问题
i had a C++ .exe i was using as a standalone image cleaner. But i now want to use its fonction into my own c# app, so i started to translate it. But i REALLY TOTALLY know nothing about C++ and its logic. So i come here for some help.
First, does anyone know any equivalent for this function? Corona "getPixels()" (yes with an "s" because i know c# have a built-in getPixel) : here is the function explaination from corona doc : getPixels() Corona dll it is used in the lines i am looking to translate.
here is all the thing:
original C++ code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "corona.h"
#define IMAGE_FORMAT corona::PF_R8G8B8 /* RGB mode - 8 bits each */
#define GetXY(x,y, w) ((x) + ((w) * (y)))
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define SQ(a) ((a) * (a))
#define DISTANCE(a, b, c, d) (SQ(a - c) + SQ(b - d))
int main(int argc, char **argv)
{
corona::Image *img;
unsigned char *pixels;
int threshold = 0;
int distance = 0;
int pixel;
char str[255];
int rows, cols;
int row, col;
unsigned char *bitmap, *p;
unsigned char *outmap;
pixels = (unsigned char*)img->getPixels();
rows = img->getHeight();
cols = img->getWidth();
bitmap = new unsigned char[rows * cols];
p = bitmap;
outmap = new unsigned char[rows * cols];
//convert to single byte grayscale
for (row = 0; row < rows; row++)
for (col = 0; col < cols; col++)
{
pixel = *pixels++;
pixel += *pixels++;
pixel += *pixels++;
*p++ = pixel / 3;
}
//free corona loading
delete img;
int distance = 8;
int threshold = 7;
//check our threshold
for (row = 0; row < rows; row++)
for (col = 0; col < cols; col++)
{
if (bitmap[GetXY(col, row, cols)])
{
int count = 0;
int x, y;
int dhalf = distance / 2 + 1;
//optimization possible here by checking inside a circle rather than square+dist
for (x = MAX(col - dhalf, 0); x < MIN(col + dhalf, cols); x++)
for (y = MAX(row - dhalf, 0); y < MIN(row + dhalf, rows); y++)
{
if (SQ(distance) > DISTANCE(col, row, x, y) && bitmap[GetXY(x, y, cols)])
count++;
}
if (count >= threshold)
outmap[GetXY(col, row, cols)] = 255;
else
outmap[GetXY(col, row, cols)] = 0;
}
else
outmap[GetXY(col, row, cols)] = 0;
}
}
What i have now with what i could translate... i hope correctly at least...:
private Bitmap optIm2(Bitmap _img)
{
int rows = _img.Height;
int cols = _img.Width;
pixels = (unsigned char)img->getPixels(); //here i dont know at all
bitmap = new unsigned char[rows * cols]; //here i dont know at all
p = bitmap;
outmap = new unsigned char[rows * cols]; //here i dont know at all
//convert to single byte grayscale
for (int row = 0; row < rows; row++)
{
for (int col = 0; col < cols; col++)
{
pixel = *pixels++; //here i dont know at all
pixel += *pixels++; //here i dont know at all
pixel += *pixels++; //here i dont know at all
*p++ = pixel / 3; //here i dont know at all
}
}
//free corona loading
delete img;
int distance = 9;
int threshold = 7;
//check our threshold
for (int row = 0; row < rows; row++)
{
for (int col = 0; col < cols; col++)
{
if (bitmap[GetXY(col, row, cols)])
{
int count = 0;
int x, y;
int dhalf = distance / 2 + 1;
//optimization possible here by checking inside a circle rather than square+dist
for (x = Math.Max(col - dhalf, 0); x < Math.Min(col + dhalf, cols); x++)
{
for (y = Math.Max(row - dhalf, 0); y < Math.Min(row + dhalf, rows); y++)
{
if (SQ(distance) > DISTANCE(col, row, x, y) && bitmap[GetXY(x, y, cols)])
count++;
}
}
if (count >= threshold)
{
outmap[GetXY(col, row, cols)] = 255;
}
else
{
outmap[GetXY(col, row, cols)] = 0;
}
}
else
{
outmap[GetXY(col, row, cols)] = 0;
}
}
}
return iDontKnowWhatYet;
}
private int GetXY(int x,int y, int w) { return ((x) + ((w) * (y))); }
private int SQ(int a) { return ((a) * (a)); }
private int DISTANCE(int a, int b, int c, int d) { return (SQ(a - c) + SQ(b - d)); }
Could anyone help me understand and convert this please?
