我想扩展
我觉得Flutter源代码采取了类似的方法,但也许我没有看到什么。
编辑 将我的paint样式更改为PaintingStyle.fill,因此绘制一个矩形覆盖原始矩形而不是边框,我似乎确实得到了正确的边框:
ShapeBorder
类以添加一些功能。但是,在尝试使用paint
方法时,我发现了一些意外的问题:
class CustomRoundedRectangleBorder extends ShapeBorder {
final double borderWidth;
final BorderRadius borderRadius;
const CustomRoundedRectangleBorder({
this.borderWidth: 1.0,
this.borderRadius: BorderRadius.zero,
})
: assert(borderRadius != null);
@override
EdgeInsetsGeometry get dimensions {
return new EdgeInsets.all(borderWidth);
}
@override
ShapeBorder scale(double t) {
return new CustomRoundedRectangleBorder(
borderWidth: borderWidth * (t),
borderRadius: borderRadius * (t),
);
}
@override
ShapeBorder lerpFrom(ShapeBorder a, double t) {
assert(t != null);
if (a is CustomRoundedRectangleBorder) {
return new CustomRoundedRectangleBorder(
borderWidth: ui.lerpDouble(a.borderWidth, borderWidth, t),
borderRadius: BorderRadius.lerp(a.borderRadius, borderRadius, t),
);
}
return super.lerpFrom(a, t);
}
@override
ShapeBorder lerpTo(ShapeBorder b, double t) {
assert(t != null);
if (b is CustomRoundedRectangleBorder) {
return new CustomRoundedRectangleBorder(
borderWidth: ui.lerpDouble(borderWidth, b.borderWidth, t),
borderRadius: BorderRadius.lerp(borderRadius, b.borderRadius, t),
);
}
return super.lerpTo(b, t);
}
@override
Path getInnerPath(Rect rect, { TextDirection textDirection }) {
return new Path()
..addRRect(borderRadius.resolve(textDirection).toRRect(rect).deflate(
borderWidth));
}
@override
Path getOuterPath(Rect rect, { TextDirection textDirection }) {
return new Path()
..addRRect(borderRadius.resolve(textDirection).toRRect(rect));
}
@override
void paint(Canvas canvas, Rect rect, { TextDirection textDirection }) {
rect = rect.deflate(borderWidth / 2.0);
Paint paint;
final RRect borderRect = borderRadius.resolve(textDirection).toRRect(rect);
paint = new Paint()
..color = Colors.red
..style = PaintingStyle.stroke
..strokeWidth = borderWidth;
canvas.drawRRect(borderRect, paint);
}
}
然后创建如下矩形:
new Container(
height: 100.0,
width: 200.0,
padding: new EdgeInsets.all(10.0),
decoration: new ShapeDecoration(
color: Colors.black,
shape: new CustomRoundedRectangleBorder(
borderRadius: new BorderRadius.all(new Radius.circular(20.0)),
borderWidth: 10.0,
),
// side: new BorderSide(color: Colors.white)
),
child: new Center(child: new Text("My Button"),),
),
我觉得Flutter源代码采取了类似的方法,但也许我没有看到什么。
编辑 将我的paint样式更改为PaintingStyle.fill,因此绘制一个矩形覆盖原始矩形而不是边框,我似乎确实得到了正确的边框:
void paint(Canvas canvas, Rect rect, { TextDirection textDirection }) {
// rect = rect.deflate(borderWidth / 2.0);
Paint paint;
final RRect borderRect = borderRadius.resolve(textDirection).toRRect(rect);
paint = new Paint()
..color = Colors.red.withOpacity(0.25)
..style = PaintingStyle.fill
..strokeWidth = borderWidth;
canvas.drawRRect(borderRect, paint);
}
我仍然困惑于如何做到这一点...