ref: 7d61c4cee43984b05d8515fe5dcf0780a8fab10b
dir: /emcclib.js/
/*
* emcclib.js: one of the Javascript components of an Emscripten-based
* web/Javascript front end for Puzzles.
*
* The other parts of this system live in emcc.c and emccpre.js. It
* also depends on being run in the context of a web page containing
* an appropriate collection of bits and pieces (a canvas, some
* buttons and links etc), which is generated for each puzzle by the
* script html/jspage.pl.
*
* This file contains a set of Javascript functions which we insert
* into Emscripten's library object via the --js-library option; this
* allows us to provide JS code which can be called from the
* Emscripten-compiled C, mostly dealing with UI interaction of
* various kinds.
*/
mergeInto(LibraryManager.library, {
/*
* void js_debug(const char *message);
*
* A function to write a diagnostic to the Javascript console.
* Unused in production, but handy in development.
*/
js_debug: function(ptr) {
console.log(UTF8ToString(ptr));
},
/*
* void js_error_box(const char *message);
*
* A wrapper around Javascript's alert(), so the C code can print
* simple error message boxes (e.g. when invalid data is entered
* in a configuration dialog).
*/
js_error_box: function(ptr) {
alert(UTF8ToString(ptr));
},
/*
* void js_remove_type_dropdown(void);
*
* Get rid of the drop-down list on the web page for selecting
* game presets. Called at setup time if the game back end
* provides neither presets nor configurability.
*/
js_remove_type_dropdown: function() {
var gametypeitem = gametypelist.closest("li");
if (gametypeitem === null) return;
gametypeitem.parentNode.removeChild(gametypeitem);
},
/*
* void js_remove_solve_button(void);
*
* Get rid of the Solve button on the web page. Called at setup
* time if the game doesn't support an in-game solve function.
*/
js_remove_solve_button: function() {
var solvebutton = document.getElementById("solve");
if (solvebutton === null) return;
var solveitem = solvebutton.closest("li");
if (solveitem === null) return;
solveitem.parentNode.removeChild(solveitem);
},
/*
* void js_add_preset(int menuid, const char *name, int value);
*
* Add a preset to the drop-down types menu, or to a submenu of
* it. 'menuid' specifies an index into our array of submenus
* where the item might be placed; 'value' specifies the number
* that js_get_selected_preset() will return when this item is
* clicked.
*/
js_add_preset: function(menuid, ptr, value) {
var name = UTF8ToString(ptr);
var item = document.createElement("li");
var label = document.createElement("label");
var tick = document.createElement("input");
tick.type = "radio";
tick.className = "tick";
tick.name = "preset";
tick.value = value;
label.appendChild(tick);
label.appendChild(document.createTextNode(" " + name));
item.appendChild(label);
gametypesubmenus[menuid].appendChild(item);
tick.onclick = function(event) {
if (dlg_dimmer === null) {
command(2);
}
}
},
/*
* int js_add_preset_submenu(int menuid, const char *name);
*
* Add a submenu in the presets menu hierarchy. Returns its index,
* for passing as the 'menuid' argument in further calls to
* js_add_preset or this function.
*/
js_add_preset_submenu: function(menuid, ptr, value) {
var name = UTF8ToString(ptr);
var item = document.createElement("li");
// We still create a transparent tick element, even though it
// won't ever be selected, to make submenu titles line up
// nicely with their neighbours.
var label = document.createElement("div");
var tick = document.createElement("span");
tick.className = "tick";
label.appendChild(tick);
label.tabIndex = 0;
label.appendChild(document.createTextNode(" " + name));
item.appendChild(label);
var submenu = document.createElement("ul");
label.appendChild(submenu);
gametypesubmenus[menuid].appendChild(item);
var toret = gametypesubmenus.length;
gametypesubmenus.push(submenu);
return toret;
},
/*
* int js_get_selected_preset(void);
*
* Return the index of the currently selected value in the type
* dropdown.
*/
js_get_selected_preset: function() {
return menuform.elements["preset"].value;
},
/*
* void js_select_preset(int n);
*
* Cause a different value to be selected in the type dropdown
* (for when the user selects values from the Custom configurer
* which turn out to exactly match a preset).
