+namespace
+{
+
+struct BoxPrecalc
+{
+ int boxStart;
+ int boxEnd;
+};
+
+inline int BoxBetween(int value, int low, int high)
+{
+ return wxMax(wxMin(value, high), low);
+}
+
+void ResampleBoxPrecalc(wxVector<BoxPrecalc>& boxes, int oldDim)
+{
+ const int newDim = boxes.size();
+ const double scale_factor_1 = double(oldDim) / newDim;
+ const int scale_factor_2 = (int)(scale_factor_1 / 2);
+
+ for ( int dst = 0; dst < newDim; ++dst )
+ {
+ // Source pixel in the Y direction
+ const int src_p = int(dst * scale_factor_1);
+
+ BoxPrecalc& precalc = boxes[dst];
+ precalc.boxStart = BoxBetween(int(src_p - scale_factor_1/2.0 + 1),
+ 0, oldDim - 1);
+ precalc.boxEnd = BoxBetween(wxMax(precalc.boxStart + 1,
+ int(src_p + scale_factor_2)),
+ 0, oldDim - 1);
+ }
+}
+
+} // anonymous namespace
+
+wxImage wxImage::ResampleBox(int width, int height) const
+{
+ // This function implements a simple pre-blur/box averaging method for
+ // downsampling that gives reasonably smooth results To scale the image
+ // down we will need to gather a grid of pixels of the size of the scale
+ // factor in each direction and then do an averaging of the pixels.
+
+ wxImage ret_image(width, height, false);
+
+ wxVector<BoxPrecalc> vPrecalcs(height);
+ wxVector<BoxPrecalc> hPrecalcs(width);
+
+ ResampleBoxPrecalc(vPrecalcs, M_IMGDATA->m_height);
+ ResampleBoxPrecalc(hPrecalcs, M_IMGDATA->m_width);
+
+
+ const unsigned char* src_data = M_IMGDATA->m_data;
+ const unsigned char* src_alpha = M_IMGDATA->m_alpha;
+ unsigned char* dst_data = ret_image.GetData();
+ unsigned char* dst_alpha = NULL;
+
+ if ( src_alpha )
+ {
+ ret_image.SetAlpha();
+ dst_alpha = ret_image.GetAlpha();
+ }
+
+ int averaged_pixels, src_pixel_index;
+ double sum_r, sum_g, sum_b, sum_a;
+
+ for ( int y = 0; y < height; y++ ) // Destination image - Y direction
+ {
+ // Source pixel in the Y direction
+ const BoxPrecalc& vPrecalc = vPrecalcs[y];
+
+ for ( int x = 0; x < width; x++ ) // Destination image - X direction
+ {
+ // Source pixel in the X direction
+ const BoxPrecalc& hPrecalc = hPrecalcs[x];
+
+ // Box of pixels to average
+ averaged_pixels = 0;
+ sum_r = sum_g = sum_b = sum_a = 0.0;
+
+ for ( int j = vPrecalc.boxStart; j <= vPrecalc.boxEnd; ++j )
+ {
+ for ( int i = hPrecalc.boxStart; i <= hPrecalc.boxEnd; ++i )
+ {
+ // Calculate the actual index in our source pixels
+ src_pixel_index = j * M_IMGDATA->m_width + i;
+
+ sum_r += src_data[src_pixel_index * 3 + 0];
+ sum_g += src_data[src_pixel_index * 3 + 1];
+ sum_b += src_data[src_pixel_index * 3 + 2];
+ if ( src_alpha )
+ sum_a += src_alpha[src_pixel_index];
+
+ averaged_pixels++;
+ }
+ }
+
+ // Calculate the average from the sum and number of averaged pixels
+ dst_data[0] = (unsigned char)(sum_r / averaged_pixels);
+ dst_data[1] = (unsigned char)(sum_g / averaged_pixels);
+ dst_data[2] = (unsigned char)(sum_b / averaged_pixels);
+ dst_data += 3;
+ if ( src_alpha )
+ *dst_alpha++ = (unsigned char)(sum_a / averaged_pixels);
+ }
+ }
+
+ return ret_image;
+}
+
+namespace
+{
+
+struct BilinearPrecalc
