/// <summary> /// Implements bicubic filtering with bounds checking at every pixel. /// </summary> private unsafe void BicubicFitSurfaceChecked(Surface source, Rectangle dstRoi) { Rectangle roi = Rectangle.Intersect(dstRoi, this.Bounds); Rectangle roiIn = Rectangle.Intersect(dstRoi, new Rectangle(1, 1, width - 1, height - 1)); IntPtr rColCacheIP = Memory.Allocate(4 * (ulong)roi.Width * (ulong)sizeof(double)); double *rColCache = (double *)rColCacheIP.ToPointer(); // Precompute and then cache the value of R() for each column for (int dstX = roi.Left; dstX < roi.Right; ++dstX) { double srcColumn = (double)(dstX * (source.width - 1)) / (double)(width - 1); double srcColumnFloor = Math.Floor(srcColumn); double srcColumnFrac = srcColumn - srcColumnFloor; for (int m = -1; m <= 2; ++m) { int index = (m + 1) + ((dstX - roi.Left) * 4); double x = m - srcColumnFrac; rColCache[index] = R(x); } } // Set this up so we can cache the R()'s for every row double *rRowCache = stackalloc double[4]; for (int dstY = roi.Top; dstY < roi.Bottom; ++dstY) { double srcRow = (double)(dstY * (source.height - 1)) / (double)(height - 1); double srcRowFloor = (double)Math.Floor(srcRow); double srcRowFrac = srcRow - srcRowFloor; int srcRowInt = (int)srcRow; ColorBgra *dstPtr = this.GetPointAddressUnchecked(roi.Left, dstY); // Compute the R() values for this row for (int n = -1; n <= 2; ++n) { double x = srcRowFrac - n; rRowCache[n + 1] = R(x); } // See Perf Note below //int nFirst = Math.Max(-srcRowInt, -1); //int nLast = Math.Min(source.height - srcRowInt - 1, 2); for (int dstX = roi.Left; dstX < roi.Right; dstX++) { double srcColumn = (double)(dstX * (source.width - 1)) / (double)(width - 1); double srcColumnFloor = Math.Floor(srcColumn); double srcColumnFrac = srcColumn - srcColumnFloor; int srcColumnInt = (int)srcColumn; double blueSum = 0; double greenSum = 0; double redSum = 0; double alphaSum = 0; double totalWeight = 0; // See Perf Note below //int mFirst = Math.Max(-srcColumnInt, -1); //int mLast = Math.Min(source.width - srcColumnInt - 1, 2); ColorBgra *srcPtr = source.GetPointAddressUnchecked(srcColumnInt - 1, srcRowInt - 1); for (int n = -1; n <= 2; ++n) { int srcY = srcRowInt + n; for (int m = -1; m <= 2; ++m) { // Perf Note: It actually benchmarks faster on my system to do // a bounds check for every (m,n) than it is to limit the loop // to nFirst-Last and mFirst-mLast. // I'm leaving the code above, albeit commented out, so that // benchmarking between these two can still be performed. if (source.IsVisible(srcColumnInt + m, srcY)) { double w0 = rColCache[(m + 1) + (4 * (dstX - roi.Left))]; double w1 = rRowCache[n + 1]; double w = w0 * w1; blueSum += srcPtr->B * w * srcPtr->A; greenSum += srcPtr->G * w * srcPtr->A; redSum += srcPtr->R * w * srcPtr->A; alphaSum += srcPtr->A * w; totalWeight += w; } ++srcPtr; } srcPtr = (ColorBgra *)((byte *)(srcPtr - 4) + source.stride); } double alpha = alphaSum / totalWeight; double blue; double green; double red; if (alpha == 0) { blue = 0; green = 0; red = 0; } else { blue = blueSum / alphaSum; green = greenSum / alphaSum; red = redSum / alphaSum; // add 0.5 to ensure truncation to uint results in rounding alpha += 0.5; blue += 0.5; green += 0.5; red += 0.5; } dstPtr->Bgra = (uint)blue + ((uint)green << 8) + ((uint)red << 16) + ((uint)alpha << 24); ++dstPtr; } // for (dstX... } // for (dstY... Memory.Free(rColCacheIP); }
