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Fix incorrect blending of rasters with alpha channel. Use pixfmt_rgba32_plain rather than pixfmt_rgba32, and undo old changes to blender_rgba<>::blender_pix which aren't needed anymore. Thanks @rfw, @cdestigter, @albertov [fixes #759]

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This commit is contained in:
Robert Coup 2011-07-15 03:59:44 +00:00
parent b18a536194
commit 8e8f43e50f
3 changed files with 11 additions and 21 deletions
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26
agg/include/agg_pixfmt_rgba.h
View file

@ -144,24 +144,14 @@ namespace agg
unsigned alpha,
unsigned cover=0)
{
if (alpha)
{
calc_type r = p[Order::R];
calc_type g = p[Order::G];
calc_type b = p[Order::B];
calc_type a = p[Order::A];
p[Order::A] = (value_type)(alpha + a - ((alpha * a + base_mask) >> base_shift));
if (p[Order::A]) {
if (!cover)
{
cover = base_mask;
}
p[Order::R] = (value_type)((cr * alpha / cover) + (r * a * (base_mask - alpha) / base_mask / p[Order::A]));
p[Order::G] = (value_type)((cg * alpha / cover) + (g * a * (base_mask - alpha) / base_mask / p[Order::A]));
p[Order::B] = (value_type)((cb * alpha / cover) + (b * a * (base_mask - alpha) / base_mask / p[Order::A]));
}
}
calc_type r = p[Order::R];
calc_type g = p[Order::G];
calc_type b = p[Order::B];
calc_type a = p[Order::A];
p[Order::R] = (value_type)(((cr - r) * alpha + (r << base_shift)) >> base_shift);
p[Order::G] = (value_type)(((cg - g) * alpha + (g << base_shift)) >> base_shift);
p[Order::B] = (value_type)(((cb - b) * alpha + (b << base_shift)) >> base_shift);
p[Order::A] = (value_type)((alpha + a) - ((alpha * a + base_mask) >> base_shift));
}
};

4
src/agg/process_polygon_pattern_symbolizer.cpp
View file

@ -51,7 +51,7 @@ void agg_renderer<T>::process(polygon_pattern_symbolizer const& sym,
typedef agg::renderer_base<agg::pixfmt_rgba32_plain> ren_base;
typedef agg::wrap_mode_repeat wrap_x_type;
typedef agg::wrap_mode_repeat wrap_y_type;
typedef agg::pixfmt_alpha_blend_rgba<agg::blender_rgba32,
typedef agg::pixfmt_alpha_blend_rgba<agg::blender_rgba32_plain,
agg::row_accessor<agg::int8u>, agg::pixel32_type> rendering_buffer;
typedef agg::image_accessor_wrap<rendering_buffer,
wrap_x_type,
@ -94,7 +94,7 @@ void agg_renderer<T>::process(polygon_pattern_symbolizer const& sym,
unsigned h=(*pat)->height();
agg::row_accessor<agg::int8u> pattern_rbuf((agg::int8u*)(*pat)->getBytes(),w,h,w*4);
agg::span_allocator<agg::rgba8> sa;
agg::pixfmt_alpha_blend_rgba<agg::blender_rgba32,
agg::pixfmt_alpha_blend_rgba<agg::blender_rgba32_plain,
agg::row_accessor<agg::int8u>, agg::pixel32_type> pixf_pattern(pattern_rbuf);
img_source_type img_src(pixf_pattern);

2
src/image_util.cpp
View file

@ -499,7 +499,7 @@ void scale_image_bilinear8 (Image& target,const Image& source, double x_off_f, d
template <typename Image>
void scale_image_agg (Image& target,const Image& source, scaling_method_e scaling_method, double scale_factor, double x_off_f, double y_off_f, double filter_radius, double ratio)
{
typedef agg::pixfmt_rgba32 pixfmt;
typedef agg::pixfmt_rgba32_plain pixfmt;
typedef agg::renderer_base<pixfmt> renderer_base;
// define some stuff we'll use soon