// Copyright 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Known Issues:
//
// * Patterns are not implemented.
// * Radial gradient are not implemented. The VML version of these look very
// different from the canvas one.
// * Clipping paths are not implemented.
// * Coordsize. The width and height attribute have higher priority than the
// width and height style values which isn't correct.
// * Painting mode isn't implemented.
// * Canvas width/height should is using content-box by default. IE in
// Quirks mode will draw the canvas using border-box. Either change your
// doctype to HTML5
// (http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)
// or use Box Sizing Behavior from WebFX
// (http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)
// * Non uniform scaling does not correctly scale strokes.
// * Optimize. There is always room for speed improvements.
// Only add this code if we do not already have a canvas implementation
if (!document.createElement('canvas').getContext) {
(function() {
// alias some functions to make (compiled) code shorter
var m = Math;
var mr = m.round;
var ms = m.sin;
var mc = m.cos;
var abs = m.abs;
var sqrt = m.sqrt;
// this is used for sub pixel precision
var Z = 10;
var Z2 = Z / 2;
/**
* This funtion is assigned to the <canvas> elements as element.getContext().
* @this {HTMLElement}
* @return {CanvasRenderingContext2D_}
*/
function getContext() {
return this.context_ ||
(this.context_ = new CanvasRenderingContext2D_(this));
}
var slice = Array.prototype.slice;
/**
* Binds a function to an object. The returned function will always use the
* passed in {@code obj} as {@code this}.
*
* Example:
*
* g = bind(f, obj, a, b)
* g(c, d) // will do f.call(obj, a, b, c, d)
*
* @param {Function} f The function to bind the object to
* @param {Object} obj The object that should act as this when the function
* is called
* @param {*} var_args Rest arguments that will be used as the initial
* arguments when the function is called
* @return {Function} A new function that has bound this
*/
function bind(f, obj, var_args) {
var a = slice.call(arguments, 2);
return function() {
return f.apply(obj, a.concat(slice.call(arguments)));
};
}
var G_vmlCanvasManager_ = {
init: function(opt_doc) {
if (/MSIE/.test(navigator.userAgent) && !window.opera) {
var doc = opt_doc || document;
// Create a dummy element so that IE will allow canvas elements to be
// recognized.
doc.createElement('canvas');
doc.attachEvent('onreadystatechange', bind(this.init_, this, doc));
}
},
init_: function(doc) {
// create xmlns
if (!doc.namespaces['g_vml_']) {
doc.namespaces.add('g_vml_', 'urn:schemas-microsoft-com:vml',
'#default#VML');
}
if (!doc.namespaces['g_o_']) {
doc.namespaces.add('g_o_', 'urn:schemas-microsoft-com:office:office',
'#default#VML');
}
// Setup default CSS. Only add one style sheet per document
if (!doc.styleSheets['ex_canvas_']) {
var ss = doc.createStyleSheet();
ss.owningElement.id = 'ex_canvas_';
ss.cssText = 'canvas{display:inline-block;overflow:hidden;' +
// default size is 300x150 in Gecko and Opera
'text-align:left;300px;height:150px}' +
'g_vml_\\:*{behavior:url(#default#VML)}' +
'g_o_\\:*{behavior:url(#default#VML)}';
}
// find all canvas elements
var els = doc.getElementsByTagName('canvas');
for (var i = 0; i < els.length; i++) {
this.initElement(els[i]);
}
},
/**
* Public initializes a canvas element so that it can be used as canvas
* element from now on. This is called automatically before the page is
* loaded but if you are creating elements using createElement you need to
* make sure this is called on the element.
* @param {HTMLElement} el The canvas element to initialize.
* @return {HTMLElement} the element that was created.
