Added chess game

Human with white and computer with black.

Based on p4wn engine[1]. Computations are rather slow but it works.

Usage: Drag on the touchscreen to move the green cursor onto a piece, select it with a single touch and drag the now red cursor around. Release the piece with another touch to finish the move. The button opens a menu.

[1] https://p4wn.sourceforge.net/

apps/chess/app-icon.js

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+require("heatshrink").decompress(atob("mEwxH+AH4A/AH4A/AEnPAEAv/wAAcF6XWAAYdFBQgLLF/4v/F/4vTFKoLGF/4v/F/4v/F4QpWBQov/F7UslgKBAYIABEgIDDF/4v/F4es1gvTdKoLBFYYAHF/4vTmQvuvQwJFxAvbAAOIxIAFFxIvzFKYLG6CMNF8GsF92BdpwvfqwvtRwgvQAC+IxIAJF5QAYF93OwEyRwqSPACwsJGEov/AH4A/AH4AwA="))

apps/chess/app.js

@@ -0,0 +1,280 @@
+// Using p4wn chess engine: https://p4wn.sourceforge.net/ | https://github.com/douglasbagnall/p4wn
+const engine = require("chessengine");
+
+Bangle.loadWidgets(); // load before first appRect call
+
+const FIELD_WIDTH = Bangle.appRect.w/8;
+const FIELD_HEIGHT = Bangle.appRect.h/8;
+const SETTINGS_FILE = "chess.json";
+const DEFAULT_TIMEOUT = Bangle.getOptions().lockTimeout;
+const ICON_SIZE=45;
+const ICON_BISHOP = require("heatshrink").decompress(atob("lstwMB/4Ac/wFE4IED/kPAofgn4FDGon8j4QEBQgQE4EHBQcACwfAgF/BQYWD8EAHAX+NgI4C+AQEwAQDDYIhDDYMDCAQKBGQQsHHogKDCAJODCAI3CHoQKCHoIQDHoIQCFgoQBFgfgIQYmBEIQECKgIrCBYQKDC4OBg/8iCvEAC+AA="));
+const ICON_PAWN = require("heatshrink").decompress(atob("lstwMB/4At/AFEGon4h4FDwE/AgX8CAngCAkAv4bDgYbECAf4gAhD4AhD/kAg4mDCAkACAYbBEIYQBG4gbDEII9DFhXAgEfBQYWDEwJUC/wKBGQXwCAgEBE4RCBCAYmBCAQmCCAQmBCAbdCCAIbCQ4gAYwA="));
+const ICON_KING = require("heatshrink").decompress(atob("lstwMB/4Ac/wFE+4KEh4FD+F/AofvCwgKE+IKEg4bEj4FDwADC/k8g+HAoJhCC4PwAoQXBNod//AECgYfBAoUP/gQE8AQEBQcfCAaLBCAZmBEIZuBBQgyDJAIWCPgXAEAQWDBQRUCPgQnBHgJqBLwYhDOwRvDGQc/EIaSDCwLedwAA=="));
+const ICON_QUEEN = require("heatshrink").decompress(atob("lstwMB/4Ac/l/AgXn4PzAgP+j0Ph4FB8FwuE///PgeDwPn/k8n0+j0f4Hz+Px8F+g/Px+fgf4vgACn/jAAf/x8Pj0en/8vAsB+P/+PBwcHj//w0MjEwJgMwsHBw5CBwMEhBDBPoR6B/gFCDYPgAoRZBAgUH//4AoQbB4AbDCAYbBCAZ1CAgJ7CwAKDGQQmBCAYmBEIQmC+AQEDYQQBDYQQCFgo3CXQIsFBYIEDACmAA="));
+const ICON_ROOK = require("heatshrink").decompress(atob("lstwMB/4Ax/0HgPAAoPwnEOg4FBwBFBn///gEBI4XgAoMPAoJWCv4QDDYXwBQf/4AKD/wmDCARuDGQImCEIQbCGQMDCAQKBj4EB/AFBBQQsgDYQQCNQQhCOog3CCAQ3BEIRvCAoSRCE4IxCKgQmCKgYAZwA="));
+const ICON_KNIGHT = require("heatshrink").decompress(atob("lstwMB/4Ann1/AgX48IKD4UPAgX+gEHAoXwgALDJQMfDYQFBEQWAgBSCBQQcC4AFBn///hnCBQPgAgMDGIQnDGIIQDAgQQBEwQQCGIIQCEwMECAQxBsAQBEwMPCAQmBAIJDB4EPDoM/CAIoBKgP4BQQQB/AzCKgJlIPgQ+COwJlCHoJlDJwJlDS4aBDDYQsCADOA"));
+
+const settings = Object.assign({
+  state: engine.P4_INITIAL_BOARD,
+  computer_level: 0, // default to "stupid" which is the fastest
+}, require("Storage").readJSON(SETTINGS_FILE,1) || {});
