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Objects

There are two ways to create an object on the screen:

  • Uploading a pages.jsonl file onto the internal flash
  • Use the jsonl command (via MQTT, serial or telnet console)

Cheatsheet~

obj Type Description Extra Parts
btn Binary Button
switch Toggle Switch indicator, knob
checkbox Toggle Checkbox indicator
label Visual Label
led Visual LED
spinner Visual Spinner indicator
obj Visual Base Object
line Visual Line
img Visual Image
cpicker Selector Color picker knob
roller Selector Roller selected
dropdown Selector Dropdown List selected, items, scrollbar
btnmatrix Selector Button Matrix items
msgbox Selector Messagebox items, items_bg
tabview Selector Tabview items, items_bg, indicator, selected
tab Selector Tab
bar Range Progress Bar indicator
slider Range Slider indicator, knob
arc Range Arc indicator, knob
linemeter Range Line Meter
gauge Range Gauge indicator, ticks

Common Parameters~

Common Properties~

These are the common properties shared among all objects, but only the id and obj properties are required to create an object:

Property Value Default Description
id 1..254 n/a Required. ID of the object on this page. 0 for the page itself.
obj string n/a Required. Name of the object type (see below)
page 0..12 n/a ID of the page the object appears on (see below)
groupid 0..15 0 (none) ID of the GPIO group the object belongs to
x int16 0 Horizontal position on the page
y int16 0 Vertical position on the page
w int16 0 Width of the object
h int16 0 Height of the object
enabled bool true Object is touchable, if false, a disabled style is applied
hidden bool false Object is hidden
opacity uint8 255 How much the the object is opaque
swipe bool false Page navigation using swipe gestures (see below)
action string 0 Command handled locally (see below)
click bool true Object is touch/clickable (also see enabled)
ext_click_h uint8 0 Extended horizontal clickable are on the left and right
ext_click_v uint8 0 Extended vertical clickable are on the top and bottom
parentid uint8 0 Set the object to be the child of another object.
x and y will be relative to the parent object. Property inheritance can affect the appearance of the of the children (more info in styling).
tag JSONobject n/a Arbitrary attribute data. Once set, it will be included in each event message. For advanced scenarios (more info in an example).
jsonl JSONobject n/a Pseudo-property to set multiple properties of an existing object in one go with a JSON object.

Tip

Further customizable properties can be found in styling.

Ids start from 1 on each page. You can have a maximum of 254 ids on each page. You don't have to use them in ascending order, you can for example use them for logical numbering (start labels from 11, 12, 13, buttons from 21, 22, 23 etc.)

Pages~

If the page parameter is not present, the object is placed on the same page as the previous object. If page is not specified for the first object either, the current page being displayed is used.

"page":0 indicates that the object is visible on all pages. It can be used for example to specify a static menu bar. You can still hide the object on select pages if needed. Objects on page 0 appear on top of any objects on the underlying page.

Actions~

Action commands are supported only by binary or visual type of objects and they are performed locally on the plate. The following actions can be set for these objects:

  • p1 to p12 to switch to the corresponding page numbers directly
  • prev to switch to the previous page
  • next to switch to the next page
  • back to go back to the home page

Check out the example for how to implement actions.
You can change the target pages using prev, back and next page attributes operation on the page objectpXb0.

Swipe ~

Objects and page area (p0bY) support swipe property. Enabling this will process left, right and down swipes on the object as next, prev and back page changes, respectively. The start of the swipe needs to be on the element which has this property enabled for the feature to activate.

Note

Page id p0b0 is not valid to set this property as it has to be set on real elements.

Events~

All objects are touchable by default and respond to touch events. To disable touch events for an object set its enabled property to false. In this case the touch event "goes through" to the object on the layer below or to the page itself.