*/
initElement: function(el) {
if (!el.getContext) {
el.getContext = getContext;
// Remove fallback content. There is no way to hide text nodes so we
// just remove all childNodes. We could hide all elements and remove
// text nodes but who really cares about the fallback content.
el.innerHTML = '';
// do not use inline function because that will leak memory
el.attachEvent('onpropertychange', onPropertyChange);
el.attachEvent('onresize', onResize);
var attrs = el.attributes;
if (attrs.width && attrs.width.specified) {
// TODO: use runtimeStyle and coordsize
// el.getContext().setWidth_(attrs.width.nodeValue);
el.style.width = attrs.width.nodeValue + 'px';
} else {
el.width = el.clientWidth;
}
if (attrs.height && attrs.height.specified) {
// TODO: use runtimeStyle and coordsize
// el.getContext().setHeight_(attrs.height.nodeValue);
el.style.height = attrs.height.nodeValue + 'px';
} else {
el.height = el.clientHeight;
}
//el.getContext().setCoordsize_()
}
return el;
}
};
function onPropertyChange(e) {
var el = e.srcElement;
switch (e.propertyName) {
case 'width':
el.style.width = el.attributes.width.nodeValue + 'px';
el.getContext().clearRect();
break;
case 'height':
el.style.height = el.attributes.height.nodeValue + 'px';
el.getContext().clearRect();
break;
}
}
function onResize(e) {
var el = e.srcElement;
if (el.firstChild) {
el.firstChild.style.width = el.clientWidth + 'px';
el.firstChild.style.height = el.clientHeight + 'px';
}
}
G_vmlCanvasManager_.init();
// precompute "00" to "FF"
var dec2hex = [];
for (var i = 0; i < 16; i++) {
for (var j = 0; j < 16; j++) {
dec2hex[i * 16 + j] = i.toString(16) + j.toString(16);
}
}
function createMatrixIdentity() {
return [
[1, 0, 0],
[0, 1, 0],
[0, 0, 1]
];
}
function matrixMultiply(m1, m2) {
var result = createMatrixIdentity();
for (var x = 0; x < 3; x++) {
for (var y = 0; y < 3; y++) {
var sum = 0;
for (var z = 0; z < 3; z++) {
sum += m1[x][z] * m2[z][y];
}
result[x][y] = sum;
}
}
return result;
}
function copyState(o1, o2) {
o2.fillStyle = o1.fillStyle;
o2.lineCap = o1.lineCap;
o2.lineJoin = o1.lineJoin;
o2.lineWidth = o1.lineWidth;
o2.miterLimit = o1.miterLimit;
o2.shadowBlur = o1.shadowBlur;
o2.shadowColor = o1.shadowColor;
o2.shadowOffsetX = o1.shadowOffsetX;
o2.shadowOffsetY = o1.shadowOffsetY;
o2.strokeStyle = o1.strokeStyle;
o2.globalAlpha = o1.globalAlpha;
o2.arcScaleX_ = o1.arcScaleX_;
o2.arcScaleY_ = o1.arcScaleY_;
o2.lineScale_ = o1.lineScale_;
}
function processStyle(styleString) {
var str, alpha = 1;
styleString = String(styleString);
if (styleString.substring(0, 3) == 'rgb') {
var start = styleString.indexOf('(', 3);
var end = styleString.indexOf(')', start + 1);
var guts = styleString.substring(start + 1, end).split(',');
str = '#';
for (var i = 0; i < 3; i++) {
str += dec2hex[Number(guts[i])];
}
if (guts.length == 4 && styleString.substr(3, 1) == 'a') {
alpha = guts[3];
}
} else {
str = styleString;
}
return {color: str, alpha: alpha};
}
function processLineCap(lineCap) {
switch (lineCap) {
case 'butt':
return 'flat';
case 'round':
return 'round';
case 'square':
default:
return 'square';
}
}
/**
* This class implements CanvasRenderingContext2D interface as described by
* the WHATWG.