回答1:
The C# code will look something like this
private unsafe Bitmap optIm2(Bitmap img)
{
int rows = img.Height;
int cols = img.Width;
var dstImg = new Bitmap(cols, rows, img.PixelFormat);
var srcImageData = img.LockBits(new Rectangle(0, 0, cols, rows), System.Drawing.Imaging.ImageLockMode.ReadOnly, img.PixelFormat);
var dstImageData = dstImg.LockBits(new Rectangle(0, 0, cols, rows), System.Drawing.Imaging.ImageLockMode.ReadOnly, dstImg.PixelFormat);
try
{
var bitmap = new byte[rows * cols];
var outmap = new byte[rows * cols];
fixed (byte* ptr = &bitmap[0])
{
byte* pixels = (byte*)srcImageData.Scan0;
byte* p = ptr;
//convert to single byte grayscale
for (int row = 0; row < rows; row++)
{
for (int col = 0; col < cols; col++)
{
var pixel = *pixels++;
pixel += *pixels++;
pixel += *pixels++;
*p++ = (byte)(pixel / 3); //here i dont know at all
}
}
}
int distance = 9;
int threshold = 7;
//check our threshold
for (int row = 0; row < rows; row++)
{
for (int col = 0; col < cols; col++)
{
if (bitmap[GetXY(col, row, cols)] != 0)
{
int count = 0;
int x, y;
int dhalf = distance / 2 + 1;
//optimization possible here by checking inside a circle rather than square+dist
for (x = Math.Max(col - dhalf, 0); x < Math.Min(col + dhalf, cols); x++)
{
for (y = Math.Max(row - dhalf, 0); y < Math.Min(row + dhalf, rows); y++)
if ((SQ(distance) > DISTANCE(col, row, x, y)) && (bitmap[GetXY(x, y, cols)] != 0))
count++;
}
if (count >= threshold)
outmap[GetXY(col, row, cols)] = 255;
else
outmap[GetXY(col, row, cols)] = 0;
}
else
outmap[GetXY(col, row, cols)] = 0;
}
}
// Copy data from outmap to pixels of bitmap. Since outmap is grayscale data, we replicate it for all channels
byte* dstPtr = (byte*)dstImageData.Scan0;
for (int row = 0; row < rows; row++)
{
byte* rowPtr = dstPtr;
for (int col = 0; col < cols; col++)
{
*rowPtr++ = outmap[GetXY(col, row, cols)];
*rowPtr++ = outmap[GetXY(col, row, cols)];
*rowPtr++ = outmap[GetXY(col, row, cols)];
}
dstPtr += dstImageData.Stride;
}
}
finally
{
img.UnlockBits(srcImageData);
img.Dispose();
dstImg.UnlockBits(dstImageData);
}
return dstImg;
}
private int GetXY(int x, int y, int w) { return ((x) + ((w) * (y))); }
private int SQ(int a) { return ((a) * (a)); }
private int DISTANCE(int a, int b, int c, int d) { return (SQ(a - c) + SQ(b - d)); }
While I haven't checked your actual logic for the correct algorithm, the code above contains all the bits you need to do that yourself. The main points to note are:
- How to get a pointer from an IntPtr (fixed)
- How to get pixel data from a bitmap
- How to write pixel data back to a bitmap
Hope this helps!
来源：https://stackoverflow.com/questions/29526246/translating-a-c-dealing-with-corona-function-into-c-sharp