package controllers import ( "github.com/jesseduffield/lazygit/pkg/gui/types" "github.com/jesseduffield/lazygit/pkg/utils" ) // To be called after pressing up-arrow; checks whether the cursor entered the // top scroll-off margin, and so the view needs to be scrolled up one line func checkScrollUp(view types.IViewTrait, scrollOffMargin int, lineIdxBefore int, lineIdxAfter int) { viewPortStart, viewPortHeight := view.ViewPortYBounds() linesToScroll := calculateLinesToScrollUp( viewPortStart, viewPortHeight, scrollOffMargin, lineIdxBefore, lineIdxAfter) if linesToScroll != 0 { view.ScrollUp(linesToScroll) } } // To be called after pressing down-arrow; checks whether the cursor entered the // bottom scroll-off margin, and so the view needs to be scrolled down one line func checkScrollDown(view types.IViewTrait, scrollOffMargin int, lineIdxBefore int, lineIdxAfter int) { viewPortStart, viewPortHeight := view.ViewPortYBounds() linesToScroll := calculateLinesToScrollDown( viewPortStart, viewPortHeight, scrollOffMargin, lineIdxBefore, lineIdxAfter) if linesToScroll != 0 { view.ScrollDown(linesToScroll) } } func calculateLinesToScrollUp(viewPortStart int, viewPortHeight int, scrollOffMargin int, lineIdxBefore int, lineIdxAfter int) int { // Cap the margin to half the view height. This allows setting the config to // a very large value to keep the cursor always in the middle of the screen. // Use +.5 so that if the height is even, the top margin is one line higher // than the bottom margin. scrollOffMargin = utils.Min(scrollOffMargin, int((float64(viewPortHeight)+.5)/2)) // Scroll only if the "before" position was visible (this could be false if // the scroll wheel was used to scroll the selected line out of view) ... if lineIdxBefore >= viewPortStart && lineIdxBefore < viewPortStart+viewPortHeight { marginEnd := viewPortStart + scrollOffMargin // ... and the "after" position is within the top margin (or before it) if lineIdxAfter < marginEnd { return marginEnd - lineIdxAfter } } return 0 } func calculateLinesToScrollDown(viewPortStart int, viewPortHeight int, scrollOffMargin int, lineIdxBefore int, lineIdxAfter int) int { // Cap the margin to half the view height. This allows setting the config to // a very large value to keep the cursor always in the middle of the screen. // Use -.5 so that if the height is even, the bottom margin is one line lower // than the top margin. scrollOffMargin = utils.Min(scrollOffMargin, int((float64(viewPortHeight)-.5)/2)) // Scroll only if the "before" position was visible (this could be false if // the scroll wheel was used to scroll the selected line out of view) ... if lineIdxBefore >= viewPortStart && lineIdxBefore < viewPortStart+viewPortHeight { marginStart := viewPortStart + viewPortHeight - scrollOffMargin - 1 // ... and the "after" position is within the bottom margin (or after it) if lineIdxAfter > marginStart { return lineIdxAfter - marginStart } } return 0 }