paint method
Called whenever the object needs to paint. The given Canvas has its
coordinate space configured such that the origin is at the top left of the
box. The area of the box is the size of the size argument.
Paint operations should remain inside the given area. Graphical operations outside the bounds may be silently ignored, clipped, or not clipped. It may sometimes be difficult to guarantee that a certain operation is inside the bounds (e.g., drawing a rectangle whose size is determined by user inputs). In that case, consider calling Canvas.clipRect at the beginning of paint so everything that follows will be guaranteed to only draw within the clipped area.
Implementations should be wary of correctly pairing any calls to Canvas.save/Canvas.saveLayer and Canvas.restore, otherwise all subsequent painting on this canvas may be affected, with potentially hilarious but confusing results.
To paint text on a Canvas, use a TextPainter.
To paint an image on a Canvas:
-
Obtain an ImageStream, for example by calling ImageProvider.resolve on an AssetImage or NetworkImage object.
-
Whenever the ImageStream's underlying ImageInfo object changes (see ImageStream.addListener), create a new instance of your custom paint delegate, giving it the new ImageInfo object.
-
In your delegate's paint method, call the Canvas.drawImage, Canvas.drawImageRect, or Canvas.drawImageNine methods to paint the ImageInfo.image object, applying the ImageInfo.scale value to obtain the correct rendering size.
Implementation
@override
void paint(Canvas canvas, Size size) {
print('width: ${size.width}');
print('height: ${size.height}');
final paint = Paint();
paint.color = Colors.white;
final background = Rect.fromLTRB(0, 0, size.width, size.height);
canvas.drawRect(background, paint);
paint.color = Colors.black;
paint.style = PaintingStyle.stroke;
paint.strokeWidth = size.height * 0.005;
// Nome do acorde
TextSpan textSpan = TextSpan(
text: this.acordeViola.nome,
style: TextStyle(
fontSize: size.height * 0.07,
color: Colors.black,
fontWeight: FontWeight.w700
)
);
TextPainter textPainter = TextPainter(
text: textSpan,
textDirection: TextDirection.ltr
);
textPainter.layout(
minWidth: 0,
maxWidth: size.width
);
textPainter.paint(canvas, Offset((size.width - textPainter.width) * 0.5,
(size.height - textPainter.height) * 0.06));
// Desenhar bordas do acorde
final bordasAcorde = Rect.fromLTRB(
size.width * 0.15, size.height * 0.15, size.width * 0.85,
size.height * 0.90);
canvas.drawRect(bordasAcorde, paint);
// Desenhar numeroCasa se tiver
if (this.acordeViola.textNumeroCasa != null) {
TextSpan textSpan2 = TextSpan(
text: this.acordeViola.textNumeroCasa,
style: TextStyle(
fontSize: size.height * 0.06,
color: Colors.black
)
);
TextPainter textPainter2 = TextPainter(
text: textSpan2,
textDirection: TextDirection.ltr
);
textPainter2.layout(
minWidth: 0,
maxWidth: size.width
);
textPainter2.paint(canvas, Offset(
size.width * 0.90,
size.height * 0.19
));
}
// Linhas verticais
paint.strokeWidth = 2;
// Calculo interpolacao linhas verticais
// var res = (((size.width - ((size.width * 0.15) * 2)) / 4) * 3 + size.width * 0.15) / size.width;
// print(res);
canvas.drawLine(Offset(size.width * 0.17, size.height * 0.15),
Offset(size.width * 0.17, size.height * 0.9), paint);
canvas.drawLine(Offset(size.width * 0.314, size.height * 0.15),