*/
js_select_preset: function(n) {
menuform.elements["preset"].value = n;
},
/*
* void js_set_background_colour(const char *bg);
*
* Record the puzzle background colour in a CSS variable so
* the style sheet can use it if it wants.
*/
js_set_background_colour: function(bgptr) {
document.documentElement.style.setProperty("--puzzle-background",
UTF8ToString(bgptr));
},
/*
* void js_get_date_64(unsigned *p);
*
* Return the current date, in milliseconds since the epoch
* (Javascript's native format), as a 64-bit integer. Used to
* invent an initial random seed for puzzle generation.
*/
js_get_date_64: function(ptr) {
var d = (new Date()).valueOf();
setValue(ptr, d, 'i64');
},
/*
* void js_update_permalinks(const char *desc, const char *seed);
*
* Update the permalinks on the web page for a new game
* description and optional random seed. desc can never be NULL,
* but seed might be (if the game was generated by entering a
* descriptive id by hand), in which case we suppress display of
* the random seed permalink.
*/
js_update_permalinks: function(desc, seed) {
desc = encodeURI(UTF8ToString(desc)).replace(/#/g, "%23");
if (permalink_desc !== null)
permalink_desc.href = "#" + desc;
if (permalink_seed !== null) {
if (seed == 0) {
permalink_seed.style.display = "none";
} else {
seed = encodeURI(UTF8ToString(seed)).replace(/#/g, "%23");;
permalink_seed.href = "#" + seed;
permalink_seed.style.display = "";
}
}
},
/*
* void js_enable_undo_redo(int undo, int redo);
*
* Set the enabled/disabled states of the undo and redo buttons,
* after a move.
*/
js_enable_undo_redo: function(undo, redo) {
disable_menu_item(undo_button, (undo == 0));
disable_menu_item(redo_button, (redo == 0));
},
/*
* void js_activate_timer();
*
* Start calling the C timer_callback() function every frame.
* The C code ensures that the activate and deactivate functions
* are called in a sensible order.
*/
js_activate_timer: function() {
timer_reference = performance.now();
var frame = function(now) {
timer = window.requestAnimationFrame(frame);
// The callback might call js_deactivate_timer() below.
timer_callback((now - timer_reference) / 1000.0);
timer_reference = now;
};
timer = window.requestAnimationFrame(frame);
},
/*
* void js_deactivate_timer();
*
* Stop calling the C timer_callback() function every frame.
*/
js_deactivate_timer: function() {
window.cancelAnimationFrame(timer);
},
/*
* void js_canvas_start_draw(void);
*
* Prepare to do some drawing on the canvas.
*/
js_canvas_start_draw: function() {
update_xmin = update_xmax = update_ymin = update_ymax = undefined;
},
/*
* void js_canvas_draw_update(int x, int y, int w, int h);
*
* Mark a rectangle of the off-screen canvas as needing to be
* copied to the on-screen one.
*/
js_canvas_draw_update: function(x, y, w, h) {
/*
* Currently we do this in a really simple way, just by taking
* the smallest rectangle containing all updates so far. We
* could instead keep the data in a richer form (e.g. retain
* multiple smaller rectangles needing update, and only redraw
* the whole thing beyond a certain threshold) but this will
* do for now.
*/
if (update_xmin === undefined || update_xmin > x) update_xmin = x;
if (update_ymin === undefined || update_ymin > y) update_ymin = y;
if (update_xmax === undefined || update_xmax < x+w) update_xmax = x+w;
if (update_ymax === undefined || update_ymax < y+h) update_ymax = y+h;
},
/*
* void js_canvas_end_draw(void);
*
* Finish the drawing, by actually copying the newly drawn stuff
* to the on-screen canvas.
*/
js_canvas_end_draw: function() {
if (update_xmin !== undefined) {
var onscreen_ctx =
onscreen_canvas.getContext('2d', { alpha: false });
onscreen_ctx.drawImage(offscreen_canvas,
update_xmin, update_ymin,
update_xmax - update_xmin,
update_ymax - update_ymin,
update_xmin, update_ymin,
update_xmax - update_xmin,
update_ymax - update_ymin);
}
},
/*
* void js_canvas_draw_rect(int x, int y, int w, int h,
* const char *colour);
*
* Draw a rectangle.
