JavaScript高级程序设计:Canvas绘图

Canvas 绘制矩形

var drawing = document.getElementById('drawing');

		if( drawing.getContext ){

			var context = drawing.getContext('2d');
			
			// 绘制矩形
			context.fillStyle = '#0000ff';
			context.fillRect( 10, 10 , 50 , 50 );

			// 绘制半透明红色矩形
			context.fillStyle = 'rgba(255,0,0,0.5)';
			context.fillRect( 30, 30, 50, 50);

			// 绘制描边矩形
			context.lineWidth = 1;
			context.strokeStyle = '#000000';
			context.strokeRect( 50 , 50, 50, 50 );

			// 清除一个小矩形
			context.clearRect( 40,40,10,10 );
		}
var drawing = document.getElement