Feature Request: Drag & drop file to upload

lib/ui/app/dashed_rect.dart

@@ -0,0 +1,115 @@
+// https://stackoverflow.com/a/55428017/497368
+import 'package:flutter/material.dart';
+import 'dart:math' as math;
+
+class DashedRect extends StatelessWidget {
+  const DashedRect(
+      {this.color = Colors.black, this.strokeWidth = 1.0, this.gap = 5.0});
+
+  final Color color;
+  final double strokeWidth;
+  final double gap;
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      height: 100,
+      width: double.infinity,
+      child: Padding(
+        padding: EdgeInsets.all(strokeWidth / 2),
+        child: CustomPaint(
+          painter:
+              DashRectPainter(color: color, strokeWidth: strokeWidth, gap: gap),
+        ),
+      ),
+    );
+  }
+}
+
+class DashRectPainter extends CustomPainter {
+  DashRectPainter(
+      {this.strokeWidth = 5.0, this.color = Colors.red, this.gap = 5.0});
+
+  double strokeWidth;
+  Color color;
+  double gap;
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final dashedPaint = Paint()
+      ..color = color
+      ..strokeWidth = strokeWidth
+      ..style = PaintingStyle.stroke;
+
+    final x = size.width;
+    final y = size.height;
+
+    final _topPath = getDashedPath(
+      a: math.Point(0, 0),
+      b: math.Point(x, 0),
+      gap: gap,
+    );
+
+    final _rightPath = getDashedPath(
+      a: math.Point(x, 0),
+      b: math.Point(x, y),
+      gap: gap,
+    );
+
+    final _bottomPath = getDashedPath(
+      a: math.Point(0, y),
+      b: math.Point(x, y),
+      gap: gap,
+    );
+
+    final _leftPath = getDashedPath(
+      a: math.Point(0, 0),
+      b: math.Point(0.001, y),
+      gap: gap,
+    );
+
+    canvas.drawPath(_topPath, dashedPaint);
+    canvas.drawPath(_rightPath, dashedPaint);
+    canvas.drawPath(_bottomPath, dashedPaint);
+    canvas.drawPath(_leftPath, dashedPaint);
+  }
+
+  Path getDashedPath({
+    @required math.Point<double> a,
+    @required math.Point<double> b,
+    @required double gap,
+  }) {
+    final size = Size(b.x - a.x, b.y - a.y);
+    final path = Path();
+    path.moveTo(a.x, a.y);
+    bool shouldDraw = true;
+    math.Point currentPoint = math.Point(a.x, a.y);
+
+    final radians = math.atan(size.height / size.width);
+
+    final dx = math.cos(radians) * gap < 0
+        ? math.cos(radians) * gap * -1
+        : math.cos(radians) * gap;
+
+    final dy = math.sin(radians) * gap < 0
+        ? math.sin(radians) * gap * -1
+        : math.sin(radians) * gap;
+
+    while (currentPoint.x <= b.x && currentPoint.y <= b.y) {
+      shouldDraw
+          ? path.lineTo(currentPoint.x, currentPoint.y)
+          : path.moveTo(currentPoint.x, currentPoint.y);
+      shouldDraw = !shouldDraw;
+      currentPoint = math.Point(
+        currentPoint.x + dx,
+        currentPoint.y + dy,
+      );
+    }
+    return path;
+  }
+
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) {
+    return true;
+  }
+}