2 * emccpre.js: one of the Javascript components of an Emscripten-based
3 * web/Javascript front end for Puzzles.
5 * The other parts of this system live in emcc.c and emcclib.js. It
6 * also depends on being run in the context of a web page containing
7 * an appropriate collection of bits and pieces (a canvas, some
8 * buttons and links etc), which is generated for each puzzle by the
9 * script html/jspage.pl.
11 * This file contains the Javascript code which is prefixed unmodified
12 * to Emscripten's output via the --pre-js option. It declares all our
13 * global variables, and provides the puzzle init function and a
14 * couple of other helper functions.
17 // To avoid flicker while doing complicated drawing, we use two
18 // canvases, the same size. One is actually on the web page, and the
19 // other is off-screen. We do all our drawing on the off-screen one
20 // first, and then copy rectangles of it to the on-screen canvas in
21 // response to draw_update() calls by the game backend.
22 var onscreen_canvas, offscreen_canvas;
24 // A persistent drawing context for the offscreen canvas, to save
25 // constructing one per individual graphics operation.
28 // Bounding rectangle for the copy to the onscreen canvas that will be
29 // done at drawing end time. Updated by js_canvas_draw_update and used
30 // by js_canvas_end_draw.
31 var update_xmin, update_xmax, update_ymin, update_ymax;
33 // Module object for Emscripten. We fill in these parameters to ensure
34 // that Module.run() won't be called until we're ready (we want to do
35 // our own init stuff first), and that when main() returns nothing
36 // will get cleaned up so we remain able to call the puzzle's various
43 // Variables used by js_canvas_find_font_midpoint().
44 var midpoint_test_str = "ABCDEFGHIKLMNOPRSTUVWXYZ0123456789";
45 var midpoint_cache = [];
47 // Variables used by js_activate_timer() and js_deactivate_timer().
49 var timer_reference_date;
51 // void timer_callback(double tplus);
53 // Called every 20ms while timing is active.
56 // The status bar object, if we create one.
59 // Currently live blitters. We keep an integer id for each one on the
60 // JS side; the C side, which expects a blitter to look like a struct,
61 // simply defines the struct to contain that integer id.
65 // State for the dialog-box mechanism. dlg_dimmer and dlg_form are the
66 // page-darkening overlay and the actual dialog box respectively;
67 // dlg_next_id is used to allocate each checkbox a unique id to use
68 // for linking its label to it (see js_dialog_boolean);
69 // dlg_return_funcs is a list of JS functions to be called when the OK
70 // button is pressed, to pass the results back to C.
71 var dlg_dimmer = null, dlg_form = null;
73 var dlg_return_funcs = null;
75 // void dlg_return_sval(int index, const char *val);
76 // void dlg_return_ival(int index, int val);
78 // C-side entry points called by functions in dlg_return_funcs, to
79 // pass back the final value in each dialog control.
80 var dlg_return_sval, dlg_return_ival;
82 // The <ul> object implementing the game-type drop-down, and a list of
83 // the <li> objects inside it. Used by js_add_preset(),
84 // js_get_selected_preset() and js_select_preset().
85 var gametypelist = null, gametypeitems = [], gametypecustom = null;
86 var gametypeselectedindex = null;
88 // The two anchors used to give permalinks to the current puzzle. Used
89 // by js_update_permalinks().
90 var permalink_seed, permalink_desc;
92 // The undo and redo buttons. Used by js_enable_undo_redo().
93 var undo_button, redo_button;
95 // A div element enclosing both the puzzle and its status bar, used
96 // for positioning the resize handle.
99 // Helper function to find the absolute position of a given DOM
100 // element on a page, by iterating upwards through the DOM finding
101 // each element's offset from its parent, and thus calculating the
102 // page-relative position of the target element.
103 function element_coords(element) {
105 while (element.offsetParent) {
106 ex += element.offsetLeft;
107 ey += element.offsetTop;
108 element = element.offsetParent;
110 return {x: ex, y:ey};
113 // Helper function which is passed a mouse event object and a DOM
114 // element, and returns the coordinates of the mouse event relative to
115 // the top left corner of the element by subtracting element_coords
116 // from event.page{X,Y}.
117 function relative_mouse_coords(event, element) {
118 var ecoords = element_coords(element);
119 return {x: event.pageX - ecoords.x,
120 y: event.pageY - ecoords.y};
123 // Enable and disable items in the CSS menus.
