feat(lcd_touch): support trank id (BSP-536)

[lijunru-hub]

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link #358

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[espzav]

We cannot change API. We can create another function with similar API.

[espzav]

We cannot change API. We can create another function with similar API.

[lijunru-hub]

What would be a good name for the new function?

The current function name is static bool esp_lcd_touch_ft5x06_get_xy.

[espzav]

We have two options for it:

1. bool esp_lcd_touch_get_coordinates_track_id(esp_lcd_touch_handle_t tp, uint8_t *track_id);
2. bool esp_lcd_touch_get_coordinates_track_id(esp_lcd_touch_handle_t tp, uint16_t *x, uint16_t *y, uint16_t *strength, uint8_t *track_id, uint8_t *point_num, uint8_t max_point_num)

Same for bool (*get_xy)(...) and callback void (*process_coordinates)(...)

[lijunru-hub]

However, the touch chip actually supports some additional special features. For example, the FT5x06 can indicate whether a swipe is to the left or right, and whether each touch point is currently being pressed or swiped, among other things. It would be best to address these issues all at once and lay the groundwork for future requirements.

bool esp_lcd_touch_get_coordinates_data(esp_lcd_touch_handle_t tp, void *data)
{
   ft5x06_data_t *ft_data = (ft5x06_data_t *)data；
   // ft_data->x[i]
   // ft_data->trank_id
   //...
}

[espzav]

It is good idea, but it looks little dangerous use void type and we don't know const count of touches.

We can do something like this:

typedef struct {
   uint16_t x;
   uint16_t y;
   uint16_t strength;
   uint16_t track_id;
   void * user_data;
} esp_lcd_touch_coordinates_data_t;

bool esp_lcd_touch_get_coordinates_data(esp_lcd_touch_handle_t tp, esp_lcd_touch_coordinates_data_t * data, uint8_t *point_num, uint8_t max_point_num);

Usage:

esp_lcd_touch_coordinates_data_t data[4];
uint8_t points = 0;
esp_lcd_touch_get_coordinates_data(tp, data, &points, sizeof(data)/sizeof(esp_lcd_touch_coordinates_data_t));

Note: This structure can be very easily extended in future. And any driver can use user_data for specific strusture. There should be any data type check (I don't know, if it is possible in C - something like compare typeof())

@igrr @tore-espressif What do you think about this solution?

[lijunru-hub]

How about handling everything within a struct?

typedef struct {
uint16_t x;
uint16_t y;
uint16_t strength;
uint16_t track_id;
} point_data_t;

typedef struct {
esp_lcd_touch_gesture_t gesture_id;
point_data_t *data;
uint32_t num_points;
} esp_lcd_touch_coordinates_data_t;

However, it's important to note that not every chip has all of this information

[espzav]

As you said, some features are not supported in all chips, I think the gestures should be in own function and we can return NOT_SUPPORTED error.

[tore-espressif]

And any driver can use user_data for specific structure. There should be any data type check (I don't know, if it is possible in C - something like compare typeof())

If we want to return device specific data, this should be handled in the specific touch driver eg. esp_lcd_touch_ft5x06 and NOT in esp_lcd_touch base component. C language does not have runtime type information

So there are 2 types of returned data

1. somewhat common across different touch controllers (eg. track_id). These could be added to base esp_lcd_touch with a function similar to esp_lcd_touch_get_coordinates_data
2. Specific to the touch driver e.g. gestures. These function should be added to the specific touch driver eg. esp_lcd_touch_ft5x06_gesture()

What do you think?

[espzav]

2. Specific to the touch driver e.g. gestures. These function should be added to the specific touch driver eg. esp_lcd_touch_ft5x06_gesture()

Are gestures specific for touch driver? Aren't it more common over lot of drivers?

[tore-espressif]

Are gestures specific for touch driver? Aren't it more common over lot of drivers?

🤷‍♂️ :D

If yes, let's make it all common