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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
// Description: Generic implementation of the scroll pattern for
// controls having scroll bars.
//
using System;
using System.ComponentModel;
using System.Globalization;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Automation;
using System.Windows.Automation.Provider;
using MS.Win32;
namespace MS.Internal.AutomationProxies
{
// Static class used to support the Scroll pattern for controls that have scroll bars.
static class WindowScroll
{
#region Internal Methods
// ------------------------------------------------------
//
// Internal Methods
//
// ------------------------------------------------------
// Request to scroll Horizontally and vertically by the specified amount
static internal void SetScrollPercent (IntPtr hwnd, double horizontalPercent, double verticalPercent, bool forceResults)
{
if (!IsScrollable(hwnd))
{
throw new InvalidOperationException(SR.OperationCannotBePerformed);
}
bool resultsNoCheck;
bool isHorizontal = SetScrollPercent (hwnd, horizontalPercent, NativeMethods.SB_HORZ, out resultsNoCheck);
// This is needed for Controls that do not return the proper return codes to WinAPI Calls
if (!isHorizontal && (forceResults && resultsNoCheck))
{
isHorizontal = true;
}
bool isVertical = SetScrollPercent (hwnd, verticalPercent, NativeMethods.SB_VERT, out resultsNoCheck);
// This is needed for Controls that do not return the proper return codes to WinAPI Calls
if (!isVertical && (forceResults && resultsNoCheck))
{
isVertical = true;
}
if (isHorizontal && isVertical)
{
return;
}
throw new InvalidOperationException(SR.OperationCannotBePerformed);
}
// Request to scroll horizontally and vertically by the specified scrolling amount
static internal void Scroll (IntPtr hwnd, ScrollAmount HorizontalAmount, ScrollAmount VerticalAmount, bool fForceResults)
{
if (!IsScrollable(hwnd))
{
throw new InvalidOperationException(SR.OperationCannotBePerformed);
}
bool fHz = ScrollCursor(hwnd, HorizontalAmount, NativeMethods.SB_HORZ, fForceResults);
bool fVt = ScrollCursor (hwnd, VerticalAmount, NativeMethods.SB_VERT, fForceResults);
if ( fHz && fVt )
return;
throw new InvalidOperationException(SR.OperationCannotBePerformed);
}
// Process the Scroll Properties
static internal object GetPropertyScroll (AutomationProperty idProp, IntPtr hwnd)
{
// ...handle the scroll properties...
if (idProp == ScrollPattern.HorizontalScrollPercentProperty)
{
return Scrollable (hwnd, NativeMethods.SB_HORZ) ? GetScrollInfo (hwnd, NativeMethods.SB_HORZ) : ScrollPattern.NoScroll;
}
else if (idProp == ScrollPattern.VerticalScrollPercentProperty)
{
return Scrollable (hwnd, NativeMethods.SB_VERT) ? GetScrollInfo (hwnd, NativeMethods.SB_VERT) : ScrollPattern.NoScroll;
}
else if (idProp == ScrollPattern.HorizontalViewSizeProperty)
{
return Scrollable (hwnd, NativeMethods.SB_HORZ) ? ScrollViewSize (hwnd, NativeMethods.SB_HORZ) : 100.0;
}
else if (idProp == ScrollPattern.VerticalViewSizeProperty)
{
return Scrollable (hwnd, NativeMethods.SB_VERT) ? ScrollViewSize (hwnd, NativeMethods.SB_VERT) : 100.0;
}
else if (idProp == ScrollPattern.HorizontallyScrollableProperty)
{
return Scrollable (hwnd, NativeMethods.SB_HORZ);
}
else if (idProp == ScrollPattern.VerticallyScrollableProperty)
{
return Scrollable (hwnd, NativeMethods.SB_VERT);
}
return null;
}
// Finds if a control can be scrolled
static internal bool Scrollable (IntPtr hwnd, int sbFlag)
{
int style = Misc.GetWindowStyle(hwnd);
if ((sbFlag == NativeMethods.SB_HORZ && !Misc.IsBitSet(style, NativeMethods.WS_HSCROLL)) ||
(sbFlag == NativeMethods.SB_VERT && !Misc.IsBitSet(style, NativeMethods.WS_VSCROLL)))
{
return false;
}
if (!Misc.IsEnabled(hwnd))
{
return false;
}
// Check if the scroll info shows the scroll bar as enabled.
