int ScrollbarThemeOverlay::thumbPosition(const ScrollbarThemeClient& scrollbar)
{
if (!scrollbar.totalSize())
return 0;
int trackLen = trackLength(scrollbar);
float proportion = static_cast<float>(scrollbar.currentPos()) / scrollbar.totalSize();
return round(proportion * trackLen);
}
int ScrollbarThemeOverlay::thumbLength(const ScrollbarThemeClient& scrollbar)
{
int trackLen = trackLength(scrollbar);
if (!scrollbar.totalSize())
return trackLen;
float proportion = static_cast<float>(scrollbar.visibleSize()) / scrollbar.totalSize();
int length = round(proportion * trackLen);
int minLen = std::min(minimumThumbLength(scrollbar), trackLen);
length = clampTo(length, minLen, trackLen);
return length;
}
int ScrollbarTheme::thumbPosition(const ScrollbarThemeClient& scrollbar,
float scrollPosition) {
if (scrollbar.enabled()) {
float size = scrollbar.totalSize() - scrollbar.visibleSize();
// Avoid doing a floating point divide by zero and return 1 when
// usedTotalSize == visibleSize.
if (!size)
return 0;
float pos = std::max(0.0f, scrollPosition) *
(trackLength(scrollbar) - thumbLength(scrollbar)) / size;
return (pos < 1 && pos > 0) ? 1 : pos;
}
return 0;
}
int ScrollbarTheme::thumbLength(const ScrollbarThemeClient& scrollbar) {
if (!scrollbar.enabled())
return 0;
float overhang = fabsf(scrollbar.elasticOverscroll());
float proportion = 0.0f;
float totalSize = scrollbar.totalSize();
if (totalSize > 0.0f) {
proportion = (scrollbar.visibleSize() - overhang) / totalSize;
}
int trackLen = trackLength(scrollbar);
int length = round(proportion * trackLen);
length = std::max(length, minimumThumbLength(scrollbar));
if (length > trackLen)
length = 0; // Once the thumb is below the track length, it just goes away
// (to make more room for the track).
return length;
}
