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Codechange: Don't update window contents if scrollbar position has not moved.

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(cherry picked from commit 52b16237ad)
This commit is contained in:
Peter Nelson
2021-05-07 12:36:08 +01:00
committed by Jonathan G Rennison
parent ad554d913f
commit 065ae3964a
3 changed files with 23 additions and 15 deletions
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12
src/widget_type.h
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@@ -763,12 +763,15 @@ public:
/**
* Sets the position of the first visible element
* @param position the position of the element
* @return true iff the position has changed
*/
void SetPosition(int position)
bool SetPosition(int position)
{
assert(position >= 0);
assert(this->count <= this->cap ? (position == 0) : (position + this->cap <= this->count));
uint16 old_pos = this->pos;
this->pos = position;
return this->pos != old_pos;
}
/**
@@ -776,16 +779,17 @@ public:
* If the position would be too low or high it will be clamped appropriately
* @param difference the amount of change requested
* @param unit The stepping unit of \a difference
* @return true iff the position has changed
*/
void UpdatePosition(int difference, ScrollbarStepping unit = SS_SMALL)
bool UpdatePosition(int difference, ScrollbarStepping unit = SS_SMALL)
{
if (difference == 0) return;
if (difference == 0) return false;
switch (unit) {
case SS_SMALL: difference *= this->stepsize; break;
case SS_BIG: difference *= this->cap; break;
default: break;
}
this->SetPosition(Clamp(this->pos + difference, 0, std::max(this->count - this->cap, 0)));
return this->SetPosition(Clamp(this->pos + difference, 0, std::max(this->count - this->cap, 0)));
}
/**