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package patch_exploring
func calculateOrigin(currentOrigin int, bufferHeight int, numLines int, firstLineIdx int, lastLineIdx int, selectedLineIdx int, mode selectMode) int {
needToSeeIdx, wantToSeeIdx := getNeedAndWantLineIdx(firstLineIdx, lastLineIdx, selectedLineIdx, mode)
return calculateNewOriginWithNeededAndWantedIdx(currentOrigin, bufferHeight, numLines, needToSeeIdx, wantToSeeIdx)
}
// we want to scroll our origin so that the index we need to see is in view
// and the other index we want to see (e.g. the other side of a line range)
// is as close to being in view as possible.
func calculateNewOriginWithNeededAndWantedIdx(currentOrigin int, bufferHeight int, numLines int, needToSeeIdx int, wantToSeeIdx int) int {
origin := currentOrigin
if needToSeeIdx < currentOrigin || needToSeeIdx > currentOrigin+bufferHeight {
origin = max(min(needToSeeIdx-bufferHeight/2, numLines-bufferHeight-1), 0)
}
bottom := origin + bufferHeight
if wantToSeeIdx < origin {
requiredChange := origin - wantToSeeIdx
allowedChange := bottom - needToSeeIdx
return origin - min(requiredChange, allowedChange)
} else if wantToSeeIdx > origin+bufferHeight {
requiredChange := wantToSeeIdx - bottom
allowedChange := needToSeeIdx - origin
return origin + min(requiredChange, allowedChange)
} else {
return origin
}
}
func getNeedAndWantLineIdx(firstLineIdx int, lastLineIdx int, selectedLineIdx int, mode selectMode) (int, int) {
switch mode {
case LINE:
return selectedLineIdx, selectedLineIdx
case RANGE:
if selectedLineIdx == firstLineIdx {
return firstLineIdx, lastLineIdx
} else {
return lastLineIdx, firstLineIdx
}
case HUNK:
return firstLineIdx, lastLineIdx
default:
// we should never land here
panic("unknown mode")
}
}
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