+{
+ int offset1;
+ int offset2;
+ double dd;
+ double dd1;
+};
+
+void ResampleBilinearPrecalc(wxVector<BilinearPrecalc>& precalcs, int oldDim)
+{
+ const int newDim = precalcs.size();
+ const double scale_factor = double(oldDim) / newDim;
+ const int srcpixmax = oldDim - 1;
+
+ for ( int dsty = 0; dsty < newDim; dsty++ )
+ {
+ // We need to calculate the source pixel to interpolate from - Y-axis
+ double srcpix = double(dsty) * scale_factor;
+ double srcpix1 = int(srcpix);
+ double srcpix2 = srcpix1 == srcpixmax ? srcpix1 : srcpix1 + 1.0;
+
+ BilinearPrecalc& precalc = precalcs[dsty];
+
+ precalc.dd = srcpix - (int)srcpix;
+ precalc.dd1 = 1.0 - precalc.dd;
+ precalc.offset1 = srcpix1 < 0.0
+ ? 0
+ : srcpix1 > srcpixmax
+ ? srcpixmax
+ : (int)srcpix1;
+ precalc.offset2 = srcpix2 < 0.0
+ ? 0
+ : srcpix2 > srcpixmax
+ ? srcpixmax
+ : (int)srcpix2;
+ }
+}
+
+} // anonymous namespace
+
+wxImage wxImage::ResampleBilinear(int width, int height) const
+{
+ // This function implements a Bilinear algorithm for resampling.
+ wxImage ret_image(width, height, false);
+ const unsigned char* src_data = M_IMGDATA->m_data;
+ const unsigned char* src_alpha = M_IMGDATA->m_alpha;
+ unsigned char* dst_data = ret_image.GetData();
+ unsigned char* dst_alpha = NULL;
+
+ if ( src_alpha )
+ {
+ ret_image.SetAlpha();
+ dst_alpha = ret_image.GetAlpha();
+ }
+
+ wxVector<BilinearPrecalc> vPrecalcs(height);
+ wxVector<BilinearPrecalc> hPrecalcs(width);
+ ResampleBilinearPrecalc(vPrecalcs, M_IMGDATA->m_height);
+ ResampleBilinearPrecalc(hPrecalcs, M_IMGDATA->m_width);
+
+ // initialize alpha values to avoid g++ warnings about possibly
+ // uninitialized variables
+ double r1, g1, b1, a1 = 0;
+ double r2, g2, b2, a2 = 0;
+
+ for ( int dsty = 0; dsty < height; dsty++ )
+ {
+ // We need to calculate the source pixel to interpolate from - Y-axis
+ const BilinearPrecalc& vPrecalc = vPrecalcs[dsty];
+ const int y_offset1 = vPrecalc.offset1;
+ const int y_offset2 = vPrecalc.offset2;
+ const double dy = vPrecalc.dd;
+ const double dy1 = vPrecalc.dd1;
+
+
+ for ( int dstx = 0; dstx < width; dstx++ )
+ {
+ // X-axis of pixel to interpolate from
+ const BilinearPrecalc& hPrecalc = hPrecalcs[dstx];
+
+ const int x_offset1 = hPrecalc.offset1;
+ const int x_offset2 = hPrecalc.offset2;
+ const double dx = hPrecalc.dd;
+ const double dx1 = hPrecalc.dd1;
+
+ int src_pixel_index00 = y_offset1 * M_IMGDATA->m_width + x_offset1;
+ int src_pixel_index01 = y_offset1 * M_IMGDATA->m_width + x_offset2;
+ int src_pixel_index10 = y_offset2 * M_IMGDATA->m_width + x_offset1;
+ int src_pixel_index11 = y_offset2 * M_IMGDATA->m_width + x_offset2;
+
+ // first line
+ r1 = src_data[src_pixel_index00 * 3 + 0] * dx1 + src_data[src_pixel_index01 * 3 + 0] * dx;
+ g1 = src_data[src_pixel_index00 * 3 + 1] * dx1 + src_data[src_pixel_index01 * 3 + 1] * dx;
+ b1 = src_data[src_pixel_index00 * 3 + 2] * dx1 + src_data[src_pixel_index01 * 3 + 2] * dx;
+ if ( src_alpha )
+ a1 = src_alpha[src_pixel_index00] * dx1 + src_alpha[src_pixel_index01] * dx;
+