* @param {HTMLElement} surfaceElement The element that the 2D context should
* be associated with
*/
function CanvasRenderingContext2D_(surfaceElement) {
this.m_ = createMatrixIdentity();
this.mStack_ = [];
this.aStack_ = [];
this.currentPath_ = [];
// Canvas context properties
this.strokeStyle = '#000';
this.fillStyle = '#000';
this.font = '12px sans-serif';
this.lineWidth = 1;
this.lineJoin = 'miter';
this.lineCap = 'butt';
this.miterLimit = Z * 1;
this.globalAlpha = 1;
this.canvas = surfaceElement;
var el = surfaceElement.ownerDocument.createElement('div');
el.style.width = surfaceElement.clientWidth + 'px';
el.style.height = surfaceElement.clientHeight + 'px';
el.style.overflow = 'hidden';
el.style.position = 'absolute';
surfaceElement.appendChild(el);
this.element_ = el;
this.arcScaleX_ = 1;
this.arcScaleY_ = 1;
this.lineScale_ = 1;
}
var contextPrototype = CanvasRenderingContext2D_.prototype;
contextPrototype.clearRect = function() {
this.element_.innerHTML = '';
};
contextPrototype.beginPath = function() {
// TODO: Branch current matrix so that save/restore has no effect
// as per safari docs.
this.currentPath_ = [];
};
contextPrototype.moveTo = function(aX, aY) {
var p = this.getCoords_(aX, aY);
this.currentPath_.push({type: 'moveTo', x: p.x, y: p.y});
this.currentX_ = p.x;
this.currentY_ = p.y;
};
contextPrototype.lineTo = function(aX, aY) {
var p = this.getCoords_(aX, aY);
this.currentPath_.push({type: 'lineTo', x: p.x, y: p.y});
this.currentX_ = p.x;
this.currentY_ = p.y;
};
contextPrototype.bezierCurveTo = function(aCP1x, aCP1y,
aCP2x, aCP2y,
aX, aY) {
var p = this.getCoords_(aX, aY);
var cp1 = this.getCoords_(aCP1x, aCP1y);
var cp2 = this.getCoords_(aCP2x, aCP2y);
bezierCurveTo(this, cp1, cp2, p);
};
// Helper function that takes the already fixed cordinates.
function bezierCurveTo(self, cp1, cp2, p) {
self.currentPath_.push({
type: 'bezierCurveTo',
cp1x: cp1.x,
cp1y: cp1.y,
cp2x: cp2.x,
cp2y: cp2.y,
x: p.x,
y: p.y
});
self.currentX_ = p.x;
self.currentY_ = p.y;
}
contextPrototype.quadraticCurveTo = function(aCPx, aCPy, aX, aY) {
// the following is lifted almost directly from
// http://developer.mozilla.org/en/docs/Canvas_tutorial:Drawing_shapes
var cp = this.getCoords_(aCPx, aCPy);
var p = this.getCoords_(aX, aY);
var cp1 = {
x: this.currentX_ + 2.0 / 3.0 * (cp.x - this.currentX_),
y: this.currentY_ + 2.0 / 3.0 * (cp.y - this.currentY_)
};
var cp2 = {
x: cp1.x + (p.x - this.currentX_) / 3.0,
y: cp1.y + (p.y - this.currentY_) / 3.0
};
bezierCurveTo(this, cp1, cp2, p);
};
contextPrototype.arc = function(aX, aY, aRadius,
aStartAngle, aEndAngle, aClockwise) {
aRadius *= Z;
var arcType = aClockwise ? 'at' : 'wa';
var xStart = aX + mc(aStartAngle) * aRadius - Z2;
var yStart = aY + ms(aStartAngle) * aRadius - Z2;
var xEnd = aX + mc(aEndAngle) * aRadius - Z2;
var yEnd = aY + ms(aEndAngle) * aRadius - Z2;
// IE won't render arches drawn counter clockwise if xStart == xEnd.
