Method WndProc

scrollview.go:168–225

(hwnd win.HWND, msg uint32, wParam, lParam uintptr)

}

func (sv *ScrollView) WndProc(hwnd win.HWND, msg uint32, wParam, lParam uintptr) uintptr {
	if sv.composite != nil {
		avoidBGArtifacts := func() {
			if sv.hasComplexBackground() {
				sv.composite.Invalidate()
			}
		}

		switch msg {
		case win.WM_HSCROLL:
			sv.composite.SetXPixels(sv.scroll(win.SB_HORZ, win.LOWORD(uint32(wParam))))
			if wParam == win.SB_ENDSCROLL {
				avoidBGArtifacts()
			}

		case win.WM_VSCROLL:
			sv.composite.SetYPixels(sv.scroll(win.SB_VERT, win.LOWORD(uint32(wParam))))
			if wParam == win.SB_ENDSCROLL {
				avoidBGArtifacts()
			}

		case win.WM_MOUSEWHEEL:
			if win.GetWindowLong(sv.hWnd, win.GWL_STYLE)&win.WS_VSCROLL == 0 {
				break
			}

			var cmd uint16
			if delta := int16(win.HIWORD(uint32(wParam))); delta < 0 {
				cmd = win.SB_LINEDOWN
			} else {
				cmd = win.SB_LINEUP
			}

			sv.composite.SetYPixels(sv.scroll(win.SB_VERT, cmd))
			avoidBGArtifacts()

			return 0

		case win.WM_COMMAND, win.WM_NOTIFY:
			sv.composite.WndProc(hwnd, msg, wParam, lParam)

		case win.WM_WINDOWPOSCHANGED:
			wp := (*win.WINDOWPOS)(unsafe.Pointer(lParam))

			if wp.Flags&win.SWP_NOSIZE != 0 {
				break
			}

			sv.updateScrollBars()

			if h, v := sv.Scrollbars(); !h || !v {
				sv.RequestLayout()
			}
		}
	}

	return sv.WidgetBase.WndProc(hwnd, msg, wParam, lParam)
}