124 function disable_menu_item(item, disabledFlag) {
126 item.className = "disabled";
131 // Init function called from body.onload.
132 function initPuzzle() {
133 // Construct the off-screen canvas used for double buffering.
134 onscreen_canvas = document.getElementById("puzzlecanvas");
135 offscreen_canvas = document.createElement("canvas");
136 offscreen_canvas.width = onscreen_canvas.width;
137 offscreen_canvas.height = onscreen_canvas.height;
139 // Stop right-clicks on the puzzle from popping up a context menu.
140 // We need those right-clicks!
141 onscreen_canvas.oncontextmenu = function(event) { return false; }
143 // Set up mouse handlers. We do a bit of tracking of the currently
144 // pressed mouse buttons, to avoid sending mousemoves with no
145 // button down (our puzzles don't want those events).
146 mousedown = Module.cwrap('mousedown', 'void',
147 ['number', 'number', 'number']);
149 onscreen_canvas.onmousedown = function(event) {
150 var xy = relative_mouse_coords(event, onscreen_canvas);
151 mousedown(xy.x, xy.y, event.button);
152 buttons_down |= 1 << event.button;
153 onscreen_canvas.setCapture(true);
155 mousemove = Module.cwrap('mousemove', 'void',
156 ['number', 'number', 'number']);
157 onscreen_canvas.onmousemove = function(event) {
159 var xy = relative_mouse_coords(event, onscreen_canvas);
160 mousemove(xy.x, xy.y, buttons_down);
163 mouseup = Module.cwrap('mouseup', 'void',
164 ['number', 'number', 'number']);
165 onscreen_canvas.onmouseup = function(event) {
166 if (buttons_down & (1 << event.button)) {
167 buttons_down ^= 1 << event.button;
168 var xy = relative_mouse_coords(event, onscreen_canvas);
169 mouseup(xy.x, xy.y, event.button);
173 // Set up keyboard handlers. We do all the actual keyboard
174 // handling in onkeydown; but we also call event.preventDefault()
175 // in both the keydown and keypress handlers. This means that
176 // while the canvas itself has focus, _all_ keypresses go only to
177 // the puzzle - so users of this puzzle collection in other media
178 // can indulge their instinct to press ^R for redo, for example,
179 // without accidentally reloading the page.
180 key = Module.cwrap('key', 'void', ['number', 'number', 'string',
181 'string', 'number', 'number']);
182 onscreen_canvas.onkeydown = function(event) {
183 key(event.keyCode, event.charCode, event.key, event.char,
184 event.shiftKey ? 1 : 0, event.ctrlKey ? 1 : 0);
185 event.preventDefault();
187 onscreen_canvas.onkeypress = function(event) {
188 event.preventDefault();
191 // command() is a C function called to pass back events which
192 // don't fall into other categories like mouse and key events.
193 // Mostly those are button presses, but there's also one for the
194 // game-type dropdown having been changed.
195 command = Module.cwrap('command', 'void', ['number']);
197 // Event handlers for buttons and things, which call command().
198 document.getElementById("specific").onclick = function(event) {
199 // Ensure we don't accidentally process these events when a
200 // dialog is actually active, e.g. because the button still
201 // has keyboard focus
202 if (dlg_dimmer === null)
205 document.getElementById("random").onclick = function(event) {
206 if (dlg_dimmer === null)
209 document.getElementById("new").onclick = function(event) {
210 if (dlg_dimmer === null)
213 document.getElementById("restart").onclick = function(event) {
214 if (dlg_dimmer === null)
217 undo_button = document.getElementById("undo");
218 undo_button.onclick = function(event) {
219 if (dlg_dimmer === null)
222 redo_button = document.getElementById("redo");
223 redo_button.onclick = function(event) {
224 if (dlg_dimmer === null)
227 document.getElementById("solve").onclick = function(event) {
228 if (dlg_dimmer === null)
232 gametypelist = document.getElementById("gametype");
234 // In IE, the canvas doesn't automatically gain focus on a mouse
235 // click, so make sure it does
236 onscreen_canvas.addEventListener("mousedown", function(event) {
237 onscreen_canvas.focus();
240 // In our dialog boxes, Return and Escape should be like pressing
241 // OK and Cancel respectively
242 document.addEventListener("keydown", function(event) {
244 if (dlg_dimmer !== null && event.keyCode == 13) {
245 for (var i in dlg_return_funcs)
246 dlg_return_funcs[i]();
250 if (dlg_dimmer !== null && event.keyCode == 27)
254 // Set up the function pointers we haven't already grabbed.