+
+var ovr = Graphics.createArrayBuffer(Bangle.appRect.w,Bangle.appRect.h,2,{msb:true});
+const curfield = [4*FIELD_WIDTH, 6*FIELD_HEIGHT]; // e2
+const startfield = Array(2);
+let piece_sel = 0;
+let showmenu = false;
+
+const writeSettings = () => {
+  settings.state = engine.p4_state2fen(state);
+  require('Storage').writeJSON(SETTINGS_FILE, settings);
+};
+
+const generateBgImage = () => {
+  var buf = Graphics.createArrayBuffer(Bangle.appRect.w,Bangle.appRect.h,1,{msb:true});
+  for(let idxrow=0; idxrow<8; idxrow++) {
+    for(let idxcol=0; idxcol<8; idxcol++) {
+      const bgCol = idxrow % 2 != idxcol % 2 ? 0 : 1;
+      const x = idxcol*FIELD_WIDTH;
+      const y = idxrow*FIELD_HEIGHT;
+      buf.setColor(bgCol).fillRect({x:x, y:y, w:FIELD_WIDTH, h:FIELD_HEIGHT});
+    }
+  }
+  return {width:buf.getWidth(), height:buf.getHeight(),
+          buffer:buf.buffer
+        };
+};
+
+const idx2Pos = (idxcol, idxrow) => {
+  "ram"
+  return 2*(1+8+1) + (7-idxrow)*(1+8+1) + idxcol + 1;
+};
+
+const drawPiece = (buf, x, y, piece) => {
+  let icon;
+
+  switch(piece & ~0x1) {
+    case engine.P4_PAWN:
+      icon = ICON_PAWN;
+      break;
+    case engine.P4_BISHOP:
+      icon = ICON_BISHOP;
+      break;
+    case engine.P4_KING:
+      icon = ICON_KING;
+      break;
+    case engine.P4_QUEEN:
+      icon = ICON_QUEEN;
+      break;
+    case engine.P4_ROOK:
+      icon = ICON_ROOK;
+      break;
+    case engine.P4_KNIGHT:
+      icon = ICON_KNIGHT;
+      break;
+  }
+
+  if (icon) {
+    const scale = FIELD_HEIGHT/ICON_SIZE;
+    buf.drawImage(icon, x+(FIELD_WIDTH-(ICON_SIZE*scale))/2, y, {scale: scale});
+  }
+  return buf;
+};
+
+const drawBoard = () => {
+  console.log("Free: " + process.memory().free);
+
+  g.setBgColor("#555").setColor("#aaa").drawImage(bgImage, Bangle.appRect.x, Bangle.appRect.y);
+  for(let idxrow=0; idxrow<8; idxrow++) {
+    for(let idxcol=0; idxcol<8; idxcol++) {
+      const x = idxcol*FIELD_WIDTH+Bangle.appRect.x;
+      const y = idxrow*FIELD_HEIGHT+Bangle.appRect.y;
+
+      const pos = idx2Pos(idxcol, idxrow);
+      const field = state.board[pos];
+
+      if (field) {
+        const fgCol = field & 0x1 ? "#000" : "#fff";
+        drawPiece(g.setBgColor(fgCol), x, y, field);
+      }
+    }
+  }
+};
+
+const roundX = (x) => {
+  return Math.round(x/FIELD_WIDTH)*FIELD_WIDTH;
+};
+
+const roundY = (y) => {
+  return Math.round(y/FIELD_HEIGHT)*FIELD_HEIGHT;
+};
+
+const drawSelectedField = () => {
+  ovr.clear();
+  if (!showmenu) {
+    if (startfield[0] !== undefined && startfield[1] !== undefined) {
+      // remove piece from startfield
+      const x = startfield[0];
+      const y = startfield[1];
+      ovr.setColor(2).fillRect({x:x, y:y, w:FIELD_WIDTH, h:FIELD_HEIGHT});
+    }
+
+    const x = roundX(curfield[0]);
