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515 lines
No EOL
18 KiB
C#
515 lines
No EOL
18 KiB
C#
#region License Information (GPL v3)
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/*
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ShareX - A program that allows you to take screenshots and share any file type
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Copyright (c) 2007-2018 ShareX Team
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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Optionally you can also view the license at <http://www.gnu.org/licenses/>.
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*/
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#endregion License Information (GPL v3)
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using System;
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using System.Collections;
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using System.Drawing;
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using System.Drawing.Imaging;
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namespace ShareX.HelpersLib
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{
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/// <summary>
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/// Quantize using an Octree
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/// </summary>
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public class OctreeQuantizer : Quantizer
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{
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/// <summary>
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/// Construct the octree quantizer
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/// </summary>
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/// <remarks>
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/// The Octree quantizer is a two pass algorithm. The initial pass sets up the octree,
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/// the second pass quantizes a color based on the nodes in the tree
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/// </remarks>
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/// <param name="maxColors">The maximum number of colors to return</param>
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/// <param name="maxColorBits">The number of significant bits</param>
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public OctreeQuantizer(int maxColors, int maxColorBits)
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: base(false)
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{
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if (maxColors > 255)
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throw new ArgumentOutOfRangeException("maxColors", maxColors, "The number of colors should be less than 256");
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if ((maxColorBits < 1) | (maxColorBits > 8))
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throw new ArgumentOutOfRangeException("maxColorBits", maxColorBits, "This should be between 1 and 8");
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// Construct the octree
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_octree = new Octree(maxColorBits);
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_maxColors = maxColors;
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}
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/// <summary>
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/// Process the pixel in the first pass of the algorithm
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/// </summary>
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/// <param name="pixel">The pixel to quantize</param>
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/// <remarks>
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/// This function need only be overridden if your quantize algorithm needs two passes,
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/// such as an Octree quantizer.
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/// </remarks>
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protected override void InitialQuantizePixel(Color32 pixel)
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{
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// Add the color to the octree
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_octree.AddColor(pixel);
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}
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/// <summary>
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/// Override this to process the pixel in the second pass of the algorithm
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/// </summary>
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/// <param name="pixel">The pixel to quantize</param>
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/// <returns>The quantized value</returns>
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protected override byte QuantizePixel(Color32 pixel)
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{
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byte paletteIndex = (byte)_maxColors; // The color at [_maxColors] is set to transparent
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// Get the palette index if this non-transparent
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if (pixel.Alpha > 0)
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paletteIndex = (byte)_octree.GetPaletteIndex(pixel);
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return paletteIndex;
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}
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/// <summary>
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/// Retrieve the palette for the quantized image
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/// </summary>
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/// <param name="original">Any old palette, this is overrwritten</param>
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/// <returns>The new color palette</returns>
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protected override ColorPalette GetPalette(ColorPalette original)
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{
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// First off convert the octree to _maxColors colors
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ArrayList palette = _octree.Palletize(_maxColors - 1);
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// Then convert the palette based on those colors
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for (int index = 0; index < palette.Count; index++)
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original.Entries[index] = (Color)palette[index];
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// Add the transparent color
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original.Entries[_maxColors] = Color.FromArgb(0, 0, 0, 0);
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return original;
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}
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/// <summary>
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/// Stores the tree
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/// </summary>
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private Octree _octree;
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/// <summary>
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/// Maximum allowed color depth
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/// </summary>
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private int _maxColors;
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/// <summary>
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/// Class which does the actual quantization
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/// </summary>
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private class Octree
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{
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/// <summary>
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/// Construct the octree
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/// </summary>
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/// <param name="maxColorBits">The maximum number of significant bits in the image</param>
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public Octree(int maxColorBits)
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{
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_maxColorBits = maxColorBits;
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_leafCount = 0;
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_reducibleNodes = new OctreeNode[9];
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_root = new OctreeNode(0, _maxColorBits, this);
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_previousColor = 0;
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_previousNode = null;
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}
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/// <summary>
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/// Add a given color value to the octree
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/// </summary>
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/// <param name="pixel"></param>
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public void AddColor(Color32 pixel)
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{
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// Check if this request is for the same color as the last
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if (_previousColor == pixel.ARGB)
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{
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// If so, check if I have a previous node setup. This will only ocurr if the first color in the image
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// happens to be black, with an alpha component of zero.
