+ M_IMGDATA->m_maskGreen,
+ M_IMGDATA->m_maskBlue );
+ }
+
+ // In case this is a cursor, make sure the hotspot is scaled accordingly:
+ if ( HasOption(wxIMAGE_OPTION_CUR_HOTSPOT_X) )
+ image.SetOption(wxIMAGE_OPTION_CUR_HOTSPOT_X,
+ (GetOptionInt(wxIMAGE_OPTION_CUR_HOTSPOT_X)*width)/old_width);
+ if ( HasOption(wxIMAGE_OPTION_CUR_HOTSPOT_Y) )
+ image.SetOption(wxIMAGE_OPTION_CUR_HOTSPOT_Y,
+ (GetOptionInt(wxIMAGE_OPTION_CUR_HOTSPOT_Y)*height)/old_height);
+
+ return image;
+}
+
+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);
+
+ const double scale_factor_x = double(M_IMGDATA->m_width) / width;
+ const double scale_factor_y = double(M_IMGDATA->m_height) / height;
+
+ const int scale_factor_x_2 = (int)(scale_factor_x / 2);
+ const int scale_factor_y_2 = (int)(scale_factor_y / 2);
+
+ // If we want good-looking results we need to pre-blur the image a bit first
+ wxImage src_image(*this);
+ src_image = src_image.BlurHorizontal(scale_factor_x_2);
+ src_image = src_image.BlurVertical(scale_factor_y_2);
+
+ unsigned char* src_data = src_image.GetData();
+ unsigned char* src_alpha = src_image.GetAlpha();
+ 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
+ int src_y = (int)(y * scale_factor_y);
+
+ for ( int x = 0; x < width; x++ ) // Destination image - X direction
+ {
+ // Source pixel in the X direction
+ int src_x = (int)(x * scale_factor_x);
+
+ // Box of pixels to average
+ averaged_pixels = 0;
+ sum_r = sum_g = sum_b = sum_a = 0.0;
+
+ for ( int j = int(src_y - scale_factor_y/2.0 + 1);
+ j <= int(src_y + scale_factor_y_2);
+ j++ )
+ {
+ // We don't care to average pixels that don't exist (edges)
+ if ( j < 0 || j > M_IMGDATA->m_height )
+ continue;
+
+ for ( int i = int(src_x - scale_factor_x/2.0 + 1);
+ i <= src_x + scale_factor_x_2;
+ i++ )
+ {
+ // Don't average edge pixels
+ if ( i < 0 || i > M_IMGDATA->m_width )
+ continue;
+
+ // Calculate the actual index in our source pixels
+ src_pixel_index = src_y * M_IMGDATA->m_width + src_x;
+
+ 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;
+}
+
+// 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);
+
+ unsigned char* src_data = M_IMGDATA->m_data;
+ 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 = 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 = 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)
+{
+ wxImage ret_image;
+ ret_image.Create(M_IMGDATA->m_width, M_IMGDATA->m_height, false);
+
+ unsigned char* src_data = M_IMGDATA->m_data;
+ unsigned char* dst_data = ret_image.GetData();
+ unsigned char* src_alpha = M_IMGDATA->m_alpha;
+ unsigned char* dst_alpha = NULL;
+
+ // Check for a mask or alpha
+ if ( M_IMGDATA->m_hasMask )
+ {
+ ret_image.SetMaskColour(M_IMGDATA->m_maskRed,
+ M_IMGDATA->m_maskGreen,
+ M_IMGDATA->m_maskBlue);
projects / wxWidgets.git / blobdiff