*/
js_canvas_draw_rect: function(x, y, w, h, colptr) {
ctx.fillStyle = UTF8ToString(colptr);
ctx.fillRect(x, y, w, h);
},
/*
* void js_canvas_clip_rect(int x, int y, int w, int h);
*
* Set a clipping rectangle.
*/
js_canvas_clip_rect: function(x, y, w, h) {
ctx.save();
ctx.beginPath();
ctx.rect(x, y, w, h);
ctx.clip();
},
/*
* void js_canvas_unclip(void);
*
* Reset to no clipping.
*/
js_canvas_unclip: function() {
ctx.restore();
},
/*
* void js_canvas_draw_line(float x1, float y1, float x2, float y2,
* int width, const char *colour);
*
* Draw a line. We must adjust the coordinates by 0.5 because
* Javascript's canvas coordinates appear to be pixel corners,
* whereas we want pixel centres. Also, we manually draw the pixel
* at each end of the line, which our clients will expect but
* Javascript won't reliably do by default (in common with other
* Postscriptish drawing frameworks).
*/
js_canvas_draw_line: function(x1, y1, x2, y2, width, colour) {
colour = UTF8ToString(colour);
ctx.beginPath();
ctx.moveTo(x1 + 0.5, y1 + 0.5);
ctx.lineTo(x2 + 0.5, y2 + 0.5);
ctx.lineWidth = width;
ctx.lineCap = 'round';
ctx.lineJoin = 'round';
ctx.strokeStyle = colour;
ctx.stroke();
ctx.fillStyle = colour;
ctx.fillRect(x1, y1, 1, 1);
ctx.fillRect(x2, y2, 1, 1);
},
/*
* void js_canvas_draw_poly(int *points, int npoints,
* const char *fillcolour,
* const char *outlinecolour);
*
* Draw a polygon.
*/
js_canvas_draw_poly: function(pointptr, npoints, fill, outline) {
ctx.beginPath();
ctx.moveTo(getValue(pointptr , 'i32') + 0.5,
getValue(pointptr+4, 'i32') + 0.5);
for (var i = 1; i < npoints; i++)
ctx.lineTo(getValue(pointptr+8*i , 'i32') + 0.5,
getValue(pointptr+8*i+4, 'i32') + 0.5);
ctx.closePath();
if (fill != 0) {
ctx.fillStyle = UTF8ToString(fill);
ctx.fill();
}
ctx.lineWidth = '1';
ctx.lineCap = 'round';
ctx.lineJoin = 'round';
ctx.strokeStyle = UTF8ToString(outline);
ctx.stroke();
},
/*
* void js_canvas_draw_circle(int x, int y, int r,
* const char *fillcolour,
* const char *outlinecolour);
*
* Draw a circle.
*/
js_canvas_draw_circle: function(x, y, r, fill, outline) {
ctx.beginPath();
ctx.arc(x + 0.5, y + 0.5, r, 0, 2*Math.PI);
if (fill != 0) {
ctx.fillStyle = UTF8ToString(fill);
ctx.fill();
}
ctx.lineWidth = '1';
ctx.lineCap = 'round';
ctx.lineJoin = 'round';
ctx.strokeStyle = UTF8ToString(outline);
ctx.stroke();
},
/*
* int js_canvas_find_font_midpoint(int height, const char *fontptr);
*
* Return the adjustment required for text displayed using
* ALIGN_VCENTRE. We want to place the midpoint between the
* baseline and the cap-height at the specified position; so this
* function returns the adjustment which, when added to the
* desired centre point, returns the y-coordinate at which you
* should put the baseline.
*
* There is no sensible method of querying this kind of font
* metric in Javascript, so instead we render a piece of test text
* to a throwaway offscreen canvas and then read the pixel data
* back out to find the highest and lowest pixels. That's good
* _enough_ (in that we only needed the answer to the nearest
* pixel anyway), but rather disgusting!
*
* Since this is a very expensive operation, we cache the results
* per (font,height) pair.
