feat(indev) change the prototype of indev read_cb

Instead of returning bool to indicate that there is more data to read
set data->continue_reading = true.
It's less error porne because if the user doesn't set the flag the indev will be read once
which is usually the inteded behaviour.

examples/porting/lv_port_indev_template.c

@@ -24,17 +24,17 @@
  **********************/
 
 static void touchpad_init(void);
-static bool touchpad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
+static void touchpad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
 static bool touchpad_is_pressed(void);
 static void touchpad_get_xy(lv_coord_t * x, lv_coord_t * y);
 
 static void mouse_init(void);
-static bool mouse_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
+static void mouse_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
 static bool mouse_is_pressed(void);
 static void mouse_get_xy(lv_coord_t * x, lv_coord_t * y);
 
 static void keypad_init(void);
-static bool keypad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
+static void keypad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
 static uint32_t keypad_get_key(void);
 
 static void encoder_init(void);
@@ -42,7 +42,7 @@ static bool encoder_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
 static void encoder_handler(void);
 
 static void button_init(void);
-static bool button_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
+static void button_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
 static int8_t button_get_pressed_id(void);
 static bool button_is_pressed(uint8_t id);
 
@@ -185,7 +185,7 @@ static void touchpad_init(void)
 }
 
 /*Will be called by the library to read the touchpad*/
-static bool touchpad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
+static void touchpad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
 {
     static lv_coord_t last_x = 0;
     static lv_coord_t last_y = 0;
@@ -201,9 +201,6 @@ static bool touchpad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
     /*Set the last pressed coordinates*/
     data->point.x = last_x;
     data->point.y = last_y;
-
-    /*Return `false` because we are not buffering and no more data to read*/
-    return false;
 }
 
 /*Return true is the touchpad is pressed*/
@@ -234,7 +231,7 @@ static void mouse_init(void)
 }
 
 /*Will be called by the library to read the mouse*/
-static bool mouse_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
+static void mouse_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
 {
     /*Get the current x and y coordinates*/
     mouse_get_xy(&data->point.x, &data->point.y);
@@ -245,9 +242,6 @@ static bool mouse_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
     } else {
         data->state = LV_INDEV_STATE_REL;
     }
-
-    /*Return `false` because we are not buffering and no more data to read*/
-    return false;
 }
 
 /*Return true is the mouse button is pressed*/
@@ -278,7 +272,7 @@ static void keypad_init(void)
 }
 
 /*Will be called by the library to read the mouse*/
-static bool keypad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
+static void keypad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
 {
     static uint32_t last_key = 0;
 
@@ -315,9 +309,6 @@ static bool keypad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
     }
 
     data->key = last_key;
-
-    /*Return `false` because we are not buffering and no more data to read*/
-    return false;
 }
 
 /*Get the currently being pressed key.  0 if no key is pressed*/
@@ -339,14 +330,11 @@ static void encoder_init(void)
 }
 
 /*Will be called by the library to read the encoder*/
-static bool encoder_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
+static void encoder_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
 {
 
     data->enc_diff = encoder_diff;
     data->state = encoder_state;
-
-    /*Return `false` because we are not buffering and no more data to read*/
-    return false;
 }
 
 /*Call this function in an interrupt to process encoder events (turn, press)*/
@@ -369,7 +357,7 @@ static void button_init(void)
 }
 
 /*Will be called by the library to read the button*/
-static bool button_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
+static void button_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
 {
 
     static uint8_t last_btn = 0;
@@ -386,9 +374,6 @@ static bool button_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
 
     /*Save the last pressed button's ID*/
     data->btn_id = last_btn;
-
-    /*Return `false` because we are not buffering and no more data to read*/
-    return false;
 }
 
 /*Get ID  (0, 1, 2 ..) of the pressed button*/

src/core/lv_indev.c

@@ -76,10 +76,11 @@ void lv_indev_read_timer_cb(lv_timer_t * timer)
     indev_proc_reset_query_handler(indev_act);
 
     if(indev_act->proc.disabled) return;
-    bool more_to_read;
+    bool continue_reading;
     do {
         /*Read the data*/
-        more_to_read = _lv_indev_read(indev_act, &data);
+        _lv_indev_read(indev_act, &data);
+        continue_reading = data.continue_reading;
 
         /*The active object might deleted even in the read function*/
         indev_proc_reset_query_handler(indev_act);
@@ -109,7 +110,7 @@ void lv_indev_read_timer_cb(lv_timer_t * timer)
         }
         /*Handle reset query if it happened in during processing*/
         indev_proc_reset_query_handler(indev_act);
-    } while(more_to_read);
+    } while(continue_reading);
 
     /*End of indev processing, so no act indev*/
     indev_act     = NULL;

src/hal/lv_hal_indev.c

@@ -127,12 +127,9 @@ lv_indev_t * lv_indev_get_next(lv_indev_t * indev)
  * Read data from an input device.
  * @param indev pointer to an input device
  * @param data input device will write its data here
- * @return false: no more data; true: there more data to read (buffered)
  */
-bool _lv_indev_read(lv_indev_t * indev, lv_indev_data_t * data)
+void _lv_indev_read(lv_indev_t * indev, lv_indev_data_t * data)
 {
-    bool cont = false;
-
     lv_memset_00(data, sizeof(lv_indev_data_t));
 
     /* For touchpad sometimes users don't set the last pressed coordinate on release.
@@ -152,13 +149,11 @@ bool _lv_indev_read(lv_indev_t * indev, lv_indev_data_t * data)
 
     if(indev->driver->read_cb) {
         INDEV_TRACE("calling indev_read_cb");
-        cont = indev->driver->read_cb(indev->driver, data);
+        indev->driver->read_cb(indev->driver, data);
     }
     else {
         LV_LOG_WARN("indev_read_cb is not registered");
     }
-
-    return cont;
 }
 
 /**********************

src/hal/lv_hal_indev.h

@@ -81,6 +81,7 @@ typedef struct {
     int16_t enc_diff; /**< For LV_INDEV_TYPE_ENCODER number of steps since the previous read*/
 
     lv_indev_state_t state; /**< LV_INDEV_STATE_REL or LV_INDEV_STATE_PR*/
+    bool continue_reading;  /**< Call the read callback until it's set to true*/
 } lv_indev_data_t;
 
 /** Initialized by the user and registered by 'lv_indev_add()'*/
@@ -89,10 +90,8 @@ typedef struct _lv_indev_drv_t {
     /**< Input device type*/
     lv_indev_type_t type;
 
-    /**< Function pointer to read input device data.
-     * Return 'true' if there is more data to be read (buffered).
-     * Most drivers can safely return 'false'*/
-    bool (*read_cb)(struct _lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
+    /**< Function pointer to read input device data.*/
+    void (*read_cb)(struct _lv_indev_drv_t * indev_drv, lv_indev_data_t * data);
 
     /** Called when an action happened on the input device.
      * The second parameter is the event from `lv_event_t`*/
@@ -220,9 +219,8 @@ lv_indev_t * lv_indev_get_next(lv_indev_t * indev);
  * Read data from an input device.
  * @param indev pointer to an input device
  * @param data input device will write its data here
- * @return false: no more data; true: there more data to read (buffered)
  */
-bool _lv_indev_read(lv_indev_t * indev, lv_indev_data_t * data);
+void _lv_indev_read(lv_indev_t * indev, lv_indev_data_t * data);
 
 /**********************
  *      MACROS