/// <summary> /// Implements bicubic filtering with bounds checking at every pixel. /// </summary> private void BicubicFitSurfaceChecked(Surface source, Rectangle dstRoi) { if (this.width < 2 || this.height < 2 || source.width < 2 || source.height < 2) { SuperSamplingFitSurface(source, dstRoi); } else { unsafe { Rectangle roi = Rectangle.Intersect(dstRoi, this.Bounds); Rectangle roiIn = Rectangle.Intersect(dstRoi, new Rectangle(1, 1, width - 1, height - 1)); IntPtr rColCacheIP = Memory.Allocate(4 * (ulong)roi.Width * (ulong)sizeof(double)); double* rColCache = (double*)rColCacheIP.ToPointer(); // Precompute and then cache the value of R() for each column for (int dstX = roi.Left; dstX < roi.Right; ++dstX) { double srcColumn = (double)(dstX * (source.width - 1)) / (double)(width - 1); double srcColumnFloor = Math.Floor(srcColumn); double srcColumnFrac = srcColumn - srcColumnFloor; int srcColumnInt = (int)srcColumn; for (int m = -1; m <= 2; ++m) { int index = (m + 1) + ((dstX - roi.Left) * 4); double x = m - srcColumnFrac; rColCache[index] = R(x); } } // Set this up so we can cache the R()'s for every row double* rRowCache = stackalloc double[4]; for (int dstY = roi.Top; dstY < roi.Bottom; ++dstY) { double srcRow = (double)(dstY * (source.height - 1)) / (double)(height - 1); double srcRowFloor = (double)Math.Floor(srcRow); double srcRowFrac = srcRow - srcRowFloor; int srcRowInt = (int)srcRow; ColorBgra *dstPtr = this.GetPointAddressUnchecked(roi.Left, dstY); // Compute the R() values for this row for (int n = -1; n <= 2; ++n) { double x = srcRowFrac - n; rRowCache[n + 1] = R(x); } // See Perf Note below //int nFirst = Math.Max(-srcRowInt, -1); //int nLast = Math.Min(source.height - srcRowInt - 1, 2); for (int dstX = roi.Left; dstX < roi.Right; dstX++) { double srcColumn = (double)(dstX * (source.width - 1)) / (double)(width - 1); double srcColumnFloor = Math.Floor(srcColumn); double srcColumnFrac = srcColumn - srcColumnFloor; int srcColumnInt = (int)srcColumn; double blueSum = 0; double greenSum = 0; double redSum = 0; double alphaSum = 0; double totalWeight = 0; // See Perf Note below //int mFirst = Math.Max(-srcColumnInt, -1); //int mLast = Math.Min(source.width - srcColumnInt - 1, 2); ColorBgra *srcPtr = source.GetPointAddressUnchecked(srcColumnInt - 1, srcRowInt - 1); for (int n = -1; n <= 2; ++n) { int srcY = srcRowInt + n; for (int m = -1; m <= 2; ++m) { // Perf Note: It actually benchmarks faster on my system to do // a bounds check for every (m,n) than it is to limit the loop // to nFirst-Last and mFirst-mLast. // I'm leaving the code above, albeit commented out, so that // benchmarking between these two can still be performed. if (source.IsVisible(srcColumnInt + m, srcY)) { double w0 = rColCache[(m + 1) + (4 * (dstX - roi.Left))]; double w1 = rRowCache[n + 1]; double w = w0 * w1; blueSum += srcPtr->B * w * srcPtr->A; greenSum += srcPtr->G * w * srcPtr->A; redSum += srcPtr->R * w * srcPtr->A; alphaSum += srcPtr->A * w; totalWeight += w; } ++srcPtr; } srcPtr = (ColorBgra *)((byte *)(srcPtr - 4) + source.stride); } double alpha = alphaSum / totalWeight; double blue; double green; double red; if (alpha == 0) { blue = 0; green = 0; red = 0; } else { blue = blueSum / alphaSum; green = greenSum / alphaSum; red = redSum / alphaSum; // add 0.5 to ensure truncation to uint results in rounding alpha += 0.5; blue += 0.5; green += 0.5; red += 0.5; } dstPtr->Bgra = (uint)blue + ((uint)green << 8) + ((uint)red << 16) + ((uint)alpha << 24); ++dstPtr; } // for (dstX... } // for (dstY... Memory.Free(rColCacheIP); } // unsafe } }