Lua:Class:Canvas - Revision history

Leunsel: Syntax Highlighting.

2026-06-25T15:38:21Z

Syntax Highlighting.

Leunsel at 21:00, 24 June 2026

2026-06-24T21:00:27Z

Leunsel: Added a fun RGB-Spectrum Code Example to showcase the drawing capabilites.

2026-06-21T09:50:09Z

Added a fun RGB-Spectrum Code Example to showcase the drawing capabilites.

Leunsel: Initial page creation.

2026-06-21T09:46:45Z

Initial page creation.

New page

[[Category:Lua]]
{{CodeBox|'''class''' Canvas ''':''' CustomCanvas}}

The Canvas class represents a drawing surface.

A Canvas inherits from CustomCanvas and Object. It provides access to drawing tools such as Brush, Pen, and Font, and offers methods for drawing shapes, text, images, pixels, and copied regions.

===Inheritance===
{|width="85%" cellpadding="10%" cellspacing="0" border="0"
!align="left"|Class
!align="left"|Inherits From
!style="width: 70%;background-color:white;" align="left"|Description
|-
|Canvas
|CustomCanvas
|A drawing surface used to render shapes, text, images, and pixels.
|-
|CustomCanvas
|Object
|Base class for canvas objects.
|}

===Properties===
{|width="85%" cellpadding="10%" cellspacing="0" border="0"
!align="left"|Property
!align="left"|Type
!style="width: 70%;background-color:white;" align="left"|Description
|-
|Brush
|Brush
|The brush object used for filling shapes and areas.
|-
|Pen
|Pen
|The pen object used for drawing lines and outlines.
|-
|Font
|Font
|The font object used for drawing text.
|-
|Width
|Integer
|The width of the canvas.
|-
|Height
|Integer
|The height of the canvas.
|-
|Handle
|Integer
|The device context handle of the canvas.
|}

===Methods===
{|width="85%" cellpadding="10%" cellspacing="0" border="0"
!align="left"|Method
!align="left"|Return Type
!style="width: 70%;background-color:white;" align="left"|Description
|-
|getBrush()
|Brush
|Returns the brush object of this canvas.
|-
|getPen()
|Pen
|Returns the pen object of this canvas.
|-
|getFont()
|Font
|Returns the font object of this canvas.
|-
|getWidth()
|Integer
|Returns the width of the canvas.
|-
|getHeight()
|Integer
|Returns the height of the canvas.
|-
|getPenPosition()
|Integer, Integer
|Returns the current pen position.
|-
|setPenPosition(x, y)
|void
|Sets the current pen position.
|-
|clear()
|void
|Clears the canvas.
|-
|line(sourcex, sourcey, destinationx, destinationy)
|void
|Draws a line from the source coordinates to the destination coordinates.
|-
|lineTo(destinationx, destinationy)
|void
|Draws a line from the current pen position to the destination coordinates.
|-
|moveTo(destinationx, destinationy)
|void
|Moves the current pen position to the destination coordinates.
|-
|rect(x1, y1, x2, y2)
|void
|Draws a rectangle.
|-
|fillRect(x1, y1, x2, y2)
|void
|Draws a filled rectangle.
|-
|roundRect(x1, y1, x2, y2, rx, ry)
|void
|Draws a rectangle with rounded corners.
|-
|drawFocusRect(x1, y1, x2, y2)
|void
|Draws a focus rectangle shape.
|-
|textOut(x, y, text)
|void
|Draws text at the specified coordinates.
|-
|textRect(rect, x, y, text)
|void
|Writes text within the given rectangle. The text supports some ANSI escape characters.
|-
|getTextWidth(text)
|Integer
|Returns the width of the given text.
|-
|getTextHeight(text)
|Integer
|Returns the height of the given text.
|-
|getPixel(x, y)
|Integer
|Returns the color value of the pixel at the specified coordinates.
|-
|setPixel(x, y, color)
|void
|Sets the color value of the pixel at the specified coordinates.
|-
|floodFill(x, y, color, filltype)
|void
|Fills an area starting at the specified coordinates.
|-
|ellipse(x1, y1, x2, y2)
|void
|Draws an ellipse within the specified rectangle.
|-
|gradientFill(x1, y1, x2, y2, startcolor, stopcolor, direction)
|void
|Fills a rectangle with a gradient.
|-
|copyRect(dest_x1, dest_y1, dest_x2, dest_y2, sourceCanvas, source_x1, source_y1, source_x2, source_y2)
|void
|Draws an image from one canvas to another. This is useful for double buffering.
|-
|draw(x, y, graphic)
|void
|Draws the image of a specific Graphic class object.
|-
|stretchDraw(rect, graphic)
|void
|Draws the image of a specific Graphic class object and stretches it to fit inside the given rectangle.
|-
|getClipRect()
|Table
|Returns a table containing the fields Left, Top, Right, and Bottom, which define the invalidated region of the graphical object.
|}

===Flood Fill Types===
{|width="85%" cellpadding="10%" cellspacing="0" border="0"
!align="left"|Value
!align="left"|Description
|-
|fsSurface
|Fills until the specified color is reached. It fills all connected pixels except this color.
|-
|fsBorder
|Fills only connected pixels of the specified color.
|}

===Gradient Directions===
{|width="85%" cellpadding="10%" cellspacing="0" border="0"
!align="left"|Value
!align="left"|Direction
!style="width: 80%;background-color:white;" align="left"|Description
|-
|0
|Vertical
|Creates a vertical gradient.
|-
|1
|Horizontal
|Creates a horizontal gradient.
|}

