diff options
| -rw-r--r-- | area_windows.go | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/area_windows.go b/area_windows.go index d9497bf..c8d201f 100644 --- a/area_windows.go +++ b/area_windows.go @@ -54,6 +54,7 @@ var ( _getUpdateRect = user32.NewProc("GetUpdateRect") _beginPaint = user32.NewProc("BeginPaint") _endPaint = user32.NewProc("EndPaint") + _fillRect = user32.NewProc("FillRect") _gdipCreateBitmapFromScan0 = gdiplus.NewProc("GdipCreateBitmapFromScan0") _gdipCreateFromHDC = gdiplus.NewProc("GdipCreateFromHDC") _gdipDrawImageI = gdiplus.NewProc("GdipDrawImageI") @@ -62,6 +63,8 @@ var ( ) const ( + areaBackgroundBrush = _HBRUSH(_COLOR_BTNFACE + 1) + // from winuser.h _WM_PAINT = 0x000F ) @@ -104,6 +107,19 @@ func paintArea(s *sysData) { } hdc := _HANDLE(r1) + // Windows won't necessarily erase the update rect for us; we need to do so ourselves + // thanks to the people at http://stackoverflow.com/questions/23001890/winapi-getupdaterect-with-brepaint-true-inside-wm-paint-doesnt-clear-the-pai + // TODO this whole thing is inefficient, as explained in the page; we probably don't need _getUpdateRect + if ps.fErase != 0 { // if Windows didn't + r1, _, err := _fillRect.Call( + uintptr(hdc), + uintptr(unsafe.Pointer(&xrect)), + uintptr(areaBackgroundBrush)) + if r1 == 0 { // failure + panic(fmt.Errorf("error manually clearing Area background: %v", err)) + } + } + i := s.handler.Paint(cliprect) // the pixels are arranged in RGBA order, but GDI+ requires BGRA // we don't have a choice but to convert it ourselves @@ -250,8 +266,7 @@ func scrollArea(s *sysData, wparam _WPARAM, which uintptr) { uintptr(0), uintptr(0), uintptr(0), - // TODO also SW_ERASE? or will the GetUpdateRect() call handle it? - uintptr(_SW_INVALIDATE)) // mark the remaining rect as needing redraw... + uintptr(_SW_INVALIDATE | _SW_ERASE)) // mark the remaining rect as needing redraw and erase... if r1 == _ERROR { // failure panic(fmt.Errorf("error scrolling Area: %v", err)) } @@ -317,7 +332,7 @@ func repaintArea(s *sysData) { r1, _, err := _invalidateRect.Call( uintptr(s.hwnd), uintptr(0), // the whole area - uintptr(_FALSE)) // TODO use _TRUE to mark that we should erase? or will the GetUpdateRect() call handle it? + uintptr(_TRUE)) // have Windows erase if possible if r1 == 0 { // failure panic(fmt.Errorf("error flagging Area as needing repainting after event (last error: %v)", err)) } @@ -596,7 +611,7 @@ func registerAreaWndClass(s *sysData) (newClassName string, err error) { hInstance: hInstance, hIcon: icon, hCursor: cursor, - hbrBackground: _HBRUSH(_COLOR_BTNFACE + 1), + hbrBackground: areaBackgroundBrush, } ret := make(chan uiret) |