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Canvas Widget

The Canvas widget provides a 2D drawing area where you can programmatically render lines, rectangles, ovals, and text. Every draw method returns a Tk item ID (as a string) that can be used to delete specific items later.

Constructor

new Canvas(string $parentId, array $options = [])
Parameter Type Description
$parentId string getId() of the parent widget.
$options array Configuration options — see table below.

Options

Key Type Description
width int Canvas width in pixels.
height int Canvas height in pixels.
bg string Background color of the canvas.

All options are forwarded directly to the Tk canvas command.

Example

use PhpGui\Widget\Canvas;

$canvas = new Canvas($window->getId(), [
    'width'  => 400,
    'height' => 300,
    'bg'     => 'white'
]);
$canvas->pack(['pady' => 10]);

// Draw shapes
$lineId = $canvas->drawLine(10, 10, 200, 10, ['fill' => 'black', 'width' => 2]);
$rectId = $canvas->drawRectangle(50, 50, 200, 150, ['fill' => 'lightblue', 'outline' => 'navy']);
$ovalId = $canvas->drawOval(220, 50, 370, 150, ['fill' => 'salmon']);
$textId = $canvas->drawText(100, 180, 'Hello Canvas', ['fill' => 'darkgreen', 'font' => 'Arial 14 bold']);

// Delete a specific item by its returned ID
$canvas->delete($rectId);

// Clear the entire canvas
$canvas->clear();

Methods

Method Signature Returns Description
drawLine() (int $x1, int $y1, int $x2, int $y2, array $options = []): string item ID Draws a line between two points.
drawRectangle() (int $x1, int $y1, int $x2, int $y2, array $options = []): string item ID Draws a rectangle from top-left to bottom-right.
drawOval() (int $x1, int $y1, int $x2, int $y2, array $options = []): string item ID Draws an oval/ellipse bounded by the given rectangle.
drawText() (int $x, int $y, string $text, array $options = []): string item ID Draws text anchored at the given coordinates.
delete() (string $itemId): void — Deletes a single item by the ID returned from a draw method.
clear() (): void — Deletes all items on the canvas (delete all).
pack() (array $opts = []): void — Inherited. Pack layout manager.
place() (array $opts = []): void — Inherited. Place layout manager.
grid() (array $opts = []): void — Inherited. Grid layout manager.
destroy() (): void — Inherited. Removes the canvas widget.

Draw Options Reference

Options arrays for draw methods accept standard Tk item configuration keys:

Key Applicable to Description
fill all shapes, text Fill color.
outline rectangle, oval Border color.
width line, rectangle, oval Border/stroke width in pixels.
font text Font string, e.g. 'Arial 14 bold'.
anchor text Anchor point: center, nw, etc.

Notes

  • drawText() uses -text {text} so the text string is passed as a Tk list element — it can contain spaces.
  • All coordinate values are in pixels, measured from the top-left corner of the canvas.
  • Canvas overrides formatOptions() from AbstractWidget to produce -key value without wrapping values in quotes (important for numeric coordinates).