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 = [];
86 var gametypeselectedindex = null;
87 var gametypesubmenus = [];
89 // The two anchors used to give permalinks to the current puzzle. Used
90 // by js_update_permalinks().
91 var permalink_seed, permalink_desc;
93 // The undo and redo buttons. Used by js_enable_undo_redo().
94 var undo_button, redo_button;
96 // A div element enclosing both the puzzle and its status bar, used
97 // for positioning the resize handle.
100 // Helper function to find the absolute position of a given DOM
101 // element on a page, by iterating upwards through the DOM finding
102 // each element's offset from its parent, and thus calculating the
103 // page-relative position of the target element.
104 function element_coords(element) {
106 while (element.offsetParent) {
107 ex += element.offsetLeft;
108 ey += element.offsetTop;
109 element = element.offsetParent;
111 return {x: ex, y:ey};
114 // Helper function which is passed a mouse event object and a DOM
115 // element, and returns the coordinates of the mouse event relative to
116 // the top left corner of the element by subtracting element_coords
117 // from event.page{X,Y}.
118 function relative_mouse_coords(event, element) {
119 var ecoords = element_coords(element);
120 return {x: event.pageX - ecoords.x,
121 y: event.pageY - ecoords.y};
124 // Enable and disable items in the CSS menus.
125 function disable_menu_item(item, disabledFlag) {
127 item.className = "disabled";
132 // Init function called from body.onload.
133 function initPuzzle() {
134 // Construct the off-screen canvas used for double buffering.
135 onscreen_canvas = document.getElementById("puzzlecanvas");
136 offscreen_canvas = document.createElement("canvas");
137 offscreen_canvas.width = onscreen_canvas.width;
138 offscreen_canvas.height = onscreen_canvas.height;
140 // Stop right-clicks on the puzzle from popping up a context menu.
141 // We need those right-clicks!
142 onscreen_canvas.oncontextmenu = function(event) { return false; }
144 // Set up mouse handlers. We do a bit of tracking of the currently
145 // pressed mouse buttons, to avoid sending mousemoves with no
146 // button down (our puzzles don't want those events).
147 mousedown = Module.cwrap('mousedown', 'void',
148 ['number', 'number', 'number']);
150 onscreen_canvas.onmousedown = function(event) {
151 var xy = relative_mouse_coords(event, onscreen_canvas);
152 mousedown(xy.x, xy.y, event.button);
153 buttons_down |= 1 << event.button;
154 onscreen_canvas.setCapture(true);
156 mousemove = Module.cwrap('mousemove', 'void',
157 ['number', 'number', 'number']);
158 onscreen_canvas.onmousemove = function(event) {
160 var xy = relative_mouse_coords(event, onscreen_canvas);
161 mousemove(xy.x, xy.y, buttons_down);
164 mouseup = Module.cwrap('mouseup', 'void',
165 ['number', 'number', 'number']);
166 onscreen_canvas.onmouseup = function(event) {
167 if (buttons_down & (1 << event.button)) {
168 buttons_down ^= 1 << event.button;
169 var xy = relative_mouse_coords(event, onscreen_canvas);
170 mouseup(xy.x, xy.y, event.button);
174 // Set up keyboard handlers. We do all the actual keyboard
175 // handling in onkeydown; but we also call event.preventDefault()
176 // in both the keydown and keypress handlers. This means that
177 // while the canvas itself has focus, _all_ keypresses go only to
178 // the puzzle - so users of this puzzle collection in other media
179 // can indulge their instinct to press ^R for redo, for example,
180 // without accidentally reloading the page.
181 key = Module.cwrap('key', 'void', ['number', 'number', 'string',
182 'string', 'number', 'number']);
183 onscreen_canvas.onkeydown = function(event) {
184 key(event.keyCode, event.charCode, event.key, event.char,
185 event.shiftKey ? 1 : 0, event.ctrlKey ? 1 : 0);
186 event.preventDefault();
188 onscreen_canvas.onkeypress = function(event) {
189 event.preventDefault();
192 // command() is a C function called to pass back events which
193 // don't fall into other categories like mouse and key events.
194 // Mostly those are button presses, but there's also one for the
195 // game-type dropdown having been changed.
196 command = Module.cwrap('command', 'void', ['number']);
198 // Event handlers for buttons and things, which call command().
