How to Scroll pdfView automatically with button click or volume buttons - android-studio

Question

I'm using barteksc pdf viewer library to load pdf in my application.
pdfView = findViewById(R.id.pdfView);
pdfView.fromAsset(getResources().getString(R.string.pdfname))
.enableDoubletap(true)
.enableSwipe(true)
.defaultPage(pageNumber)
.onPageChange(mainreading.this)
.pageFitPolicy(FitPolicy.WIDTH)
.pageFling(true)
.linkHandler(null)
.enableAnnotationRendering(true)
.swipeHorizontal(true)
.scrollHandle(new DefaultScrollHandlenew(mainreading.this))
.enableAntialiasing(true)
.load();
}
I want pdf to start scroll automatically when user click the button of volume up and down buttons to start stop. I tried with below code while wrapping it in the handler with handler.performClick(); but it shows blank screen while scrolling up and down.
scrollbutton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
pdfView.scrollTo(0, pdfView.getScrollY() + 24);
}
});
Example :
https://play.google.com/store/apps/details?id=com.emptysheet.pdfreader_autoscroll&hl=en&gl=US
I want to make as like this. Can anyone help please.
Also tried with this. But it shows blank page after some scrolls.
#Override
public boolean dispatchKeyEvent(KeyEvent event) {
int action = event.getAction();
int keyCode = event.getKeyCode();
switch (keyCode) {
case KeyEvent.KEYCODE_VOLUME_UP:
if (action == KeyEvent.ACTION_DOWN) {
pdfView.scrollTo(0, pdfView.getScrollY() -24);
}
return true;
case KeyEvent.KEYCODE_VOLUME_DOWN:
if (action == KeyEvent.ACTION_DOWN) {
pdfView.scrollTo(0, pdfView.getScrollY() + 24);
}
return true;
default:
return super.dispatchKeyEvent(event);
}
}

Answer 1

You can simply use this PDF viewer from github.
It's based on the same 'barsteksc' pdf viewer with the feature to jump to any pages.
It's MagicalPdfViewer and you can use 'jumpTo(pageNo)' method to simply jump to the specific page. It also gives you the option to animate to the specific page with the same method, just pass 'true' as the 2nd parameter.
Moreover, if you pass the values like '-1' and 'bigger than pageNo', It will automatically scroll to the 0 & last page respectively.
Give it a try & let me know if you got what you wanted.