+    const y = roundY(curfield[1]);
+    ovr.setColor(piece_sel ? 1 : 2)
+      .drawRect({x:x+1, y:y, w:FIELD_WIDTH-2, h:FIELD_HEIGHT})
+      .drawRect({x:x+2, y:y+1, w:FIELD_WIDTH-4, h:FIELD_HEIGHT-2})
+      .drawRect({x:x+3, y:y+2, w:FIELD_WIDTH-6, h:FIELD_HEIGHT-4});
+    if (piece_sel) {
+      drawPiece(ovr.setBgColor(1), x, y, piece_sel);
+      ovr.setBgColor(0); // back to transparent
+    }
+  }
+  Bangle.setLCDOverlay({width:ovr.getWidth(), height:ovr.getHeight(),
+          bpp:2, transparent:0,
+          palette:new Uint16Array([0, g.toColor("#F00"), g.toColor("#0F0"), 0]),
+          buffer:ovr.buffer
+        },Bangle.appRect.x,Bangle.appRect.y);
+};
+
+const isInside = (rect, e) => {
+  return e.x>=rect.x && e.x<rect.x+rect.w
+    && e.y>=rect.y && e.y<=rect.y+rect.h;
+};
+
+const showAlert = (msg) => {
+  showmenu = true;
+  drawSelectedField();
+  E.showAlert(msg).then(function() {
+    showmenu = false;
+    drawBoard();
+    drawSelectedField();
+  });
+};
+
+const move = (from,to) => {
+  const res = state.move(from, to);
+  console.log(res);
+  if (!res.ok) {
+    showAlert("Illegal move");
+  } else {
+    if (res.flags & engine.P4_MOVE_FLAG_MATE) {
+      showAlert("Checkmate or stalemate");
+    } else if (res.flags & engine.P4_MOVE_FLAG_CHECK) {
+      showAlert("A king is in check");
+    } else if (res.flags & engine.P4_MOVE_FLAG_DRAW) {
+      showAlert("A draw is available");
+    } else {
+      drawBoard();
+      drawSelectedField();
+    }
+  }
+  return res.ok;
+};
+
+const showMessage = (msg) => {
+  g.setColor("#f00").setFont("4x6:2").setFontAlign(-1,1).drawString(msg, 10, Bangle.appRect.y2-10);
+};
+
+// Run
+
+g.reset();
+const bgImage = generateBgImage();
+let state = engine.p4_fen2state(settings.state);
+drawBoard();
+drawSelectedField();
+Bangle.drawWidgets();
+
+// drag selected field
+Bangle.on('drag', (ev) => {
+  const newx = curfield[0]+ev.dx;
+  const newy = curfield[1]+ev.dy;
+  if (newx >= 0 && newx <= 7*FIELD_WIDTH) {
+    curfield[0] = newx;
+  }
+  if (newy >= 0 && newy <= 7*FIELD_HEIGHT) {
+    curfield[1] = newy;
+  }
+  drawSelectedField();
+});
+
+// touch to start/stop moving a piece
+Bangle.on('touch', (button, xy) => {
+  if (isInside(Bangle.appRect, xy) && !showmenu) {
+    if (piece_sel === 0) {
+      startfield[0] = roundX(curfield[0]);
+      startfield[1] = roundY(curfield[1]);
+      const startpos = idx2Pos(startfield[0]/FIELD_WIDTH, startfield[1]/FIELD_HEIGHT);
+      piece_sel = state.board[startpos];
+      if (piece_sel === 0) {
+        startfield[0] = startfield[1] = undefined;
+        // nothing here, do nothing
+        return;
+      }
+    } else { // piece_sel === 0
+      const colTo = roundX(curfield[0]);
+      const rowTo = roundY(curfield[1]);