255 dlg_return_sval = Module.cwrap('dlg_return_sval', 'void',
256 ['number','string']);
257 dlg_return_ival = Module.cwrap('dlg_return_ival', 'void',
258 ['number','number']);
259 timer_callback = Module.cwrap('timer_callback', 'void', ['number']);
261 // Save references to the two permalinks.
262 permalink_desc = document.getElementById("permalink-desc");
263 permalink_seed = document.getElementById("permalink-seed");
265 // Default to giving keyboard focus to the puzzle.
266 onscreen_canvas.focus();
268 // Create the resize handle.
269 var resize_handle = document.createElement("canvas");
270 resize_handle.width = 10;
271 resize_handle.height = 10;
273 var ctx = resize_handle.getContext("2d");
275 for (var i = 1; i <= 7; i += 3) {
276 ctx.moveTo(8.5, i + 0.5);
277 ctx.lineTo(i + 0.5, 8.5);
279 ctx.lineWidth = '1px';
280 ctx.lineCap = 'round';
281 ctx.lineJoin = 'round';
282 ctx.strokeStyle = '#000000';
285 resizable_div = document.getElementById("resizable");
286 resizable_div.appendChild(resize_handle);
287 resize_handle.style.position = 'absolute';
288 resize_handle.style.zIndex = 98;
289 resize_handle.style.bottom = "0";
290 resize_handle.style.right = "0";
291 resize_handle.style.cursor = "se-resize";
292 resize_handle.title = "Drag to resize the puzzle. Right-click to restore the default size.";
293 var resize_xbase = null, resize_ybase = null, restore_pending = false;
294 var resize_xoffset = null, resize_yoffset = null;
295 var resize_puzzle = Module.cwrap('resize_puzzle',
296 'void', ['number', 'number']);
297 var restore_puzzle_size = Module.cwrap('restore_puzzle_size', 'void', []);
298 resize_handle.oncontextmenu = function(event) { return false; }
299 resize_handle.onmousedown = function(event) {
300 if (event.button == 0) {
301 var xy = element_coords(onscreen_canvas);
302 resize_xbase = xy.x + onscreen_canvas.width / 2;
304 resize_xoffset = xy.x + onscreen_canvas.width - event.pageX;
305 resize_yoffset = xy.y + onscreen_canvas.height - event.pageY;
307 restore_pending = true;
309 resize_handle.setCapture(true);
310 event.preventDefault();
312 window.addEventListener("mousemove", function(event) {
313 if (resize_xbase !== null && resize_ybase !== null) {
314 resize_puzzle((event.pageX + resize_xoffset - resize_xbase) * 2,
315 (event.pageY + resize_yoffset - resize_ybase));
316 event.preventDefault();
317 // Chrome insists on selecting text during a resize drag
318 // no matter what I do
319 if (window.getSelection)
320 window.getSelection().removeAllRanges();
322 document.selection.empty(); }
324 window.addEventListener("mouseup", function(event) {
325 if (resize_xbase !== null && resize_ybase !== null) {
328 onscreen_canvas.focus(); // return focus to the puzzle
329 event.preventDefault();
330 } else if (restore_pending) {
331 // If you have the puzzle at larger than normal size and
332 // then right-click to restore, I haven't found any way to
333 // stop Chrome and IE popping up a context menu on the
334 // revealed piece of document when you release the button
335 // except by putting the actual restore into a setTimeout.
337 setTimeout(function() {
338 restore_pending = false;
339 restore_puzzle_size();
340 onscreen_canvas.focus();
342 event.preventDefault();
346 // Run the C setup function, passing argv[1] as the fragment
347 // identifier (so that permalinks of the form puzzle.html#game-id
348 // can launch the specified id).
349 Module.callMain([location.hash]);
351 // And if we get here with everything having gone smoothly, i.e.
352 // we haven't crashed for one reason or another during setup, then
353 // it's probably safe to hide the 'sorry, no puzzle here' div and
354 // show the div containing the actual puzzle.
355 document.getElementById("apology").style.display = "none";
356 document.getElementById("puzzle").style.display = "inline";