Events (and values) are published in a state topic corresponding to the object, eg. hasp/<nodename>/state/p1b2 with payload in json format eg. {"event":"up","val":1}.
Possible events (depending on object type) are:

Event Description
down Occurs when a button goes from depressed to pressed (the moment of touch)
up The button was released within a short time i.e. a short press has occurred
release The button is released after being pressed for over the threshold time
long Event is sent when the button is still being pressed after the threshold time of 400ms
hold The HOLD event is repeated every 200ms while the button is still pressed
changed Event is sent when the value of the object has changed during the event

Tip

To actively see the sent out events you can use an MQTT client app and subscribe to the hasp/# topic.

Common Methods~

These are the common methods shared among all objects,

Method Parameters Description
clear Delete the children from the object
delete Delete the object and its children from the page
to_front Bring the object to the front on the page
to_back Send the object to the back on the page

Example commands:

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p1b5.delete
p1b3.to_front

Object Types

Each object type is an ID that indicates which object type that line represents. Besides the common properties listed above, each object type can have specific properties.

Text Label~

obj:label

lv_label

Property Value Default Description
text string "Text" The text of the label, \n for line break. Can also be a variable.
mode string crop The wrapping mode of long text labels:
expand Expand the object size to the text size
break Keep the object width, break the too long lines and expand the object height
dots Keep the size and write dots at the end if the text is too long
scroll Keep the size and roll the text back and forth
loop Keep the size and roll the text circularly
crop Keep the size and crop the text out of it
align string left Text alignment: left, center, right

It's possible to set the color of characters in the text indvidually, just prefix the text to be re-colored with a #RRGGBB hexadecimal color code and a space, and close with a single hash # tag.

Example jsonl
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{"page":1,"id":1,"obj":"label","x":10,"y":5,"w":150,"h":50,"text":"\uE64A Hello world!"}
{"page":1,"id":1,"obj":"label","x":10,"y":5,"w":150,"h":50,"text":"#0000FF \uE64A# #FF0000 Hello# #008000 world#!"}

Button~

obj:btn

lv_btn

Property Value Default Description
toggle bool false When enabled, creates a toggle-on/toggle-off button. If false, creates a normal button
val int16 0 The value: 0 = untoggled, 1 = toggled
text string "" The text of the label
mode string expand The wrapping mode of long text labels.
expand Expand the object size to the text size
break Keep the object width, break the too long lines and expand the object height
dots Keep the size and write dots at the end if the text is too long
scroll Keep the size and roll the text back and forth
loop Keep the size and roll the text circularly
crop Keep the size and crop the text out of it
align string left Text alignment: left, center, right

Similar to the text label, it's possible to set the color of characters in the text indvidually, just prefix the text to be re-colored with a #RRGGBB hexadecimal color code and a space, and close with a single hash # tag.

Example jsonl
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{"page":1,"id":2,"obj":"btn","x":10,"y":40,"w":105,"h":90,"toggle":false,"text":"Normal Button","mode":"break","align":"center"}
{"page":1,"id":3,"obj":"btn","x":125,"y":40,"w":105,"h":90,"toggle":true,"text":"#FFD700 Toggle# Button","mode":"break","align":"center"}

Normal buttons (toggle=false) send touch events while they occur:

Short touch:

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{"event":"down"}
{"event":"up"}

Long press:

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{"event":"down"}
{"event":"long"}
{"event":"hold"}
{"event":"hold"}
{"event":"release"}

Toggle buttons (toggle=true) send out the old value in the down event and the new value in the up event when released:

Toggle ON:

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{"event":"down","val":0}
{"event":"up","val":1}

Toggle OFF:

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{"event":"down","val":1}
{"event":"up","val":0}

Switch~

obj:switch

lv_switch

Property Value Default Description
val bool 0 1 = on, 0 = off
bg_color10 color 0 changes indicator color
bg_color20 color 0 changes knob color
radius20 int16 depends
on theme
changes knob corner radius (also see radius)
Example jsonl
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{"page":1,"id":4,"obj":"switch","x":125,"y":145,"w":105,"h":55,"radius":15}

Events generated by switch are similar to the ones generate by the toggle buttons.

