LV_EVENT_CLICKED should only be fired if the release takes place over the same object where the press happened

[Viatorus]

LVGL version

9.0.0

What happened?

If a user tries to scroll although scrolling is not possible, unwanted click events occur at the point where the user started scrolling. Even though, the release position happend at a different object.

Think on a list of buttons which is sometimes scrollable, sometimes not.

I don't know of such behavior anywhere on Windows, Linux, Web or Android. If you leave the clickable, no click will happen.

P.S. Thank you for already fixing this: #5660

How to reproduce?

Run the code below.
Press the button, than leave the button area and release the mouse. "Clicked" will is printed in the console.

Simulator: https://sim.lvgl.io/v9.0/micropython/ports/webassembly/index.html

# Initialize

import display_driver
import lvgl as lv

# Create a button with a label

    
def event_cb(e):
        print("Clicked")

scr = lv.obj()
btn = lv.button(scr)
btn.align(lv.ALIGN.CENTER, 0, 0)
btn.add_event_cb(event_cb, lv.EVENT.CLICKED, None)
label = lv.label(btn)
label.set_text('Hello World!')
lv.screen_load(scr)

[liamHowatt]

I confirmed this is still a thing in the latest master.

C equivalent for reference

static void cl_cb(lv_event_t * e)
{
    LV_LOG_USER("clicked");
}
static void click_scroll(void)
{
    lv_obj_t * btn = lv_button_create(lv_screen_active());
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, 0);
    lv_obj_add_event_cb(btn, cl_cb, LV_EVENT_CLICKED, NULL);
    lv_label_set_text(lv_label_create(btn), "Hello World!");
}

list of buttons in Micropython

# Initialize

import display_driver
import lvgl as lv

# Create a button with a label

    
def make_cb(i):
    return lambda e: print("Clicked", i)

scr = lv.obj()

scr.set_flex_flow(lv.FLEX_FLOW.COLUMN)
for i in range(20):
    btn = lv.button(scr)
    btn.align(lv.ALIGN.CENTER, 0, 0)
    btn.add_event_cb(make_cb(i), lv.EVENT.CLICKED, None)
    label = lv.label(btn)
    label.set_text(str(i).center(20))
    lv.screen_load(scr)

This change in lv_indev.c seems to give the desired effect. On release, if we did not scroll, and we're still over the object, send the click.

@kisvegabor, is a PR in order?

diff --git a/src/indev/lv_indev.c b/src/indev/lv_indev.c
index 08ff5be07..e18b81d14 100644
--- a/src/indev/lv_indev.c
+++ b/src/indev/lv_indev.c
@@ -1310,7 +1310,7 @@ static void indev_proc_release(lv_indev_t * indev)
         }
 
         if(is_enabled) {
-            if(scroll_obj == NULL) {
+            if(scroll_obj == NULL && lv_obj_hit_test(indev_obj_act, &indev->pointer.act_point)) {
                 if(indev->long_pr_sent == 0) {
                     if(send_event(LV_EVENT_SHORT_CLICKED, indev_act) == LV_RESULT_INVALID) return;
                 }

[kisvegabor]

Hi,

It can be controlled by LV_OBJ_FLAG_PRESS_LOCK:

btn.remove_flag(btn.FLAG.PRESS_LOCK)

[Viatorus]

Oh, thank you!