Class

MobileCanvas

Description

Used to draw graphics.

Events

Name

Parameters

Returns

AppearanceChanged

dark As Boolean

Closing

Opening

Paint

g As Graphics

PointerDown

position As Point, pointerInfo() As PointerEvent

PointerDrag

position As Point, pointerInfo() As PointerEvent

PointerUp

position As Point, pointerInfo() As PointerEvent

Property descriptions

MobileCanvas.AccessibilityHint

AccessibilityHint As String

The accessibility hint is a longer description that is read aloud when VoiceOver is enabled.

Me.AccessibilityHint = "Click to calculate the value and display the next screen."

MobileCanvas.AccessibilityLabel

AccessibilityLabel As String

The accessibility label of of a control is a short name that is read aloud when VoiceOver is enabled.

Me.AccessibilityLabel = "Calculate the value."

MobileCanvas.ControlCount

ControlCount As Integer

The number of child controls in the control.

This property is read-only.

MobileCanvas.Enabled

Enabled As Boolean

Indicates whether the control is enabled or disabled.

Disable the button:

Button1.Enabled = False

MobileCanvas.Height

Height As Double

The height of the control.

This property is read-only.

MobileCanvas.Left

Left As Double

The left position of the control.

This property is read-only.

MobileCanvas.Name

Name As String

The name of the control.

MobileCanvas.Parent

Parent As MobileUIControl

The parent (sometimes called a "Super") class of the control.

This property is read-only.

MobileCanvas.TintColor

TintColor As ColorGroup

Changes a control's tint color.

On iOS, the following controls support TintColor:

Enum

Description

ProgressBar

The area indicating the value of the control will be drawn in the TintColor.

Slider

The area indicating the value of the control will be drawn in the TintColor.

TextArea

The cursor and text highlight color will be drawn in the TintColor.

TextField

The cursor and text highlight color will be drawn in the TintColor.

MobileCanvas.Top

Top As Double

The top position of the control.

This property is read-only.

MobileCanvas.Visible

Visible As Boolean

Indicates whether the control is visible.

Make a button invisible:

Button1.Visible = False

MobileCanvas.Width

Width As Double

The width of the control.

This property is read-only.

Method descriptions

MobileCanvas.AddConstraint

AddConstraint(constraint As iOSLayoutConstraint)

Adds a constraint to the control.

This constraint is used by child controls that have been added to this control.

MobileCanvas.AddControl

AddControl(child As MobileUIControl)

Adds a child control to the control.

MobileCanvas.ClearFocus

ClearFocus

Removes the focus from the control.

TextField1.ClearFocus

MobileCanvas.ControlAt

ControlAt(index As Integer) As MobileUIControl

Gets the child control at the specified index.

MobileCanvas.Controls

Controls As Iterable

Allows you to iterate through all the controls that have been added to this control.

MobileCanvas.Handle

Handle As Ptr

The a handle to the underlying native OS control.

MobileCanvas.Refresh

Refresh

Marks the control so that it will be redrawn during the next event loop.

Call Refresh to force a Canvas to redraw itself:

Canvas1.Refresh

MobileCanvas.RemoveConstraint

RemoveConstraint(constraint As iOSLayoutConstraint)

Removes a constraint from the control.

MobileCanvas.RemoveControl

RemoveControl(child As MobileUIControl)

Removes the control from the control.

MobileCanvas.SetFocus

SetFocus

Sets the focus to the control.

TextField1.SetFocus

Event descriptions

MobileCanvas.AppearanceChanged

AppearanceChanged(dark As Boolean)

Called when the device switches between Light and Dark mode.

Use this event to update any graphics or other UI as needed.

MobileCanvas.Closing

Closing

Called when the control's layout is closing.

MobileCanvas.Opening

Opening

Called when the control's layout is opening.

This is where you typically put initialization code.

This example in the Opening event of a label sets its text to "Hello":

Me.Text = "Hello"

MobileCanvas.Paint

Paint(g As Graphics)

Called when the Canvas needs to be redrawn.

To draw a blue rectangle in the Canvas:

g.DrawingColor = Color.Blue
g.FillRectangle(0, 0, g.Width, g.Height)

MobileCanvas.PointerDown

PointerDown(position As Point, pointerInfo() As PointerEvent)

Called when the pointing device (finger or pen) touches the Canvas.

This code saves all touch points to an array, which is used to display circles in the Paint event:

// touchPoints is an PointerEvent array property of screen the Canvas is also on
touchPoints = pointerInfo
Me.Refresh

This code goes in the Paint event handler:

For Each tap As PointerEvent In touchPoints
  g.DrawingColor = Color.Blue
  g.FillOval(tap.Position.X, tap.Position.Y, 30, 30)
Next

MobileCanvas.PointerDrag

PointerDrag(position As Point, pointerInfo() As PointerEvent)

Called when the pointing device (finger or pen) is dragged.

MobileCanvas.PointerUp

PointerUp(position As Point, pointerInfo() As PointerEvent)

Called when the pointing device (finger or pen) is raised or released.

Compatibility

Mobile projects on all supported mobile operating systems.

See also

MobileUIControl parent class; PointerEvent, Graphics classes