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309 lines
No EOL
12 KiB
C#
309 lines
No EOL
12 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) 2008-2014 ShareX Developers
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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.Drawing;
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using System.Drawing.Imaging;
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using System.Runtime.InteropServices;
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namespace HelpersLib
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{
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/// <summary>
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/// Summary description for Class1.
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/// </summary>
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public abstract class Quantizer
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{
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/// <summary>
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/// Construct the quantizer
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/// </summary>
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/// <param name="singlePass">If true, the quantization only needs to loop through the source pixels once</param>
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/// <remarks>
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/// If you construct this class with a true value for singlePass, then the code will, when quantizing your image,
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/// only call the 'QuantizeImage' function. If two passes are required, the code will call 'InitialQuantizeImage'
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/// and then 'QuantizeImage'.
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/// </remarks>
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protected Quantizer(bool singlePass)
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{
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_singlePass = singlePass;
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_pixelSize = Marshal.SizeOf(typeof(Color32));
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}
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/// <summary>
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/// Quantize an image and return the resulting output bitmap
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/// </summary>
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/// <param name="source">The image to quantize</param>
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/// <returns>A quantized version of the image</returns>
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public Bitmap Quantize(Image source)
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{
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// Get the size of the source image
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int height = source.Height;
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int width = source.Width;
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// And construct a rectangle from these dimensions
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Rectangle bounds = new Rectangle(0, 0, width, height);
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// First off take a 32bpp copy of the image
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Bitmap copy = new Bitmap(width, height, PixelFormat.Format32bppArgb);
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// And construct an 8bpp version
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Bitmap output = new Bitmap(width, height, PixelFormat.Format8bppIndexed);
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// Now lock the bitmap into memory
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using (Graphics g = Graphics.FromImage(copy))
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{
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g.PageUnit = GraphicsUnit.Pixel;
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// Draw the source image onto the copy bitmap,
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// which will effect a widening as appropriate.
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g.DrawImage(source, bounds);
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}
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// Define a pointer to the bitmap data
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BitmapData sourceData = null;
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try
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{
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// Get the source image bits and lock into memory
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sourceData = copy.LockBits(bounds, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
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// Call the FirstPass function if not a single pass algorithm.
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// For something like an octree quantizer, this will run through
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// all image pixels, build a data structure, and create a palette.
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if (!_singlePass)
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FirstPass(sourceData, width, height);
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// Then set the color palette on the output bitmap. I'm passing in the current palette
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// as there's no way to construct a new, empty palette.
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output.Palette = GetPalette(output.Palette);
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// Then call the second pass which actually does the conversion
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SecondPass(sourceData, output, width, height, bounds);
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}
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finally
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{
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// Ensure that the bits are unlocked
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copy.UnlockBits(sourceData);
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}
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// Last but not least, return the output bitmap
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return output;
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}
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/// <summary>
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/// Execute the first pass through the pixels in the image
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/// </summary>
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/// <param name="sourceData">The source data</param>
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/// <param name="width">The width in pixels of the image</param>
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/// <param name="height">The height in pixels of the image</param>
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protected virtual void FirstPass(BitmapData sourceData, int width, int height)
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{
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// Define the source data pointers. The source row is a byte to
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// keep addition of the stride value easier (as this is in bytes)
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IntPtr pSourceRow = sourceData.Scan0;
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// Loop through each row
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for (int row = 0; row < height; row++)
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{
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// Set the source pixel to the first pixel in this row
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IntPtr pSourcePixel = pSourceRow;
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// And loop through each column
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for (int col = 0; col < width; col++)
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{
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InitialQuantizePixel(new Color32(pSourcePixel));
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pSourcePixel = (IntPtr)((Int32)pSourcePixel + _pixelSize);
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} // Now I have the pixel, call the FirstPassQuantize function...
