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Updating checkmark animation (#15850)

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Greg Spencer 2018-03-23 08:58:29 -07:00 committed by GitHub
parent ce28378178
commit b3b9b2215a
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1 changed files with 14 additions and 7 deletions
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21
packages/flutter/lib/src/material/checkbox.dart
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@ -253,17 +253,24 @@ class _RenderCheckbox extends RenderToggleable {
void _drawCheck(Canvas canvas, Offset origin, double t, Paint paint) {
assert(t >= 0.0 && t <= 1.0);
// As t goes from 0.0 to 1.0, animate the two checkmark strokes from the
// mid point outwards.
// As t goes from 0.0 to 1.0, animate the two check mark strokes from the
// short side to the long side.
final Path path = new Path();
const Offset start = const Offset(_kEdgeSize * 0.15, _kEdgeSize * 0.45);
const Offset mid = const Offset(_kEdgeSize * 0.4, _kEdgeSize * 0.7);
const Offset end = const Offset(_kEdgeSize * 0.85, _kEdgeSize * 0.25);
final Offset drawStart = Offset.lerp(start, mid, 1.0 - t);
final Offset drawEnd = Offset.lerp(mid, end, t);
path.moveTo(origin.dx + drawStart.dx, origin.dy + drawStart.dy);
path.lineTo(origin.dx + mid.dx, origin.dy + mid.dy);
path.lineTo(origin.dx + drawEnd.dx, origin.dy + drawEnd.dy);
if (t < 0.5) {
final double strokeT = t * 2.0;
final Offset drawMid = Offset.lerp(start, mid, strokeT);
path.moveTo(origin.dx + start.dx, origin.dy + start.dy);
path.lineTo(origin.dx + drawMid.dx, origin.dy + drawMid.dy);
} else {
final double strokeT = (t - 0.5) * 2.0;
final Offset drawEnd = Offset.lerp(mid, end, strokeT);
path.moveTo(origin.dx + start.dx, origin.dy + start.dy);
path.lineTo(origin.dx + mid.dx, origin.dy + mid.dy);
path.lineTo(origin.dx + drawEnd.dx, origin.dy + drawEnd.dy);
}
canvas.drawPath(path, paint);
}