HTML5 移动开发 -- Canvas 9.4 表格 ， 折线图
表格
<!DOCTYPE html>
<html>
<head>
<meta charset='utf-8'>
</head>
<body>
<canvas id="a_canvas" width="300" height="300"></canvas>
<script type="text/javascript">
(function (){
window.addEventListener("load", function(){
// 获取上下文
var a_canvas = document.getElementById('a_canvas');
var context = a_canvas.getContext("2d");
// 绘制背景
var gradient = context.createLinearGradient(0,0,0,300);
gradient.addColorStop(0,"#e0e0e0");
gradient.addColorStop(1,"#ffffff");
context.fillStyle = gradient;
context.fillRect(0,0,a_canvas.width,a_canvas.height);
// 描绘边框
var grid_cols = 10;
var grid_rows = 10;
var cell_height = a_canvas.height / grid_rows;
var cell_width = a_canvas.width / grid_cols;
context.lineWidth = 1;
context.strokeStyle = "#a0a0a0";
// 结束边框描绘
context.beginPath();
// 准备画横线
for (var col = 0; col <= grid_cols; col++) {
var x = col * cell_width;
context.moveTo(x,0);
context.lineTo(x,a_canvas.height);
}
// 准备画竖线
for(var row = 0; row <= grid_rows; row++){
var y = row * cell_height;
context.moveTo(0,y);
context.lineTo(a_canvas.width, y);
}
context.stroke();
},false);
})();
</script>
</body>
折线图
<!DOCTYPE html>
<html>
<head>
<meta charset='utf-8'>
</head>
<body>
<canvas id="a_canvas" width="300" height="300"></canvas>
<script type="text/javascript">
(function (){
window.addEventListener("load", function(){
var data = [80,92,104,110,68,50,45,90,74,68,98,103];
// 获取上下文
var a_canvas = document.getElementById('a_canvas');
var context = a_canvas.getContext("2d");
// 绘制背景
var gradient = context.createLinearGradient(0,0,0,300);
gradient.addColorStop(0,"#e0e0e0");
gradient.addColorStop(1,"#ffffff");
context.fillStyle = gradient;
context.fillRect(0,0,a_canvas.width,a_canvas.height);
// 描绘边框
var grid_cols = data.length + 1;
var grid_rows = 4;
var cell_height = a_canvas.height / grid_rows;
var cell_width = a_canvas.width / grid_cols;
context.lineWidth = 1;
context.strokeStyle = "#a0a0a0";
// 结束边框描绘
context.beginPath();
// 准备画横线
for (var col = 0; col <= grid_cols; col++) {
var x = col * cell_width;
context.moveTo(x,0);
context.lineTo(x,a_canvas.height);
}
// 准备画竖线
for(var row = 0; row <= grid_rows; row++){
var y = row * cell_height;
context.moveTo(0,y);
context.lineTo(a_canvas.width, y);
}
context.lineWidth = 1;
context.strokeStyle = "#c0c0c0";
context.stroke();
var max_v = 0;
for(var i = 0; i<data.length; i++){
if (data[i] > max_v) { max_v = data[i]};
}
max_v = max_v * 1.1;
// 将数据换算为坐标
var points = [];
for( var i=0; i < data.length; i++){
var v= data[i];
var px = cell_width * (i +1);
var py = a_canvas.height - a_canvas.height*(v / max_v);
points.push({"x":px,"y":py});
}
// 绘制折现
context.beginPath();
context.moveTo(points[0].x, points[0].y);
for(var i= 1; i< points.length; i++){
context.lineTo(points[i].x,points[i].y);
}
context.lineWidth = 2;
context.strokeStyle = "#ee0000";
context.stroke();
//绘制坐标图形
for(var i in points){
var p = points[i];
context.beginPath();
context.arc(p.x,p.y,6,0,2*Math.PI);
context.fillStyle = "#ee0000";
context.fill();
}
},false);
})();
</script>
</body>
