int ScrollbarTheme::thumbLength(ScrollbarThemeClient* scrollbar)
{
if (!scrollbar->enabled())
return 0;
// It is safe to compute the overhang by adding the result from the main
// thread overscroll mode (first) and then adding the result from compositor
// thread overscroll (second) because the modes are mutually exclusive (and
// determining which mode is in use here will require lots of temporary
// plumbing, and the main thread mode is to be deleted).
float overhang = 0;
if (scrollbar->currentPos() < 0)
overhang = -scrollbar->currentPos();
else if (scrollbar->visibleSize() + scrollbar->currentPos() > scrollbar->totalSize())
overhang = scrollbar->currentPos() + scrollbar->visibleSize() - scrollbar->totalSize();
overhang += fabsf(scrollbar->elasticOverscroll());
float proportion = 0.0f;
float totalSize = usedTotalSize(scrollbar);
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;
}
int ScrollbarThemeComposite::thumbPosition(ScrollbarThemeClient* scrollbar)
{
if (scrollbar->enabled()) {
float size = usedTotalSize(scrollbar) - scrollbar->visibleSize();
// Avoid doing a floating point divide by zero and return 1 when usedTotalSize == visibleSize.
if (!size)
return 1;
float pos = max(0.0f, scrollbar->currentPos()) * (trackLength(scrollbar) - thumbLength(scrollbar)) / size;
return (pos < 1 && pos > 0) ? 1 : pos;
}
return 0;
}
int ScrollbarThemeComposite::thumbLength(Scrollbar* scrollbar)
{
if (!scrollbar->enabled())
return 0;
float proportion = scrollbar->visibleSize() / usedTotalSize(scrollbar);
int trackLen = trackLength(scrollbar);
int length = proportion * trackLen;
length = 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;
}
int ScrollbarThemeComposite::thumbLength(ScrollbarThemeClient* scrollbar)
{
if (!scrollbar->enabled())
return 0;
float proportion = scrollbar->visibleSize() / usedTotalSize(scrollbar);
int trackLen = trackLength(scrollbar);
#if PLATFORM(MAC) && !PLATFORM(CHROMIUM)
int length = round(proportion * trackLen);
#else
int length = proportion * trackLen;
#endif
length = 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;
}
int ScrollbarTheme::thumbLength(ScrollbarThemeClient* scrollbar)
{
if (!scrollbar->enabled())
return 0;
float overhang = 0;
if (scrollbar->currentPos() < 0)
overhang = -scrollbar->currentPos();
else if (scrollbar->visibleSize() + scrollbar->currentPos() > scrollbar->totalSize())
overhang = scrollbar->currentPos() + scrollbar->visibleSize() - scrollbar->totalSize();
float proportion = (scrollbar->visibleSize() - overhang) / usedTotalSize(scrollbar);
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;
}