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implement display rotation #18

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24 changes: 24 additions & 0 deletions ssd1306.c
Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@ bool ssd1306_init(ssd1306_t *p, uint16_t width, uint16_t height, uint8_t address
p->height=height;
p->pages=height/8;
p->address=address;
p->rotation=ROT_0;

p->i2c_i=i2c_instance;

Expand Down Expand Up @@ -140,13 +141,36 @@ inline void ssd1306_clear(ssd1306_t *p) {
memset(p->buffer, 0, p->bufsize);
}

inline void ssd1306_set_rotation(ssd1306_t *p, rotation_t rotation) {
p->rotation = rotation;
}

void rotate_coordinates(ssd1306_t *p, uint32_t* x, uint32_t* y) {
uint32_t tmp_x = *x;
if(p->rotation == ROT_90) {
*x = p->height - *y - 1;
*y = tmp_x;
} else if(p->rotation == ROT_180) {
*x = p->width - *x - 1;
*y = p->height - *y - 1;
} else if(p->rotation == ROT_270) {
*x = *y;
*y = p->width - tmp_x - 1;
}
// Keep coordinates as is for ROT_0
}

void ssd1306_clear_pixel(ssd1306_t *p, uint32_t x, uint32_t y) {
rotate_coordinates(p, &x, &y);

if(x>=p->width || y>=p->height) return;

p->buffer[x+p->width*(y>>3)]&=~(0x1<<(y&0x07));
}

void ssd1306_draw_pixel(ssd1306_t *p, uint32_t x, uint32_t y) {
rotate_coordinates(p, &x, &y);

if(x>=p->width || y>=p->height) return;

p->buffer[x+p->width*(y>>3)]|=0x1<<(y&0x07); // y>>3==y/8 && y&0x7==y%8
Expand Down
20 changes: 20 additions & 0 deletions ssd1306.h
Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,17 @@ typedef enum {
SET_CHARGE_PUMP = 0x8D
} ssd1306_command_t;

/**
* @brief defines rotations/orientations
*/
typedef enum {
ROT_0 = 0,
ROT_90 = 1,
ROT_180 = 2,
ROT_270 = 3,
} rotation_t;


/**
* @brief holds the configuration
*/
Expand All @@ -68,6 +79,7 @@ typedef struct {
bool external_vcc; /**< whether display uses external vcc */
uint8_t *buffer; /**< display buffer */
size_t bufsize; /**< buffer size */
rotation_t rotation; /**< rotation of display */
} ssd1306_t;

/**
Expand Down Expand Up @@ -143,6 +155,14 @@ void ssd1306_show(ssd1306_t *p);
*/
void ssd1306_clear(ssd1306_t *p);

/**
@brief sets the rotation for

@param[in] p : instance of display
@param[in] rotation : rotation angle
*/
void ssd1306_set_rotation(ssd1306_t *p, rotation_t rotation);

/**
@brief clear pixel on buffer

Expand Down