jellyfin-server/Jellyfin.Drawing.Skia/StripCollageBuilder.cs
2020-07-19 14:12:53 -04:00

195 lines
7.2 KiB
C#

using System;
using System.Collections.Generic;
using System.IO;
using SkiaSharp;
namespace Jellyfin.Drawing.Skia
{
/// <summary>
/// Used to build collages of multiple images arranged in vertical strips.
/// </summary>
public class StripCollageBuilder
{
private readonly SkiaEncoder _skiaEncoder;
/// <summary>
/// Initializes a new instance of the <see cref="StripCollageBuilder"/> class.
/// </summary>
/// <param name="skiaEncoder">The encoder to use for building collages.</param>
public StripCollageBuilder(SkiaEncoder skiaEncoder)
{
_skiaEncoder = skiaEncoder;
}
/// <summary>
/// Check which format an image has been encoded with using its filename extension.
/// </summary>
/// <param name="outputPath">The path to the image to get the format for.</param>
/// <returns>The image format.</returns>
public static SKEncodedImageFormat GetEncodedFormat(string outputPath)
{
if (outputPath == null)
{
throw new ArgumentNullException(nameof(outputPath));
}
var ext = Path.GetExtension(outputPath);
if (string.Equals(ext, ".jpg", StringComparison.OrdinalIgnoreCase)
|| string.Equals(ext, ".jpeg", StringComparison.OrdinalIgnoreCase))
{
return SKEncodedImageFormat.Jpeg;
}
if (string.Equals(ext, ".webp", StringComparison.OrdinalIgnoreCase))
{
return SKEncodedImageFormat.Webp;
}
if (string.Equals(ext, ".gif", StringComparison.OrdinalIgnoreCase))
{
return SKEncodedImageFormat.Gif;
}
if (string.Equals(ext, ".bmp", StringComparison.OrdinalIgnoreCase))
{
return SKEncodedImageFormat.Bmp;
}
// default to png
return SKEncodedImageFormat.Png;
}
/// <summary>
/// Create a square collage.
/// </summary>
/// <param name="paths">The paths of the images to use in the collage.</param>
/// <param name="outputPath">The path at which to place the resulting collage image.</param>
/// <param name="width">The desired width of the collage.</param>
/// <param name="height">The desired height of the collage.</param>
public void BuildSquareCollage(string[] paths, string outputPath, int width, int height)
{
using var bitmap = BuildSquareCollageBitmap(paths, width, height);
using var outputStream = new SKFileWStream(outputPath);
using var pixmap = new SKPixmap(new SKImageInfo(width, height), bitmap.GetPixels());
pixmap.Encode(outputStream, GetEncodedFormat(outputPath), 90);
}
/// <summary>
/// Create a thumb collage.
/// </summary>
/// <param name="paths">The paths of the images to use in the collage.</param>
/// <param name="outputPath">The path at which to place the resulting image.</param>
/// <param name="width">The desired width of the collage.</param>
/// <param name="height">The desired height of the collage.</param>
public void BuildThumbCollage(string[] paths, string outputPath, int width, int height)
{
using var bitmap = BuildThumbCollageBitmap(paths, width, height);
using var outputStream = new SKFileWStream(outputPath);
using var pixmap = new SKPixmap(new SKImageInfo(width, height), bitmap.GetPixels());
pixmap.Encode(outputStream, GetEncodedFormat(outputPath), 90);
}
private SKBitmap BuildThumbCollageBitmap(string[] paths, int width, int height)
{
var bitmap = new SKBitmap(width, height);
using var canvas = new SKCanvas(bitmap);
canvas.Clear(SKColors.Black);
// number of images used in the thumbnail
var iCount = 3;
// determine sizes for each image that will composited into the final image
var iSlice = Convert.ToInt32(width / iCount);
int iHeight = Convert.ToInt32(height * 1.00);
int imageIndex = 0;
for (int i = 0; i < iCount; i++)
{
using var currentBitmap = GetNextValidImage(paths, imageIndex, out int newIndex);
imageIndex = newIndex;
if (currentBitmap == null)
{
continue;
}
// resize to the same aspect as the original
int iWidth = Math.Abs(iHeight * currentBitmap.Width / currentBitmap.Height);
using var resizeBitmap = new SKBitmap(iWidth, iHeight, currentBitmap.ColorType, currentBitmap.AlphaType);
currentBitmap.ScalePixels(resizeBitmap, SKFilterQuality.High);
// crop image
int ix = Math.Abs((iWidth - iSlice) / 2);
using var image = SKImage.FromBitmap(resizeBitmap);
using var subset = image.Subset(SKRectI.Create(ix, 0, iSlice, iHeight));
// draw image onto canvas
canvas.DrawImage(subset ?? image, iSlice * i, 0);
}
return bitmap;
}
private SKBitmap? GetNextValidImage(string[] paths, int currentIndex, out int newIndex)
{
var imagesTested = new Dictionary<int, int>();
SKBitmap? bitmap = null;
while (imagesTested.Count < paths.Length)
{
if (currentIndex >= paths.Length)
{
currentIndex = 0;
}
bitmap = _skiaEncoder.Decode(paths[currentIndex], false, null, out _);
imagesTested[currentIndex] = 0;
currentIndex++;
if (bitmap != null)
{
break;
}
}
newIndex = currentIndex;
return bitmap;
}
private SKBitmap BuildSquareCollageBitmap(string[] paths, int width, int height)
{
var bitmap = new SKBitmap(width, height);
var imageIndex = 0;
var cellWidth = width / 2;
var cellHeight = height / 2;
using var canvas = new SKCanvas(bitmap);
for (var x = 0; x < 2; x++)
{
for (var y = 0; y < 2; y++)
{
using var currentBitmap = GetNextValidImage(paths, imageIndex, out int newIndex);
imageIndex = newIndex;
if (currentBitmap == null)
{
continue;
}
using var resizedBitmap = new SKBitmap(cellWidth, cellHeight, currentBitmap.ColorType, currentBitmap.AlphaType);
// scale image
currentBitmap.ScalePixels(resizedBitmap, SKFilterQuality.High);
// draw this image into the strip at the next position
var xPos = x * cellWidth;
var yPos = y * cellHeight;
canvas.DrawBitmap(resizedBitmap, xPos, yPos);
}
}
return bitmap;
}
}
}