Offset(size.width * 0.314, size.height * 0.9), paint);
canvas.drawLine(Offset(size.width * 0.334, size.height * 0.15),
Offset(size.width * 0.334, size.height * 0.9), paint);
canvas.drawLine(Offset(size.width * 0.49, size.height * 0.15),
Offset(size.width * 0.49, size.height * 0.9), paint);
canvas.drawLine(Offset(size.width * 0.51, size.height * 0.15),
Offset(size.width * 0.51, size.height * 0.9), paint);
canvas.drawLine(Offset(size.width * 0.665, size.height * 0.15),
Offset(size.width * 0.665, size.height * 0.9), paint);
canvas.drawLine(Offset(size.width * 0.685, size.height * 0.15),
Offset(size.width * 0.685, size.height * 0.9), paint);
canvas.drawLine(Offset(size.width * 0.83, size.height * 0.15),
Offset(size.width * 0.83, size.height * 0.9), paint);
// Linhas horizontais
paint.strokeWidth = size.height * 0.015;
canvas.drawLine(Offset(size.width * 0.15, size.height * 0.30),
Offset(size.width * 0.85, size.height * 0.30), paint);
canvas.drawLine(Offset(size.width * 0.15, size.height * 0.449),
Offset(size.width * 0.85, size.height * 0.449), paint);
canvas.drawLine(Offset(size.width * 0.15, size.height * 0.6),
Offset(size.width * 0.85, size.height * 0.6), paint);
canvas.drawLine(Offset(size.width * 0.15, size.height * 0.75),
Offset(size.width * 0.85, size.height * 0.75), paint);
// Linha horizontal pestana fixa
paint.strokeWidth = size.height * 0.025;
paint.strokeCap = StrokeCap.round;
canvas.drawLine(Offset(size.width * 0.15, size.height * 0.15),
Offset(size.width * 0.85, size.height * 0.15), paint);
// Linha horizontal pestana dinamica
if (this.acordeViola.pestana != null) {
var p1 = size.height * 0.15;
var p2 = size.height * 0.10;
var sobras = p1 + p2;
var tamanhoQuadrado = size.height - sobras;
var tamanhoCasa = tamanhoQuadrado / 10;
var linha1 = (acordeViola.pestana!.casa * tamanhoCasa) + p1;
double dy = linha1 / size.height;
paint.strokeWidth = size.height * 0.022;
canvas.drawLine(Offset(
size.width * this.acordeViola.pestana!.tamanho, size.height * dy),
Offset(size.width * Constants.DX2_DETAULT_VIOLA, size.height * dy),
paint);
}
// Desenhar circulo posicao dedo
paint.style = PaintingStyle.fill;
this.acordeViola.posicoes.forEach((posicao) {
double dx = _calculoDxPosicao(size, posicao.corda);
double dy = _calculoDyPosicao(size, posicao.casa);
canvas.drawCircle(
Offset(size.width * dx, size.height * dy), size.height * 0.04, paint);
// Desenhar texto no centro do circulo do dedo
final textSpan3 = TextSpan(
text: posicao.text,
style: TextStyle(
fontSize: size.height * 0.06,
color: Colors.white,
fontWeight: FontWeight.w700
)
);
final textPainter3 = TextPainter();
textPainter3.text = textSpan3;
textPainter3.textDirection = TextDirection.ltr;
textPainter3.layout(minWidth: 0, maxWidth: size.width);
textPainter3.paint(canvas, Offset(
(size.width * dx - textPainter3.width / 2),
size.height * dy - textPainter3.height / 2));
});
// Desenhar labels tocar ou nao
for (int i = 4; i >= 0; i--) {
var dx = _calculoDxPosicao(size, i.toDouble());
print(dx);
final labelCorda = TextPainter();
labelCorda.text = TextSpan(
text: this.acordeViola.labels![i],
style: TextStyle(
fontSize: size.height * 0.05,
color: Colors.black,
fontWeight: FontWeight.w600
)
);
labelCorda.textDirection = TextDirection.ltr;
labelCorda.layout(minWidth: 0, maxWidth: size.width);
labelCorda.paint(canvas, Offset(
(size.width * dx) - labelCorda.width / 2,
size.height * 0.9
));
}
}