コード例

var cs=document.getElementById("myCanvas");

var ctx=c.getContext("2d");

ctx.strokeRect(5,5,25,15);

ctx.scale(2,2);

ctx.strokeRect(5,5,25,15);

The scale(x, y) method must add the scaling transformation described by the arguments to the transformation matrix. The x argument represents the scale factor in the horizontal direction and the y argument represents the scale factor in the vertical direction. The factors are multiples.