Drawing on canvas HTML-Element shown in Android WebView: always lines from bottom to his touch are drawn -

i have website signature field in it, user needs paint signature. on google chrome, on firefox mobile , on safari mobile - iphone , ipod touch- looks should be:

but on built in android browser, , custom webview needed built our app, looks like:

the code on website is:

<canvas height="120" width="410"></canvas>    <input ... 

i presumed problem focusing webview, but

webview.setfocusable(true); webview.setfocusableintouchmode(true); webview.requestfocus(view.focus_down); 

was not solving this.

have experienced such behaviour , know solution? help.

i solved changing website , javascript code signature pad on customer side. after using new version of https://github.com/thomasjbradley/signature-pad , behaviour on android webview , built-in android browser fixed.