flame/lib/src/sprite.dart

import 'dart:ui';

import '../image_composition.dart';
import 'anchor.dart';
import 'extensions/offset.dart';
import 'extensions/vector2.dart';
import 'flame.dart';
import 'palette.dart';
import 'assets/images.dart';

class Sprite {
  Paint paint = BasicPalette.white.paint;
  Image image;
  Rect src = Rect.zero;

  Sprite(
    this.image, {
    Vector2 srcPosition,
    Vector2 srcSize,
  }) : assert(image != null, "image can't be null") {
    this.srcSize = srcSize;
    this.srcPosition = srcPosition;
  }

  /// Takes a path of an image, a [srcPosition] and [srcSize] and loads the sprite animation
  /// When the [images] is omitted, the global [Flame.images] is used
  static Future<Sprite> load(
    String src, {
    Vector2 srcPosition,
    Vector2 srcSize,
    Images images,
  }) async {
    final _images = images ?? Flame.images;
    final image = await _images.load(src);
    return Sprite(image, srcPosition: srcPosition, srcSize: srcSize);
  }

  double get _imageWidth => image.width.toDouble();

  double get _imageHeight => image.height.toDouble();

  Vector2 get originalSize => Vector2(_imageWidth, _imageHeight);

  Vector2 get srcSize => Vector2(src.width, src.height);

  set srcSize(Vector2 size) {
    size ??= Vector2Extension.fromInts(image.width, image.height);
    src = srcPosition.toPositionedRect(size);
  }

  Vector2 get srcPosition => src.topLeft.toVector2();

  set srcPosition(Vector2 position) {
    src = (position ?? Vector2.zero()).toPositionedRect(srcSize);
  }

  /// Renders this sprite onto the canvas.
  ///
  /// * position: x,y coordinates where it will be drawn; default to origin.
  /// * size: width/height dimensions; it can be bigger or smaller than the original size -- but it defaults to the original texture size.
  /// * overridePaint: paint to use. You can also change the paint on your Sprite instance. Default is white.
  /// * anchor: where in the sprite the x/y coordinates refer to; defaults to topLeft.
  void render(
    Canvas canvas, {
    Vector2 position,
    Vector2 size,
    Anchor anchor = Anchor.topLeft,
    Paint overridePaint,
  }) {
    final drawPosition = position ?? Vector2.zero();
    final drawSize = size ?? srcSize;

    final delta = anchor.toVector2()..multiply(drawSize);
    final drawRect = (drawPosition + delta).toPositionedRect(drawSize);

    final drawPaint = overridePaint ?? paint;

    canvas.drawImageRect(image, src, drawRect, drawPaint);
  }

  /// Return a new Image based on the [src] of the Sprite.
  ///
  /// **Note:** This is a heavy async operation and should not be called on each [Game.render].
  Future<Image> toImage() async {
    final composition = ImageComposition()
      ..add(image, Vector2.zero(), source: src);
    return composition.compose();
  }
}