c# - Drawing on the canvas using mouse pointer does not work -


i've created web page in following. want allow user draw on canvas. following code not draw content.

   <asp:content runat="server" id="featuredcontent"            contentplaceholderid="featuredcontent">           <section class="featured">              <div class="content-wrapper">                 <script type="text/javascript">              var canvas, ctx, flag = false,                  prevx = 0,                  currx = 0,                  prevy = 0,                  curry = 0,                  dot_flag = false;               var x = "black",                  y = 2;               function init() {                  canvas = document.getelementbyid('can');                  ctx = canvas.getcontext("2d");                  w = canvas.width;                  h = canvas.height;                   canvas.addeventlistener("mousemove", function (e) {                      findxy('move', e)                  }, false);                  canvas.addeventlistener("mousedown", function (e) {                      findxy('down', e)                  }, false);                  canvas.addeventlistener("mouseup", function (e) {                      findxy('up', e)                  }, false);                  canvas.addeventlistener("mouseout", function (e) {                      findxy('out', e)                  }, false);              }               function color(obj) {                  switch (obj.id) {                      case "green":                          x = "green";                          break;                      case "blue":                          x = "blue";                          break;                      case "red":                          x = "red";                          break;                      case "yellow":                          x = "yellow";                          break;                      case "orange":                          x = "orange";                          break;                      case "black":                          x = "black";                          break;                      case "white":                          x = "white";                          break;                  }                  if (x == "white") y = 14;                  else y = 2;               }               function draw() {                  ctx.beginpath();                  ctx.moveto(prevx, prevy);                  ctx.lineto(currx, curry);                  ctx.strokestyle = x;                  ctx.linewidth = y;                  ctx.stroke();                  ctx.closepath();              }               function erase() {                  var m = confirm("want clear");                  if (m) {                      ctx.clearrect(0, 0, w, h);                      document.getelementbyid("canvasimg").style.display =                                    "none";                  }              }               function save() {                  document.getelementbyid("canvasimg").style.border = "2px                    solid";                  var dataurl = canvas.todataurl();                  document.getelementbyid("canvasimg").src = dataurl;                  document.getelementbyid("canvasimg").style.display =                                                                 "inline";              }               function findxy(res, e) {                  if (res == 'down') {                      prevx = currx;                      prevy = curry;                      currx = e.clientx - canvas.offsetleft;                      curry = e.clienty - canvas.offsettop;                       flag = true;                      dot_flag = true;                      if (dot_flag) {                          ctx.beginpath();                          ctx.fillstyle = x;                          ctx.fillrect(currx, curry, 2, 2);                          ctx.closepath();                          dot_flag = false;                      }                  }                  if (res == 'up' || res == "out") {                      flag = false;                  }                  if (res == 'move') {                      if (flag) {                          prevx = currx;                          prevy = curry;                          currx = e.clientx - canvas.offsetleft;                          curry = e.clienty - canvas.offsettop;                          draw();                      }                  }              }             </script>        <canvas id="can" width="400" height="400"      style="position:absolute;top:10%;left:10%;border:2px solid;"></canvas>     </div> </section>

but when include above code in html file extension .html, works. can pls tell me what's wrong in ? in cases, "canvas" not valid element too.


Comments

Post a Comment

Popular posts from this blog

python - Operations inside variables -

this question has answer here: evaluating mathematical expression in string 12 answers i want make python script finds maximum possible output using 2 operations. problem says there syntax error @ 2nd last line, in b in there. how can fix it? x = 0 = int(input("1st number:")) c = int(input("2nd number:" )) e = int(input("3rd number:" )) in range(4): if == 0: b = "+" elif == 1: b = "-" elif == 2: b = "/" else: b = "*" j in range(4): if j == 0: d = "+" elif j == 1: d = "-" elif j == 2: d = "/" else: d = "*" k = b c d e print(k) if you're after variables e on single line, couldn...
Read more

Generic Map Parameter java -

i having lot of methods of type: public static list<eduusers> getdetails(class c, map<string, integer> params) { list<eduusers> details = null; session session = hibernateutil.getsessionfactory().opensession(); transaction tx = null; try { tx = session.begintransaction(); criteria cr = session.createcriteria(c); (map.entry<string, integer> entry : params.entryset()) { cr.add(restrictions.eq(entry.getkey(), entry.getvalue())); } details = cr.list(); tx.commit(); } catch (exception asd) { log.debug(asd.getmessage()); if (tx != null) { tx.commit(); } } { session.close(); } return details; } i trying have generic method them , have written far: public static <t> list<t> getdetails(class<t> c, class<t> b) { l...
Read more

arrays - What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it? -

what arrayindexoutofboundsexception mean , how rid of it? here code sample triggers exception: string[] name = {"tom", "dick", "harry"}; for(int = 0; i<=name.length; i++) { system.out.print(name[i] +'\n'); } your first port of call should documentation explains reasonably clearly: thrown indicate array has been accessed illegal index. index either negative or greater or equal size of array. so example: int[] array = new int[5]; int boom = array[10]; // throws exception as how avoid it... um, don't that. careful array indexes. one problem people run thinking arrays 1-indexed, e.g. int[] array = new int[5]; // ... populate array here ... (int index = 1; index <= array.length; index++) { system.out.println(array[index]); } that miss out first element (index 0) , throw exception when index 5. valid indexes here 0-4 inclusive. correct, idiomatic for statement here be: for (int index = 0; index <...
Read more