199 document.getElementById("specific").onclick = function(event) {
200 // Ensure we don't accidentally process these events when a
201 // dialog is actually active, e.g. because the button still
202 // has keyboard focus
203 if (dlg_dimmer === null)
206 document.getElementById("random").onclick = function(event) {
207 if (dlg_dimmer === null)
210 document.getElementById("new").onclick = function(event) {
211 if (dlg_dimmer === null)
214 document.getElementById("restart").onclick = function(event) {
215 if (dlg_dimmer === null)
218 undo_button = document.getElementById("undo");
219 undo_button.onclick = function(event) {
220 if (dlg_dimmer === null)
223 redo_button = document.getElementById("redo");
224 redo_button.onclick = function(event) {
225 if (dlg_dimmer === null)
228 document.getElementById("solve").onclick = function(event) {
229 if (dlg_dimmer === null)
233 gametypelist = document.getElementById("gametype");
234 gametypesubmenus.push(gametypelist);
236 // In IE, the canvas doesn't automatically gain focus on a mouse
237 // click, so make sure it does
238 onscreen_canvas.addEventListener("mousedown", function(event) {
239 onscreen_canvas.focus();
242 // In our dialog boxes, Return and Escape should be like pressing
243 // OK and Cancel respectively
244 document.addEventListener("keydown", function(event) {
246 if (dlg_dimmer !== null && event.keyCode == 13) {
247 for (var i in dlg_return_funcs)
248 dlg_return_funcs[i]();
252 if (dlg_dimmer !== null && event.keyCode == 27)
256 // Set up the function pointers we haven't already grabbed.
257 dlg_return_sval = Module.cwrap('dlg_return_sval', 'void',
258 ['number','string']);
259 dlg_return_ival = Module.cwrap('dlg_return_ival', 'void',
260 ['number','number']);
261 timer_callback = Module.cwrap('timer_callback', 'void', ['number']);
263 // Save references to the two permalinks.
264 permalink_desc = document.getElementById("permalink-desc");
265 permalink_seed = document.getElementById("permalink-seed");
267 // Default to giving keyboard focus to the puzzle.
268 onscreen_canvas.focus();
270 // Create the resize handle.
271 var resize_handle = document.createElement("canvas");
272 resize_handle.width = 10;
273 resize_handle.height = 10;
275 var ctx = resize_handle.getContext("2d");
277 for (var i = 1; i <= 7; i += 3) {
278 ctx.moveTo(8.5, i + 0.5);
279 ctx.lineTo(i + 0.5, 8.5);
281 ctx.lineWidth = '1px';
282 ctx.lineCap = 'round';
283 ctx.lineJoin = 'round';
284 ctx.strokeStyle = '#000000';
287 resizable_div = document.getElementById("resizable");
288 resizable_div.appendChild(resize_handle);
289 resize_handle.style.position = 'absolute';
290 resize_handle.style.zIndex = 98;
291 resize_handle.style.bottom = "0";
292 resize_handle.style.right = "0";
293 resize_handle.style.cursor = "se-resize";
294 resize_handle.title = "Drag to resize the puzzle. Right-click to restore the default size.";
295 var resize_xbase = null, resize_ybase = null, restore_pending = false;
296 var resize_xoffset = null, resize_yoffset = null;
297 var resize_puzzle = Module.cwrap('resize_puzzle',
298 'void', ['number', 'number']);
299 var restore_puzzle_size = Module.cwrap('restore_puzzle_size', 'void', []);
300 resize_handle.oncontextmenu = function(event) { return false; }
301 resize_handle.onmousedown = function(event) {
302 if (event.button == 0) {
303 var xy = element_coords(onscreen_canvas);
304 resize_xbase = xy.x + onscreen_canvas.width / 2;
306 resize_xoffset = xy.x + onscreen_canvas.width - event.pageX;
307 resize_yoffset = xy.y + onscreen_canvas.height - event.pageY;
309 restore_pending = true;
311 resize_handle.setCapture(true);
312 event.preventDefault();
314 window.addEventListener("mousemove", function(event) {
315 if (resize_xbase !== null && resize_ybase !== null) {
316 resize_puzzle((event.pageX + resize_xoffset - resize_xbase) * 2,
317 (event.pageY + resize_yoffset - resize_ybase));
318 event.preventDefault();
319 // Chrome insists on selecting text during a resize drag
320 // no matter what I do
321 if (window.getSelection)
322 window.getSelection().removeAllRanges();
324 document.selection.empty(); }
326 window.addEventListener("mouseup", function(event) {
327 if (resize_xbase !== null && resize_ybase !== null) {
330 onscreen_canvas.focus(); // return focus to the puzzle
331 event.preventDefault();
332 } else if (restore_pending) {
333 // If you have the puzzle at larger than normal size and
334 // then right-click to restore, I haven't found any way to
335 // stop Chrome and IE popping up a context menu on the
336 // revealed piece of document when you release the button
337 // except by putting the actual restore into a setTimeout.
339 setTimeout(function() {
340 restore_pending = false;
341 restore_puzzle_size();
342 onscreen_canvas.focus();
344 event.preventDefault();
348 // Run the C setup function, passing argv[1] as the fragment
349 // identifier (so that permalinks of the form puzzle.html#game-id
350 // can launch the specified id).
351 Module.callMain([location.hash]);
353 // And if we get here with everything having gone smoothly, i.e.
354 // we haven't crashed for one reason or another during setup, then
355 // it's probably safe to hide the 'sorry, no puzzle here' div and
356 // show the div containing the actual puzzle.
357 document.getElementById("apology").style.display = "none";
358 document.getElementById("puzzle").style.display = "inline";