Lua:Class:CustomControl

{} Class

class CustomControl : WinControl

The CustomControl class represents a windowed control that exposes a Canvas for custom drawing.

CustomControl inherits from WinControl, Control, Component, and Object.

Inheritance

Class	Inherits From	Description
CustomControl	WinControl	Base class for windowed controls that support custom painting.
WinControl	Control	Base class for controls that have a window handle, can contain child controls, and can receive focus.
Control	Component	Base class for visual controls.
Component	Object	Base class for owned components.
Object	None	Base class for Lua-exposed objects.

Properties

Property	Type	Description
Canvas	Canvas	Read-only canvas object used for drawing on the control.
OnPaint	Function	Event handler that can be assigned to perform custom painting.

Methods

Method	Return Type	Description
getCanvas()	Canvas	Returns the Canvas object for the object that inherited from CustomControl.

Method Parameters

getCanvas

This method has no parameters.

Examples

Get the Canvas through the property

1 local form = createForm(false)
2 local paintBox = createPaintBox(form)
3 
4 local canvas = paintBox.Canvas
5 
6 print(canvas.ClassName)
7 
8 form.destroy()

Get the Canvas through getCanvas

1 local form = createForm(false)
2 local paintBox = createPaintBox(form)
3 
4 local canvas = paintBox.getCanvas()
5 
6 print(canvas.ClassName)
7 
8 form.destroy()

Assign an OnPaint event

1 local form = createForm(false)
2 local paintBox = createPaintBox(form)
3 
4 paintBox.OnPaint = function(sender)
5   local canvas = sender.Canvas
6   canvas.TextOut(10, 10, "Custom painting")
7 end
8 
9 form.show()

Draw a rectangle in OnPaint

1 local form = createForm(false)
2 local paintBox = createPaintBox(form)
3 
4 paintBox.OnPaint = function(sender)
5   local canvas = sender.Canvas
6   canvas.Rectangle(10, 10, 150, 80)
7 end
8 
9 form.show()

Draw text on the control

1 local form = createForm(false)
2 local paintBox = createPaintBox(form)
3 
4 paintBox.OnPaint = function(sender)
5   local canvas = sender.Canvas
6   canvas.TextOut(10, 10, "Hello Canvas")
7 end
8 
9 form.show()

Use the same handler for multiple controls

 1 local form = createForm(false)
 2 local paintBox1 = createPaintBox(form)
 3 local paintBox2 = createPaintBox(form)
 4 
 5 local function paintHandler(sender)
 6   sender.Canvas.TextOut(10, 10, sender.Name)
 7 end
 8 
 9 paintBox1.OnPaint = paintHandler
10 paintBox2.OnPaint = paintHandler
11 
12 form.show()

Use getCanvas inside a helper function

 1 local function drawCaption(control, text)
 2   local canvas = control.getCanvas()
 3   canvas.TextOut(10, 10, text)
 4 end
 5 
 6 local form = createForm(false)
 7 local paintBox = createPaintBox(form)
 8 
 9 paintBox.OnPaint = function(sender)
10   drawCaption(sender, "Drawn by helper")
11 end
12 
13 form.show()

Force repaint after changing state

 1 local form = createForm(false)
 2 local paintBox = createPaintBox(form)
 3 local text = "Initial text"
 4 
 5 paintBox.OnPaint = function(sender)
 6   sender.Canvas.TextOut(10, 10, text)
 7 end
 8 
 9 text = "Updated text"
10 
11 paintBox.repaint()
12 
13 form.show()

Main Pages

Core Lua documentation entry points

◆ Lua
◆ Script Engine

Form Related Functions

◆ getForm
◆ getFormCount
◆ getMainForm
◆ getSettingsForm
◆ getLuaEngine
◆ registerFormAddNotification

Form Related Classes

◆ Form
◆ Component
◆ Control
◆ WinControl
◆ Application
◆ Object