/// <summary>
/// Rotates the bitmap in any degree returns a new rotated WriteableBitmap.
/// </summary>
/// <param name="bmp">The WriteableBitmap.</param>
/// <param name="angle">Arbitrary angle in 360 Degrees (positive = clockwise).</param>
/// <param name="crop">if true: keep the size, false: adjust canvas to new size</param>
/// <returns>A new WriteableBitmap that is a rotated version of the input.</returns>
public static unsafe BitmapBuffer RotateFree(this BitmapBuffer bmp, double angle, bool crop = true)
{
// rotating clockwise, so it's negative relative to Cartesian quadrants
double cnAngle = -1.0 * (Math.PI / 180) * angle;
// general iterators
int i, j;
// calculated indices in Cartesian coordinates
int x, y;
double fDistance, fPolarAngle;
// for use in neighboring indices in Cartesian coordinates
int iFloorX, iCeilingX, iFloorY, iCeilingY;
// calculated indices in Cartesian coordinates with trailing decimals
double fTrueX, fTrueY;
// for interpolation
double fDeltaX, fDeltaY;
// interpolated "top" pixels
double fTopRed, fTopGreen, fTopBlue, fTopAlpha;
// interpolated "bottom" pixels
double fBottomRed, fBottomGreen, fBottomBlue, fBottomAlpha;
// final interpolated color components
int iRed, iGreen, iBlue, iAlpha;
int iCentreX, iCentreY;
int iDestCentreX, iDestCentreY;
int iWidth, iHeight, newWidth, newHeight;
using (var bmpContext = bmp.GetBitmapContext(ReadWriteMode.ReadOnly))
{
iWidth = bmpContext.Width;
iHeight = bmpContext.Height;
if (crop)
{
newWidth = iWidth;
newHeight = iHeight;
}
else
{
double rad = angle / (180 / Math.PI);
newWidth = (int)Math.Ceiling(Math.Abs(Math.Sin(rad) * iHeight) + Math.Abs(Math.Cos(rad) * iWidth));
newHeight = (int)Math.Ceiling(Math.Abs(Math.Sin(rad) * iWidth) + Math.Abs(Math.Cos(rad) * iHeight));
}
iCentreX = iWidth / 2;
iCentreY = iHeight / 2;
iDestCentreX = newWidth / 2;
iDestCentreY = newHeight / 2;
BitmapBuffer bmBilinearInterpolation = BitmapBufferFactory.New(newWidth, newHeight);
using (BitmapContext bilinearContext = bmBilinearInterpolation.GetBitmapContext())
{
int *newp = bilinearContext.Pixels._inf32Buffer;
int *oldp = bmpContext.Pixels._inf32Buffer;
//
int oldw = bmpContext.Width;
// assigning pixels of destination image from source image
// with bilinear interpolation
for (i = 0; i < newHeight; ++i)
{
for (j = 0; j < newWidth; ++j)
{
// convert raster to Cartesian
x = j - iDestCentreX;
y = iDestCentreY - i;
// convert Cartesian to polar
fDistance = Math.Sqrt(x * x + y * y);
if (x == 0)
{
if (y == 0)
{
// center of image, no rotation needed
newp[i * newWidth + j] = oldp[iCentreY * oldw + iCentreX];
continue;
}
if (y < 0)
{
fPolarAngle = 1.5 * Math.PI;
}
else
{
fPolarAngle = 0.5 * Math.PI;
}
}
else
{
fPolarAngle = Math.Atan2(y, x);
}
// the crucial rotation part
// "reverse" rotate, so minus instead of plus
fPolarAngle -= cnAngle;
// convert polar to Cartesian
fTrueX = fDistance * Math.Cos(fPolarAngle);
fTrueY = fDistance * Math.Sin(fPolarAngle);
// convert Cartesian to raster
fTrueX = fTrueX + iCentreX;
fTrueY = iCentreY - fTrueY;
iFloorX = (int)(Math.Floor(fTrueX));
iFloorY = (int)(Math.Floor(fTrueY));
iCeilingX = (int)(Math.Ceiling(fTrueX));
iCeilingY = (int)(Math.Ceiling(fTrueY));
// check bounds
if (iFloorX < 0 || iCeilingX < 0 || iFloorX >= iWidth || iCeilingX >= iWidth || iFloorY < 0 ||
iCeilingY < 0 || iFloorY >= iHeight || iCeilingY >= iHeight)
{
continue;
}
fDeltaX = fTrueX - iFloorX;
fDeltaY = fTrueY - iFloorY;
int clrTopLeft = oldp[iFloorY * oldw + iFloorX];
int clrTopRight = oldp[iFloorY * oldw + iCeilingX];
