144 lines
3.8 KiB
C++
144 lines
3.8 KiB
C++
/*
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* \brief Generic pixel representation
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* \author Norman Feske
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* \date 2006-08-04
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*/
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/*
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* Copyright (C) 2006-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _INCLUDE__OS__PIXEL_RGBA_H_
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#define _INCLUDE__OS__PIXEL_RGBA_H_
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#include <os/surface.h>
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namespace Genode {
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template <typename ST, Genode::Surface_base::Pixel_format FORMAT,
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int R_MASK, int R_SHIFT,
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int G_MASK, int G_SHIFT,
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int B_MASK, int B_SHIFT,
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int A_MASK, int A_SHIFT>
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class Pixel_rgba;
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}
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/*
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* \param ST storage type of one pixel
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* \param FORMAT pixel format
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*/
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template <typename ST, Genode::Surface_base::Pixel_format FORMAT,
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int R_MASK, int R_SHIFT,
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int G_MASK, int G_SHIFT,
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int B_MASK, int B_SHIFT,
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int A_MASK, int A_SHIFT>
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class Genode::Pixel_rgba
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{
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private:
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/**
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* Shift left with positive or negative shift value
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*/
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static inline int _shift(int value, int shift) {
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return shift > 0 ? value << shift : value >> -shift; }
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public:
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static const int r_mask = R_MASK, r_shift = R_SHIFT;
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static const int g_mask = G_MASK, g_shift = G_SHIFT;
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static const int b_mask = B_MASK, b_shift = B_SHIFT;
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static const int a_mask = A_MASK, a_shift = A_SHIFT;
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ST pixel = 0;
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/**
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* Constructors
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*/
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Pixel_rgba() {}
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Pixel_rgba(int red, int green, int blue, int alpha = 255) :
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pixel((_shift(red, r_shift) & r_mask)
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| (_shift(green, g_shift) & g_mask)
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| (_shift(blue, b_shift) & b_mask)
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| (_shift(alpha, a_shift) & a_mask)) { }
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static Surface_base::Pixel_format format() { return FORMAT; }
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/**
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* Assign new rgba values
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*/
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void rgba(int red, int green, int blue, int alpha = 255)
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{
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pixel = (_shift(red, r_shift) & r_mask)
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| (_shift(green, g_shift) & g_mask)
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| (_shift(blue, b_shift) & b_mask)
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| (_shift(alpha, a_shift) & a_mask);
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}
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inline int r() const { return _shift(pixel & r_mask, -r_shift); }
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inline int g() const { return _shift(pixel & g_mask, -g_shift); }
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inline int b() const { return _shift(pixel & b_mask, -b_shift); }
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inline int a() const { return _shift(pixel & a_mask, -a_shift); }
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/**
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* Compute average color value of two pixels
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*/
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static inline Pixel_rgba avr(Pixel_rgba p1, Pixel_rgba p2);
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/**
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* Multiply pixel with alpha value
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*/
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static inline Pixel_rgba blend(Pixel_rgba pixel, int alpha);
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/**
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* Mix two pixels at the ratio specified as alpha
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*/
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static inline Pixel_rgba mix(Pixel_rgba p1, Pixel_rgba p2, int alpha);
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/**
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* Mix two pixels where p2 may be of a different pixel format
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*
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* This is useful for drawing operations that apply the same texture
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* to a pixel surface as well as an alpha surface. When drawing on the
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* alpha surface, 'p1' will be of type 'Pixel_alpha8' whereas 'p2'
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* corresponds to the pixel type of the texture.
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*/
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template <typename PT>
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static inline Pixel_rgba mix(Pixel_rgba p1, PT p2, int alpha);
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/**
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* Compute average color value of four pixels
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*/
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static inline Pixel_rgba avr(Pixel_rgba p1, Pixel_rgba p2,
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Pixel_rgba p3, Pixel_rgba p4) {
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return avr(avr(p1, p2), avr(p3, p4)); }
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/**
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* Copy pixel with alpha
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*
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* \param src source color value (e.g., obtained from a texture)
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* \param src_a alpha value corresponding to the 'src' pixel
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* \param alpha alpha value
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* \param dst destination pixel
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*/
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template <typename TPT, typename PT>
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static void transfer(TPT const &src, int src_a, int alpha, PT &dst)
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{
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if (src_a) {
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int a = (src_a * alpha)>>8;
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if (a) dst = PT::mix(dst, src, a);
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}
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}
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/**
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* Return alpha value of pixel
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*/
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int alpha();
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} __attribute__((packed));
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#endif /* _INCLUDE__OS__PIXEL_RGBA_H_ */
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