ListElement.cpp

#include "ListElement.hpp"
 
bool ListElement::process(InputEvents* event)
{
    bool ret = false;
 
    // if we're hidden, don't process input
    if (hidden) return ret;
 
    // perform inertia scrolling for this element
    ret |= this->handleInertiaScroll(event);
 
    ret |= super::process(event);
 
    return ret;
}
 
bool ListElement::processUpDown(InputEvents* event)
{
    bool ret = false;
    int SPEED = 1;
 
    // handle up and down for the scroll view
    if (event->isKeyDown())
    {
        // scroll the view by offsetting the elastic counter
        event->wheelScroll += (SPEED * event->held(UP_BUTTON) - SPEED * event->held(DOWN_BUTTON));
 
        ret |= event->held(UP_BUTTON) || event->held(DOWN_BUTTON);
    }
 
    return ret;
}
 
bool ListElement::handleInertiaScroll(InputEvents* event)
{
    bool ret = false;
    ListElement* elem = this;
 
    if (event->isTouchDown())
    {
        // make sure that the mouse down's X coordinate is over the app list (not sidebar)
        if (event->xPos < elem->xAbs)
            return false;
 
        // saw mouse down so set it in our element object
        elem->dragging = true;
        elem->lastMouseY = event->yPos;
        elem->initialTouchDown = event->yPos;
 
        ret |= true;
    }
    // drag event for scrolling up or down
    else if (event->isTouchDrag())
    {
        if (elem->dragging)
        {
            // prevent scrolling until we exceed a treshold distance in the Y direction
            if (this->initialTouchDown >= 0 && (abs(event->yPos - this->initialTouchDown) < 10 / SCALER))
                return false;
 
            this->initialTouchDown = -1;
 
            int distance = event->yPos - elem->lastMouseY;
            elem->y += distance;
            elem->lastMouseY = event->yPos;
 
            // use the last distance as the rubber band value
            elem->elasticCounter = distance;
 
            ret |= true;
        }
    }
    else if (event->isTouchUp())
    {
        // mouse up, no more mouse down (TODO: fire selected event here)
        elem->dragging = false;
 
        // if the scroll offset is less than the total number of apps
        // (put on the mouse up to make it "snap" when going out of bounds)
        // TODO: account for max number of apps too (prevent scrolling down forever)
        if (elem->y > minYScroll)
            elem->y = minYScroll;
 
        ret |= true;
    }
 
    // if mouse is up, and there's some elastic counter left, burn out remaining elastic value
    if (!elem->dragging && elem->elasticCounter != 0)
    {
        elem->y += elem->elasticCounter;
 
        // reduce the elastic counter by 5% each time (slows down the scroll)
        elem->elasticCounter *= 0.95;
        
        // if we're less than 10 pixels on the counter, just stop
        if (abs(elem->elasticCounter) < 10)
            elem->elasticCounter = 0;
 
        // TODO: same problem as above todo, also extract into method?
        if (elem->y > minYScroll)
            elem->y = minYScroll;
 
        ret |= true;
    }
 
    if (ret) event->isScrolling = true;
 
    if (event->wheelScroll != 0)
    {
        // apply wheel scroll directly to y position, and then reset
        elem->y += event->wheelScroll * 10;
        if (elem->y > minYScroll)
            elem->y = minYScroll;
        event->wheelScroll *= 0.95;
 
        if (abs(event->wheelScroll) < 0.1)
            event->wheelScroll = 0;
            
        ret |= true;
    }
 
    return ret;
}