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drawing with mouse events

Posted on 2009-05-06
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Last Modified: 2015-01-05
I have a div tag on my page with the following attributes:

<DIV onmouseup="toggleLoading(true);setEnd(event.offsetX, event.offsetY);drawPic();setData();"onmousedown="setStart(event.offsetX, event.offsetY);"
onmouseover="setIndex();setPoints(event.offsetX, event.offsetY);" id="divCanvas" >

The onmouseup function sets the end coordinates  and the onmousedown sets the start coordinates.  I want to use the onmouseover to capture all of the points inbetween.

I do that with creating two new arrays in my js file:
var Xpoints = new Array();
var YPoints = new Array();

THen in the setPoints function:

function setPoints(inpX, inpY) {

    if (CurrentTool == "DRAWPOLYLINE") {
        Xpoints[index] = inpX;
        YPoints[index] = inpY;
        index++;
    }
    else {
//do nothing
    }

THen after the mousup is called, I have something like this:
Here I want to draw each point saved in the arrays.
for (x in Xpoints)
             jg.freeform(Xpoints[x], YPoints[x], CurrentStroke, CurrentStroke);

I have two problems:

1) WIth my original div tag, I am getting an error with the mouseover event...that an object was expected.

2) When I draw the array I don't get anything...I suspect that is becuase the onmoueover is not working.  If I try to draw just one coordinate (the first or last, which I record with the mousedown and mouseup events, it draws the one point, but I want all of them drawn).

Thanks
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Question by:wizkid2332
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2 Comments
 
LVL 10

Expert Comment

by:bugada
ID: 24320020
You must use onmousemove event to capture each pixel while the mouse is moving. Mouseover only fires when your pointer enters the div.

A code like your is not crossbrowser but IE oriented. If this is not a problem, continue on this road, otherway try to change it like the following snippet

To get coords you must use pageX, pageY (FF/GC/Safari) or a more complex function for IE (see Mousecoords function).

This code is untested, it's just an example, may contain typos or bugs.

<script>
window.onload = function() {
   var div = document.getElementById("divCanvas");
   
   div.onmouseup = function(e) {
      e = e || window.event;
      toggleLoading(true);
      setEnd(event.offsetX, event.offsetY);
      drawPic();
      setData();
   };
   
   div.onmousedown = function(e) {
      e = e || window.event;
      var coords = mouseCoords(e);
      setStart(coords.x, coords );
   };
   
   div.onmousemove = function(e) {
      e = e || window.event;
      setIndex();
      var coords = mouseCoords(e);
      setPoints(coords.x, coords.y);
   }; 
   
   function mouseCoords(e){
      if (e.pageX || e.pageY) {
         return {x:e.pageX, y:e.pageY};
      }
      return {
         x:e.clientX + document.body.scrollLeft - document.body.clientLeft,
         y:e.clientY + document.body.scrollTop  - document.body.clientTop
      };
   };
};
 
function setPoints(inpX, inpY) {
 
    if (CurrentTool == "DRAWPOLYLINE") {
        Xpoints[index] = inpX;
        YPoints[index] = inpY;
        index++;
    } else {
//do nothing
    }
};
 
</script>
 
<div id="divcanvas"></div>

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LVL 10

Accepted Solution

by:
bugada earned 500 total points
ID: 24320036
sorry i've made some typos, try this code

<script>
window.onload = function() {
   var div = document.getElementById("divCanvas");
   
   div.onmouseup = function(e) {
      e = e || window.event;
      toggleLoading(true);
      var coords = mouseCoords(e);
      setEnd(coords.x, coords.y);
      drawPic();
      setData();
   };
   
   div.onmousedown = function(e) {
      e = e || window.event;
      var coords = mouseCoords(e);
      setStart(coords.x, coords.y);
   };
   
   div.onmousemove = function(e) {
      e = e || window.event;
      setIndex();
      var coords = mouseCoords(e);
      setPoints(coords.x, coords.y);
   }; 
   
   function mouseCoords(e){
      if (e.pageX || e.pageY) {
         return {x:e.pageX, y:e.pageY};
      }
      return {
         x:e.clientX + document.body.scrollLeft - document.body.clientLeft,
         y:e.clientY + document.body.scrollTop  - document.body.clientTop
      };
   };
};
</script>

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