+// 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;
+}
+
+// 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();
+ }
+
+ for ( int dsty = 0; dsty < height; dsty++ )
+ {
+ // We need to calculate the source pixel to interpolate from - Y-axis
+ double srcpixy = double(dsty * M_IMGDATA->m_height) / height;
+ double dy = srcpixy - (int)srcpixy;
+
+ for ( int dstx = 0; dstx < width; dstx++ )
+ {
+ // X-axis of pixel to interpolate from
+ double srcpixx = double(dstx * M_IMGDATA->m_width) / width;
+ double dx = srcpixx - (int)srcpixx;
+
+ // 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
+ int y_offset = srcpixy + k < 0.0
+ ? 0
+ : srcpixy + k >= M_IMGDATA->m_height
+ ? M_IMGDATA->m_height - 1
+ : (int)(srcpixy + k);
+
+ // Loop across the X axis
+ for ( int i = -1; i <= 2; i++ )
+ {
+ // X offset
+ int x_offset = srcpixx + i < 0.0
+ ? 0
+ : srcpixx + i >= M_IMGDATA->m_width
+ ? M_IMGDATA->m_width - 1
+ : (int)(srcpixx + i);
+
+ // 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
+ double
+ pixel_weight = spline_weight(i - dx)*spline_weight(k - dy);
+
+ // 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