Canvas

Definition

A two-dimensional touch-sensitive rectangular panel on which drawing can be done and sprites can be moved.

The BackgroundColor, PaintColor, BackgroundImage, Width, and Height of the Canvas can be set in either the Designer or in the Blocks Editor. The Width and Height are measured in pixels and must be positive.

Any location on the Canvas can be specified as a pair of (X, Y) values, where

• X is the number of pixels away from the left edge of the Canvas
• Y is the number of pixels away from the top edge of the Canvas

There are events to tell when and where a Canvas has been touched or a Sprite (ImageSprite or Ball) has been dragged. There are also methods for drawing points, lines, circles, shapes, arcs, and text.

Properties

BackgroundColor

Specifies the Canvas’s background color as an alpha-red-green-blue integer, i.e., 0xAARRGGBB. An alpha of 00 indicates fully transparent and FF means opaque. The background color only shows if there is no background image.

BackgroundImage

Specifies the name of a file containing the background image for the Canvas.

BackgroundImageinBase64

Set the background image in Base64 format. This requires API level >= 8. For devices with API level less than 8, setting this will end up with an empty background.

ExtendMovesOutsideCanvas

Determines whether moves can extend beyond the canvas borders. Default is false. This should normally be false, and the property is provided for backwards compatibility.

FontSize

Specifies the font size of text drawn on the Canvas.

Height

Specifies the Canvas’s vertical height, measured in pixels.

HeightPercent

Specifies the Canvas’s vertical height as a percentage of the Screen’s Height.

LineWidth

Specifies the width of lines drawn on the Canvas.

PaintColor

Specifies the paint color as an alpha-red-green-blue integer, i.e., 0xAARRGGBB. An alpha of 00 indicates fully transparent and FF means opaque.

TapThreshold

Specifies the movement threshold to differentiate a drag from a tap.

TextAlignment

Specifies the alignment of the canvas’s text: center, normal (starting at the specified point in DrawText or DrawTextAtAngle), or opposite (ending at the specified point in DrawText or DrawTextAtAngle).

Visible

Specifies whether the Canvas should be visible on the screen. Value is true if the Canvas is showing and false if hidden.

Width

Specifies the horizontal width of the Canvas, measured in pixels.

WidthPercent

Specifies the horizontal width of the Canvas as a percentage of the Screen’s Width.