bool scrollBarEnabled = false;
NativeMethods.ScrollBarInfo sbi = new NativeMethods.ScrollBarInfo();
sbi.cbSize = Marshal.SizeOf(sbi.GetType());
int scrollBarObjectId =
(sbFlag == NativeMethods.SB_VERT) ? NativeMethods.OBJID_VSCROLL : NativeMethods.OBJID_HSCROLL;
if (Misc.GetScrollBarInfo(hwnd, scrollBarObjectId, ref sbi))
{
scrollBarEnabled =
!Misc.IsBitSet(sbi.scrollBarInfo, NativeMethods.STATE_SYSTEM_UNAVAILABLE);
}
if (!scrollBarEnabled)
{
return false;
}
// Get scroll range
NativeMethods.ScrollInfo si = new NativeMethods.ScrollInfo ();
si.cbSize = Marshal.SizeOf (si.GetType ());
si.fMask = NativeMethods.SIF_ALL;
if (!Misc.GetScrollInfo(hwnd, sbFlag, ref si))
{
return false;
}
return (si.nMax != si.nMin && si.nPage != si.nMax - si.nMin + 1);
}
static internal bool HasScrollableStyle(IntPtr hwnd)
{
int style = Misc.GetWindowStyle(hwnd);
bool hasScrollableStyle = Misc.IsBitSet(style, NativeMethods.WS_HSCROLL) || Misc.IsBitSet(style, NativeMethods.WS_VSCROLL);
string className = Misc.ProxyGetClassName(hwnd);
if (className.StartsWith("RichEdit", StringComparison.OrdinalIgnoreCase) ||
className.StartsWith("WindowForms10.RichEdit", StringComparison.OrdinalIgnoreCase) ||
string.Equals(className, "Edit", StringComparison.OrdinalIgnoreCase))
{
hasScrollableStyle = Misc.IsBitSet(style, NativeMethods.ES_MULTILINE);
}
return hasScrollableStyle;
}
// Finds if a control can be scrolled
static internal bool IsScrollable(IntPtr hwnd)
{
return Scrollable(hwnd, NativeMethods.SB_HORZ) || Scrollable(hwnd, NativeMethods.SB_VERT);
}
#endregion
#region Private Methods
// ------------------------------------------------------
//
// Private Methods
//
// ------------------------------------------------------
// Retrieve the scrollbar position in the [0..100]% range
static private double GetScrollInfo(IntPtr hwnd, int sbFlag)
{
// check if there is a scrollbar
NativeMethods.ScrollInfo si = new NativeMethods.ScrollInfo ();
si.fMask = NativeMethods.SIF_ALL;
si.cbSize = Marshal.SizeOf (si.GetType ());
if (Misc.GetScrollInfo(hwnd, sbFlag, ref si))
{
if (si.nMax != si.nMin && si.nPage != si.nMax - si.nMin + 1)
{
int delta;
// NOTE:
// Proportional scrollbars have a few key values: min, max, page, and current.
//
// Min and max represent the endpoints of the scrollbar; page is the side of the thumb,
// and current is the position of the leading edge of the thumb (top for a vert scrollbar).
//
// Because of this arrangment, current can't be any value between min and max, it's actually
// confied to min...(max-page)+1. That +1 is a quirk of the scrollbar's internal logic.
//
// For example, in an edit in notepad, these might be:
// min = 0
// max = 33 (~total lines in file)
// current = { any value from 0 .. 12 inclusive }
// page = 22
//
// Most controls just let the scrollbar do all the proportional logic: they pass the incoming
// values from the scroll messages (eg as a reuslt of dragging with a mouse or from UIA's SetValue)
// straight down to the scrollbar APIs.
