jellyfin/Emby.Drawing/GDI/ImageExtensions.cs

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7.6 KiB
C#
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2015-04-08 14:38:02 +00:00
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
namespace Emby.Drawing.GDI
{
public static class ImageExtensions
{
/// <summary>
/// Saves the image.
/// </summary>
/// <param name="outputFormat">The output format.</param>
/// <param name="image">The image.</param>
/// <param name="toStream">To stream.</param>
/// <param name="quality">The quality.</param>
public static void Save(this Image image, ImageFormat outputFormat, Stream toStream, int quality)
{
// Use special save methods for jpeg and png that will result in a much higher quality image
// All other formats use the generic Image.Save
if (ImageFormat.Jpeg.Equals(outputFormat))
{
SaveAsJpeg(image, toStream, quality);
}
else if (ImageFormat.Png.Equals(outputFormat))
{
image.Save(toStream, ImageFormat.Png);
}
else
{
image.Save(toStream, outputFormat);
}
}
/// <summary>
/// Saves the JPEG.
/// </summary>
/// <param name="image">The image.</param>
/// <param name="target">The target.</param>
/// <param name="quality">The quality.</param>
public static void SaveAsJpeg(this Image image, Stream target, int quality)
{
using (var encoderParameters = new EncoderParameters(1))
{
encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
image.Save(target, GetImageCodecInfo("image/jpeg"), encoderParameters);
}
}
private static readonly ImageCodecInfo[] Encoders = ImageCodecInfo.GetImageEncoders();
/// <summary>
/// Gets the image codec info.
/// </summary>
/// <param name="mimeType">Type of the MIME.</param>
/// <returns>ImageCodecInfo.</returns>
private static ImageCodecInfo GetImageCodecInfo(string mimeType)
{
foreach (var encoder in Encoders)
{
if (string.Equals(encoder.MimeType, mimeType, StringComparison.OrdinalIgnoreCase))
{
return encoder;
}
}
return Encoders.Length == 0 ? null : Encoders[0];
}
/// <summary>
/// Crops an image by removing whitespace and transparency from the edges
/// </summary>
/// <param name="bmp">The BMP.</param>
/// <returns>Bitmap.</returns>
/// <exception cref="System.Exception"></exception>
public static Bitmap CropWhitespace(this Bitmap bmp)
{
var width = bmp.Width;
var height = bmp.Height;
var topmost = 0;
for (int row = 0; row < height; ++row)
{
if (IsAllWhiteRow(bmp, row, width))
topmost = row;
else break;
}
int bottommost = 0;
for (int row = height - 1; row >= 0; --row)
{
if (IsAllWhiteRow(bmp, row, width))
bottommost = row;
else break;
}
int leftmost = 0, rightmost = 0;
for (int col = 0; col < width; ++col)
{
if (IsAllWhiteColumn(bmp, col, height))
leftmost = col;
else
break;
}
for (int col = width - 1; col >= 0; --col)
{
if (IsAllWhiteColumn(bmp, col, height))
rightmost = col;
else
break;
}
if (rightmost == 0) rightmost = width; // As reached left
if (bottommost == 0) bottommost = height; // As reached top.
var croppedWidth = rightmost - leftmost;
var croppedHeight = bottommost - topmost;
if (croppedWidth == 0) // No border on left or right
{
leftmost = 0;
croppedWidth = width;
}
if (croppedHeight == 0) // No border on top or bottom
{
topmost = 0;
croppedHeight = height;
}
// Graphics.FromImage will throw an exception if the PixelFormat is Indexed, so we need to handle that here
var thumbnail = new Bitmap(croppedWidth, croppedHeight, PixelFormat.Format32bppPArgb);
// Preserve the original resolution
TrySetResolution(thumbnail, bmp.HorizontalResolution, bmp.VerticalResolution);
using (var thumbnailGraph = Graphics.FromImage(thumbnail))
{
thumbnailGraph.CompositingQuality = CompositingQuality.HighQuality;
thumbnailGraph.SmoothingMode = SmoothingMode.HighQuality;
thumbnailGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
thumbnailGraph.PixelOffsetMode = PixelOffsetMode.HighQuality;
thumbnailGraph.CompositingMode = CompositingMode.SourceCopy;
thumbnailGraph.DrawImage(bmp,
new RectangleF(0, 0, croppedWidth, croppedHeight),
new RectangleF(leftmost, topmost, croppedWidth, croppedHeight),
GraphicsUnit.Pixel);
}
return thumbnail;
}
/// <summary>
/// Tries the set resolution.
/// </summary>
/// <param name="bmp">The BMP.</param>
/// <param name="x">The x.</param>
/// <param name="y">The y.</param>
private static void TrySetResolution(Bitmap bmp, float x, float y)
{
if (x > 0 && y > 0)
{
bmp.SetResolution(x, y);
}
}
/// <summary>
/// Determines whether or not a row of pixels is all whitespace
/// </summary>
/// <param name="bmp">The BMP.</param>
/// <param name="row">The row.</param>
/// <param name="width">The width.</param>
/// <returns><c>true</c> if [is all white row] [the specified BMP]; otherwise, <c>false</c>.</returns>
private static bool IsAllWhiteRow(Bitmap bmp, int row, int width)
{
for (var i = 0; i < width; ++i)
{
if (!IsWhiteSpace(bmp.GetPixel(i, row)))
{
return false;
}
}
return true;
}
/// <summary>
/// Determines whether or not a column of pixels is all whitespace
/// </summary>
/// <param name="bmp">The BMP.</param>
/// <param name="col">The col.</param>
/// <param name="height">The height.</param>
/// <returns><c>true</c> if [is all white column] [the specified BMP]; otherwise, <c>false</c>.</returns>
private static bool IsAllWhiteColumn(Bitmap bmp, int col, int height)
{
for (var i = 0; i < height; ++i)
{
if (!IsWhiteSpace(bmp.GetPixel(col, i)))
{
return false;
}
}
return true;
}
/// <summary>
/// Determines if a color is whitespace
/// </summary>
/// <param name="color">The color.</param>
/// <returns><c>true</c> if [is white space] [the specified color]; otherwise, <c>false</c>.</returns>
private static bool IsWhiteSpace(Color color)
{
return (color.R == 255 && color.G == 255 && color.B == 255) || color.A == 0;
}
}
}