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add clamp(v, min, max) function + clamp opacity in ctor

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This commit is contained in:
artemp 2015-05-14 10:43:25 +01:00
parent c3dfda4977
commit 78c56968c1
1 changed files with 11 additions and 12 deletions
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23
src/image_util.cpp
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@ -624,23 +624,24 @@ template MAPNIK_DECL void set_premultiplied_alpha(image_gray64f &, bool);
namespace detail {
namespace {
template <typename T>
inline double clamp(T d, T min, T max)
{
const T t = d < min ? min : d;
return t > max ? max : t;
}
}
struct visitor_set_alpha
{
visitor_set_alpha(float opacity)
: opacity_(opacity) {}
: opacity_(clamp(opacity, 0.0f, 1.0f)) {}
void operator() (image_rgba8 & data)
{
using pixel_type = image_rgba8::pixel_type;
if (opacity_ > 1.0)
{
opacity_ = 1.0;
}
if (opacity_ < 0.0)
{
opacity_ = 0.0;
}
pixel_type a1 = static_cast<pixel_type>(255.0 * opacity_);
for (unsigned int y = 0; y < data.height(); ++y)
{
@ -649,7 +650,6 @@ struct visitor_set_alpha
{
pixel_type rgba = row_to[x];
pixel_type a0 = (rgba >> 24) & 0xff;
//unsigned a1 = opacity;
if (a0 == a1) continue;
pixel_type r = rgba & 0xff;
@ -669,7 +669,6 @@ struct visitor_set_alpha
private:
float opacity_;
};
} // end detail ns