void scale_image_agg(T & target, T const& source, scaling_method_e scaling_method,
double image_ratio_x, double image_ratio_y, double x_off_f, double y_off_f,
double filter_factor)
{
// "the image filters should work namely in the premultiplied color space"
// http://old.nabble.com/Re:--AGG--Basic-image-transformations-p1110665.html
// "Yes, you need to use premultiplied images only. Only in this case the simple weighted averaging works correctly in the image fitering."
// http://permalink.gmane.org/gmane.comp.graphics.agg/3443
using image_type = T;
using pixel_type = typename image_type::pixel_type;
using pixfmt_pre = typename detail::agg_scaling_traits<image_type>::pixfmt_pre;
using color_type = typename detail::agg_scaling_traits<image_type>::color_type;
using img_src_type = typename detail::agg_scaling_traits<image_type>::img_src_type;
using interpolator_type = typename detail::agg_scaling_traits<image_type>::interpolator_type;
using renderer_base_pre = agg::renderer_base<pixfmt_pre>;
constexpr std::size_t pixel_size = sizeof(pixel_type);
// define some stuff we'll use soon
agg::rasterizer_scanline_aa<> ras;
agg::scanline_u8 sl;
agg::span_allocator<color_type> sa;
// initialize source AGG buffer
agg::rendering_buffer rbuf_src(const_cast<unsigned char*>(source.bytes()),
source.width(), source.height(), source.width() * pixel_size);
pixfmt_pre pixf_src(rbuf_src);
img_src_type img_src(pixf_src);
// initialize destination AGG buffer (with transparency)
agg::rendering_buffer rbuf_dst(target.bytes(), target.width(), target.height(), target.width() * pixel_size);
pixfmt_pre pixf_dst(rbuf_dst);
renderer_base_pre rb_dst_pre(pixf_dst);
// create a scaling matrix
agg::trans_affine img_mtx;
img_mtx /= agg::trans_affine_scaling(image_ratio_x, image_ratio_y);
// create a linear interpolator for our scaling matrix
interpolator_type interpolator(img_mtx);
// draw an anticlockwise polygon to render our image into
double scaled_width = target.width();
double scaled_height = target.height();
ras.reset();
ras.move_to_d(x_off_f, y_off_f);
ras.line_to_d(x_off_f + scaled_width, y_off_f);
ras.line_to_d(x_off_f + scaled_width, y_off_f + scaled_height);
ras.line_to_d(x_off_f, y_off_f + scaled_height);
if (scaling_method == SCALING_NEAR)
{
using span_gen_type = typename detail::agg_scaling_traits<image_type>::span_image_filter;
span_gen_type sg(img_src, interpolator);
agg::render_scanlines_aa(ras, sl, rb_dst_pre, sa, sg);
}
else
{
using span_gen_type = typename detail::agg_scaling_traits<image_type>::span_image_resample_affine;
agg::image_filter_lut filter;
detail::set_scaling_method(filter, scaling_method, filter_factor);
span_gen_type sg(img_src, interpolator, filter);
agg::render_scanlines_aa(ras, sl, rb_dst_pre, sa, sg);
}
}
void scale_image_agg(Image & target,
Image const& source,
scaling_method_e scaling_method,
double image_ratio,
double x_off_f,
double y_off_f,
double filter_radius,
double ratio)
{
// "the image filters should work namely in the premultiplied color space"
// http://old.nabble.com/Re:--AGG--Basic-image-transformations-p1110665.html
// "Yes, you need to use premultiplied images only. Only in this case the simple weighted averaging works correctly in the image fitering."
