angular2-signaturepad use

For detailed reading this https://blog.csdn.net/qq_29594393/article/details/76913495

npm Address: https://www.npmjs.com/package/signature_pad

Problems encountered

Test page sizes intact, a small mobile terminal initialization pictures

solution

the let Canvas = . Document querySelector ( "Canvas"); 
the let ratio = the Math. max ( window. devicePixelRatio || . 1, . 1); 
the let signaWidth = this.platform. width () * 0.92; Ionic // acquisition apparatus used in width 
canvas.width = signaWidth; 
canvas.height = signaWidth; 
. Canvas the getContext ( . "2D") Scale ( ratio, ratio); // this step is the most critical than the column adjust 
the this. signaturePad. Clear (); // otherwise isEmpty () Might value in here Incorrect return 
the this. signaturePad. fromDataURL (the this. vehicleDamageImage)   // Base64 initialization value of the picture