B4X Requires Chilkat v11.7.0+

QR Code Colors and Transparent Background

See more QR Code Examples

Demonstrates colored QR codes. render.foreground is the color of the dark modules and render.background the color behind them, each as #RRGGBB. Either can instead be an object with a color and an opacity from 0 to 1, and a background opacity of 0 gives a PNG with a transparent background to place over a page or a design. Readers need contrast: keep the modules clearly darker than whatever ends up behind them. B4X

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim fmt As ChilkatFormats
fmt.Initialize
Dim jsonOut As ChilkatJsonObject
jsonOut.Initialize

'  Dark blue modules on a pale yellow background.
Dim json As ChilkatJsonObject
json.Initialize
json.UpdateString("payload.text", "https://www.chilkatsoft.com/")
json.UpdateInt("render.moduleSize", 6)
json.UpdateString("render.foreground", "#1B3A6B")
json.UpdateString("render.background", "#FFF8DC")
json.UpdateString("output.path", "qa_output/qr_blue.png")
json.UpdateBool("output.overwrite", True)
json.UpdateString("output.return", "none")
success = fmt.QrCode("generate", json, jsonOut)
If success = False Then
    Log(fmt.LastErrorText)
    Return
End If

Log("colored: " & jsonOut.StringOf("outputs[0].path") & ", " & jsonOut.IntOf("outputs[0].byteCount") & " bytes")

'  The image written to qa_output/qr_blue.png:

'  

'  The same modules on a fully transparent background.
Dim json2 As ChilkatJsonObject
json2.Initialize
json2.UpdateString("payload.text", "https://www.chilkatsoft.com/")
json2.UpdateInt("render.moduleSize", 6)
json2.UpdateString("render.foreground", "#1B3A6B")
json2.UpdateString("render.background.color", "#FFFFFF")
json2.UpdateNumber("render.background.opacity", "0")
json2.UpdateString("output.path", "qa_output/qr_transparent.png")
json2.UpdateBool("output.overwrite", True)
json2.UpdateString("output.return", "none")
success = fmt.QrCode("generate", json2, jsonOut)
If success = False Then
    Log(fmt.LastErrorText)
    Return
End If

Log("transparent: " & jsonOut.StringOf("outputs[0].path") & ", " & jsonOut.IntOf("outputs[0].byteCount") & " bytes")

'  qa_output/qr_transparent.png, placed here over a checkerboard and over a colored page
'  to show that whatever is behind the image shows through:

'  

'  Sample output:

'  colored: qa_output/qr_blue.png, 1345 bytes
'  transparent: qa_output/qr_transparent.png, 1377 bytes