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工具类代码: using System; using System.Collections.Generic; using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging; using System.IO; using System.Linq; using System.Text; using System.Threading.Tasks; namespace ZoomImage.Utils { /// <summary> /// 图片缩放 /// </summary> public class ZoomImageUtil { #region 图片缩放 /// <summary> /// 图片缩放 /// </summary> /// <param name="bArr">图片字节流</param> /// <param name="width">目标宽度,若为0,表示宽度按比例缩放</param> /// <param name="height">目标长度,若为0,表示长度按比例缩放</param> public static byte[] GetThumbnail(byte[] bArr, int width, int height) { if (bArr == null) return null; MemoryStream ms = new MemoryStream(bArr); Bitmap bmp = (Bitmap)Image.FromStream(ms); ms.Close(); bmp = GetThumbnail(bmp, width, height); ImageCodecInfo imageCodecInfo = GetEncoder(ImageFormat.Jpeg); EncoderParameters encoderParameters = new EncoderParameters(1); EncoderParameter encoderParameter = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 75L); encoderParameters.Param[0] = encoderParameter; ms = new MemoryStream(); bmp.Save(ms, imageCodecInfo, encoderParameters); byte[] result = ms.ToArray(); ms.Close(); bmp.Dispose(); return result; } #endregion #region 图片缩放 /// <summary> /// 图片缩放 /// </summary> /// <param name="bmp">图片</param> /// <param name="width">目标宽度,若为0,表示宽度按比例缩放</param> /// <param name="height">目标长度,若为0,表示长度按比例缩放</param> private static Bitmap GetThumbnail(Bitmap bmp, int width, int height) { if (width == 0 && height == 0) { width = bmp.Width; height = bmp.Height; } else { if (width == 0) { width = height * bmp.Width / bmp.Height; } if (height == 0) { height = width * bmp.Height / bmp.Width; } } Image imgSource = bmp; Bitmap outBmp = new Bitmap(width, height); Graphics g = Graphics.FromImage(outBmp); g.Clear(Color.Transparent); // 设置画布的描绘质量 g.CompositingQuality = CompositingQuality.Default; g.SmoothingMode = SmoothingMode.Default; g.InterpolationMode = InterpolationMode.Default; g.DrawImage(imgSource, new Rectangle(0, 0, width, height + 1), 0, 0, imgSource.Width, imgSource.Height, GraphicsUnit.Pixel); g.Dispose(); imgSource.Dispose(); bmp.Dispose(); return outBmp; } #endregion #region 椭圆形缩放 /// <summary> /// 椭圆形缩放 /// </summary> /// <param name="bArr">图片字节流</param> /// <param name="width">目标宽度,若为0,表示宽度按比例缩放</param> /// <param name="height">目标长度,若为0,表示长度按比例缩放</param> public static byte[] GetEllipseThumbnail(byte[] bArr, int width, int height) { if (bArr == null) return null; MemoryStream ms = new MemoryStream(bArr); Bitmap bmp = (Bitmap)Image.FromStream(ms); Bitmap newBmp = new Bitmap(width, height); using (Graphics g = Graphics.FromImage(newBmp)) { using (TextureBrush br = new TextureBrush(bmp)) { br.ScaleTransform(width / (float)bmp.Width, height / (float)bmp.Height); g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias; g.FillEllipse(br, new Rectangle(Point.Empty, new Size(width, height))); } } MemoryStream newMs = new MemoryStream(); newBmp.Save(newMs, System.Drawing.Imaging.ImageFormat.Png); byte[] result = newMs.ToArray(); bmp.Dispose(); newBmp.Dispose(); ms.Close(); newMs.Dispose(); return result; } #endregion #region GetEncoder private static ImageCodecInfo GetEncoder(ImageFormat format) { ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders(); foreach (ImageCodecInfo codec in codecs) { if (codec.FormatID == format.Guid) { return codec; } } return null; } #endregion } } 使用示例: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.IO; using System.Linq; using System.Text; using System.Threading; using System.Threading.Tasks; using System.Windows.Forms; using ZoomImage.Utils; namespace ZoomImage { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { openFileDialog1.Multiselect = true; } private void txtWidth_KeyPress(object sender, KeyPressEventArgs e) { if (e.KeyChar != 8 && !Char.IsDigit(e.KeyChar)) { e.Handled = true; } } private void txtHeight_KeyPress(object sender, KeyPressEventArgs e) { if (e.KeyChar != 8 && !Char.IsDigit(e.KeyChar)) { e.Handled = true; } } private void btnSelectImage_Click(object sender, EventArgs e) { try { if (txtWidth.Text == "" && txtHeight.Text == "") { MessageBox.Show("请输入宽度或高度!"); return; } if (openFileDialog1.ShowDialog() == DialogResult.OK) { Task.Factory.StartNew(() => { try { string path = Path.GetDirectoryName(openFileDialog1.FileNames[0]) + "\\NewImage\\"; if (!Directory.Exists(path)) { Directory.CreateDirectory(path); } foreach (string file in Directory.GetFiles(path)) { File.Delete(file); } int i = 0; foreach (string fileName in openFileDialog1.FileNames) { Bitmap bmp = ZoomImageUtil.GetThumbnail(new Bitmap(fileName), Convert.ToInt32(txtWidth.Text == "" ? "0" : txtWidth.Text), Convert.ToInt32(txtHeight.Text == "" ? "0" : txtHeight.Text)); this.Invoke(new InvokeDelegate(() => { if (cbxExt.SelectedItem == null) { bmp.Save(path + Path.GetFileName(fileName)); } else { bmp.Save(path + Path.GetFileNameWithoutExtension(fileName) + (string)cbxExt.SelectedItem); } })); this.Invoke(new InvokeDelegate(() => { lblProgress.Text = string.Format("进度:{1}/{0}", openFileDialog1.FileNames.Length, ++i); })); Thread.Sleep(1); } MessageBox.Show("成功!"); } catch (Exception ex) { MessageBox.Show(ex.Message); } }); } } catch (Exception ex) { MessageBox.Show(ex.Message); } } } /// <summary> /// 跨线程访问控件的委托 /// </summary> public delegate void InvokeDelegate(); }
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