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热力图.html
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热力图.html
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<html>
<head></head>
<body>
<div>
<canvas id="test" width="100" height="100"></canvas>
</div>
<div id="container"></div>
<script type="text/javascript">
// var testNode = document.getElementById("test");
// var ctx = testNode.getContext('2d');
// var radius = 20;
// ctx.beginPath();
// ctx.arc(radius,radius,radius,0, 2 * Math.PI,false);
// //添加径向/圆渐变
// var gradient = ctx.createRadialGradient(radius,radius,0,radius,radius,radius)
// gradient.addColorStop(0,'rgba(0,0,0,1)');
// gradient.addColorStop(1,'rgba(0,0,0,0)');
// ctx.fillStyle = gradient;
// ctx.closePath();
// ctx.fill();
var warpper = document.getElementById("container");
var defaultRadius = 30;
var distance = 0;
var minCount = 0;
var maxCount = 100;
var renderBoundaries = [10000, 10000, 0, 0];
var palette = getPointColor();
var canvas = document.createElement('canvas');
var shadowCanvas = document.createElement('canvas');
var shadowCtx = shadowCanvas.getContext('2d');
var ctx = canvas.getContext('2d');
canvas.className = 'heatmap-canvas';
canvas.width = shadowCanvas.width = 1500;
canvas.height = shadowCanvas.height = 700;
canvas.style.cssText = shadowCanvas.style.cssText = 'position:absolute;left:0;top:0;';
warpper.appendChild(canvas);
for(i = 0; i < 500;i++){
var point = {};
point.x = Math.floor(Math.random()*(1000-1)+200);
point.y = Math.floor(Math.random()*(500-1)+100);
point.value = Math.floor(Math.random()*(100-1)+1);
//distance = Math.floor(Math.random()*(100-1)- 50)
//warpper.appendChild(pointTmp(point,defaultRadius));
//distance = distance ;
drawPoint(point,defaultRadius);
}
//drawPanel();
colorizeCtx();
warpper.style.position = 'relative';
warpper.appendChild(document.createElement('br'));
warpper.appendChild(document.createElement('br'));
warpper.appendChild(document.createElement('br'));
warpper.appendChild(getColorPalette());
function pointTmp(point,radius){
var tplCanvas = document.createElement('canvas');
var tplCtx = tplCanvas.getContext('2d');
var x = radius;
var y = radius;
tplCanvas.width = radius*2;
tplCanvas.height = radius*2;
tplCtx.beginPath();
//添加径向/圆渐变
tplCtx.arc(x,y,radius,0, 2 * Math.PI,false);
var gradient = tplCtx.createRadialGradient(x,y,0,x,y,radius)
gradient.addColorStop(0,'rgba(0,0,0,1)');
gradient.addColorStop(1,'rgba(0,0,0,0)');
tplCtx.fillStyle = gradient;
tplCtx.closePath();
tplCtx.fill();
return tplCanvas
}
function drawPoint(point,radius){
var x = radius;
var y = radius;
var tmp = pointTmp(point,radius);
var rectX = point.x - radius;
var rectY = point.y - radius;
var alpha = (point.value - minCount)/(maxCount - minCount);
alpha = alpha > 1 ? 1:alpha;
console.log(alpha)
shadowCtx.globalAlpha = alpha;
shadowCtx.drawImage(tmp,rectX,rectY);
if (rectX < renderBoundaries[0]) {
renderBoundaries[0] = rectX;
}
if (rectY < renderBoundaries[1]) {
renderBoundaries[1] = rectY;
}
if (rectX + 2*radius > renderBoundaries[2]) {
renderBoundaries[2] = rectX + 2*radius;
}
if (rectY + 2*radius > renderBoundaries[3]) {
renderBoundaries[3] = rectY + 2*radius;
}
}
function drawPanel(){
var width = renderBoundaries[2] - renderBoundaries[0];
var height = renderBoundaries[3] - renderBoundaries[1];
var x = renderBoundaries[0];
var y = renderBoundaries[1];
var img = shadowCtx.getImageData(x, y, width, height);
ctx.putImageData(img,x,y)
}
//着色
function colorizeCtx(){
var width = renderBoundaries[2] - renderBoundaries[0];
var height = renderBoundaries[3] - renderBoundaries[1];
var x = renderBoundaries[0];
var y = renderBoundaries[1];
var img = shadowCtx.getImageData(x, y, width, height);
var imgData = img.data;
var len = imgData.length;
var opacity = 0;
var maxOpacity = 255;
var minOpacity = 0;
var bln = false;
for(var i = 3;i<len;i+=4){
var alpha = imgData[i];
var offset = alpha * 4;
if(!offset){
continue;
}
var finalAlpha;
if (opacity > 0) {
finalAlpha = opacity;
} else {
if (alpha < maxOpacity) {
if (alpha < minOpacity) {
finalAlpha = minOpacity;
} else {
finalAlpha = alpha;
}
} else {
finalAlpha = maxOpacity;
}
}
imgData[i-3] = palette[offset];
imgData[i-2] = palette[offset + 1];
imgData[i-1] = palette[offset + 2];
imgData[i] = bln ? palette[offset + 3] : finalAlpha;
}
img.data = imgData;
ctx.putImageData(img,x,y)
}
//创建色带
function getColorPalette(){
var paletteCanvas = document.createElement('canvas');
var paletteCtx = paletteCanvas.getContext('2d');
var defaultGradient = { 0.25: "rgb(0,0,255)",
0.55: "rgb(0,255,255)",
0.65: "rgb(0,255,0)",
0.95: "yellow",
1.0: "rgb(255,0,0)"} ;
paletteCanvas.width = 256;
paletteCanvas.height = 10;
var gradient = paletteCtx.createLinearGradient(0,0,256,1);
for(var key in defaultGradient){
gradient.addColorStop(key,defaultGradient[key]);
}
paletteCtx.fillStyle = gradient;
paletteCtx.fillRect(0,0,256,10);
return paletteCanvas;
}
function getPointColor(){
var paletteCanvas = document.createElement('canvas');
var paletteCtx = paletteCanvas.getContext('2d');
var defaultGradient = { 0.25: "rgb(0,0,255)",
//0.55: "rgb(0,255,255)",
0.55: "rgb(0,255,0)",
0.85: "yellow",
1.0: "rgb(255,0,0)"} ;
paletteCanvas.width = 256;
paletteCanvas.height = 1;
var gradient = paletteCtx.createLinearGradient(0,0,256,1);
for(var key in defaultGradient){
gradient.addColorStop(key,defaultGradient[key]);
}
paletteCtx.fillStyle = gradient;
paletteCtx.fillRect(0,0,256,1);
return paletteCtx.getImageData(0,0,256,1).data;
}
</script>
</body>
</html>