+ // second line
+ r2 = src_data[src_pixel_index10 * 3 + 0] * dx1 + src_data[src_pixel_index11 * 3 + 0] * dx;
+ g2 = src_data[src_pixel_index10 * 3 + 1] * dx1 + src_data[src_pixel_index11 * 3 + 1] * dx;
+ b2 = src_data[src_pixel_index10 * 3 + 2] * dx1 + src_data[src_pixel_index11 * 3 + 2] * dx;
+ if ( src_alpha )
+ a2 = src_alpha[src_pixel_index10] * dx1 + src_alpha[src_pixel_index11] * dx;
+
+ // result lines
+
+ dst_data[0] = static_cast<unsigned char>(r1 * dy1 + r2 * dy);
+ dst_data[1] = static_cast<unsigned char>(g1 * dy1 + g2 * dy);
+ dst_data[2] = static_cast<unsigned char>(b1 * dy1 + b2 * dy);
+ dst_data += 3;
+
+ if ( src_alpha )
+ *dst_alpha++ = static_cast<unsigned char>(a1 * dy1 + a2 * dy);
+ }
+ }
+
+ return ret_image;
+}
+
+// The following two local functions are for the B-spline weighting of the
+// bicubic sampling algorithm
+static inline double spline_cube(double value)
+{
+ return value <= 0.0 ? 0.0 : value * value * value;
+}
+
+static inline double spline_weight(double value)
+{
+ return (spline_cube(value + 2) -
+ 4 * spline_cube(value + 1) +
+ 6 * spline_cube(value) -
+ 4 * spline_cube(value - 1)) / 6;
+}
+
+
+namespace
+{
+
+struct BicubicPrecalc
+{
+ double weight[4];
+ int offset[4];
+};
+
+void ResampleBicubicPrecalc(wxVector<BicubicPrecalc> &aWeight, int oldDim)
+{
+ const int newDim = aWeight.size();
+ for ( int dstd = 0; dstd < newDim; dstd++ )
+ {
+ // We need to calculate the source pixel to interpolate from - Y-axis
+ const double srcpixd = static_cast<double>(dstd * oldDim) / newDim;
+ const double dd = srcpixd - static_cast<int>(srcpixd);
+
+ BicubicPrecalc &precalc = aWeight[dstd];
+
+ for ( int k = -1; k <= 2; k++ )
+ {
+ precalc.offset[k + 1] = srcpixd + k < 0.0
+ ? 0
+ : srcpixd + k >= oldDim
+ ? oldDim - 1
+ : static_cast<int>(srcpixd + k);
+
+ precalc.weight[k + 1] = spline_weight(k - dd);
+ }
+ }
+}
+
+} // anonymous namespace
+
+// This is the bicubic resampling algorithm
+wxImage wxImage::ResampleBicubic(int width, int height) const
+{
+ // This function implements a Bicubic B-Spline algorithm for resampling.
+ // This method is certainly a little slower than wxImage's default pixel
+ // replication method, however for most reasonably sized images not being
+ // upsampled too much on a fairly average CPU this difference is hardly
+ // noticeable and the results are far more pleasing to look at.
+ //
+ // This particular bicubic algorithm does pixel weighting according to a
+ // B-Spline that basically implements a Gaussian bell-like weighting
+ // kernel. Because of this method the results may appear a bit blurry when
+ // upsampling by large factors. This is basically because a slight
+ // gaussian blur is being performed to get the smooth look of the upsampled
+ // image.
+
+ // Edge pixels: 3-4 possible solutions
+ // - (Wrap/tile) Wrap the image, take the color value from the opposite
+ // side of the image.
+ // - (Mirror) Duplicate edge pixels, so that pixel at coordinate (2, n),
+ // where n is nonpositive, will have the value of (2, 1).