+      if (startfield[0] !== colTo || startfield[1] !== rowTo) {
+        showMessage(/*LANG*/"Moving..");
+        const posFrom = idx2Pos(startfield[0]/FIELD_WIDTH, startfield[1]/FIELD_HEIGHT);
+        const posTo = idx2Pos(colTo/FIELD_WIDTH, rowTo/FIELD_HEIGHT);
+        setTimeout(() => {
+          if (move(posFrom, posTo)) {
+            // human move ok, do computer move
+            Bangle.setLCDTimeout(0.1); // this can take some time, turn off to save power
+            showMessage(/*LANG*/"Calculating..");
+            setTimeout(() => {
+              const compMove = state.findmove(settings.computer_level+1);
+              move(compMove[0], compMove[1]);
+              writeSettings();
+              Bangle.setLCDPower(true);
+              Bangle.setLocked(false);
+              Bangle.setLCDTimeout(DEFAULT_TIMEOUT/1000); // restore
+            }, 200); // execute after display update
+          }
+        }, 100); // execute after display update
+      } // piece_sel === 0
+      startfield[0] = startfield[1] = undefined;
+      piece_sel = 0;
+    }
+    drawSelectedField();
+  }
+});
+
+// show menu on button
+setWatch(() => {
+  showmenu = true;
+  drawSelectedField();
+
+  const closeMenu = () => {
+      showmenu = false;
+      E.showMenu();
+      drawBoard();
+      drawSelectedField();
+  };
+
+  E.showMenu({
+    "" : { title : /*LANG*/"Chess settings" },
+    "< Back" : () => closeMenu(),
+    /*LANG*/"New Game" : () => {
+      state = engine.p4_fen2state(engine.P4_INITIAL_BOARD);
+      writeSettings();
+      closeMenu();
+    },
+    /*LANG*/"Undo Move" : () => {
+      state.jump_to_moveno(-2);
+      closeMenu();
+    },
+    /*LANG*/'Level': {
+      value: settings.computer_level,
+      min: 0, max: 4,
+      format: v => [/*LANG*/'stupid', /*LANG*/'middling', /*LANG*/'default', /*LANG*/'slow', /*LANG*/'slowest'][v],
+      onchange: v => {
+        settings.computer_level = v;
+        writeSettings();
+      }
+    },
+    /*LANG*/"Exit" : () => load(),
+  });
+}, BTN, { repeat: true, edge: "falling" });

apps/chess/metadata.json

@@ -0,0 +1,17 @@
+{
+  "id": "chess",
+  "name": "Chess",
+  "shortName": "Chess",
+  "version": "0.01",
+  "description": "Chess game based on the [p4wn engine](https://p4wn.sourceforge.net/). Drag on the touchscreen to move the green cursor onto a piece, select it with a single touch and drag the now red cursor around. Release the piece with another touch to finish the move. The button opens a menu.",
+  "icon": "app.png",
+  "tags": "game",
+  "supports": ["BANGLEJS2"],
+  "storage": [
+    {"name":"chess.app.js","url":"app.js"},
+    {"name":"chessengine","url":"engine.js"},
+    {"name":"chess.img","url":"app-icon.js","evaluate":true}
+  ],
+  "data": [{"name":"chess.json"}],
+  "screenshots": [ {"url":"screenshot.png"} ]
+}