color_dither.h

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/*
 * SPDX-FileCopyrightText: Copyright The Zephyr Project Contributors
 * SPDX-License-Identifier: Apache-2.0
 */

 
#ifndef ZEPHYR_INCLUDE_DRIVERS_DISPLAY_COLOR_DITHER_H_
#define ZEPHYR_INCLUDE_DRIVERS_DISPLAY_COLOR_DITHER_H_

 
#include <zephyr/drivers/display.h>
#include <zephyr/sys/util.h>
 
#ifdef __cplusplus
extern "C" {
#endif

struct display_color_dither_rgb_error {
        int16_t r; 
        int16_t g; 
        int16_t b; 
};
 
#if defined(CONFIG_DISPLAY_COLOR_DITHER_DEFAULT_RGB888)
#define COLOR_DITHER_DEFAULT_FMT PIXEL_FORMAT_RGB_888
#elif defined(CONFIG_DISPLAY_COLOR_DITHER_DEFAULT_RGB565)
#define COLOR_DITHER_DEFAULT_FMT PIXEL_FORMAT_RGB_565
#else
#define COLOR_DITHER_DEFAULT_FMT PIXEL_FORMAT_I_4
#endif
 
#define COLOR_DITHER_I4_BYTES(w, h) (DIV_ROUND_UP((w), 2U) * (h))
 
/*
 * Per-instance row buffers for the error-diffusion algorithms only.
 */
#if defined(CONFIG_DISPLAY_COLOR_DITHER_ALGORITHM_ATKINSON)
#define COLOR_DITHER_ERRDIFF_NROWS 3
#elif defined(CONFIG_DISPLAY_COLOR_DITHER_ALGORITHM_FLOYD_STEINBERG)
#define COLOR_DITHER_ERRDIFF_NROWS 2
#else
#define COLOR_DITHER_ERRDIFF_NROWS 0
#endif
 
#if COLOR_DITHER_ERRDIFF_NROWS > 0
#define COLOR_DITHER_ERRDIFF_LEN(w)   ((w) + 2U)
#define COLOR_DITHER_ERRDIFF_ROW(tag) color_dither_errdiff_row_##tag
 
#define COLOR_DITHER_ERRDIFF_DEFINE(tag, w)                                                        \
        static struct display_color_dither_rgb_error COLOR_DITHER_ERRDIFF_ROW(                     \
                tag)[COLOR_DITHER_ERRDIFF_NROWS][COLOR_DITHER_ERRDIFF_LEN(w)]
#define COLOR_DITHER_ERRDIFF_R0(tag) COLOR_DITHER_ERRDIFF_ROW(tag)[0]
#define COLOR_DITHER_ERRDIFF_R1(tag) COLOR_DITHER_ERRDIFF_ROW(tag)[1]
#if COLOR_DITHER_ERRDIFF_NROWS >= 3
#define COLOR_DITHER_ERRDIFF_R2(tag) COLOR_DITHER_ERRDIFF_ROW(tag)[2]
#else
#define COLOR_DITHER_ERRDIFF_R2(tag) NULL
#endif
 
#else /* no error-diffusion algorithm selected */
#define COLOR_DITHER_ERRDIFF_DEFINE(tag, w)
#define COLOR_DITHER_ERRDIFF_LEN(w)  0U
#define COLOR_DITHER_ERRDIFF_R0(tag) NULL
#define COLOR_DITHER_ERRDIFF_R1(tag) NULL
#define COLOR_DITHER_ERRDIFF_R2(tag) NULL
#endif


struct display_color_dither_state {
#if defined(CONFIG_DISPLAY_COLOR_DITHER)
        enum display_pixel_format input_format;
        uint8_t *converted_buf;
        size_t converted_buf_size;
        struct display_color_dither_rgb_error *err_rows[3];
        size_t err_row_len;
#elif defined(CONFIG_CPP)
        /* An empty struct is not valid C, and compilers that accept it give
         * it size 0 while C++ gives 1. Keep a byte so both languages agree.
         */
        uint8_t c;
#endif /* CONFIG_DISPLAY_COLOR_DITHER */
};
 
#if defined(CONFIG_DISPLAY_COLOR_DITHER) || defined(__DOXYGEN__)

#define DISPLAY_COLOR_DITHER_DEFINE(inst)                                                          \
        static uint8_t color_dither_buf_##inst[COLOR_DITHER_I4_BYTES(DT_INST_PROP(inst, width),    \
                                                                     DT_INST_PROP(inst, height))]; \
        COLOR_DITHER_ERRDIFF_DEFINE(inst, DT_INST_PROP(inst, width))

#define DISPLAY_COLOR_DITHER_INIT(inst)                                                            \
        {                                                                                          \
                .input_format = COLOR_DITHER_DEFAULT_FMT,                                          \
                .converted_buf = color_dither_buf_##inst,                                          \
                .converted_buf_size = sizeof(color_dither_buf_##inst),                             \
                .err_rows =                                                                        \
                        {                                                                          \
                                COLOR_DITHER_ERRDIFF_R0(inst),                                     \
                                COLOR_DITHER_ERRDIFF_R1(inst),                                     \
                                COLOR_DITHER_ERRDIFF_R2(inst),                                     \
                        },                                                                         \
                .err_row_len = COLOR_DITHER_ERRDIFF_LEN(DT_INST_PROP(inst, width)),                \
        }

int display_color_dither_prepare(const struct device *dev, struct display_color_dither_state *state,
                                 const struct display_buffer_descriptor **desc, const void **buf,
                                 struct display_buffer_descriptor *scratch);

void display_color_dither_patch_caps(struct display_color_dither_state *state,
                                     struct display_capabilities *caps);

int display_color_dither_set_input_format(struct display_color_dither_state *state,
                                          enum display_pixel_format pf);

bool display_color_dither_is_active(const struct display_color_dither_state *state,
                                    enum display_pixel_format current_pixel_format);
 
#else /* !CONFIG_DISPLAY_COLOR_DITHER */

 
#define DISPLAY_COLOR_DITHER_DEFINE(inst)
#define DISPLAY_COLOR_DITHER_INIT(inst)                                                            \
        {                                                                                          \
        }
 
static inline int display_color_dither_prepare(const struct device *dev,
                                               struct display_color_dither_state *state,
                                               const struct display_buffer_descriptor **desc,
                                               const void **buf,
                                               struct display_buffer_descriptor *scratch)
{
        (void)dev;
        (void)state;
        (void)desc;
        (void)buf;
        (void)scratch;
 
        return 0;
}
 
static inline void display_color_dither_patch_caps(struct display_color_dither_state *state,
                                                   struct display_capabilities *caps)
{
        (void)state;
        (void)caps;
}
 
static inline int display_color_dither_set_input_format(struct display_color_dither_state *state,
                                                        enum display_pixel_format pf)
{
        (void)state;
 
        return pf == PIXEL_FORMAT_I_4 ? 0 : -ENOTSUP;
}
 
static inline bool display_color_dither_is_active(const struct display_color_dither_state *state,
                                                  enum display_pixel_format current_pixel_format)
{
        (void)state;
        (void)current_pixel_format;
 
        return false;
}

 
#endif /* CONFIG_DISPLAY_COLOR_DITHER */
 
#ifdef __cplusplus
}
#endif

 
#endif /* ZEPHYR_INCLUDE_DRIVERS_DISPLAY_COLOR_DITHER_H_ */