if (xStart == xEnd && !aClockwise) {
xStart += 0.125; // Offset xStart by 1/80 of a pixel. Use something
// that can be represented in binary
}
var p = this.getCoords_(aX, aY);
var pStart = this.getCoords_(xStart, yStart);
var pEnd = this.getCoords_(xEnd, yEnd);
this.currentPath_.push({type: arcType,
x: p.x,
y: p.y,
radius: aRadius,
xStart: pStart.x,
yStart: pStart.y,
xEnd: pEnd.x,
yEnd: pEnd.y});
};
contextPrototype.rect = function(aX, aY, aWidth, aHeight) {
this.moveTo(aX, aY);
this.lineTo(aX + aWidth, aY);
this.lineTo(aX + aWidth, aY + aHeight);
this.lineTo(aX, aY + aHeight);
this.closePath();
};
contextPrototype.strokeRect = function(aX, aY, aWidth, aHeight) {
var oldPath = this.currentPath_;
this.beginPath();
this.moveTo(aX, aY);
this.lineTo(aX + aWidth, aY);
this.lineTo(aX + aWidth, aY + aHeight);
this.lineTo(aX, aY + aHeight);
this.closePath();
this.stroke();
this.currentPath_ = oldPath;
};
contextPrototype.fillRect = function(aX, aY, aWidth, aHeight) {
var oldPath = this.currentPath_;
this.beginPath();
this.moveTo(aX, aY);
this.lineTo(aX + aWidth, aY);
this.lineTo(aX + aWidth, aY + aHeight);
this.lineTo(aX, aY + aHeight);
this.closePath();
this.fill();
this.currentPath_ = oldPath;
};
contextPrototype.createLinearGradient = function(aX0, aY0, aX1, aY1) {
var gradient = new CanvasGradient_('gradient');
gradient.x0_ = aX0;
gradient.y0_ = aY0;
gradient.x1_ = aX1;
gradient.y1_ = aY1;
return gradient;
};
contextPrototype.createRadialGradient = function(aX0, aY0, aR0,
aX1, aY1, aR1) {
var gradient = new CanvasGradient_('gradientradial');
gradient.x0_ = aX0;
gradient.y0_ = aY0;
gradient.r0_ = aR0;
gradient.x1_ = aX1;
gradient.y1_ = aY1;
gradient.r1_ = aR1;
return gradient;
};
contextPrototype.drawImage = function(image, var_args) {
if (image.getContext) {
this.element_.innerHTML += image.getContext("2d").element_.innerHTML;
}
var dx, dy, dw, dh, sx, sy, sw, sh;
// to find the original width we overide the width and height
var oldRuntimeWidth = image.runtimeStyle.width;
var oldRuntimeHeight = image.runtimeStyle.height;
image.runtimeStyle.width = 'auto';
image.runtimeStyle.height = 'auto';
// get the original size
var w = image.width;
var h = image.height;
// and remove overides
image.runtimeStyle.width = oldRuntimeWidth;
image.runtimeStyle.height = oldRuntimeHeight;
if (arguments.length == 3) {
dx = arguments[1];
dy = arguments[2];
sx = sy = 0;
sw = dw = w;
sh = dh = h;
} else if (arguments.length == 5) {
dx = arguments[1];
dy = arguments[2];
dw = arguments[3];
dh = arguments[4];
sx = sy = 0;
sw = w;
sh = h;
} else if (arguments.length == 9) {
sx = arguments[1];
sy = arguments[2];
sw = arguments[3];
sh = arguments[4];
dx = arguments[5];
dy = arguments[6];
dw = arguments[7];
dh = arguments[8];
} else {
throw Error('Invalid number of arguments');
}
var d = this.getCoords_(dx, dy);
var w2 = sw / 2;
var h2 = sh / 2;
var vmlStr = [];
var W = 10;
var H = 10;
// For some reason that I've now forgotten, using divs didn't work
vmlStr.push(' <g_vml_:group',
' coordsize="', Z * W, ',', Z * H, '"',
' coordorigin="0,0"' ,
' style="', W, 'px;height:', H, 'px;position:absolute;');
// If filters are necessary (rotation exists), create them
// filters are bog-slow, so only create them if abbsolutely necessary
// The following check doesn't account for skews (which don't exist
// in the canvas spec (yet) anyway.
if (this.m_[0][0] != 1 || this.m_[0][1]) {
var filter = [];
// Note the 12/21 reversal
filter.push('M11=', this.m_[0][0], ',',
'M12=', this.m_[1][0], ',',
'M21=', this.m_[0][1], ',',
'M22=', this.m_[1][1], ',',
'Dx=', mr(d.x / Z), ',',
'Dy=', mr(d.y / Z), '');
// Bounding box calculation (need to minimize displayed area so that
// filters don't waste time on unused pixels.