Checkbox~

obj:checkbox

lv_checkbox

Property Value Default Description
val int16 0 1 = checked
0 = unchecked
text string "Checkbox" The label of the checkbox

Note

The checkbox object ignores the w and h attribute. These are calculated based on the font and text.

Example jsonl
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{"page":1,"id":5,"obj":"checkbox","x":10,"y":145,"w":105,"text":" Checkbox"}

Events generated by checkbox are similar to the ones generate by the toggle buttons.

Progress Bar~

obj:bar

lv_bar

Property Value Default Description
min int16 0 minimum value of the indicator
max int16 100 maximum value of the indicator
val int16 0 current value of the indicator
start_value int16 0 optional minimal allowed value of the indicator

Vertical bars can be created if the width of the object is smaller than its height.

Note

min, max, val and start_value also support negative values.

Slider~

obj:slider

lv_slider

Property Value Default Description
min int16 0 minimum value of the indicator
max int16 100 maximum value of the indicator
val int16 0 current value of the indicator
start_value int16 0 optional minimal allowed value of the indicator

Vertical sliders can be created if the width of the object is smaller than its height.

Note

min, max, val and start_value also support negative values.

Example jsonl
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{"page":1,"id":6,"obj":"slider","x":20,"y":250,"w":200,"h":20,"min":15,"max":35}

While pressing and dragging the slider object the following events are sent: down (old value), changed (repeatedly until released) and up (value at the moment of releasing it):

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{"event":"down","val":21}
{"event":"changed","val":22}
{"event":"changed","val":23}
{"event":"changed","val":25}
{"event":"changed","val":27}
{"event":"changed","val":29}
{"event":"up","val":31}

Arc~

obj:arc

lv_arc

Property Value Default Description
min int16 0 minimum value of the indicator
max int16 100 maximum value of the indicator
val int16 0 current value of the indicator
rotation int16 0 offset to the 0 degree position
type 0-2 0 0 = normal, 1 = symmetrical, 2 = reverse
adjustable bool false Add knob that the user can operate to change the value
start_angle 0-360 start angle of the arc background (see note)
end_angle 0-360 end angle of the arc background (see note)
start_angle10 0-360 start angle of the arc indicator (see note)
end_angle10 0-360 end angle of the arc indicator (see note)

Note

Zero degree is at the middle right (3 o'clock) of the object and the degrees are increasing in a clockwise direction. The angles should be in the [0-360] range.
min, max and val also support negative values.

Tip

To adjust the size of the knob, use pad_top20, pad_bottom20, pad_left20, pad_right20 styling properties. If you increase the knob beyond the margins of the object, you also need to increase pad_top, pad_bottom, pad_left, pad_right for the arc itself.
Check out value styling to display a textual value in the middle of the arc.

Example jsonl
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{"page":1,"id":9,"obj":"arc","x":20,"y":75,"w":200,"h":200,"min":15,"max":35,"border_side":0,"type":0,"rotation":0,"start_angle":135,"end_angle":45,"start_angle10":135,"end_angle10":45,"adjustable":true}

While pressing and dragging the arc object the following events are sent: down (old value), changed (repeatedly until released) and up (value at the moment of releasing it):

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{"event":"down","val":21}
{"event":"changed","val":22}
{"event":"changed","val":23}
{"event":"changed","val":25}
{"event":"changed","val":27}
{"event":"changed","val":29}
{"event":"up","val":31}

obj:dropdown

lv_dropdown

Property Value Default Description
options string "" List of items separated by \n
val int16 0 The number of the selected item
text string "" Read-only The text of the selected item
direction byte 0 Direction where the dropdown expands:
0 = down, 1 = up, 2 = left, 3 = right
Note: up and down are superseeded by the screen size.
show_selected bool true Show the selected option or a static text
max_height int16 3/4 of screen height The maximum height of the open drop-down list
Method Parameters Description
open To manually open the drop-down list
close To manually close the drop-down list

To change the currently selected item, use the val attribute.
To change the items in the list, use the options attribute.

