CODEWITHSUNDEEP
dartflutter
Mike Miller
Mike Miller

Reputation: 3507

Draw part of an image onto a widget

I'm trying to draw a sprite onto a CustomPaint widget. The sprite comes from an image containing multiple sprites in a grid, so I need to be able to specify the source rectangle (and preferably a destination rectangle that matches the size of the widget).

Upvotes: 5

Views: 2007

Answers (1)

Mike Miller
Mike Miller

Reputation: 3507

I resolved this using canvas.drawAtlas:

import 'package:flutter/painting.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
import 'dart:ui' as ui;

class SquarePainter extends CustomPainter {
  final ui.Image theImage;
  SquarePainter({this.theImage});
  @override
  void paint(Canvas canvas, Size size) {

    canvas.drawAtlas(
        theImage,
        [
          /* Identity transform */
          RSTransform.fromComponents(
              rotation: 0.0,
              scale: 1.0,
              anchorX: 0.0,
              anchorY: 0.0,
              translateX: 0.0,
              translateY: 0.0)
        ],
        [
            /* A 5x5 source rectangle within the image at position (10, 10) */
            Rect.fromLTWH(10.0, 10.0, 5.0, 5.0)
        ],
        [/* No need for colors */],
        BlendMode.src,
        null /* No need for cullRect */,
        Paint());
  }

  @override
  bool shouldRepaint(SquarePainter oldDelegate) => false;
  @override
  bool shouldRebuildSemantics(SquarePainter oldDelegate) => false;
}

Upvotes: 8

Related Questions