var max = d;
var c2 = this.getCoords_(dx + dw, dy);
var c3 = this.getCoords_(dx, dy + dh);
var c4 = this.getCoords_(dx + dw, dy + dh);
max.x = m.max(max.x, c2.x, c3.x, c4.x);
max.y = m.max(max.y, c2.y, c3.y, c4.y);
vmlStr.push('padding:0 ', mr(max.x / Z), 'px ', mr(max.y / Z),
'px 0;filter:progid:DXImageTransform.Microsoft.Matrix(',
filter.join(''), ", sizingmethod='clip');")
} else {
vmlStr.push('top:', mr(d.y / Z), 'px;left:', mr(d.x / Z), 'px;');
}
vmlStr.push(' ">' ,
'<g_vml_:image src="', image.src, '"',
' style="', Z * dw, 'px;',
' height:', Z * dh, 'px;"',
' cropleft="', sx / w, '"',
' croptop="', sy / h, '"',
' cropright="', (w - sx - sw) / w, '"',
' cropbottom="', (h - sy - sh) / h, '"',
' />',
'</g_vml_:group>');
this.element_.insertAdjacentHTML('BeforeEnd',
vmlStr.join(''));
};
contextPrototype.stroke = function(aFill) {
var lineStr = [];
var lineOpen = false;
var a = processStyle(aFill ? this.fillStyle : this.strokeStyle);
var color = a.color;
var opacity = a.alpha * this.globalAlpha;
var W = 10;
var H = 10;
lineStr.push('<g_vml_:shape',
' filled="', !!aFill, '"',
' style="position:absolute;', W, 'px;height:', H, 'px;"',
' coordorigin="0 0" coordsize="', Z * W, ' ', Z * H, '"',
' stroked="', !aFill, '"',
' path="');
var newSeq = false;
var min = {x: null, y: null};
var max = {x: null, y: null};
for (var i = 0; i < this.currentPath_.length; i++) {
var p = this.currentPath_[i];
var c;
switch (p.type) {
case 'moveTo':
c = p;
lineStr.push(' m ', mr(p.x), ',', mr(p.y));
break;
case 'lineTo':
lineStr.push(' l ', mr(p.x), ',', mr(p.y));
break;
case 'close':
lineStr.push(' x ');
p = null;
break;
case 'bezierCurveTo':
lineStr.push(' c ',
mr(p.cp1x), ',', mr(p.cp1y), ',',
mr(p.cp2x), ',', mr(p.cp2y), ',',
mr(p.x), ',', mr(p.y));
break;
case 'at':
case 'wa':
lineStr.push(' ', p.type, ' ',
mr(p.x - this.arcScaleX_ * p.radius), ',',
mr(p.y - this.arcScaleY_ * p.radius), ' ',
mr(p.x + this.arcScaleX_ * p.radius), ',',
mr(p.y + this.arcScaleY_ * p.radius), ' ',
mr(p.xStart), ',', mr(p.yStart), ' ',
mr(p.xEnd), ',', mr(p.yEnd));
break;
}
// TODO: Following is broken for curves due to
// move to proper paths.
// Figure out dimensions so we can do gradient fills
// properly
if (p) {
if (min.x == null || p.x < min.x) {
min.x = p.x;
}
if (max.x == null || p.x > max.x) {
max.x = p.x;
}
if (min.y == null || p.y < min.y) {
min.y = p.y;
}
if (max.y == null || p.y > max.y) {
max.y = p.y;
}
}
}
lineStr.push(' ">');
if (!aFill) {
var lineWidth = this.lineScale_ * this.lineWidth;
// VML cannot correctly render a line if the width is less than 1px.
