[FIXED] How to scroll smoothly with Selenium WebDriver and/or Sikuli in Java

Issue

As part of a test suite measuring FPS for a web application I need to perform a smooth scroll of the web page. That is, the same smoothness as when a user grabs the scroll bar and moves it with the mouse.

So far I have tried by using simulating key presses with sikuli, i.e. pressing the arrow up/down keys multiple times to scroll the whole page. I have also tried using a Javascript approach:

public void scrollSmooth(int durationOfScroll){
    long timeWhenStarting = System.currentTimeMillis() / 1000L;
while (System.currentTimeMillis() / 1000L - timeWhenStarting < durationOfScroll) {
    ((JavascriptExecutor) driver).executeScript("window.scrollBy(0,10)", "");
    }
}

Both these approaches fails to fulfill their purpose, as they both generate a step-by-step scroll, which is not suitable when I simultaneously want to measure the FPS (e.g. the smoothnes of the page when scrolling).

Solution

The solution was a lot more simple than expected. Instead of using a time-based condition for the loop I tried the following:

public void scrollSmooth(){
    for(int i=0;i<6000;i++) {
        ((JavascriptExecutor) driver).executeScript("window.scrollBy(0,1)", "");
    }
}

This works well, with the small downside that I cannot specify the length (in time) of the scroll, only the actual pixels to be scrolled.

Answered By - Agent Shoulder