components: implement basic selection algorithm

src/components/App/App.tsx

@@ -16,7 +16,7 @@ export default function App(): JSX.Element {
         <Board
           numRows={10}
           numCols={10}
-          numLines={5}
+          numLines={1}
         />
       </div>
       <div />

src/components/Board/Board.tsx

@@ -9,6 +9,11 @@ export type Point = {
   y: number;
 }
 
+type Selection = {
+  start: Point;
+  end: Point;
+}
+
 interface IBoardProps {
   numRows: number;
   numCols: number;
@@ -17,52 +22,54 @@ interface IBoardProps {
 
 interface IBoardState {
   cells: string[][];
-  lines: boolean[];
+  selections: Selection[];
   isSelecting: boolean;
-  startPos: Point;
+  start: Point;
-  endPos: Point;
+  end: Point;
 }
 
+const Point0: Point = {x: 0, y: 0};
+const Selection0: Selection = {start: Point0, end: Point0};
+
 export default class Board extends React.Component<IBoardProps, IBoardState> {
   constructor(props: IBoardProps) {
     super(props);
 
     this.state = {
       cells: Array(props.numCols).fill(Array(props.numRows).fill('A')),
-      lines: Array(props.numLines).fill(false),
+      selections: Array(props.numLines).fill(Selection0),
       isSelecting: false,
-      startPos: {x: 0, y: 0},
+      start: Point0,
-      endPos: {x: 0, y: 0},
+      end: Point0,
     }
   }
 
   moveIsValid(pos: Point): boolean {
-    const x = Math.abs(pos.x - this.state.startPos.x);
+    const x = Math.abs(pos.x - this.state.start.x);
-    const y = Math.abs(pos.y - this.state.startPos.y);
+    const y = Math.abs(pos.y - this.state.start.y);
     const lineIsValid = x === 0 || y === 0 || x === y;
 
     return this.state.isSelecting && lineIsValid;
   }
 
-  handleMouseDown(startPos: Point) {
+  handleMouseDown(start: Point) {
-    const endPos = startPos;
+    const end = start;
-    let lines = [...this.state.lines];
+    let selections = [...this.state.selections];
-    lines[0] = true;
+    this.setState({...this.state, start, end, selections, isSelecting: true});
-    this.setState({...this.state, startPos, endPos, lines, isSelecting: true});
   }
 
-  handleMouseUp(endPos: Point) {
+  handleMouseUp(end: Point) {
-    if (!this.moveIsValid(endPos))
+    if (!this.moveIsValid(end))
       return;
 
-    this.setState({...this.state, endPos, isSelecting: false});
+    this.setState({...this.state, end, isSelecting: false});
   }
 
-  handleMouseOver(endPos: Point) {
+  handleMouseOver(end: Point) {
-    if (!this.moveIsValid(endPos))
+    if (!this.moveIsValid(end))
       return;
 
-    this.setState({...this.state, endPos});
+    this.setState({...this.state, end});
   }
 
   renderCell(s: string, pos: Point): JSX.Element {
@@ -83,8 +90,8 @@ export default class Board extends React.Component<IBoardProps, IBoardState> {
     return (
       <Line
         key={`Line${x}`}
-        startPos={{...this.state.startPos}}
+        startPos={{...this.state.start}}
-        endPos={{...this.state.endPos}}
+        endPos={{...this.state.end}}
         cellSize={60}
       />
     );
@@ -96,7 +103,7 @@ export default class Board extends React.Component<IBoardProps, IBoardState> {
         oy.map((s, x) =>
           this.renderCell(s, {x, y})));
 
-    let lines = this.state.lines.filter(x => x).map((ox, x) =>
+    let lines = this.state.selections.filter(x => x).map((ox, x) =>
       this.renderLine(x));
 
     return (

src/components/Line/Line.scss

@@ -1,5 +1,11 @@
 .Line {
-  stroke: red;
+  stroke: #8b8be5;
-  stroke-width: 10px;
+  stroke-width: 5px;
-  opacity: 0.3;
+  fill: none;
+}
+
+.Line2 {
+  stroke: #d6a54d;
+  stroke-width: 5px;
+  fill: none;
 }

src/components/Line/Line.tsx

@@ -4,6 +4,18 @@ import {Point} from '../Board/Board'
 
 import './Line.scss';
 