+ // - (Ignore) Simply ignore the edge pixels and apply the kernel only to
+ // pixels which do have all neighbours.
+ // - (Clamp) Choose the nearest pixel along the border. This takes the
+ // border pixels and extends them out to infinity.
+ //
+ // NOTE: below the y_offset and x_offset variables are being set for edge
+ // pixels using the "Mirror" method mentioned above
+
+ wxImage ret_image;
+
+ ret_image.Create(width, height, false);
+
+ const unsigned char* src_data = M_IMGDATA->m_data;
+ const unsigned char* src_alpha = M_IMGDATA->m_alpha;
+ unsigned char* dst_data = ret_image.GetData();
+ unsigned char* dst_alpha = NULL;
+
+ if ( src_alpha )
+ {
+ ret_image.SetAlpha();
+ dst_alpha = ret_image.GetAlpha();
+ }
+
+ // Precalculate weights
+ wxVector<BicubicPrecalc> vPrecalcs(height);
+ wxVector<BicubicPrecalc> hPrecalcs(width);
+
+ ResampleBicubicPrecalc(vPrecalcs, M_IMGDATA->m_height);
+ ResampleBicubicPrecalc(hPrecalcs, M_IMGDATA->m_width);
+
+ for ( int dsty = 0; dsty < height; dsty++ )
+ {
+ // We need to calculate the source pixel to interpolate from - Y-axis
+ const BicubicPrecalc& vPrecalc = vPrecalcs[dsty];
+
+ for ( int dstx = 0; dstx < width; dstx++ )
+ {
+ // X-axis of pixel to interpolate from
+ const BicubicPrecalc& hPrecalc = hPrecalcs[dstx];
+
+ // Sums for each color channel
+ double sum_r = 0, sum_g = 0, sum_b = 0, sum_a = 0;
+
+ // Here we actually determine the RGBA values for the destination pixel
+ for ( int k = -1; k <= 2; k++ )
+ {
+ // Y offset
+ const int y_offset = vPrecalc.offset[k + 1];
+
+ // Loop across the X axis
+ for ( int i = -1; i <= 2; i++ )
+ {
+ // X offset
+ const int x_offset = hPrecalc.offset[i + 1];
+
+ // Calculate the exact position where the source data
+ // should be pulled from based on the x_offset and y_offset
+ int src_pixel_index = y_offset*M_IMGDATA->m_width + x_offset;
+
+ // Calculate the weight for the specified pixel according
+ // to the bicubic b-spline kernel we're using for
+ // interpolation
+ const double
+ pixel_weight = vPrecalc.weight[k + 1] * hPrecalc.weight[i + 1];
+
+ // Create a sum of all velues for each color channel
+ // adjusted for the pixel's calculated weight
+ sum_r += src_data[src_pixel_index * 3 + 0] * pixel_weight;
+ sum_g += src_data[src_pixel_index * 3 + 1] * pixel_weight;
+ sum_b += src_data[src_pixel_index * 3 + 2] * pixel_weight;
+ if ( src_alpha )
+ sum_a += src_alpha[src_pixel_index] * pixel_weight;
+ }
+ }
+
+ // Put the data into the destination image. The summed values are
+ // of double data type and are rounded here for accuracy
+ dst_data[0] = (unsigned char)(sum_r + 0.5);
+ dst_data[1] = (unsigned char)(sum_g + 0.5);
+ dst_data[2] = (unsigned char)(sum_b + 0.5);
+ dst_data += 3;
+
+ if ( src_alpha )
+ *dst_alpha++ = (unsigned char)sum_a;
+ }
+ }
+
+ return ret_image;
+}
+
+// Blur in the horizontal direction
+wxImage wxImage::BlurHorizontal(int blurRadius) const
+{
+ wxImage ret_image(MakeEmptyClone());
+
+ wxCHECK( ret_image.IsOk(), ret_image );
+
+ const unsigned char* src_data = M_IMGDATA->m_data;
+ unsigned char* dst_data = ret_image.GetData();
+ const unsigned char* src_alpha = M_IMGDATA->m_alpha;
