105 lines
3.3 KiB
C#
105 lines
3.3 KiB
C#
using System;
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using System.Threading.Tasks;
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using System.Drawing;
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using System.IO;
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using System.Drawing.Drawing2D;
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using System.Drawing.Imaging;
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using System.Runtime.InteropServices;
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using System.Net;
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namespace GalleryShare
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{
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public static class ThumbnailGenerator
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{
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public static async Task SendThumbnailPng(string imagePath, Size thumbnailBounds, HttpListenerContext cycle)
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{
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Image imageToSend;
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try {
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using (Bitmap rawImage = new Bitmap(imagePath)) {
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float scaleFactor = Math.Min(
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thumbnailBounds.Width / (float)rawImage.Width,
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thumbnailBounds.Height / (float)rawImage.Height
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);
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Size thumbnailSize = new Size(
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(int)(rawImage.Width * scaleFactor),
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(int)(rawImage.Height * scaleFactor)
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);
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Bitmap smallImage = new Bitmap(thumbnailSize.Width, thumbnailSize.Height);
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using (Graphics context = Graphics.FromImage(smallImage)) {
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context.CompositingMode = CompositingMode.SourceCopy;
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context.InterpolationMode = InterpolationMode.HighQualityBicubic;
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context.DrawImage(rawImage, new Rectangle(
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Point.Empty,
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thumbnailSize
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));
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//smallImage.Save(outputStream, ImageFormat.Png);
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imageToSend = smallImage;
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}
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}
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}
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catch (Exception error)
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{
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Console.WriteLine("[{0}] Error generating thumbnail {1}: {2}",
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DateTime.Now.ToShortTimeString(),
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imagePath,
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error.Message
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);
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using (Font drawingFont = new Font("Sans-serif", 12f, FontStyle.Regular, GraphicsUnit.Pixel))
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{
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imageToSend = GenerateErrorImage(error.Message, drawingFont, Color.DarkGray, Color.Transparent);
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}
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}
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byte[] imageData = GetImageBytesPng(imageToSend);
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cycle.Response.ContentType = "image/png";
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cycle.Response.ContentLength64 = imageData.LongLength;
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await cycle.Response.OutputStream.WriteAsync(imageData, 0, imageData.Length);
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imageToSend.Dispose();
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}
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public static Image GenerateErrorImage(string errorText, Font textFont, Color foregroundColour, Color backgroundColour)
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{
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SizeF textSize = SizeF.Empty;
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using(Image measuringImage = new Bitmap(1, 1))
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using(Graphics measuringContext = Graphics.FromImage(measuringImage))
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{
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textSize = measuringContext.MeasureString(errorText, textFont);
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}
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float questionMarkFontSize = 200;
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Image resultImage = new Bitmap((int)textSize.Width, (int)textSize.Height + (int)questionMarkFontSize + (int)textFont.Size * 2);
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using (Graphics resultContext = Graphics.FromImage(resultImage))
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using (SolidBrush drawingBrush = new SolidBrush(foregroundColour))
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using (Font largeFont = new Font(textFont.FontFamily, questionMarkFontSize + 10, FontStyle.Regular, GraphicsUnit.Pixel))
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{
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resultContext.Clear(backgroundColour);
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resultContext.DrawString(errorText, textFont, drawingBrush, 0f, resultImage.Height - textFont.Size * 2);
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SizeF questionMarkSize = resultContext.MeasureString("?", largeFont);
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resultContext.DrawString(
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"?", largeFont, drawingBrush,
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(textSize.Width / 2) - (questionMarkSize.Width / 2),
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-10f
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);
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}
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return resultImage;
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}
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public static byte[] GetImageBytesPng(Image sourceImage)
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{
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using (MemoryStream mStream = new MemoryStream())
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{
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sourceImage.Save(mStream, ImageFormat.Png);
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return mStream.ToArray();
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}
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}
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}
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}
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