Example jsonl
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{"page":1,"id":10,"obj":"dropdown","x":10,"y":205,"w":105,"h":30,"options":"Apple\nBanana\nOrange\nMelon"}

When the item is changed both val and text of the newly selected item are send out accompanied by the change event.

Roller~

obj:roller

lv_dropdown

Property Value Default Description
options string "" List of items separated by \n
val int16 0 The number of the selected item
text string "" Read-only The text of the selected item
rows int8 3 The number of rows that are visible
Use this property instead of h to set object height
mode 0..1 0 Roller mode: 0 = normal (finite), 1 = infinite
align string center Text alignment: left, center, right

To change the currently selected item, use the val attribute.
To change the items in the list, use the options attribute.

Example jsonl
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{"page":1,"id":11,"obj":"roller","x":125,"y":205,"w":105,"h":30,"options":"Apple\nBanana\nOrange\nMelon","mode":1}

When the item is changed both val and text of the newly selected item are send out accompanied by the change event.

Line Meter~

obj:linemeter

lv_lmeter

Property Value Default Description
min int16 0 minimum value of the indicator
max int16 100 maximum value of the indicator
val int16 0 current value of the indicator
angle 0-360 240 angle between start and end of the scale
line_count uint16 31 tick count of the scale
rotation 0-360 0 offset for the scale angles to rotate it
type 0-1 0 0 = indicator lines are activated clock-wise
1 = indicator lines are activated counter-clock-wise

Use line and scale properties to customize.

Note

min, max and val also support negative values.

Example jsonl
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{"page":1,"id":12,"obj":"linemeter","x":20,"y":70,"w":200,"h":200,"value_str":"Temp","val":75,"line_count":35,"line_rounded":1}

Gauge~

obj:gauge

lv_gauge

Property Value Default Description
min int16 0 minimum value of the indicator
max int16 100 maximum value of the indicator
val int16 0 current value of the indicator
critical_value int16 80 scale color will be changed to scale_end_color after this value
label_count uint8 number of labels (and major ticks) of the scale
line_count uint16 31 number of minor ticks of the entire scale
angle 0-360 240 angle between start and end of the scale
rotation 0-360 0 offset for the gauge's angles to rotate it
format uint16 0 divider for major tick values

To strip trailing zero's of major tick labels the format divider can be used to scale the values before printing:

  • 0 : print the major tick value as is
  • 1 : strip 1 zero, i.e. divide tick value by 10 before printing the major tick label
  • 2 : strip 2 zeros, i.e. divide tick value by 100 before printing the major tick label
  • 3 : strip 3 zeros, i.e. divide tick value by 1000 before printing the major tick label
  • 4 : strip 4 zeros, i.e. divide tick value by 10000 before printing the major tick label

Only these values are allowed, arbitrary numbers are not supported.

Note

min, max and val also support negative values.

Example jsonl
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{"page":1,"id":13,"obj":"gauge","x":20,"y":70,"w":200,"h":200}

Use scale properties to customize.

Tabview~

obj:tabview

lv_tabview

A tabview is an object that can hold multiple tab objects. You first create the tabview object and then add tab objects to it.

Property Value Default Description
val int8 0 The number of the active tab, starting at 0
text string "" The name of the active tab
btn_pos 0..4 1 Position of the tab buttons:
0 = none
1 = top
2 = bottom
3 = left
4 = right
count uint16 0 Read-only The number of tabs of the tabview

To change the currently visible tab, use the val attribute after all tabs have been added.

