Handout
This commit is contained in:
Niklas Gollenstede
317
kernel/graphics/framebuffer.h
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317
kernel/graphics/framebuffer.h
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/*! \file
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* \brief \ref Framebuffer implementing primitive graphic operations
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*/
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#pragma once
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#include "../types.h"
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#include "../utils/string.h"
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#include "primitives.h"
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/*! \brief Implementation of primitive operations on a memory area used as
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* framebuffer.
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* \ingroup gfx
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*
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* The implementation as template class allows the compiler to heavily optimize
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* the bit operations depending on the video mode.
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*
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* \tparam COLORDEPTH color depth of video mode
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* \tparam OFFSET_RED Bit position of red color mask in video mode
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* \tparam OFFSET_GREEN Bit position of green color mask in video mode
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* \tparam OFFSET_BLUE Bit position of blue color mask in video mode
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* \tparam BITS_RED Size of red color mask in video mode
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* \tparam BITS_GREEN Size of green color mask in video mode
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* \tparam BITS_BLUE Size of blue color mask in video mode
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*/
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template <unsigned char COLORDEPTH, unsigned char OFFSET_RED,
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unsigned char OFFSET_GREEN, unsigned char OFFSET_BLUE,
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unsigned char BITS_RED, unsigned char BITS_GREEN,
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unsigned char BITS_BLUE>
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class Framebuffer {
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/*! \brief Start address of the linear framebuffer
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*/
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uintptr_t framebuffer;
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/*! \brief Internal width of the screen
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*
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* At least the visible width of the screen, depends on the hardware but
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* required for calculating the rows
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*/
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unsigned pitch;
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protected:
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/*! \brief Visible width of the screen
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*/
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unsigned screen_width;
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/*! \brief Visible height of the screen
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*/
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unsigned screen_height;
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/*! \brief Initialize screen dimensions
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*
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* \param width visible width of graphics screen
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* \param height visible height of graphics screen
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* \param pitch width of graphics screen (including invisible part, has to
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* be at least `width`)
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*/
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void init(const unsigned width, const unsigned height,
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const unsigned pitch) {
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this->screen_width = width;
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this->screen_height = height;
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this->pitch = pitch;
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}
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/*! \brief Set the video memory address
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*
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* \param lfb pointer to the linear framebuffer (lfb)
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*/
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void buffer(void *lfb) { framebuffer = reinterpret_cast<uintptr_t>(lfb); }
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/*! \brief Clear all pixel of the current back buffer
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* (set full screen to black)
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*/
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void clear() {
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memset(reinterpret_cast<void *>(framebuffer), 0, screen_height * pitch);
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}
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/*! \brief Pixel component
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*
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* \tparam OFFSET Bit position of mask
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* \tparam BITS Size of mask
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*/
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template <unsigned OFFSET, unsigned SIZE>
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class PixelComponent {
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unsigned : OFFSET; ///< Reserved space for offset
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unsigned value : SIZE; ///< Value
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public:
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/*! \brief Constructor
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*
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* \param value Initial component value
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*/
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explicit PixelComponent(unsigned value) : value(value) {}
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/*! \brief Assign component value
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* (from a \ref SpritePixelComponent with different bit mask size)
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*
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* \tparam BITS Size of bit mask
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* \param other new component value
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*/
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template <unsigned BITS>
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void set(const struct SpritePixelComponent<BITS> &other) {
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value = BITS > SIZE ? (other.value >> (BITS - SIZE))
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: (other.value << (SIZE - BITS));
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}
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/*! \brief Assign component value
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* (from a \ref SpritePixelComponent with same bit mask size)
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*
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* \param other new component value
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*/
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void set(const struct SpritePixelComponent<SIZE> &other) {
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value = other.value;
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}
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/*! \brief Assign component value
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* (from an integer)
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*
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* \param value new component value
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*/
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void set(unsigned value) {
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value = 8 > SIZE ? (value >> (8 - SIZE)) : (value << (SIZE - 8));
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}
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/*! \brief Alpha blend component value
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* (from a \ref SpritePixelComponent with different bit mask size)
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*
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* \tparam BITS Size of bit mask
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* \param other component value to blend
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* \param alpha transparency used for blending
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*/
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template <unsigned BITS>
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void blend(const struct SpritePixelComponent<BITS> &other,
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const struct SpritePixelComponent<BITS> &alpha) {
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int other_value = BITS > SIZE ? (other.value >> (BITS - SIZE))
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: (other.value << (SIZE - BITS));
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int other_alpha = BITS > SIZE ? (alpha.value >> (BITS - SIZE))
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: (alpha.value << (SIZE - BITS));
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value +=
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((other_value - static_cast<int>(value)) * other_alpha) >> SIZE;
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}
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/*! \brief Alpha blend component value
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* (from a \ref SpritePixelComponent with same bit mask size)
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*
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* \param other component value to blend
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* \param alpha transparency used for blending
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*/
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void blend(const struct SpritePixelComponent<SIZE> &other,
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const struct SpritePixelComponent<SIZE> &alpha) {
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value +=
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((static_cast<int>(other.value) - static_cast<int>(value)) *
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alpha.value) >>
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SIZE;
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}
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} __attribute__((packed));
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/*! \brief Pixel (colored)
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*/
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union Pixel {
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/*! \brief Bits per pixel
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*/
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struct {
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unsigned data : COLORDEPTH; ///< RGB value
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} __attribute__((packed));
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PixelComponent<OFFSET_RED, BITS_RED> red; ///< Red color component
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PixelComponent<OFFSET_GREEN, BITS_GREEN>
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green; ///< Green color component
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PixelComponent<OFFSET_BLUE, BITS_BLUE> blue; ///< Blue color component
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/*! \brief Constructor (using RGB value)
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*
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* \param data RGB value
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*/
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explicit Pixel(const unsigned data) : data(data) {}
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/*! \brief Constructor (using explicit RGB components)
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*
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* Unused bits are zeroed.
