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()
Core Lua documentation entry points
