71 lines
2.1 KiB
C#
71 lines
2.1 KiB
C#
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using System;
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using System.Runtime.InteropServices;
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using NetVips.Internal;
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namespace NetVips;
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/// <summary>
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/// Wrap a <see cref="VipsRegion"/> object.
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/// </summary>
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/// <remarks>
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/// A region is a small part of an image. You use regions to read pixels
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/// out of images without storing the entire image in memory.
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/// At least libvips 8.8 is needed.
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/// </remarks>
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public class Region : VipsObject
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{
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private Region(nint pointer) : base(pointer)
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{
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}
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/// <summary>
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/// Make a region on an image.
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/// </summary>
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/// <param name="image"><see cref="Image"/> to create this region on.</param>
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/// <returns>A new <see cref="Region"/>.</returns>
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/// <exception cref="VipsException">If unable to make a new region on <paramref name="image"/>.</exception>
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public static Region New(Image image)
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{
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var vi = VipsRegion.New(image);
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if (vi == IntPtr.Zero)
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{
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throw new VipsException("unable to make region");
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}
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return new Region(vi);
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}
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/// <summary>
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/// Width of pixels held by region.
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/// </summary>
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public int Width => VipsRegion.Width(this);
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/// <summary>
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/// Height of pixels held by region.
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/// </summary>
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public int Height => VipsRegion.Height(this);
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/// <summary>
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/// Fetch an area of pixels.
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/// </summary>
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/// <param name="left">Left edge of area to fetch.</param>
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/// <param name="top">Top edge of area to fetch.</param>
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/// <param name="width">Width of area to fetch.</param>
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/// <param name="height">Height of area to fetch.</param>
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/// <returns>An array of bytes filled with pixel data.</returns>
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public byte[] Fetch(int left, int top, int width, int height)
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{
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var pointer = VipsRegion.Fetch(this, left, top, width, height, out var size);
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if (pointer == IntPtr.Zero)
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{
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throw new VipsException("unable to fetch from region");
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}
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var managedArray = new byte[size];
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Marshal.Copy(pointer, managedArray, 0, (int)size);
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GLib.GFree(pointer);
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return managedArray;
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}
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}
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