+enum Direction {
+  None = 0,
+  Up = 1,
+  Down = 2,
+  Left = 10,
+  LeftUp = 11,
+  LeftDown = 12,
+  Right = 20,
+  RightUp = 21,
+  RightDown = 22,
+}
+
 interface ILineProps {
   startPos: Point;
   endPos: Point;
@@ -12,14 +24,103 @@ interface ILineProps {
 
 export default function Line(props: ILineProps): JSX.Element {
   const pos = (v: number) => v * props.cellSize + props.cellSize / 2;
+  const dir = (v: number) => v < 0 ? 2 : v > 0 ? 1 : 0;
+
+  const offset = 2.5;
+  const margin = 30;
+
+  let [x, y, w, h, t] = [0, 0, 0, 0, ''];
+
+  const ox = dir(props.startPos.x - props.endPos.x);
+  const oy = dir(props.startPos.y - props.endPos.y);
+  const d = Number(`${ox}${oy}`) as Direction;
+
+  switch (d) {
+    case Direction.None:
+      break;
+    case Direction.Up:
+      x = pos(props.endPos.x) - margin + offset;
+      y = pos(props.endPos.y) - margin + offset;
+      w = 55;
+      h = pos(props.startPos.y - props.endPos.y +1) - margin - offset * 2;
+      t = '';
+      break;
+    case Direction.Down:
+      x = pos(props.startPos.x) - margin + offset;
+      y = pos(props.startPos.y) - margin + offset;
+      w = 55;
+      h = pos(props.endPos.y - props.startPos.y +1) - margin - offset * 2;
+      t = '';
+      break;
+    case Direction.Left:
+      x = pos(props.endPos.x) - margin + offset;
+      y = pos(props.endPos.y) - margin + offset;
+      w = pos(props.startPos.x - props.endPos.x +1) - margin - offset * 2;
+      h = 55;
+      t = '';
+      break;
+    case Direction.LeftUp:
+      x = pos(props.endPos.x-1) + margin;
+      y = pos(props.endPos.y) - margin + offset;
+      w = props.startPos.x - props.endPos.x;
+      w = pos(w) + (margin - offset * 2) + w * (margin - offset * 2);
+      h = 55;
+      t = `translate(29,-14),rotate(45, ${x-offset}, ${y+offset})`
+      break;
+    case Direction.LeftDown:
+      x = pos(props.endPos.x-1) + margin;
+      y = pos(props.endPos.y) - margin + offset;
+      w = props.startPos.x - props.endPos.x;
+      w = pos(w) + (margin - offset * 2) + w * (margin - offset * 2);
+      h = 55;
+      t = `translate(-12,27),rotate(-45, ${x+offset}, ${y-offset})`
+      break;
+    case Direction.Right:
+      x = pos(props.startPos.x) - margin + offset;
+      y = pos(props.startPos.y) - margin + offset;
+      w = pos(props.endPos.x - props.startPos.x +1) - margin - offset * 2;
+      h = 55;
+      t = '';
+      break;
+    case Direction.RightUp:
+      x = pos(props.startPos.x) - margin + offset;
+      y = pos(props.startPos.y) - margin + offset;
+      w = props.endPos.x - props.startPos.x;
+      w = pos(w) + (margin - offset * 2) + w * (margin - offset * 2);
+      h = 55;
+      t = `translate(-9, 29),rotate(-45, ${x-offset}, ${y+offset})`
+      break;
+    case Direction.RightDown:
+      x = pos(props.startPos.x) - margin + offset;
+      y = pos(props.startPos.y) - margin + offset;
+      w = props.endPos.x - props.startPos.x;
+      w = pos(w) + (margin - offset * 2) + w * (margin - offset * 2);
+      h = 55;
+      t = `translate(27, -14),rotate(45, ${x-offset}, ${y+offset})`
+      break;
+  }
 
   return (
-    <line
+    <svg>
-      className="Line"
+      <rect
-      x1={`${pos(props.endPos.x)}`}
+        className="Line2"
-      y1={`${pos(props.endPos.y)}`}
+        x={x}
-      x2={`${pos(props.startPos.x)}`}
+        y={y}
-      y2={`${pos(props.startPos.y)}`}
+        width={w}
+        height={h}
       />
+      <rect
+        className="Line"
+        x={x}
+        y={y}
+        width={w}
+        height={h}
+        transform={t}
+        rx={margin - offset}
+        ry={margin - offset}
+      />
+      <circle cx={x} cy={y} r="5" fill="orange" />
+      <circle cx={x+w} cy={y+h} r="5" fill="red" />
+    </svg>
   );
 }