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// Add the stride to the source row
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pSourceRow = (IntPtr)((long)pSourceRow + sourceData.Stride);
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}
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}
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/// <summary>
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/// Execute a second pass through the bitmap
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/// </summary>
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/// <param name="sourceData">The source bitmap, locked into memory</param>
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/// <param name="output">The output bitmap</param>
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/// <param name="width">The width in pixels of the image</param>
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/// <param name="height">The height in pixels of the image</param>
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/// <param name="bounds">The bounding rectangle</param>
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protected virtual void SecondPass(BitmapData sourceData, Bitmap output, int width, int height, Rectangle bounds)
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{
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BitmapData outputData = null;
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try
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{
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// Lock the output bitmap into memory
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outputData = output.LockBits(bounds, ImageLockMode.WriteOnly, PixelFormat.Format8bppIndexed);
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// Define the source data pointers. The source row is a byte to
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// keep addition of the stride value easier (as this is in bytes)
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IntPtr pSourceRow = sourceData.Scan0;
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IntPtr pSourcePixel = pSourceRow;
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IntPtr pPreviousPixel = pSourcePixel;
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// Now define the destination data pointers
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IntPtr pDestinationRow = outputData.Scan0;
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IntPtr pDestinationPixel = pDestinationRow;
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// And convert the first pixel, so that I have values going into the loop
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byte pixelValue = QuantizePixel(new Color32(pSourcePixel));
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// Assign the value of the first pixel
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Marshal.WriteByte(pDestinationPixel, pixelValue);
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// Loop through each row
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for (int row = 0; row < height; row++)
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{
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// Set the source pixel to the first pixel in this row
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pSourcePixel = pSourceRow;
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// And set the destination pixel pointer to the first pixel in the row
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pDestinationPixel = pDestinationRow;
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// Loop through each pixel on this scan line
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for (int col = 0; col < width; col++)
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{
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// Check if this is the same as the last pixel. If so use that value
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// rather than calculating it again. This is an inexpensive optimisation.
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if (Marshal.ReadInt32(pPreviousPixel) != Marshal.ReadInt32(pSourcePixel))
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{
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// Quantize the pixel
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pixelValue = QuantizePixel(new Color32(pSourcePixel));
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// And setup the previous pointer
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pPreviousPixel = pSourcePixel;
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}
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// And set the pixel in the output
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Marshal.WriteByte(pDestinationPixel, pixelValue);
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pSourcePixel = (IntPtr)((long)pSourcePixel + _pixelSize);
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pDestinationPixel = (IntPtr)((long)pDestinationPixel + 1);
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}
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// Add the stride to the source row
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pSourceRow = (IntPtr)((long)pSourceRow + sourceData.Stride);
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// And to the destination row
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pDestinationRow = (IntPtr)((long)pDestinationRow + outputData.Stride);
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}
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}
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finally
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{
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// Ensure that I unlock the output bits
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output.UnlockBits(outputData);
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}
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}
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/// <summary>
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/// Override this to 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 virtual void InitialQuantizePixel(Color32 pixel)
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{
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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 abstract byte QuantizePixel(Color32 pixel);
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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 abstract ColorPalette GetPalette(ColorPalette original);
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/// <summary>
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/// Flag used to indicate whether a single pass or two passes are needed for quantization.
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/// </summary>
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private bool _singlePass;
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private int _pixelSize;
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/// <summary>
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/// Struct that defines a 32 bpp colour
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/// </summary>
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/// <remarks>
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/// This struct is used to read data from a 32 bits per pixel image
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/// in memory, and is ordered in this manner as this is the way that
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/// the data is layed out in memory
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/// </remarks>
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[StructLayout(LayoutKind.Explicit)]
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public struct Color32
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{
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public Color32(IntPtr pSourcePixel)
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{
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this = (Color32)Marshal.PtrToStructure(pSourcePixel, typeof(Color32));
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}
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/// <summary>
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/// Holds the blue component of the colour
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/// </summary>
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[FieldOffset(0)]
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public byte Blue;
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/// <summary>
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/// Holds the green component of the colour
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/// </summary>
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[FieldOffset(1)]
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public byte Green;
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/// <summary>
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/// Holds the red component of the colour
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/// </summary>
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[FieldOffset(2)]
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public byte Red;
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/// <summary>
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/// Holds the alpha component of the colour
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/// </summary>
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[FieldOffset(3)]
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public byte Alpha;
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/// <summary>
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/// Permits the color32 to be treated as an int32
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/// </summary>
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[FieldOffset(0)]
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public int ARGB;
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/// <summary>
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/// Return the color for this Color32 object
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/// </summary>
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public Color Color
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{
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get
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{
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return Color.FromArgb(Alpha, Red, Green, Blue);
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}
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}
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}
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}
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} |