int clrBottomLeft = oldp[iCeilingY * oldw + iFloorX];
int clrBottomRight = oldp[iCeilingY * oldw + iCeilingX];
fTopAlpha = (1 - fDeltaX) * ((clrTopLeft >> 24) & 0xFF) + fDeltaX * ((clrTopRight >> 24) & 0xFF);
fTopRed = (1 - fDeltaX) * ((clrTopLeft >> 16) & 0xFF) + fDeltaX * ((clrTopRight >> 16) & 0xFF);
fTopGreen = (1 - fDeltaX) * ((clrTopLeft >> 8) & 0xFF) + fDeltaX * ((clrTopRight >> 8) & 0xFF);
fTopBlue = (1 - fDeltaX) * (clrTopLeft & 0xFF) + fDeltaX * (clrTopRight & 0xFF);
// linearly interpolate horizontally between bottom neighbors
fBottomAlpha = (1 - fDeltaX) * ((clrBottomLeft >> 24) & 0xFF) + fDeltaX * ((clrBottomRight >> 24) & 0xFF);
fBottomRed = (1 - fDeltaX) * ((clrBottomLeft >> 16) & 0xFF) + fDeltaX * ((clrBottomRight >> 16) & 0xFF);
fBottomGreen = (1 - fDeltaX) * ((clrBottomLeft >> 8) & 0xFF) + fDeltaX * ((clrBottomRight >> 8) & 0xFF);
fBottomBlue = (1 - fDeltaX) * (clrBottomLeft & 0xFF) + fDeltaX * (clrBottomRight & 0xFF);
// linearly interpolate vertically between top and bottom interpolated results
iRed = (int)(Math.Round((1 - fDeltaY) * fTopRed + fDeltaY * fBottomRed));
iGreen = (int)(Math.Round((1 - fDeltaY) * fTopGreen + fDeltaY * fBottomGreen));
iBlue = (int)(Math.Round((1 - fDeltaY) * fTopBlue + fDeltaY * fBottomBlue));
iAlpha = (int)(Math.Round((1 - fDeltaY) * fTopAlpha + fDeltaY * fBottomAlpha));
// make sure color values are valid
if (iRed < 0)
{
iRed = 0;
}
if (iRed > 255)
{
iRed = 255;
}
if (iGreen < 0)
{
iGreen = 0;
}
if (iGreen > 255)
{
iGreen = 255;
}
if (iBlue < 0)
{
iBlue = 0;
}
if (iBlue > 255)
{
iBlue = 255;
}
if (iAlpha < 0)
{
iAlpha = 0;
}
if (iAlpha > 255)
{
iAlpha = 255;
}
int a = iAlpha + 1;
newp[i * newWidth + j] = (iAlpha << 24)
| ((byte)((iRed * a) >> 8) << 16)
| ((byte)((iGreen * a) >> 8) << 8)
| ((byte)((iBlue * a) >> 8));
}
}
return(bmBilinearInterpolation);
}
}
}
/// <summary>
/// Rotates the bitmap in 90° steps clockwise and returns a new rotated WriteableBitmap.
/// </summary>
/// <param name="bmp">The WriteableBitmap.</param>
/// <param name="angle">The angle in degrees the bitmap should be rotated in 90° steps clockwise.</param>
/// <returns>A new WriteableBitmap that is a rotated version of the input.</returns>
public static unsafe BitmapBuffer Rotate(this BitmapBuffer bmp, FastRotateAngle angle)
{
using (BitmapContext context = bmp.GetBitmapContext(ReadWriteMode.ReadOnly))
{
// Use refs for faster access (really important!) speeds up a lot!
int w = context.Width;
int h = context.Height;
int *p = context.Pixels._inf32Buffer;
int i = 0;
switch (angle)
{
default:
{
return(bmp.Clone());
}
case FastRotateAngle.Rotate90:
{
BitmapBuffer result = BitmapBufferFactory.New(h, w);
using (BitmapContext destContext = result.GetBitmapContext())
{
int *rp = destContext.Pixels._inf32Buffer;
for (int x = 0; x < w; x++)
{
for (int y = h - 1; y >= 0; y--)
{
int srcInd = y * w + x;
rp[i] = p[srcInd];
i++;
}
}
}
return(result);
}
case FastRotateAngle.Rotate180:
{
BitmapBuffer result = BitmapBufferFactory.New(w, h);
using (BitmapContext destContext = result.GetBitmapContext())
{
int *rp = destContext.Pixels._inf32Buffer;
for (int y = h - 1; y >= 0; y--)
{
for (int x = w - 1; x >= 0; x--)
{
int srcInd = y * w + x;
rp[i] = p[srcInd];
i++;
}
}
}
return(result);
}
case FastRotateAngle.Rotate270:
{
var result = BitmapBufferFactory.New(h, w);
using (BitmapContext destContext = result.GetBitmapContext())
{
int *rp = destContext.Pixels._inf32Buffer;
for (int x = w - 1; x >= 0; x--)
{
for (int y = 0; y < h; y++)
{
int srcInd = y * w + x;
rp[i] = p[srcInd];
i++;
}
}
}
return(result);
}
}
}
}