*/
js_canvas_find_font_midpoint: function(height, font) {
font = UTF8ToString(font);
// Reuse cached value if possible
if (midpoint_cache[font] !== undefined)
return midpoint_cache[font];
// Find the width of the string
var ctx1 = onscreen_canvas.getContext('2d', { alpha: false });
ctx1.font = font;
var width = (ctx1.measureText(midpoint_test_str).width + 1) | 0;
// Construct a test canvas of appropriate size, initialise it to
// black, and draw the string on it in white
var measure_canvas = document.createElement('canvas');
var ctx2 = measure_canvas.getContext('2d', { alpha: false });
ctx2.canvas.width = width;
ctx2.canvas.height = 2*height;
ctx2.fillStyle = "#000000";
ctx2.fillRect(0, 0, width, 2*height);
var baseline = (1.5*height) | 0;
ctx2.fillStyle = "#ffffff";
ctx2.font = font;
ctx2.fillText(midpoint_test_str, 0, baseline);
// Scan the contents of the test canvas to find the top and bottom
// set pixels.
var pixels = ctx2.getImageData(0, 0, width, 2*height).data;
var ymin = 2*height, ymax = -1;
for (var y = 0; y < 2*height; y++) {
for (var x = 0; x < width; x++) {
if (pixels[4*(y*width+x)] != 0) {
if (ymin > y) ymin = y;
if (ymax < y) ymax = y;
break;
}
}
}
var ret = (baseline - (ymin + ymax) / 2) | 0;
midpoint_cache[font] = ret;
return ret;
},
/*
* void js_canvas_draw_text(int x, int y, int halign,
* const char *colptr, const char *fontptr,
* const char *text);
*
* Draw text. Vertical alignment has been taken care of on the C
* side, by optionally calling the above function. Horizontal
* alignment is handled here, since we can get the canvas draw
* function to do it for us with almost no extra effort.
*/
js_canvas_draw_text: function(x, y, halign, colptr, fontptr, text) {
ctx.font = UTF8ToString(fontptr);
ctx.fillStyle = UTF8ToString(colptr);
ctx.textAlign = (halign == 0 ? 'left' :
halign == 1 ? 'center' : 'right');
ctx.textBaseline = 'alphabetic';
ctx.fillText(UTF8ToString(text), x, y);
},
/*
* int js_canvas_new_blitter(int w, int h);
*
* Create a new blitter object, which is just an offscreen canvas
* of the specified size.
*/
js_canvas_new_blitter: function(w, h) {
var id = blittercount++;
blitters[id] = document.createElement("canvas");
blitters[id].width = w;
blitters[id].height = h;
return id;
},
/*
* void js_canvas_free_blitter(int id);
*
* Free a blitter (or rather, destroy our reference to it so JS
* can garbage-collect it, and also enforce that we don't
* accidentally use it again afterwards).
*/
js_canvas_free_blitter: function(id) {
blitters[id] = null;
},
/*
* void js_canvas_copy_to_blitter(int id, int x, int y, int w, int h);
*
* Copy from the puzzle image to a blitter. The size is passed to
* us, partly so we don't have to remember the size of each
* blitter, but mostly so that the C side can adjust the copy
* rectangle in the case where it partially overlaps the edge of
* the screen.
*/
js_canvas_copy_to_blitter: function(id, x, y, w, h) {
var blitter_ctx = blitters[id].getContext('2d', { alpha: false });
blitter_ctx.drawImage(offscreen_canvas,
x, y, w, h,
0, 0, w, h);
},
/*
* void js_canvas_copy_from_blitter(int id, int x, int y, int w, int h);
*
* Copy from a blitter back to the puzzle image. As above, the
* size of the copied rectangle is passed to us from the C side
* and may already have been modified.
*/
js_canvas_copy_from_blitter: function(id, x, y, w, h) {
ctx.drawImage(blitters[id],
0, 0, w, h,
x, y, w, h);
},
/*
* void js_canvas_remove_statusbar(void);
*
* Cause a status bar not to exist. Called at setup time if the
* puzzle back end turns out not to want one.
*/
js_canvas_remove_statusbar: function() {
if (statusbar !== null)
statusbar.parentNode.removeChild(statusbar);
statusbar = null;
},
/*
* void js_canvas_set_statusbar(const char *text);
*
* Set the text in the status bar.
*/
js_canvas_set_statusbar: function(ptr) {
statusbar.textContent = UTF8ToString(ptr);
},
/*
* void js_canvas_set_size(int w, int h);
*
* Set the size of the puzzle canvas. Called whenever the size of
* the canvas needs to change. That might be because of a change
* of configuration, because the user has resized the puzzle, or
* because the device pixel ratio has changed.