===Clip Rect Fields===
{|width="85%" cellpadding="10%" cellspacing="0" border="0"
!align="left"|Field
!align="left"|Type
!style="width: 80%;background-color:white;" align="left"|Description
|-
|Left
|Integer
|The left edge of the invalidated region.
|-
|Top
|Integer
|The top edge of the invalidated region.
|-
|Right
|Integer
|The right edge of the invalidated region.
|-
|Bottom
|Integer
|The bottom edge of the invalidated region.
|}

===Examples===
<pre>
local form = createForm()
form.Caption = "Canvas Example"
form.Width = 400
form.Height = 300

form.OnPaint = function(sender)
local canvas = sender.Canvas

canvas.Pen.Color = 0x0000FF
canvas.Brush.Color = 0xFFFFFF

canvas.rect(20, 20, 180, 100)
canvas.textOut(30, 40, "Hello Canvas")
end

form.show()
</pre>

<pre>
local form = createForm()
form.Caption = "Canvas Pixel Example"
form.Width = 300
form.Height = 200

form.OnPaint = function(sender)
local canvas = sender.Canvas

canvas.setPixel(50, 50, 0x0000FF)

local color = canvas.getPixel(50, 50)
canvas.textOut(20, 80, "Pixel color: " .. tostring(color))
end

form.show()
</pre>

<pre>
local form = createForm()
form.Caption = "Canvas Clip Rect Example"
form.Width = 400
form.Height = 300

form.OnPaint = function(sender)
local canvas = sender.Canvas
local clip = canvas.getClipRect()

canvas.textOut(20, 20, "Clip Left: " .. tostring(clip.Left))
canvas.textOut(20, 40, "Clip Top: " .. tostring(clip.Top))
canvas.textOut(20, 60, "Clip Right: " .. tostring(clip.Right))
canvas.textOut(20, 80, "Clip Bottom: " .. tostring(clip.Bottom))
end

form.show()
</pre>

{{LuaSeeAlso}}

@@ Line 222: / Line 222: @@
 ===Examples===
-<pre>
+<syntaxhighlight lang="lua" line>
 local form = createForm()
 form.Caption = "Canvas Example"
@@ Line 239: / Line 239: @@
 form.show()
-</pre>
+</syntaxhighlight>
-<pre>
+<syntaxhighlight lang="lua" line>
 local form = createForm()
 form.Caption = "Canvas Pixel Example"
@@ Line 257: / Line 257: @@
 form.show()
-</pre>
+</syntaxhighlight>
-<pre>
+<syntaxhighlight lang="lua" line>
 local form = createForm()
 form.Caption = "Canvas Clip Rect Example"
@@ Line 276: / Line 276: @@
 form.show()
-</pre>
+</syntaxhighlight>
-<pre>
+<syntaxhighlight lang="lua" line>
 function drawRGBSpectrum(canvas, x, y, width, height)
    if canvas == nil then
@@ Line 339: / Line 339: @@
 form.show()
-</pre>
+</syntaxhighlight>
 {{LuaSeeAlso}}

← Older revision		Revision as of 09:50, 21 June 2026
Line 278:		Line 278:
	</pre>		</pre>

		+	<pre>
		+	function drawRGBSpectrum(canvas, x, y, width, height)
		+	if canvas == nil then
		+	return
		+	end
		+
		+	width = math.max(1, width or 256)
		+	height = math.max(1, height or 32)
		+
		+	for px = 0, width - 1 do
		+	local hue = px / math.max(1, width - 1)
		+	local r, g, b
		+
		+	if hue < 1 / 6 then
		+	r = 255
		+	g = math.floor(hue * 6 * 255)
		+	b = 0
		+	elseif hue < 2 / 6 then
		+	r = math.floor((2 / 6 - hue) * 6 * 255)
		+	g = 255
		+	b = 0
		+	elseif hue < 3 / 6 then
		+	r = 0
		+	g = 255
		+	b = math.floor((hue - 2 / 6) * 6 * 255)
		+	elseif hue < 4 / 6 then
		+	r = 0
		+	g = math.floor((4 / 6 - hue) * 6 * 255)
		+	b = 255
		+	elseif hue < 5 / 6 then
		+	r = math.floor((hue - 4 / 6) * 6 * 255)
		+	g = 0
		+	b = 255
		+	else
		+	r = 255
		+	g = 0
		+	b = math.floor((1 - hue) * 6 * 255)
		+	end
		+
		+	local color = r + (g * 0x100) + (b * 0x10000)
		+
		+	canvas.Pen.Color = color
		+	canvas.line(x + px, y, x + px, y + height)
		+	end
		+	end
		+
		+	local form = createForm()
		+	form.Caption = "RGB Spectrum Canvas Example"
		+	form.Width = 400
		+	form.Height = 160
		+
		+	form.OnPaint = function(sender)
		+	local canvas = sender.Canvas
		+
		+	drawRGBSpectrum(canvas, 20, 40, 340, 40)
		+
		+	canvas.Font.Color = 0x000000
		+	canvas.textOut(20, 90, "RGB Spectrum")
		+	end
		+
		+	form.show()
		+	</pre>
	{{LuaSeeAlso}}		{{LuaSeeAlso}}

@@ Line 1: / Line 1: @@
 [[Category:Lua]]
-{{CodeBox|'''class''' Canvas ''':''' CustomCanvas}}
+{{Class|'''class''' Canvas ''':''' CustomCanvas}}
 The Canvas class represents a drawing surface.