Note

To adjust the height of the tab buttons row, use pad_top40 and pad_bottom40 styling properties. Accepts also negative values.
To adjust the text size of the tab names, use the text_font40 styling property.

Read further down to learn now to add tabs to the tabview.

Tab~

obj:tab

Property Value Default Description
parentid int8 0 The id of the tabview object to which this tab is added
text string "Tab" The name of tab button

Set the parent object (which tabview the tabs belong to) by referencing the parentid when creating the tab. To add other objects to these tabs, set the parentid when creating those objects to the id of the tab you wamt them to appear on.

Example jsonl
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{"page":1,"id":14,"obj":"tabview","btn_pos":1,"y":180}
{"page":1,"id":51,"obj":"tab","parentid":14,"text":"Tab 1"}
{"page":1,"id":52,"obj":"tab","parentid":14,"text":"Tab 2"}
{"page":1,"id":53,"obj":"tab","parentid":14,"text":"Tab 3"}
{"page":1,"id":61,"obj":"switch","x":20,"y":10,"w":60,"h":30,"parentid":51,"radius":25,"radius20":25}
{"page":1,"id":71,"obj":"dropdown","x":15,"y":10,"w":110,"h":30,"parentid":52,"options":"Apple\nBanana\nOrange\nMelon"}
{"page":1,"id":81,"obj":"checkbox","x":15,"y":10,"w":110,"h":30,"parentid":53,"text":" Nice tabview"} 

Color picker~

obj:cpicker

lv_cpicker

Property Value Default Description
color color 0 The selected color in html format #rrggbb
scale_width uint16 25 The width of the color gradient of the circle
pad_inner int16 10 The padding between the circle and the inner preview circle

The object will automatically adjust based on the w and h properties: when the object is longer then it is height a rectangular color picker is created, otherwise it will be circular.

By long pressing the inner preview circle, the color picker will through the color modes: hue > saturation > value. Double-click on the inner preview circle to reset the current value.

Setting Color~

Example MQTT commands:

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hasp/<nodename>/command/p0b2.color 13891
hasp/<nodename>/command/p1b5.color silver
hasp/<nodename>/command/p2b3.color #C0C0C0

Events~

While pressing and dragging the cpicker object the following events are sent: down (old color), changed (repeatedly until released) and up (value at the moment of releasing it):

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{"event":"down","color":"#8300ff","r":131,"g":0,"b":255}
{"event":"changed","color":"#7300ff","r":115,"g":0,"b":255}
{"event":"changed","color":"#6200ff","r":98,"g":0,"b":255}
{"event":"up","color":"#6200ff","r":98,"g":0,"b":255}

Spinner~

obj:spinner

lv_spinner

Property Value Default Description
speed int16 1000 The time for 1 turn in ms
direction int16 0 0 = clockwise, 1 = counter-clockwise
angle 0-360 60 The length of the spinning segment in degrees
type 0-2 0 0 = slow down on the top, 1 = slow down and stretch, 2 = constant speed no stretch
line_width int16 20 The width of the background circle
line_width10 int16 20 The width of the spinning segment
line_color color depends
on theme
color of the background circle
line_color10 color depends
on theme
color of the spinning segment

Tip

Check out background, border, and line styling to adjust other aspects of the appearance.

Note

Placing objects over/under the spinner will increase the CPU load because all objects need to be redrawn constantly.

Example jsonl
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{"page":1,"id":15,"obj":"spinner","x":180,"y":50,"w":36,"h":36,"bg_opa":0,"border_width":0,"line_width":6,"line_width10":6,"angle":80,"line_color":"white","line_color10":"green"}

LED Indicator~

obj:led

lv_led

Property Value Default Description
val byte 0 The brightness of the indicator [0..255]

Button Matrix~

obj:btnmatrix

lv_btnmatrix

Property Value Default Description
options json array "Text" Json array of strings where each element is the label of a button. Use "\n" for a new line of buttons
align string center Text alignment: left, center, right
toggle bool false All buttons behave as toggle buttons or normal buttons
one_check bool false Allow only one button to be checked (toggled) at once
val int8 0 The number of the active button, starting at 0. In conjunction with toggle and one_check set it to -1 to deactivate all buttons

The styling properties apply to all buttons in the matrix. To change the color of a single label you can prefix the text with a #RRGGBB hexadecimal color code and close with a single hash # tag.