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if (_previousNode == null)
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{
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_previousColor = pixel.ARGB;
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_root.AddColor(pixel, _maxColorBits, 0, this);
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}
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else
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{
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// Just update the previous node
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_previousNode.Increment(pixel);
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}
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}
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else
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{
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_previousColor = pixel.ARGB;
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_root.AddColor(pixel, _maxColorBits, 0, this);
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}
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}
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/// <summary>
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/// Reduce the depth of the tree
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/// </summary>
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public void Reduce()
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{
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int index = _maxColorBits - 1;
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// Find the deepest level containing at least one reducible node
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while (index > 0 && _reducibleNodes[index] == null)
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{
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index--;
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}
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// Reduce the node most recently added to the list at level 'index'
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OctreeNode node = _reducibleNodes[index];
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_reducibleNodes[index] = node.NextReducible;
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// Decrement the leaf count after reducing the node
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_leafCount -= node.Reduce();
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// And just in case I've reduced the last color to be added, and the next color to
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// be added is the same, invalidate the previousNode...
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_previousNode = null;
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}
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/// <summary>
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/// Get/Set the number of leaves in the tree
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/// </summary>
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public int Leaves
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{
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get
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{
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return _leafCount;
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}
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set
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{
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_leafCount = value;
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}
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}
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/// <summary>
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/// Return the array of reducible nodes
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/// </summary>
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protected OctreeNode[] ReducibleNodes
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{
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get
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{
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return _reducibleNodes;
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}
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}
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/// <summary>
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/// Keep track of the previous node that was quantized
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/// </summary>
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/// <param name="node">The node last quantized</param>
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protected void TrackPrevious(OctreeNode node)
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{
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_previousNode = node;
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}
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/// <summary>
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/// Convert the nodes in the octree to a palette with a maximum of colorCount colors
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/// </summary>
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/// <param name="colorCount">The maximum number of colors</param>
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/// <returns>An arraylist with the palettized colors</returns>
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public ArrayList Palletize(int colorCount)
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{
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while (Leaves > colorCount)
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Reduce();
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// Now palettize the nodes
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ArrayList palette = new ArrayList(Leaves);
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int paletteIndex = 0;
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_root.ConstructPalette(palette, ref paletteIndex);
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// And return the palette
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return palette;
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}
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/// <summary>
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/// Get the palette index for the passed color
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/// </summary>
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/// <param name="pixel"></param>
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/// <returns></returns>
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public int GetPaletteIndex(Color32 pixel)
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{
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return _root.GetPaletteIndex(pixel, 0);
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}
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/// <summary>
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/// Mask used when getting the appropriate pixels for a given node
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/// </summary>
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private static int[] mask = new int[] { 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01 };
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/// <summary>
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/// The root of the octree
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/// </summary>
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private OctreeNode _root;
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/// <summary>
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/// Number of leaves in the tree
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/// </summary>
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private int _leafCount;
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/// <summary>
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/// Array of reducible nodes
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/// </summary>
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private OctreeNode[] _reducibleNodes;
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/// <summary>
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/// Maximum number of significant bits in the image
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/// </summary>
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private int _maxColorBits;
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/// <summary>
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/// Store the last node quantized
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/// </summary>
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private OctreeNode _previousNode;
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/// <summary>
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/// Cache the previous color quantized
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/// </summary>
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private int _previousColor;
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/// <summary>
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/// Class which encapsulates each node in the tree
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/// </summary>
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protected class OctreeNode
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{
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/// <summary>
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/// Construct the node
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/// </summary>
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/// <param name="level">The level in the tree = 0 - 7</param>
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/// <param name="colorBits">The number of significant color bits in the image</param>
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/// <param name="octree">The tree to which this node belongs</param>
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public OctreeNode(int level, int colorBits, Octree octree)
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{
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// Construct the new node
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_leaf = (level == colorBits);
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_red = _green = _blue = 0;
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_pixelCount = 0;
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// If a leaf, increment the leaf count
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if (_leaf)
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{
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octree.Leaves++;
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NextReducible = null;
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_children = null;
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}
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else
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{
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// Otherwise add this to the reducible nodes
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NextReducible = octree.ReducibleNodes[level];
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octree.ReducibleNodes[level] = this;
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_children = new OctreeNode[8];
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}
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}
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/// <summary>
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/// Add a color into the tree
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/// </summary>
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/// <param name="pixel">The color</param>
