support initialMove field to have a custom move as the initial positi…

…on of the board (#19)
eronnen · Nov 25, 2023 · 7114ab3 · 7114ab3
1 parent e1c943e
commit 7114ab3
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Showing 4 changed files with 40 additions and 17 deletions.
diff --git a/README.md b/README.md
@@ -79,16 +79,17 @@ These properties are available both for chess and pgn blocks. when using in a pg
 
 These properties are only available for chess blocks.
 
-| **Property** | **Description**                           | **Possible values**  | **Default**                         |
-| ------------ | ----------------------------------------- | -------------------- | ----------------------------------- |
-| **fen**      | The initial position                      | Any valid FEN string | Initial                             |
-| **arrows**   | Series of arrows to draw                  | e2->e4 d2->d4        | Empty                               |
-| **squares**  | Series of squares to mark                 | e5 d5                | Empty                               |
-| **movable**  | Force to enable/disable movement          | true / false         | false if FEN supplied               |
-| **drawable** | Force to enable/disable drawing           | true / false         | false if arrows or squares supplied |
-| **lastMove** | Highlight last move                       | e2 e4                | Undefined                           |
-| **moves**    | Sequence of moves to view in the position | e4 e5 Nf3 Nf6 Nxe5   | Undefined                           |
-| **variant**  | Variant name                              | Chess960             | Undefined                           |
+| **Property**    | **Description**                                  | **Possible values**  | **Default**                         |
+| --------------- | ------------------------------------------------ | -------------------- | ----------------------------------- |
+| **fen**         | The initial position                             | Any valid FEN string | Initial                             |
+| **arrows**      | Series of arrows to draw                         | e2->e4 d2->d4        | Empty                               |
+| **squares**     | Series of squares to mark                        | e5 d5                | Empty                               |
+| **movable**     | Force to enable/disable movement                 | true / false         | false if FEN supplied               |
+| **drawable**    | Force to enable/disable drawing                  | true / false         | false if arrows or squares supplied |
+| **lastMove**    | Highlight last move                              | e2 e4                | Undefined                           |
+| **moves**       | Sequence of moves to view in the position        | e4 e5 Nf3 Nf6 Nxe5   | Undefined                           |
+| **initialMove** | Move to display in initial position. -1 for last | -1,0,1,2,3,...       | 0                                   |
+| **variant**     | Variant name                                     | Chess960             | Undefined                           |
 
 ## PGN Viewer
 

diff --git a/src/markdown/chessGame.ts b/src/markdown/chessGame.ts
@@ -40,6 +40,8 @@ class ChessGame {
   private buttonLastMove_: HTMLButtonElement;
 
   private initialPosition_: Position;
+  private initialDisplayPosition_: Position;
+  private initialMove_: number | undefined = undefined;
   private initialLastMove_: Key[] | undefined = undefined;
   private sanMoves_: string[] = [];
   private currentMove_ = 0;
@@ -74,7 +76,12 @@ class ChessGame {
       }
     }
 
-    this.reinitializeChess_();
+    this.chess_ = (
+      this.initialDisplayPosition_ !== undefined
+        ? this.initialDisplayPosition_
+        : this.initialPosition_
+    ).clone();
+    this.currentMove_ = this.initialMove_ || 0;
     this.createMovesElement_();
     this.updateMoveButtons_();
     this.createChessBoard_(chessOptions);
@@ -117,9 +124,18 @@ class ChessGame {
           .unwrap()
       : defaultPosition(rules);
 
+    this.initialDisplayPosition_ = this.initialPosition_.clone();
     if (chessOptions.moves) {
       this.sanMoves_ = chessOptions.moves.split(/\s+/);
       this.sanMoves_ = this.sanMoves_.filter((move) => !move.match(/^\d+\./)); // remove move indices
+
+      if (chessOptions.initialMove !== undefined) {
+        const numberOfIndices = this.sanMoves_.length + 1;
+        this.initialMove_ =
+          ((chessOptions.initialMove % numberOfIndices) + numberOfIndices) %
+          numberOfIndices;
+        this.playMovesUntil_(this.initialMove_, this.initialDisplayPosition_);
+      }
     }
 
     if (chessOptions.lastMove) {
@@ -215,7 +231,7 @@ class ChessGame {
 
   private createChessBoard_(chessOptions: ChessBlockOptions) {
     const config: Config = {
-      fen: makeFen(this.initialPosition_.toSetup()),
+      fen: makeFen(this.chess_.toSetup()),
       disableContextMenu: true,
       draggable: {
         enabled: false,
@@ -236,18 +252,19 @@ class ChessGame {
 
   private reinitializeChess_() {
     this.chess_ = this.initialPosition_.clone();
+    this.currentMove_ = 0;
   }
 
-  private playMovesUntil_(untilMove: number) {
+  private playMovesUntil_(untilMove: number, position: Position = this.chess_) {
     let move: Move | undefined = undefined;
     for (; this.currentMove_ < untilMove; this.currentMove_++) {
-      move = parseSan(this.chess_, this.sanMoves_[this.currentMove_]);
+      move = parseSan(position, this.sanMoves_[this.currentMove_]);
       if (!move) {
         // TODO: log error
         break;
       }
 
-      this.chess_.play(move);
+      position.play(move);
     }
 
     return move;
@@ -304,7 +321,6 @@ class ChessGame {
 
   private goToFirstMove_() {
     this.cancelOngoingAnimation_();
-    this.currentMove_ = 0;
     this.reinitializeChess_();
     this.updateBoard_();
     this.updateMoveButtons_();
@@ -418,7 +434,6 @@ class ChessGame {
     }
 
     const currentMoveTemp = this.currentMove_ - 1;
-    this.currentMove_ = 0;
     this.reinitializeChess_();
     const lastMove = this.playMovesUntil_(currentMoveTemp);
 

diff --git a/src/markdown/chessRenderer.ts b/src/markdown/chessRenderer.ts
@@ -41,6 +41,7 @@ function parseChessBlockOptions(chessElement: HTMLElement): ChessBlockOptions {
     drawable: undefined,
     lastMove: undefined,
     moves: undefined,
+    initialMove: undefined,
     variant: undefined,
   };
 
@@ -92,6 +93,11 @@ function parseChessBlockOptions(chessElement: HTMLElement): ChessBlockOptions {
       case "moves":
         options.moves = value.trim();
         break;
+      case "initialmove":
+        if (value.match(/^-?\d+/g)) {
+          options.initialMove = parseInt(value);
+        }
+        break;
       case "variant":
         options.variant = value.trim();
         break;

diff --git a/src/shared/index.d.ts b/src/shared/index.d.ts
@@ -33,6 +33,7 @@ declare interface ChessBlockOptions {
   lastMove: string | undefined;
 
   moves: string | undefined;
+  initialMove: number | undefined;
   variant: string | undefined;
 }