Example jsonl
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{"page":1,"id":20,"obj":"btnmatrix","x":10,"y":10,"w":220,"h":150,"options":["#FF0000 Red Text#","#0000FF Cyan Text#","\n","#FFFF00 Yellow Text#"],"toggle":1,"one_check":1}

Messagebox~

obj:msgbox

lv_msgbox

Property Value Default Description
text string "" The text of the message to be displayed.
options json array ["OK"] Json array of strings where each element is the label of a button
modal bool false Make the messagebox a modal dialog requiring user input
auto_close int16 0 Close the pop-up message automatically after this number of milliseconds have passed

The Message boxes act as a pop-up. The default width is the horizontal screen size, the height adjusts according to the contents of the message. The pop-up is centered on the screen.

Note

The messagebox object is automatically deleted when it is closed. You will need to create it again using jsonl to pop-up a new message.

Example jsonl
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{"page":1,"id":24,"obj":"msgbox","text":"A message box with two buttons","options":["Apply","Close"]}

Line~

obj:line

lv_line

Property Value Default Description
points JSON array "" The name of the image file
auto_size bool true Automatically set the size of the line object to the outer bounds
y_invert bool false The y direction might be counter-intuitive in some cases so the y coordinates can be inverted

The points parameter is a JSON array of [x,y] coordinates, for example [[10,25],[100,25],[100,0]].

Example jsonl
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{"page":1,"id":33,"obj":"line","points":[[10,25],[100,25],[100,0]],"auto_size":0,"y_invert":1}

Image~

obj:img

lv_img

Property Value Default Description
src string "" The name of the image file
auto_size bool true Automatically set the size of the image object to the image source
offset_x int16 0 Shift the picture horizontally relative to the image object
offset_y int16 0 Shift the picture vertically relative to the image object
zoom uint16 256 A larger value enlarges the images (e.g. 512 double size), a smaller value shrinks it (e.g. 128 half size). Fractional scale works as well. E.g. 281 for 10% enlargement.
angle int16 0 Rotate the picture around its pivot point. Angle has 0.1 degree precision, so for 45.8° use 458.
pivot_x int16 H center The pivot point of the rotation, by default centered
pivot_y int16 V center The pivot point of the rotation, by default centered
antialias bool false The quality of the angle and zoom transformation. With enabled anti-aliasing the transformations has a higher quality but they are slower.

Note

You can use image_recolor and image_recolor_opa from the image styling properties to apply a color overlay mask.

Either PNG or BIN image files are supported, from flash:

  • PNG image are decoded and kept in memory, thus you'll be able to display full-screen images only if your microcontroller has installed PSram memory, else you will be limited to small icons or BIN files.

  • BIN images are not stored in memory and are read from flash each time. This will be slower but allows the use of larger images even if your microcontroller doesn't have PSram.

  • BIN images from flash do not support zoom or angle transformations.

  • Use the online LVGL Image Converter to create BIN files. Set the output format to Binary or Binary RGB565.

Example jsonl
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{"page":1,"id":34,"obj":"img","src":"L:/image.png","auto_size":0,"w":50}

Base Object~

obj:obj

lv_base_object

The Base Object can be directly used as a simple, empty widget. It is nothing more then a (rounded) rectangle.

You can use it as a background shape for other objects by putting its jsonl line before the object. It catches touches!

Example jsonl
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{"page":1,"id":50,"obj":"obj","x":5,"y":35,"w":230,"h":250,"click":0}

Last update: 2022-09-18