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/// <param name="colorBits">The number of significant color bits</param>
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/// <param name="level">The level in the tree</param>
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/// <param name="octree">The tree to which this node belongs</param>
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public void AddColor(Color32 pixel, int colorBits, int level, Octree octree)
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{
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// Update the color information if this is a leaf
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if (_leaf)
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{
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Increment(pixel);
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// Setup the previous node
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octree.TrackPrevious(this);
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}
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else
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{
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// Go to the next level down in the tree
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int shift = 7 - level;
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int index = ((pixel.Red & mask[level]) >> (shift - 2)) |
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((pixel.Green & mask[level]) >> (shift - 1)) |
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((pixel.Blue & mask[level]) >> (shift));
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OctreeNode child = _children[index];
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if (child == null)
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{
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// Create a new child node & store in the array
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child = new OctreeNode(level + 1, colorBits, octree);
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_children[index] = child;
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}
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// Add the color to the child node
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child.AddColor(pixel, colorBits, level + 1, octree);
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}
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}
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/// <summary>
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/// Get/Set the next reducible node
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/// </summary>
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public OctreeNode NextReducible { get; set; }
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/// <summary>
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/// Return the child nodes
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/// </summary>
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public OctreeNode[] Children
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{
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get
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{
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return _children;
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}
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}
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/// <summary>
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/// Reduce this node by removing all of its children
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/// </summary>
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/// <returns>The number of leaves removed</returns>
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public int Reduce()
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{
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_red = _green = _blue = 0;
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int children = 0;
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// Loop through all children and add their information to this node
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for (int index = 0; index < 8; index++)
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{
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if (_children[index] != null)
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{
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_red += _children[index]._red;
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_green += _children[index]._green;
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_blue += _children[index]._blue;
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_pixelCount += _children[index]._pixelCount;
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++children;
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_children[index] = null;
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}
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}
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// Now change this to a leaf node
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_leaf = true;
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// Return the number of nodes to decrement the leaf count by
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return children - 1;
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}
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/// <summary>
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/// Traverse the tree, building up the color palette
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/// </summary>
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/// <param name="palette">The palette</param>
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/// <param name="paletteIndex">The current palette index</param>
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public void ConstructPalette(ArrayList palette, ref int paletteIndex)
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{
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if (_leaf)
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{
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// Consume the next palette index
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_paletteIndex = paletteIndex++;
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// And set the color of the palette entry
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palette.Add(Color.FromArgb(_red / _pixelCount, _green / _pixelCount, _blue / _pixelCount));
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}
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else
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{
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// Loop through children looking for leaves
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for (int index = 0; index < 8; index++)
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{
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if (_children[index] != null)
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{
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_children[index].ConstructPalette(palette, ref paletteIndex);
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}
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}
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}
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}
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/// <summary>
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/// Return the palette index for the passed color
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/// </summary>
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public int GetPaletteIndex(Color32 pixel, int level)
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{
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int paletteIndex = _paletteIndex;
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if (!_leaf)
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{
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int shift = 7 - level;
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int index = ((pixel.Red & mask[level]) >> (shift - 2)) |
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((pixel.Green & mask[level]) >> (shift - 1)) |
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((pixel.Blue & mask[level]) >> (shift));
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if (_children[index] != null)
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{
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paletteIndex = _children[index].GetPaletteIndex(pixel, level + 1);
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}
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else
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{
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throw new Exception("Didn't expect this!");
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}
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}
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return paletteIndex;
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}
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/// <summary>
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/// Increment the pixel count and add to the color information
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/// </summary>
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public void Increment(Color32 pixel)
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{
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_pixelCount++;
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_red += pixel.Red;
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_green += pixel.Green;
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_blue += pixel.Blue;
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}
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/// <summary>
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/// Flag indicating that this is a leaf node
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/// </summary>
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private bool _leaf;
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/// <summary>
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/// Number of pixels in this node
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/// </summary>
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private int _pixelCount;
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/// <summary>
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/// Red component
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/// </summary>
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private int _red;
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/// <summary>
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/// Green Component
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/// </summary>
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private int _green;
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/// <summary>
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/// Blue component
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/// </summary>
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private int _blue;
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/// <summary>
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/// Pointers to any child nodes
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/// </summary>
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private OctreeNode[] _children;
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/// <summary>
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/// The index of this node in the palette
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/// </summary>
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private int _paletteIndex;
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}
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}
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}
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} |