Image Button
Image Button widget improves the UI of your IoT app communicating the button or device state visually. The widget allows you to turn any image into a button and use custom images for different button states.
Image Button can operate in these modes:
End users will tap on the widget and a code scanner (camera) will open. The camera should be pointed to the code.
Once the code is successfully scanned, its contents will be sent to the hardware in a String format to the specified Datastream. The scanner screen will be closed automatically. A String Datastream should be added to the Device Template to accept these values.
Value of the code is sent as is (not pre-processed or post-processed by Blynk).
In case of scanning an unsupported format, no error will be shown. User would need to close the scanner view (camera) manually.
End-users would need to grant permissions to use the camera on the smartphone OS level. If permission wasn’t granted, a message will be shown to go to settings to enable access to the camera.
- QR
- AZTEC
- CODE_39
- CODE_39 mod 43
- CODE_93
- CODE_128
- DATA_MATRIX
- EAN_8
- EAN-13
- ITF
- PDF_417
- UPC_E
Android app can additionally support these formats:
- CODABAR
- MAXICODE
- RSS_14
- RSS_EXPANDED
- UPC_A
- UPC_EAN_EXTENSION
Select or create a datastream of data type integer, double, or string. Widget properties (label, color, etc.) are also changed via the datastream, but only for virtual, enumerable, and location pins, not digital and analog pins.
When button is pressed, value is sent and stored into the Blynk.Cloud. After that it's sent to your device.
For example, if Button Widget is set to Datastream with Virtual Pin V1, you can use such code:
BLYNK_WRITE(V1) // this command is listening when something is written to V1
{
int pinValue = param.asInt(); // assigning incoming value from pin V1 to a variable
if (pinValue == 1){
// do something when button is pressed;
} else if (pinValue == 0) {
// do something when button is released;
}
Serial.print("V1 button value is: "); // printing value to serial monitor
Serial.println(pinValue);
}
You can also update the state of the button from hardware.
Blynk.virtualWrite(vPin, HIGH);
or
Blynk.virtualWrite(vPin, 1);
Don't put
Blynk.virtualWrite()
into the void loop()
as it can cause a flood of messages and your hardware will be disconnected. Send such updates only when necessary, use flags, or timers.You can change certain properties of the Widget from your hardware. For that, use this command:
Blynk.setProperty(vPin, "widgetProperty", "propertyValue");
Where:
vPin
is: virtual pin number the widget is assigned towidgetProperty
: property you want to changepropertyValue
: value of the property you want to change
Don't put
Blynk.setProperty()
into the void loop()
as it can cause a flood of messages and your hardware will be disconnected. Send such updates only when necessary, or use timers.
You can change the properties onImageUrl, offImageUrl, label, isDisabled, isHidden, and page of the widget from your hardware, or via an HTTP API. The URL must be encoded, so spaces in labels must be replaced with %20, and color hexadecimal values in the HTTP API URL must include the hash # character urlencoded as %23.
Blynk.setProperty(V1, "onImageUrl", "URL");
Blynk.setProperty(V1, "offImageUrl", "URL");
Blynk.setProperty(V1, "label", "Toggle");
Widget will be greyed out on UI and users won't be able to tap on it.
Blynk.setProperty(V1, "isDisabled", true);
Widget will be hidden from dashboard. Design your UI so that it doesn't look weird when there is no widget.
Blynk.setProperty(V1, "isHidden", true);
This command will set which page should open when the button is pressed. PageId can be found in the mobile app in developer mode: Toolbox -> Pages
Blynk.setProperty(V1, "page", "pageId");
get
https://{server_address}
/external/api/update/property?token={your 32 char token}&pin={your vPin}&{property}={value}
Updates the Datastream Property and all assigned Widgets
You can update your hardware to the latest datastream value from Blynk.Cloud after your hardware went offline, and then came online again. Use
Blynk.syncVirtual()
to update a single virtual pin, or Blynk.syncAll()
to update all virtual pins. See State Syncing for more details.BLYNK_CONNECTED() {
// Called when hardware is connected to Blynk.Cloud
// get the latest value for V1
Blynk.syncVirtual(V1);
// Request Blynk server to re-send latest values for all pins
Blynk.syncAll()
}
Last modified 4mo ago