Why doesn't vue-signature-pad work in a modal?

Question

I am currently using the following library: https://www.npmjs.com/package/vue-signature-pad which has the following example: https://codesandbox.io/s/n5qjp3oqv4

I am applying it as the example, but I have it in a modal:

<v-dialog v-model="canvasVehiculo" fullscreen hide-overlay transition="dialog-bottom-transition">
         <v-card>
         <v-toolbar dark color="primary">
         <v-btn icon dark @click="canvasVehiculo = false">
          <v-icon>close</v-icon>
         </v-btn>
         <v-toolbar-title>Seleccionar partes del vehiculo:</v-toolbar-title>
            <v-spacer></v-spacer>
            <v-toolbar-items>
            <v-btn dark flat @click="undo">Deshacer</v-btn>
          </v-toolbar-items>
        </v-toolbar>
        <v-list three-line subheader>
        <v-subheader></v-subheader>            
        <VueSignaturePad
         id="signature"
         width="100%"
         height="450px"
         ref="signaturePad"
        />
   </v-list>
 </v-card>

<script>
import VueSignature from 'vue-signature-pad'; //Unicamente lo importo
</script>
<style scoped>
#signature {
  border: double 3px transparent;
  border-radius: 5px;
  background-image: url('imagen.png');
  background-size: 900px 456px; 
  background-position: center;
  background-origin: border-box;
  background-clip: content-box, border-box;
}
</style>

If I use it outside of the modal, it works correctly; but in the modal, to make it work, I must modify the size of the screen (for example, by using the DevTools' Toggle device toolbar to see the responsive form).

Answer 1

Its due to dialog not having width & height yet when the canvas is initializing within it, to solve it, you can pass the resizeCanvas event call to the options of the component:

<VueSignaturePad
    id="signature"
    width="100%"
    height="200px"
    ref="signaturePad"
    :options="{onBegin: () => {$refs.signaturePad.resizeCanvas()}}"
/>