+ unsigned char* dst_alpha = ret_image.GetAlpha();
+
+ // number of pixels we average over
+ const int blurArea = blurRadius*2 + 1;
+
+ // Horizontal blurring algorithm - average all pixels in the specified blur
+ // radius in the X or horizontal direction
+ for ( int y = 0; y < M_IMGDATA->m_height; y++ )
+ {
+ // Variables used in the blurring algorithm
+ long sum_r = 0,
+ sum_g = 0,
+ sum_b = 0,
+ sum_a = 0;
+
+ long pixel_idx;
+ const unsigned char *src;
+ unsigned char *dst;
+
+ // Calculate the average of all pixels in the blur radius for the first
+ // pixel of the row
+ for ( int kernel_x = -blurRadius; kernel_x <= blurRadius; kernel_x++ )
+ {
+ // To deal with the pixels at the start of a row so it's not
+ // grabbing GOK values from memory at negative indices of the
+ // image's data or grabbing from the previous row
+ if ( kernel_x < 0 )
+ pixel_idx = y * M_IMGDATA->m_width;
+ else
+ pixel_idx = kernel_x + y * M_IMGDATA->m_width;
+
+ src = src_data + pixel_idx*3;
+ sum_r += src[0];
+ sum_g += src[1];
+ sum_b += src[2];
+ if ( src_alpha )
+ sum_a += src_alpha[pixel_idx];
+ }
+
+ dst = dst_data + y * M_IMGDATA->m_width*3;
+ dst[0] = (unsigned char)(sum_r / blurArea);
+ dst[1] = (unsigned char)(sum_g / blurArea);
+ dst[2] = (unsigned char)(sum_b / blurArea);
+ if ( src_alpha )
+ dst_alpha[y * M_IMGDATA->m_width] = (unsigned char)(sum_a / blurArea);
+
+ // Now average the values of the rest of the pixels by just moving the
+ // blur radius box along the row
+ for ( int x = 1; x < M_IMGDATA->m_width; x++ )
+ {
+ // Take care of edge pixels on the left edge by essentially
+ // duplicating the edge pixel
+ if ( x - blurRadius - 1 < 0 )
+ pixel_idx = y * M_IMGDATA->m_width;
+ else
+ pixel_idx = (x - blurRadius - 1) + y * M_IMGDATA->m_width;
+
+ // Subtract the value of the pixel at the left side of the blur
+ // radius box
+ src = src_data + pixel_idx*3;
+ sum_r -= src[0];
+ sum_g -= src[1];
+ sum_b -= src[2];
+ if ( src_alpha )
+ sum_a -= src_alpha[pixel_idx];
+
+ // Take care of edge pixels on the right edge
+ if ( x + blurRadius > M_IMGDATA->m_width - 1 )
+ pixel_idx = M_IMGDATA->m_width - 1 + y * M_IMGDATA->m_width;
+ else
+ pixel_idx = x + blurRadius + y * M_IMGDATA->m_width;
+
+ // Add the value of the pixel being added to the end of our box
+ src = src_data + pixel_idx*3;
+ sum_r += src[0];
+ sum_g += src[1];
+ sum_b += src[2];
+ if ( src_alpha )
+ sum_a += src_alpha[pixel_idx];
+
+ // Save off the averaged data
+ dst = dst_data + x*3 + y*M_IMGDATA->m_width*3;
+ dst[0] = (unsigned char)(sum_r / blurArea);
+ dst[1] = (unsigned char)(sum_g / blurArea);
+ dst[2] = (unsigned char)(sum_b / blurArea);
+ if ( src_alpha )
+ dst_alpha[x + y * M_IMGDATA->m_width] = (unsigned char)(sum_a / blurArea);
+ }
+ }
+
+ return ret_image;
+}
+
+// Blur in the vertical direction
+wxImage wxImage::BlurVertical(int blurRadius) const
+{
+ wxImage ret_image(MakeEmptyClone());
+
+ wxCHECK( ret_image.IsOk(), ret_image );
+
+ const unsigned char* src_data = M_IMGDATA->m_data;
+ unsigned char* dst_data = ret_image.GetData();
+ const unsigned char* src_alpha = M_IMGDATA->m_alpha;