// In that case, we dilute the color to make the line look thinner.
if (lineWidth < 1) {
opacity *= lineWidth;
}
lineStr.push(
'<g_vml_:stroke',
' opacity="', opacity, '"',
' joinstyle="', this.lineJoin, '"',
' miterlimit="', this.miterLimit, '"',
' endcap="', processLineCap(this.lineCap), '"',
' weight="', lineWidth, 'px"',
' color="', color, '" />'
);
} else if (typeof this.fillStyle == 'object') {
var fillStyle = this.fillStyle;
var angle = 0;
var focus = {x: 0, y: 0};
// additional offset
var shift = 0;
// scale factor for offset
var expansion = 1;
if (fillStyle.type_ == 'gradient') {
var x0 = fillStyle.x0_ / this.arcScaleX_;
var y0 = fillStyle.y0_ / this.arcScaleY_;
var x1 = fillStyle.x1_ / this.arcScaleX_;
var y1 = fillStyle.y1_ / this.arcScaleY_;
var p0 = this.getCoords_(x0, y0);
var p1 = this.getCoords_(x1, y1);
var dx = p1.x - p0.x;
var dy = p1.y - p0.y;
angle = Math.atan2(dx, dy) * 180 / Math.PI;
// The angle should be a non-negative number.
if (angle < 0) {
angle += 360;
}
// Very small angles produce an unexpected result because they are
// converted to a scientific notation string.
if (angle < 1e-6) {
angle = 0;
}
} else {
var p0 = this.getCoords_(fillStyle.x0_, fillStyle.y0_);
var width = max.x - min.x;
var height = max.y - min.y;
focus = {
x: (p0.x - min.x) / width,
y: (p0.y - min.y) / height
};
width /= this.arcScaleX_ * Z;
height /= this.arcScaleY_ * Z;
var dimension = m.max(width, height);
shift = 2 * fillStyle.r0_ / dimension;
expansion = 2 * fillStyle.r1_ / dimension - shift;
}
// We need to sort the color stops in ascending order by offset,
// otherwise IE won't interpret it correctly.
var stops = fillStyle.colors_;
stops.sort(function(cs1, cs2) {
return cs1.offset - cs2.offset;
});
var length = stops.length;
var color1 = stops[0].color;
var color2 = stops[length - 1].color;
var opacity1 = stops[0].alpha * this.globalAlpha;
var opacity2 = stops[length - 1].alpha * this.globalAlpha;
var colors = [];
for (var i = 0; i < length; i++) {
var stop = stops[i];
colors.push(stop.offset * expansion + shift + ' ' + stop.color);
}
// When colors attribute is used, the meanings of opacity and o:opacity2
// are reversed.
lineStr.push('<g_vml_:fill type="', fillStyle.type_, '"',
' method="none" focus="100%"',
' color="', color1, '"',
' color2="', color2, '"',
' colors="', colors.join(','), '"',
' opacity="', opacity2, '"',
' g_o_:opacity2="', opacity1, '"',
' angle="', angle, '"',
' focusposition="', focus.x, ',', focus.y, '" />');
} else {
lineStr.push('<g_vml_:fill color="', color, '" opacity="', opacity,
'" />');
}
lineStr.push('</g_vml_:shape>');
this.element_.insertAdjacentHTML('beforeEnd', lineStr.join(''));
};
contextPrototype.fill = function() {
this.stroke(true);
}
contextPrototype.closePath = function() {
this.currentPath_.push({type: 'close'});
};
/**
* @private
*/
contextPrototype.getCoords_ = function(aX, aY) {
var m = this.m_;
return {
x: Z * (aX * m[0][0] + aY * m[1][0] + m[2][0]) - Z2,
y: Z * (aX * m[0][1] + aY * m[1][1] + m[2][1]) - Z2
}
};
contextPrototype.save = function() {
var o = {};
copyState(this, o);
this.aStack_.push(o);
this.mStack_.push(this.m_);
this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);
};
contextPrototype.restore = function() {
copyState(this.aStack_.pop(), this);
this.m_ = this.mStack_.pop();
};
function matrixIsFinite(m) {
for (var j = 0; j < 3; j++) {
for (var k = 0; k < 2; k++) {
if (!isFinite(m[j][k]) || isNaN(m[j][k])) {
return false;
}
}
}
return true;
}
function setM(ctx, m, updateLineScale) {
if (!matrixIsFinite(m)) {
return;
}
ctx.m_ = m;
if (updateLineScale) {
// Get the line scale.
