diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/viewport.cpp | 11 | ||||
| -rw-r--r-- | src/zoom.hpp | 40 |
2 files changed, 47 insertions, 4 deletions
diff --git a/src/viewport.cpp b/src/viewport.cpp index 307b90598..74c774ff2 100644 --- a/src/viewport.cpp +++ b/src/viewport.cpp @@ -296,10 +296,13 @@ static void SetViewportPosition(Window *w, int x, int y) vp->virtual_left = x; vp->virtual_top = y; - old_left = UnScaleByZoom(old_left, vp->zoom); - old_top = UnScaleByZoom(old_top, vp->zoom); - x = UnScaleByZoom(x, vp->zoom); - y = UnScaleByZoom(y, vp->zoom); + /* viewport is bound to its left top corner, so it must be rounded down (UnScaleByZoomLower) + * else glitch described in FS#1412 will happen (offset by 1 pixel with zoom level > NORMAL) + */ + old_left = UnScaleByZoomLower(old_left, vp->zoom); + old_top = UnScaleByZoomLower(old_top, vp->zoom); + x = UnScaleByZoomLower(x, vp->zoom); + y = UnScaleByZoomLower(y, vp->zoom); old_left -= x; old_top -= y; diff --git a/src/zoom.hpp b/src/zoom.hpp index e0e7cc7a0..f924b362f 100644 --- a/src/zoom.hpp +++ b/src/zoom.hpp @@ -32,6 +32,13 @@ enum ZoomLevel { extern ZoomLevel _saved_scrollpos_zoom; +/** + * Scale by zoom level, usually shift left (when zoom > ZOOM_LVL_NORMAL) + * When shifting right, value is rounded up + * @param value value to shift + * @param zoom zoom level to shift to + * @return shifted value + */ static inline int ScaleByZoom(int value, ZoomLevel zoom) { if (zoom == ZOOM_LVL_NORMAL) return value; @@ -39,6 +46,13 @@ static inline int ScaleByZoom(int value, ZoomLevel zoom) return (zoom > ZOOM_LVL_NORMAL) ? value << izoom : (value + (1 << -izoom) - 1) >> -izoom; } +/** + * Scale by zoom level, usually shift right (when zoom > ZOOM_LVL_NORMAL) + * When shifting right, value is rounded up + * @param value value to shift + * @param zoom zoom level to shift to + * @return shifted value + */ static inline int UnScaleByZoom(int value, ZoomLevel zoom) { if (zoom == ZOOM_LVL_NORMAL) return value; @@ -46,4 +60,30 @@ static inline int UnScaleByZoom(int value, ZoomLevel zoom) return (zoom > ZOOM_LVL_NORMAL) ? (value + (1 << izoom) - 1) >> izoom : value << -izoom; } +/** + * Scale by zoom level, usually shift left (when zoom > ZOOM_LVL_NORMAL) + * @param value value to shift + * @param zoom zoom level to shift to + * @return shifted value + */ +static inline int ScaleByZoomLower(int value, ZoomLevel zoom) +{ + if (zoom == ZOOM_LVL_NORMAL) return value; + int izoom = (int)zoom - (int)ZOOM_LVL_NORMAL; + return (zoom > ZOOM_LVL_NORMAL) ? value << izoom : value >> -izoom; +} + +/** + * Scale by zoom level, usually shift right (when zoom > ZOOM_LVL_NORMAL) + * @param value value to shift + * @param zoom zoom level to shift to + * @return shifted value + */ +static inline int UnScaleByZoomLower(int value, ZoomLevel zoom) +{ + if (zoom == ZOOM_LVL_NORMAL) return value; + int izoom = (int)zoom - (int)ZOOM_LVL_NORMAL; + return (zoom > ZOOM_LVL_NORMAL) ? value >> izoom : value << -izoom; +} + #endif /* ZOOM_HPP */ |