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#include "pixelbuffer.h"
#include <cassert>
namespace GUI {
PixelBuffer::PixelBuffer(size_t width, size_t height)
: buf(nullptr)
{
realloc(width, height);
}
PixelBuffer::~PixelBuffer()
{
free(buf);
}
void PixelBuffer::realloc(size_t width, size_t height)
{
free(buf);
buf = (unsigned char *)calloc(width * height, 3);
this->width = width;
this->height = height;
}
#define PX(k) ((x + y * width) * 3 + k)
void PixelBuffer::setPixel(size_t x, size_t y,
unsigned char red,
unsigned char green,
unsigned char blue,
unsigned char alpha)
{
assert(x < width);
assert(y < height);
unsigned int a = alpha;
unsigned int b = 255 - alpha;
buf[PX(0)] = (unsigned char)(((int)red * a + (int)buf[PX(0)] * b) / 255);
buf[PX(1)] = (unsigned char)(((int)green * a + (int)buf[PX(1)] * b) / 255);
buf[PX(2)] = (unsigned char)(((int)blue * a + (int)buf[PX(2)] * b) / 255);
}
PixelBufferAlpha::PixelBufferAlpha(size_t width, size_t height)
: buf(nullptr)
, x(0)
, y(0)
{
realloc(width, height);
}
PixelBufferAlpha::~PixelBufferAlpha()
{
free(buf);
}
void PixelBufferAlpha::realloc(size_t width, size_t height)
{
free(buf);
buf = (unsigned char *)calloc(width * height, 4);
this->width = width;
this->height = height;
}
#undef PX
#define PX(k) ((x + y * width) * 4 + k)
void PixelBufferAlpha::setPixel(size_t x, size_t y,
unsigned char red,
unsigned char green,
unsigned char blue,
unsigned char alpha)
{
assert(x < width);
assert(y < height);
buf[PX(0)] = red;
buf[PX(1)] = green;
buf[PX(2)] = blue;
buf[PX(3)] = alpha;
}
static inline void getAlpha(unsigned char _a, unsigned char _b,
float &a, float &b)
{
a = _a / 255.0;
b = _b / 255.0;
b *= (1 - a);
}
void PixelBufferAlpha::addPixel(size_t x, size_t y,
unsigned char red,
unsigned char green,
unsigned char blue,
unsigned char alpha)
{
assert(x < width);
assert(y < height);
if(alpha == 0)
{
return;
}
float a, b;
getAlpha(alpha, buf[PX(3)], a, b);
buf[PX(0)] = (unsigned char)((float)red * a + (float)buf[PX(0)] * b);
buf[PX(0)] /= (a + b);
buf[PX(1)] = (unsigned char)((float)green * a + (float)buf[PX(1)] * b);
buf[PX(1)] /= (a + b);
buf[PX(2)] = (unsigned char)((float)blue * a + (float)buf[PX(2)] * b);
buf[PX(2)] /= (a + b);
buf[PX(3)] = (a + b) * 255;
}
void PixelBufferAlpha::addPixel(size_t x, size_t y, const Colour& c)
{
addPixel(x, y,
c.red() * 255, c.green() * 255, c.blue() * 255, c.alpha() * 255);
}
void PixelBufferAlpha::pixel(size_t x, size_t y,
unsigned char* red,
unsigned char* green,
unsigned char* blue,
unsigned char* alpha)
{
assert(x < width);
assert(y < height);
*red = buf[PX(0)];
*green = buf[PX(1)];
*blue = buf[PX(2)];
*alpha = buf[PX(3)];
}
}
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