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Build 881
Hands-on tutorial · Input & events

Choose a time

Handle a time change with the TimePicker’s documented event contract.

1 Form / control designs1 complete BASIC filesGuided sample project

The current canonical event is Change; ValueChanged remains a supported alias used by this sample. Keep presentation formatting separate from the selected value. This lesson constrains time to 06:00–22:00, so test those boundaries before experimenting with a wider range.

Step 1Prepare a safe practice project#

Extract the archive into a new writable folder, separate from your own application. Open TimePicker.mcproj in McBasic™. Keep every declared source, layout, resource and migration file together.

To reconstruct it yourself, create a DesktopApp project and add the files declared below. In the complete project, follow these steps as a guided rebuild: replace each named source file once and Check after all its procedures are present.

Exact project configuration
TimePicker.mcproj
{
  "schemaVersion": 1,
  "projectId": "11c4a5dd-3e18-4c86-91d7-4e0c2bd0f410",
  "name": "TimePickerSample",
  "kind": "DesktopApp",
  "language": {
    "dialect": "McBasic1",
    "requireExplicit": true,
    "compare": "Binary",
    "defaultArrayBase": 0
  },
  "application": {
    "bundleIdentifier": "com.mcbasic.samples.timepicker",
    "version": "0.1.0",
    "buildNumber": "1",
    "startupFormId": "form-main",
    "shutdownMode": "OnStartupFormClosed"
  },
  "forms": [
    {
      "id": "form-main",
      "typeName": "frmMain",
      "layout": "Forms/frmMain.form.json",
      "code": "Forms/frmMain.bas"
    }
  ],
  "modules": [],
  "classes": [],
  "tests": [],
  "references": [],
  "resources": [],
  "targets": [
    "osx-arm64"
  ],
  "capabilities": []
}

Step 2Build the Form and set its properties#

frmMain

Select the Form first and set its properties. Add containers before their children. These are initial Designer values, not statements to paste into a procedure.

Form propertyValue
Caption"TimePicker — McBasic"
Width560
Height300
MinWidth440
MinHeight240
TypeNameParent
TimePickertmpTimeForm
LabellblStatusForm
CommandButtoncmdCloseForm
tmpTime · exact Inspector values
PropertyValue
Left48
Top72
Width220
Height34
Value"09:30:00"
Minimum"06:00:00"
Maximum"22:00:00"
Clock"24Hour"
UseSecondsTrue
MinuteIncrement1
SecondIncrement1
TabIndex0
Anchor edgesLeft, Top
lblStatus · exact Inspector values
PropertyValue
Left48
Top128
Width460
Height36
Caption"Time: 09:30:00"
Anchor edgesLeft, Top
cmdClose · exact Inspector values
PropertyValue
Left48
Top192
Width140
Height36
Caption"Close"
TabIndex1
Anchor edgesLeft, Top

Step 3Connect the events explicitly#

frmMain

ObjectEventProcedureParameters
tmpTimeValueChanged
Alias of Change
tmpTime_ValueChangedValueChanged()
cmdCloseClickcmdClose_ClickClick()
FormLoadForm_Load()

Step 4Enter the complete behavior#

Open the named source file. Enter declarations first, then every procedure. Expand a procedure for its full body, or copy the complete file. Helpers are required: do not stop after entering the first Click handler.

Forms/frmMain.bas

Enter these declarations at file scope, before the procedures.

Forms/frmMain.bas · declarations
Option Explicit
Private Sub Form_Load()

Initialize state before enabling dependent actions. Keep the shared declarations and startup dependencies with this procedure.

Forms/frmMain.bas · Form_Load
Private Sub Form_Load()
    tmpTime.Clock = "24Hour"
    tmpTime.UseSeconds = True
    tmpTime.MinuteIncrement = 5
    tmpTime.SecondIncrement = 5
    tmpTime.Minimum = TimeSerial(6, 0, 0)
    tmpTime.Maximum = TimeSerial(22, 0, 0)
    tmpTime.Value = TimeSerial(9, 30, 0)
    lblStatus.Caption = "Time: " & Format(tmpTime.Value, "HH:mm:ss")
End Sub
Private Sub tmpTime_ValueChanged()

Read the current value or selection and update its dependent interface. The binding above determines which object calls this handler.

Forms/frmMain.bas · tmpTime_ValueChanged
Private Sub tmpTime_ValueChanged()
    lblStatus.Caption = "Changed: " & Format(tmpTime.Value, "HH:mm:ss")
End Sub
Private Sub cmdClose_Click()

Enter the complete action, including its input checks and calls to helper procedures.

Forms/frmMain.bas · cmdClose_Click
Private Sub cmdClose_Click()
    Unload Me
End Sub
Copy the complete Forms/frmMain.bas file

Replace the file once; do not append duplicate procedures.

Forms/frmMain.bas
Option Explicit

Private Sub Form_Load()
    tmpTime.Clock = "24Hour"
    tmpTime.UseSeconds = True
    tmpTime.MinuteIncrement = 5
    tmpTime.SecondIncrement = 5
    tmpTime.Minimum = TimeSerial(6, 0, 0)
    tmpTime.Maximum = TimeSerial(22, 0, 0)
    tmpTime.Value = TimeSerial(9, 30, 0)
    lblStatus.Caption = "Time: " & Format(tmpTime.Value, "HH:mm:ss")
End Sub

Private Sub tmpTime_ValueChanged()
    lblStatus.Caption = "Changed: " & Format(tmpTime.Value, "HH:mm:ss")
End Sub

Private Sub cmdClose_Click()
    Unload Me
End Sub

Step 5Keep resources and storage reproducible#

No external resource or migration files are declared. Any inline migration, seed data or local JSON is present in the code above. Runtime application data and private preferences are not included in the archive.

Step 6Check, run and test the result#

Save all files and run Check. Resolve diagnostics before Run. Developer CLI users can work from the extracted folder:

Developer CLI
mcbasic check TimePicker.mcproj
mcbasic run TimePicker.mcproj

Acceptance checklist

  • Change the time and confirm the status updates.
  • Try the 06:00 and 22:00 range boundaries.
  • Use keyboard navigation through the picker.

Step 7Make one change and repeat the tests#

Display the selected time in a second format without changing its underlying value.

Save a working Git checkpoint first. Change one behavior, Check again and repeat the acceptance checklist. Compare with the downloaded solution if a regression appears.

Source baseline 20f4bfed6b · Build manifest