// http://permalink.gmane.org/gmane.comp.graphics.agg/3443
typedef agg::pixfmt_rgba32_pre pixfmt_pre;
typedef agg::renderer_base<pixfmt_pre> renderer_base_pre;
// define some stuff we'll use soon
agg::rasterizer_scanline_aa<> ras;
agg::scanline_u8 sl;
agg::span_allocator<agg::rgba8> sa;
agg::image_filter_lut filter;
// initialize source AGG buffer
agg::rendering_buffer rbuf_src((unsigned char*)source.getBytes(), source.width(), source.height(), source.width() * 4);
pixfmt_pre pixf_src(rbuf_src);
typedef agg::image_accessor_clone<pixfmt_pre> img_src_type;
img_src_type img_src(pixf_src);
// initialize destination AGG buffer (with transparency)
agg::rendering_buffer rbuf_dst((unsigned char*)target.getBytes(), target.width(), target.height(), target.width() * 4);
pixfmt_pre pixf_dst(rbuf_dst);
renderer_base_pre rb_dst_pre(pixf_dst);
rb_dst_pre.clear(agg::rgba(0, 0, 0, 0));
// create a scaling matrix
agg::trans_affine img_mtx;
img_mtx /= agg::trans_affine_scaling(image_ratio * ratio, image_ratio * ratio);
// create a linear interpolator for our scaling matrix
typedef agg::span_interpolator_linear<> interpolator_type;
interpolator_type interpolator(img_mtx);
// draw an anticlockwise polygon to render our image into
double scaled_width = target.width();
double scaled_height = target.height();
ras.reset();
ras.move_to_d(x_off_f, y_off_f);
ras.line_to_d(x_off_f + scaled_width, y_off_f);
ras.line_to_d(x_off_f + scaled_width, y_off_f + scaled_height);
ras.line_to_d(x_off_f, y_off_f + scaled_height);
switch(scaling_method)
{
case SCALING_NEAR:
{
typedef agg::span_image_filter_rgba_nn<img_src_type, interpolator_type> span_gen_type;
span_gen_type sg(img_src, interpolator);
agg::render_scanlines_aa(ras, sl, rb_dst_pre, sa, sg);
return;
}
case SCALING_BILINEAR:
case SCALING_BILINEAR8:
filter.calculate(agg::image_filter_bilinear(), true); break;
case SCALING_BICUBIC:
filter.calculate(agg::image_filter_bicubic(), true); break;
case SCALING_SPLINE16:
filter.calculate(agg::image_filter_spline16(), true); break;
case SCALING_SPLINE36:
filter.calculate(agg::image_filter_spline36(), true); break;
case SCALING_HANNING:
filter.calculate(agg::image_filter_hanning(), true); break;
case SCALING_HAMMING:
filter.calculate(agg::image_filter_hamming(), true); break;
case SCALING_HERMITE:
filter.calculate(agg::image_filter_hermite(), true); break;
case SCALING_KAISER:
filter.calculate(agg::image_filter_kaiser(), true); break;
case SCALING_QUADRIC:
filter.calculate(agg::image_filter_quadric(), true); break;
case SCALING_CATROM:
filter.calculate(agg::image_filter_catrom(), true); break;
case SCALING_GAUSSIAN:
filter.calculate(agg::image_filter_gaussian(), true); break;
case SCALING_BESSEL:
filter.calculate(agg::image_filter_bessel(), true); break;
case SCALING_MITCHELL:
filter.calculate(agg::image_filter_mitchell(), true); break;
case SCALING_SINC:
filter.calculate(agg::image_filter_sinc(filter_radius), true); break;
case SCALING_LANCZOS:
filter.calculate(agg::image_filter_lanczos(filter_radius), true); break;
case SCALING_BLACKMAN:
filter.calculate(agg::image_filter_blackman(filter_radius), true); break;
}
// details on various resampling considerations
// http://old.nabble.com/Re%3A-Newbie---texture-p5057255.html
// high quality resampler
//typedef agg::span_image_resample_rgba_affine<img_src_type> span_gen_type;
// faster, lower quality
//typedef agg::span_image_filter_rgba<img_src_type,interpolator_type> span_gen_type;
// local, modified agg::span_image_resample_rgba_affine
// not convinced we need this
// https://github.com/mapnik/mapnik/issues/1489
typedef mapnik::span_image_resample_rgba_affine<img_src_type> span_gen_type;
span_gen_type sg(img_src, interpolator, filter);
agg::render_scanlines_aa(ras, sl, rb_dst_pre, sa, sg);
}