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*
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* \param r Red color component
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* \param g Green color component
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* \param b Blue color component
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*/
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Pixel(const unsigned r, const unsigned g, const unsigned b) : data(0) {
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red.set(r);
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green.set(g);
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blue.set(b);
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}
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/*! \brief Constructor (using \ref SpritePixel)
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*
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* \tparam ALPHA `true` if alpha channel
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* \tparam BITS Size of mask
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* \param other other
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*/
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template <bool ALPHA, unsigned BITS>
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explicit Pixel(const struct SpritePixel<RGB, ALPHA, BITS> &other) {
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red.set(other.red);
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green.set(other.green);
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blue.set(other.blue);
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}
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/*! \brief Get color of pixel
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*
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* \return color of pixel
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*/
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Color getColor() const { return Color(red, green, blue); }
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/*! \brief Assign pixel (with colored \ref SpritePixel)
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*
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* \tparam BITS Size of other pixels mask
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* \param other other pixel
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*/
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template <unsigned BITS>
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Pixel &operator=(const struct SpritePixel<RGB, false, BITS> &other) {
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red.set(other.red);
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green.set(other.green);
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blue.set(other.blue);
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return *this;
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}
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/*! \brief Assign pixel (with greyscale \ref SpritePixel)
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*
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* \tparam BITS Size of other pixels mask
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* \param other other pixel
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*/
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template <unsigned BITS>
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Pixel &operator=(
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const struct SpritePixel<GREYSCALE, false, BITS> &other) {
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red.set(other.luminance);
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green.set(other.luminance);
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blue.set(other.luminance);
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return *this;
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}
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/*! \brief Assign pixel (with greyscale \ref SpritePixel supporting
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* transparency)
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*
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* \tparam BITS Size of other pixels mask
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* \param other other pixel
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*/
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template <unsigned BITS>
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Pixel &operator=(const struct SpritePixel<RGB, true, BITS> &other) {
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red.blend(other.red, other.alpha);
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green.blend(other.green, other.alpha);
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blue.blend(other.blue, other.alpha);
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return *this;
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}
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/*! \brief Assign pixel (with greyscale \ref SpritePixel supporting
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* transparency)
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*
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* \tparam BITS Size of other pixels mask
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* \param other other pixel
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*/
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template <unsigned BITS>
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Pixel &operator=(
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const struct SpritePixel<GREYSCALE, true, BITS> &other) {
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red.blend(other.luminance, other.alpha);
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green.blend(other.luminance, other.alpha);
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blue.blend(other.luminance, other.alpha);
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return *this;
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}
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} __attribute__((packed));
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static_assert(OFFSET_RED + BITS_RED <= COLORDEPTH &&
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OFFSET_GREEN + BITS_GREEN <= COLORDEPTH &&
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OFFSET_BLUE + BITS_BLUE <= COLORDEPTH,
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"color settings invalid!");
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/*! \brief Get pixel at position
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*
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* \param x X position
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* \param y Y position
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* \return Pointer to pixel
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*/
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Pixel *get(const unsigned x, const unsigned y) const {
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return reinterpret_cast<Pixel *>(framebuffer + y * pitch) + x;
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}
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/*! \brief Get pixel at position
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*
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* \param p Coordinate of position
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* \return Pointer to pixel
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*/
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Pixel *get(const Point &p) const { return get(p.x, p.y); }
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/*! \brief Assign color to a pixel at a given position
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*
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* \tparam COLOR color or greyscale?
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* \tparam ALPHA with transparency?
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* \tparam BITS Size of mask
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* \param x X position
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* \param y Y position
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* \param color color to assign
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*/
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template <enum SpriteColorMode COLOR, bool ALPHA, unsigned BITS>
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void set(const unsigned x, const unsigned y,
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const SpritePixel<COLOR, ALPHA, BITS> &color) {
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Pixel *pos = get(x, y);
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*pos = color;
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}
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/*! \brief Assign color to a pixel at a given position
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*
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* \tparam COLOR color or greyscale?
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* \tparam ALPHA with transparency?
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* \tparam BITS Size of mask
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* \param p Coordinate of position
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* \param color color to assign
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*/
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template <enum SpriteColorMode COLOR, bool ALPHA, unsigned BITS>
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void set(const Point &p, const SpritePixel<COLOR, ALPHA, BITS> &color) {
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set(p.x, p.y, color);
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}
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};
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