// Determinant of this.m_ means how much the area is enlarged by the
// transformation. So its square root can be used as a scale factor
// for width.
var det = m[0][0] * m[1][1] - m[0][1] * m[1][0];
ctx.lineScale_ = sqrt(abs(det));
}
}
contextPrototype.translate = function(aX, aY) {
var m1 = [
[1, 0, 0],
[0, 1, 0],
[aX, aY, 1]
];
setM(this, matrixMultiply(m1, this.m_), false);
};
contextPrototype.rotate = function(aRot) {
var c = mc(aRot);
var s = ms(aRot);
var m1 = [
[c, s, 0],
[-s, c, 0],
[0, 0, 1]
];
setM(this, matrixMultiply(m1, this.m_), false);
};
contextPrototype.scale = function(aX, aY) {
this.arcScaleX_ *= aX;
this.arcScaleY_ *= aY;
var m1 = [
[aX, 0, 0],
[0, aY, 0],
[0, 0, 1]
];
setM(this, matrixMultiply(m1, this.m_), true);
};
contextPrototype.transform = function(m11, m12, m21, m22, dx, dy) {
var m1 = [
[m11, m12, 0],
[m21, m22, 0],
[dx, dy, 1]
];
setM(this, matrixMultiply(m1, this.m_), true);
};
contextPrototype.setTransform = function(m11, m12, m21, m22, dx, dy) {
var m = [
[m11, m12, 0],
[m21, m22, 0],
[dx, dy, 1]
];
setM(this, m, true);
};
/******** STUBS ********/
contextPrototype.clip = function() {
// TODO: Implement
};
contextPrototype.arcTo = function() {
// TODO: Implement
};
contextPrototype.createPattern = function() {
return new CanvasPattern_;
};
contextPrototype.measureText = function(textToDraw) {
var hiddenSpan = document.createElement('span');
hiddenSpan.style.font = this.font;
hiddenSpan.innerHTML = textToDraw;
var bodyNode = document.getElementsByTagName("body")[0];
bodyNode.appendChild(hiddenSpan);
var width = hiddenSpan.offsetWidth;
bodyNode.removeChild(hiddenSpan);
return {"width" : width + 1};
}
contextPrototype.fillText = function(textToDraw, x, y) {
var vmlStr = [];
var textHeightStr = this.font.split("px")[0].replace(/(^\s+)|(\s+$)/g, "");
var textHeight = /^\d+$/.test(textHeightStr) ? parseInt(textHeightStr) : 0;
vmlStr.push('<g_vml_:shape style="font:' + this.font + ';',
' color:' + this.fillStyle + ';',
' position:absolute;',
' left:' + x + 'px;',
' top:' + (y - textHeight) + 'px;',
' ' + this.measureText(textToDraw).width + 'px;',
' height:' + textHeight + 'px;"',
' ><g_vml_:textbox inset="0,0,0,0">' + textToDraw,
' </g_vml_:textbox>',
'</g_vml_:shape>');
this.element_.insertAdjacentHTML('BeforeEnd', vmlStr.join(''));
}
// Gradient / Pattern Stubs
function CanvasGradient_(aType) {
this.type_ = aType;
this.x0_ = 0;
this.y0_ = 0;
this.r0_ = 0;
this.x1_ = 0;
this.y1_ = 0;
this.r1_ = 0;
this.colors_ = [];
}
CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {
aColor = processStyle(aColor);
this.colors_.push({offset: aOffset,
color: aColor.color,
alpha: aColor.alpha});
};
function CanvasPattern_() {}
// set up externs
G_vmlCanvasManager = G_vmlCanvasManager_;
CanvasRenderingContext2D = CanvasRenderingContext2D_;
CanvasGradient = CanvasGradient_;
CanvasPattern = CanvasPattern_;
})();
} // if
参考：
excanvas使得IE能通过VML支持Canvas标签,但是在一些细节方面还是不尽人意.
比如
1.动态生成的Canvas对象将不支持getContext方法,
2.drawImage方法不能用Canvas对象作为第一个参数,
3.不支持fillText等方法.