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excanvas.js
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excanvas.js
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/* ctx.setBitmapFont(url, poslist, sizelist)
set url to the bitmap font sheet of ctx with bound box infomation bblist.
url = "http://xxxxx.xx.xx/xxx/xxx.png" or "xxx.png";
poslist [i][0] = start position in x of i th charactor
poslist [i][1] = start position in y of i th charactor
sizelist[i][0] = width of i th charactor
sizelist[i][1] = height of i th charactor
*/
CanvasRenderingContext2D.prototype.setBitmapFont = function(url, poslist, sizelist, letterlist){
this.bmfont={};
this.bmfont.fontsheet = new Image();
this.bmfont.fontsheet.src = url + "?" + new Date().getTime();
this.bmfont.poslist = poslist ;
this.bmfont.sizelist = sizelist;
this.bmfont.letterlist = letterlist;
this.bmfont.maxheight = 0;
for(i=0;i<sizelist.length;i++){
if(sizelist[i][1] > this.bmfont.maxheight) this.bmfont.maxheight = sizelist[i][1];
}
};
/* ctx.fillTextBitmap(text,x,y) draw text with the bitmap font set by the setBitmapFont().
same as CanvasRenderingContext2D.fillText(text,x,y),
text = text to be written
x,y = position in ctx to put the text.
*/
CanvasRenderingContext2D.prototype.fillTextBitmap = function(text, x, y){
var px=x;
var py=y;
var poslist=this.bmfont.poslist;
var sizelist=this.bmfont.sizelist;
var letterlist=this.bmfont.letterlist;
var fontsheet=this.bmfont.fontsheet;
for(i=0;i<text.length;i++){
if(text[i]=='\n'){
py=py+this.bmfont.maxheight;
px=x;
}else{
var j=letterlist.indexOf(text[i]); // from "A"
this.drawImage(fontsheet,
poslist [j][0], poslist [j][1],
sizelist[j][0], sizelist[j][1],
px , py ,
sizelist[j][0], sizelist[j][1]
);
px+=sizelist[j][0];
}
}
};
/* ctx.measureTextBitmap(text) returns size of text in the bitmap font which set with setBitmapFont().
almost same as width in px = CanvasRenderingContext2D.measureText(text),
text = text to be written
ctx.measureTextBitmap(text) = [wx,wy]:
wx = width in px
wy = height in px
*/
CanvasRenderingContext2D.prototype.measureTextBitmap = function(text){
var px=0;
var py=0;
var maxpx=0;
var poslist=this.bmfont.poslist;
var sizelist=this.bmfont.sizelist;
var letterlist=this.bmfont.letterlist;
for(i=0;i<text.length;i++){
if(text[i]=='\n'){
py=py+this.bmfont.maxheight;
px=0;
}else{
var j=letterlist.indexOf(text[i]); // from "A"
px+=sizelist[j][0];
maxpx=(px>maxpx)?px:maxpx;
}
}
return [px,py+this.bmfont.maxheight];
};
CanvasRenderingContext2D.prototype.guideText = function(text,px,py){
var tz=this.measureTextBitmap(text);
var linex=40;
var liney=20;
//draw line
this.beginPath();
this.moveTo(px ,py );
this.lineTo(px+linex,py+liney);
this.stroke();
this.beginPath();
this.moveTo(px+linex ,py+liney);
this.lineTo(px+linex+tz[0],py+liney);
this.stroke();
this.beginPath();
//draw text
this.fillTextBitmap(text,px+linex, py+liney-tz[1]);
}