用html5绘制折线图的实例代码
更新时间:2023-04-03 05:22:31 阅读： 评论：0
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<法拉第电磁感应html> <canvasid=“a_canvas”width=“1000”height=“700”></canvas> <script> (function(){ window.addeventlistener(“load”,function(){ vardata=[100,-1000,0,700]; //获取上下文 vara_canvas=document.getelementbyid(‘a_canvas’); varcontext=a_canvas.getcontext(押韵“2d”); //绘制背景 vargradient=context.createlineargradient(0,0,0,300); //gradient.addcolorstop(0,”#e0e0e0″); //gradient.addcolorstop(1,”#ffffff”); 读万卷书context.fillstyle=gradient; context.fillrect(0,0,a_canvas.width,a_canvas.height); //描绘边框 vargrid_cols=data.length+1; vargrid_rows=4; varcell_height=a_canvas.height/grid_rows; varcell_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(varcol=0;col<=grid_cols;col++){ varx=col*cell_width; context.moveto(x,0); context.lineto(x,a_canvas.height); } //准备画竖线 for(varrow=0;row<=grid_rows;row++){ vary=row*cell_height; context.moveto(0,y); context.lineto(a_canvas.width,y); }*/ //划横线 context.moveto(0,a_canvas.height/2); context.lineto(a_canvas.width,a_canvas.height/2); //画竖线 context.moveto(0,0); context.lineto(0,a_canvas.height); context.linewidth=1; context.strokestyl想念作文e=“#c0c0c0”; context.stroke(); varmax_v=0; for(vari=0;i<data.length;i++){ vard=0; if(data[i]<0) {dd=d-data[i]; } el{d=data[i];}; if(d>max_v){max_v=d}; } max_vmax_v=max_v*1.1; //将数据换算为坐标 varpoints=[]; for(vari=0;i<data.length;i++){ varv=data[i]; varpx=cell_width* (i+1); varpy=a_canvas.height/2–a_canvas.height*(v/max_v)/2; points.push({“x”:px,”y”:py}); } //绘制折现 context.beginpath(); context.moveto(points[0].x,points[0].y); for(vari=1;i<points.length;i++){ context.lineto(points[i].x,points[i].y); } context.linewidth=2; context.strokestyle=“#8ba9ff”; context.stroke(); //绘制坐标图形 for(variinpoints){ varp=points[i]; context.beginpath(); context.arc(p.x,p.y,4,0,2*math.pi); //实心圆 /* context.fillstyle=“#000”雷锋歌词
;*/ //空心圆 context.strokestyle=“#000”; context.stroke(); context.fillstyle=“white”; context.fill(); } //添加文字 for(variinpoints) {varp=points[i]; context.beginpath(); context.fillstyle=“black”; context.filltext(data[i],p.x+1,p.y–15); } },fal); })(); </script> </html>
运行结果如下：
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