*/
js_canvas_set_size: function(w, h) {
onscreen_canvas.width = w;
offscreen_canvas.width = w;
if (resizable_div !== null)
resizable_div.style.width =
w / (window.devicePixelRatio || 1) + "px";
onscreen_canvas.height = h;
offscreen_canvas.height = h;
},
/*
* double js_get_device_pixel_ratio();
*
* Return the current device pixel ratio.
*/
js_get_device_pixel_ratio: function() {
return window.devicePixelRatio || 1;
},
/*
* void js_dialog_init(const char *title);
*
* Begin constructing a 'dialog box' which will be popped up in an
* overlay on top of the rest of the puzzle web page.
*/
js_dialog_init: function(titletext) {
dialog_init(UTF8ToString(titletext));
},
/*
* void js_dialog_string(int i, const char *title, const char *initvalue);
*
* Add a string control (that is, an edit box) to the dialog under
* construction.
*/
js_dialog_string: function(index, title, initialtext) {
var label = document.createElement("label");
label.textContent = UTF8ToString(title);
dlg_form.appendChild(label);
var editbox = document.createElement("input");
editbox.type = "text";
editbox.value = UTF8ToString(initialtext);
label.appendChild(editbox);
dlg_form.appendChild(document.createElement("br"));
dlg_return_funcs.push(function() {
dlg_return_sval(index, editbox.value);
});
},
/*
* void js_dialog_choices(int i, const char *title, const char *choicelist,
* int initvalue);
*
* Add a choices control (i.e. a drop-down list) to the dialog
* under construction. The 'choicelist' parameter is unchanged
* from the way the puzzle back end will have supplied it: i.e.
* it's still encoded as a single string whose first character
* gives the separator.
*/
js_dialog_choices: function(index, title, choicelist, initvalue) {
var label = document.createElement("label");
label.textContent = UTF8ToString(title);
dlg_form.appendChild(label);
var dropdown = document.createElement("select");
var choicestr = UTF8ToString(choicelist);
var items = choicestr.slice(1).split(choicestr[0]);
var options = [];
for (var i in items) {
var option = document.createElement("option");
option.value = i;
option.appendChild(document.createTextNode(items[i]));
if (i == initvalue) option.selected = true;
dropdown.appendChild(option);
options.push(option);
}
label.appendChild(dropdown);
dlg_form.appendChild(document.createElement("br"));
dlg_return_funcs.push(function() {
var val = 0;
for (var i in options) {
if (options[i].selected) {
val = options[i].value;
break;
}
}
dlg_return_ival(index, val);
});
},
/*
* void js_dialog_boolean(int i, const char *title, int initvalue);
*
* Add a boolean control (a checkbox) to the dialog under
* construction. Checkboxes are generally expected to be sensitive
* on their label text as well as the box itself, so for this
* control we create an actual label rather than merely a text
* node (and hence we must allocate an id to the checkbox so that
* the label can refer to it).
*/
js_dialog_boolean: function(index, title, initvalue) {
var checkbox = document.createElement("input");
checkbox.type = "checkbox";
checkbox.checked = (initvalue != 0);
var checkboxlabel = document.createElement("label");
checkboxlabel.appendChild(checkbox);
checkboxlabel.appendChild(document.createTextNode(UTF8ToString(title)));
dlg_form.appendChild(checkboxlabel);
dlg_form.appendChild(document.createElement("br"));
dlg_return_funcs.push(function() {
dlg_return_ival(index, checkbox.checked ? 1 : 0);
});
},
/*
* void js_dialog_launch(void);
*
* Finish constructing a dialog, and actually display it, dimming
* everything else on the page.
*/
js_dialog_launch: function() {
dialog_launch(function(event) {
for (var i in dlg_return_funcs)
dlg_return_funcs[i]();
command(3); // OK
}, function(event) {
command(4); // Cancel
});
},
/*
* void js_dialog_cleanup(void);
*
* Stop displaying a dialog, and clean up the internal state
* associated with it.
*/
js_dialog_cleanup: function() {
dialog_cleanup();
},
/*
* void js_focus_canvas(void);
*
* Return keyboard focus to the puzzle canvas. Called after a
* puzzle-control button is pressed, which tends to have the side
* effect of taking focus away from the canvas.
*/
js_focus_canvas: function() {
onscreen_canvas.focus();
}
});