+ unsigned char* dst_alpha = ret_image.GetAlpha();
+
+ // number of pixels we average over
+ const int blurArea = blurRadius*2 + 1;
+
+ // Vertical blurring algorithm - same as horizontal but switched the
+ // opposite direction
+ for ( int x = 0; x < M_IMGDATA->m_width; x++ )
+ {
+ // Variables used in the blurring algorithm
+ long sum_r = 0,
+ sum_g = 0,
+ sum_b = 0,
+ sum_a = 0;
+
+ long pixel_idx;
+ const unsigned char *src;
+ unsigned char *dst;
+
+ // Calculate the average of all pixels in our blur radius box for the
+ // first pixel of the column
+ for ( int kernel_y = -blurRadius; kernel_y <= blurRadius; kernel_y++ )
+ {
+ // To deal with the pixels at the start of a column so it's not
+ // grabbing GOK values from memory at negative indices of the
+ // image's data or grabbing from the previous column
+ if ( kernel_y < 0 )
+ pixel_idx = x;
+ else
+ pixel_idx = x + kernel_y * M_IMGDATA->m_width;
+
+ src = src_data + pixel_idx*3;
+ sum_r += src[0];
+ sum_g += src[1];
+ sum_b += src[2];
+ if ( src_alpha )
+ sum_a += src_alpha[pixel_idx];
+ }
+
+ dst = dst_data + x*3;
+ dst[0] = (unsigned char)(sum_r / blurArea);
+ dst[1] = (unsigned char)(sum_g / blurArea);
+ dst[2] = (unsigned char)(sum_b / blurArea);
+ if ( src_alpha )
+ dst_alpha[x] = (unsigned char)(sum_a / blurArea);
+
+ // Now average the values of the rest of the pixels by just moving the
+ // box along the column from top to bottom
+ for ( int y = 1; y < M_IMGDATA->m_height; y++ )
+ {
+ // Take care of pixels that would be beyond the top edge by
+ // duplicating the top edge pixel for the column
+ if ( y - blurRadius - 1 < 0 )
+ pixel_idx = x;
+ else
+ pixel_idx = x + (y - blurRadius - 1) * M_IMGDATA->m_width;
+
+ // Subtract the value of the pixel at the top of our blur radius box
+ src = src_data + pixel_idx*3;
+ sum_r -= src[0];
+ sum_g -= src[1];
+ sum_b -= src[2];
+ if ( src_alpha )
+ sum_a -= src_alpha[pixel_idx];
+
+ // Take care of the pixels that would be beyond the bottom edge of
+ // the image similar to the top edge
+ if ( y + blurRadius > M_IMGDATA->m_height - 1 )
+ pixel_idx = x + (M_IMGDATA->m_height - 1) * M_IMGDATA->m_width;
+ else
+ pixel_idx = x + (blurRadius + y) * M_IMGDATA->m_width;
+
+ // Add the value of the pixel being added to the end of our box
+ src = src_data + pixel_idx*3;
+ sum_r += src[0];
+ sum_g += src[1];
+ sum_b += src[2];
+ if ( src_alpha )
+ sum_a += src_alpha[pixel_idx];
+
+ // Save off the averaged data
+ dst = dst_data + (x + y * M_IMGDATA->m_width) * 3;
+ dst[0] = (unsigned char)(sum_r / blurArea);
+ dst[1] = (unsigned char)(sum_g / blurArea);
+ dst[2] = (unsigned char)(sum_b / blurArea);
+ if ( src_alpha )
+ dst_alpha[x + y * M_IMGDATA->m_width] = (unsigned char)(sum_a / blurArea);
+ }
+ }
+
+ return ret_image;
+}
+
+// The new blur function
+wxImage wxImage::Blur(int blurRadius) const
+{
+ wxImage ret_image;
+ ret_image.Create(M_IMGDATA->m_width, M_IMGDATA->m_height, false);
+
+ // Blur the image in each direction
+ ret_image = BlurHorizontal(blurRadius);
+ ret_image = ret_image.BlurVertical(blurRadius);
+
+ return ret_image;
+}
+
projects / wxWidgets.git / blobdiff