            this.ListView1.Items.Add("Item" + j);
                            this.ListView1.Items[j].ImageIndex = j;
                        }

                        this.ListView1.View = View.LargeIcon;
                        this.ListView1.LargeImageList = imageList;
                        //this.ListView1.DrawItem += new DrawListViewItemEventHandler(ListView1_DrawItem);                                                       

                        //import(folder);
                    }
                    catch (Exception ex)
                    {
                    }
}

Answer 1

我在this answer中有代码专门用于调整图像大小和分辨率：

public void GenerateThumbNail(HttpPostedFile fil, string sPhysicalPath, 
                              string sOrgFileName,string sThumbNailFileName,
                              ImageFormat oFormat, int rez)
{

    try
    {

        System.Drawing.Image oImg = System.Drawing.Image.FromStream(fil.InputStream);

        decimal pixtosubstract = 0;
        decimal percentage;

        //default
        Size ThumbNailSizeToUse = new Size();
        if (ThumbNailSize.Width < oImg.Size.Width || ThumbNailSize.Height < oImg.Size.Height)
        {
            if (oImg.Size.Width > oImg.Size.Height)
            {
                percentage = (((decimal)oImg.Size.Width - (decimal)ThumbNailSize.Width) / (decimal)oImg.Size.Width);
                pixtosubstract = percentage * oImg.Size.Height;
                ThumbNailSizeToUse.Width = ThumbNailSize.Width;
                ThumbNailSizeToUse.Height = oImg.Size.Height - (int)pixtosubstract;
            }
            else
            {
                percentage = (((decimal)oImg.Size.Height - (decimal)ThumbNailSize.Height) / (decimal)oImg.Size.Height);
                pixtosubstract = percentage * (decimal)oImg.Size.Width;
                ThumbNailSizeToUse.Height = ThumbNailSize.Height;
                ThumbNailSizeToUse.Width = oImg.Size.Width - (int)pixtosubstract;
            }

        }
        else
        {
            ThumbNailSizeToUse.Width = oImg.Size.Width;
            ThumbNailSizeToUse.Height = oImg.Size.Height;
        }

        Bitmap bmp = new Bitmap(ThumbNailSizeToUse.Width, ThumbNailSizeToUse.Height);
        bmp.SetResolution(rez, rez);
        System.Drawing.Image oThumbNail = bmp;

        bmp = null;

        Graphics oGraphic = Graphics.FromImage(oThumbNail);

        oGraphic.CompositingQuality = CompositingQuality.HighQuality;

        oGraphic.SmoothingMode = SmoothingMode.HighQuality;

        oGraphic.InterpolationMode = InterpolationMode.HighQualityBicubic;

        Rectangle oRectangle = new Rectangle(0, 0, ThumbNailSizeToUse.Width, ThumbNailSizeToUse.Height);

        oGraphic.DrawImage(oImg, oRectangle);

        oThumbNail.Save(sPhysicalPath  + sThumbNailFileName, oFormat);

        oImg.Dispose();

    }
    catch (Exception ex)
    {
        Response.Write(ex.Message);
    }

}

在listview控件上动态创建固定大小的缩略图

1 个答案: