private static Image <Bgra32> GenerateThumbnail(OpenSlideImage image, int maxWidth, int maxHeight)
{
if (image == null)
{
throw new ArgumentNullException(nameof(image));
}
(long width, long height) = image.Dimensions;
// 决定合适的level
double downsampleWidth = width / (double)maxWidth;
double downsampleHeight = height / (double)maxHeight;
double downsample = Math.Max(downsampleWidth, downsampleHeight);
int level = image.GetBestLevelForDownsample(downsample);
(long levelWidth, long levelHeight) = image.GetLevelDimensions(level);
// 计算目标大小
int targetWidth, targetHeight;
if (downsampleWidth > downsampleHeight)
{
// width缩小较大，将maxWidth作为标准
targetWidth = maxWidth;
targetHeight = (int)(height / downsampleWidth);
}
else
{
// height缩小较大，将maxHeight作为标准
targetWidth = (int)(width / downsampleHeight);
targetHeight = maxHeight;
}
Image <Bgra32> output;
checked
{
output = new Image <Bgra32>((int)levelWidth, (int)levelHeight);
}
output.Mutate(ctx =>
{
ctx.Apply(img =>
{
var frame = img.Frames.RootFrame;
image.DangerousReadRegion(
level, 0, 0, levelWidth, levelHeight,
ref Unsafe.As <Bgra32, byte>(ref frame.DangerousGetPinnableReferenceToPixelBuffer()));
});
ctx.Resize(targetWidth, targetHeight);
});
return(output);
}
/// <summary>
/// Initialize a <see cref="DeepZoomGenerator"/> instance with the specified parameters.
/// </summary>
/// <param name="image">The OpenSlide image.</param>
/// <param name="tileSize">The tile size paramter.</param>
/// <param name="overlap">The overlap paramter.</param>
/// <param name="limitBounds">Whether image bounds should be respected.</param>
/// <param name="disposeImage">Whether the OpenSlide image instance should be disposed when this <see cref="DeepZoomGenerator"/> instance is disposed.</param>
public DeepZoomGenerator(OpenSlideImage image, int tileSize = 254, int overlap = 1, bool limitBounds = true, bool disposeImage = false)
{
_image = image ?? throw new ArgumentNullException(nameof(image));
_disposeImage = disposeImage;
long width, height;
if (limitBounds)
{
_boundX = image.BoundsX ?? 0;
_boundY = image.BoundsY ?? 0;
_width = width = image.BoundsWidth ?? image.Width;
_height = height = image.BoundsHeight ?? image.Height;
}
else
{
_boundX = 0;
_boundY = 0;
_width = width = image.Width;
_height = height = image.Height;
}
DeepZoomLayer[] dzLayers = DeepZoomHelper.CalculateDeepZoomLayers(width, height);
DeepZoomLayerInformation[] layers = new DeepZoomLayerInformation[dzLayers.Length];
for (int i = 0; i < layers.Length; i++)
{
DeepZoomLayer dzLayer = dzLayers[i];
int layerDownsample = 1 << (dzLayers.Length - i - 1);
int level = image.GetBestLevelForDownsample(layerDownsample);
(long levelWidth, long levelHeight) = image.GetLevelDimensions(level);
layers[i] = new DeepZoomLayerInformation
{
Level = level,
LevelDownsample = image.GetLevelDownsample(level),
LevelWidth = levelWidth,
LevelHeight = levelHeight,
LayerDownsample = layerDownsample,
LayerWidth = dzLayer.Width,
LayerHeight = dzLayer.Height
};
}
_layers = layers;
_tileSize = tileSize;
_overlap = overlap;
}
private static Image <Bgra32> GenerateThumbnail(OpenSlideImage image, int maxWidth, int maxHeight)
{
if (image == null)
{
throw new ArgumentNullException(nameof(image));
}
(long width, long height) = image.Dimensions;
// Find the appropriate level
double downsampleWidth = width / (double)maxWidth;
double downsampleHeight = height / (double)maxHeight;
double downsample = Math.Max(downsampleWidth, downsampleHeight);
int level = image.GetBestLevelForDownsample(downsample);
(long levelWidth, long levelHeight) = image.GetLevelDimensions(level);
// Calculate target size
int targetWidth, targetHeight;
if (downsampleWidth > downsampleHeight)
{
targetWidth = maxWidth;
targetHeight = (int)(height / downsampleWidth);
}
else
{
targetWidth = (int)(width / downsampleHeight);
targetHeight = maxHeight;
}
using Bgra32ImageBuffer buffer = image.ReadImageBuffer(level, 0, 0, levelWidth, levelHeight);
return(buffer.GetImage().Clone(ctx =>
{
ctx.Resize(targetWidth, targetHeight);
}));
}