ASP. NET method for uploading pictures and generating thumbnails
- 2021-07-10 19:27:01
- OfStack
This article describes the example of ASP. NET to upload pictures and generate thumbnail method. Share it for your reference, as follows:
protected void bt_upload_Click(object sender, EventArgs e)
{
// Check whether the uploaded file format is valid
if (this.UploadFile.PostedFile.ContentType.ToLower().IndexOf("image") < 0)
{
Response.Write(" The uploaded picture format is invalid! ");
return;
}
// Generate original image
Byte[] oFileByte = new byte[this.UploadFile.PostedFile.ContentLength];
System.IO.Stream oStream = this.UploadFile.PostedFile.InputStream;
System.Drawing.Image oImage = System.Drawing.Image.FromStream(oStream);
int oWidth = oImage.Width; // Width of original drawing
int oHeight = oImage.Height; // Height of original image
int tWidth = 100; // Set the initial width of thumbnail
int tHeight = 100; // Set the initial height of thumbnail
// Calculate the width and height of thumbnails to scale
if (oWidth >= oHeight)
{
tHeight = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth) / Convert.ToDouble(oWidth)));
}
else
{
tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));
}
// Generate thumbnail original image
Bitmap tImage = new Bitmap(tWidth, tHeight);
Graphics g = Graphics.FromImage(tImage);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; // Set up high-quality interpolation method
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;// Set high quality , Smooth degree at low speed
g.Clear(Color.Transparent); // Empty the canvas and fill it with a transparent background color
g.DrawImage(oImage, new Rectangle(0, 0, tWidth, tHeight), new Rectangle(0, 0, oWidth, oHeight), GraphicsUnit.Pixel);
string oFullName = Server.MapPath(".") + "/image/" + "o" + DateTime.Now.ToShortDateString().Replace("-", "") + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() + DateTime.Now.Millisecond.ToString() + ".jpg"; // Save the physical path of the original image
string tFullName = Server.MapPath(".") + "/image/" + "t" + DateTime.Now.ToShortDateString().Replace("-", "") + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() + DateTime.Now.Millisecond.ToString() + ".jpg"; // Save the physical path of the thumbnail
try
{
// With JPG Save pictures in format
oImage.Save(oFullName, System.Drawing.Imaging.ImageFormat.Jpeg);
tImage.Save(tFullName, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (Exception ex)
{
throw ex;
}
finally
{
// Release resources
oImage.Dispose();
g.Dispose();
tImage.Dispose();
}
}
}
Here is another improvement method:
#region Upload pictures And generate thumbnails
/// <summary>
/// Upload pictures to generate thumbnails
/// </summary>
/// <param name="originalImagePath"> Image source path </param>
/// <param name="thumbnailPath"> Thumbnail path ( Physical path )</param>
/// <param name="width"> Thumbnail width </param>
/// <param name="height"> Thumbnail height </param>
/// <param name="mode"> How to generate thumbnails </param>
public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode) {
// File that gets the source picture from the path
System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);
int towidth = width;
int toheight = height;
int x = 0;
int y = 0;
// Gets the width of the picture
int ow = image.Width;
// Get the height of the picture
int oh = image.Height;
// How to generate thumbnails
switch (mode) {
case "HW":
break;
case "W":// Specify Width Highly proportional
toheight = originalImage.Height * width / originalImage.Width;
break;
case "H":// Specify the height of the picture Width proportional
towidth = originalImage.Width * height / originalImage.Height;
break;
case "Cut":// If you are in trimming mode It is not deformed
if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
{
oh = originalImage.Height;
// Width of thumbnail picture
ow = originalImage.Height * towidth / toheight;
y = 0;
x = (originalImage.Width - ow) / 2;
}
else {
ow = originalImage.Width;
// Height of thumbnail picture
oh = originalImage.Width * toheight / towidth;
x = 0;
y(originalImage.Height - oh) / 2;
}
break;
default: break;
}
// New 1 A bmp Picture
Bitmap bitmap = new Bitmap(towidth, toheight);
// New 1 Canvas With BitMap Width Height as the size of the canvas
Graphics g = Graphics.FromImage(bitmap);
// Set up high-quality interpolation method
g.InterpolationMode = InterpolationMode.High;
// With high quality Low speed Render
g.SmoothingMode = SmoothingMode.HighQuality;
// Empty a canvas Fill with white background color
g.Clear(Color.Transparent);
// Draws the specified part of the original picture at the specified position and at the specified size
g.DrawImage(originalImage,new Rectangle(towidth,toheight),new Rectangle(x,y,ow,oh),GraphicsUnit.Pixel);
try
{
// With jpg Format to save thumbnails
bitmap.Save(thumbnailPath,System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (Exception ex)
{
throw ex;
}
finally {
// Release resources
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
#endregion
I hope this article is helpful to everyone's asp. net programming.