//
// RichEdit is different: it does its own extra 'validation', and limits the current value to
// (max-page) - without that +1.
//
// The end result of this is that it's not possible using UIA to scroll a richedit to the max value:
// the richedit is exposing (implicitly through the scrollbar APIs) a max value one higher than the
// max value that it will actually allow.
string classname = Misc.GetClassName(hwnd);
if (classname.ToLower(System.Globalization.CultureInfo.InvariantCulture).Contains("richedit"))
{
delta = (si.nPage > 0) ? si.nPage : 0;
}
else
{
delta = (si.nPage > 0) ? si.nPage - 1 : 0;
}
return 100.0 * (si.nPos - si.nMin) / ((si.nMax - delta) - si.nMin);
}
}
return (double)ScrollPattern.NoScroll;
}
// View Size
static private double ScrollViewSize(IntPtr hwnd, int sbFlag)
{
// Get scroll range and page size
NativeMethods.ScrollInfo si = new NativeMethods.ScrollInfo ();
si.cbSize = Marshal.SizeOf (si.GetType ());
si.fMask = NativeMethods.SIF_RANGE | NativeMethods.SIF_PAGE;
if (!Misc.GetScrollInfo(hwnd, sbFlag, ref si) || (si.nMax == si.nMin))
{
return 100.0;
}
else
{
// "+1" because nPage can be 0 to nMax-nMin+1
int nPage = si.nPage > 0 ? si.nPage : 1;
return (100.0 * nPage) / (si.nMax + 1 - si.nMin);
}
}
// Request to scroll a control horizontally or vertically by a specified amount.
static private bool SetScrollPercent(IntPtr hwnd, double fScrollPos, int sbFlag, out bool forceResults)
{
forceResults = false;
// Check param
if ((int)fScrollPos == (int)ScrollPattern.NoScroll)
{
return true;
}
if (!Scrollable(hwnd, sbFlag))
{
return false;
}
if (fScrollPos < 0 || fScrollPos > 100)
{
throw new ArgumentOutOfRangeException(sbFlag == NativeMethods.SB_HORZ ? "horizontalPercent" : "verticalPercent", SR.ScrollBarOutOfRange);
}
// Get Max & min
NativeMethods.ScrollInfo si = new NativeMethods.ScrollInfo ();
si.fMask = NativeMethods.SIF_ALL;
si.cbSize = Marshal.SizeOf(si.GetType ());
// if no scroll bar return false
// on Win 6.0 success is false
// on other system check through the scroll info is a scroll bar is there
if (!Misc.GetScrollInfo(hwnd, sbFlag, ref si) ||
!((si.nMax != si.nMin && si.nPage != si.nMax - si.nMin + 1)))
{
return false;
}
// Set position
int delta = (si.nPage > 0) ? si.nPage - 1 : 0;
int newPos = (int) Math.Round (((si.nMax - delta) - si.nMin) * fScrollPos / 100.0 + si.nMin);
// No move, exit
if (newPos == si.nPos)
{
return true;
}
si.nPos = newPos;
forceResults = true;
int message = sbFlag == NativeMethods.SB_HORZ ? NativeMethods.WM_HSCROLL : NativeMethods.WM_VSCROLL;
int wParam = NativeMethods.Util.MAKELONG(NativeMethods.SB_THUMBPOSITION, si.nPos);
bool fRet = Misc.ProxySendMessageInt(hwnd, message, (IntPtr)wParam, IntPtr.Zero) == 0;
if (fRet && Misc.GetScrollInfo(hwnd, sbFlag, ref si) && si.nPos != newPos)
{
// WinForms treeview has some problems. The first is that the SendMessage with WM_HSCROLL/WM_VSCROLL
// with SB_THUMBPOSITION is not moving the scroll position. The second problem is that SetScrollInfo()
// lose the theming for the scroll bars and it really does not move the scroll position. The
// scrollbars change but it does not scroll the treeview control.
int prevPos = newPos;
ScrollAmount prevAmount = si.nPos > newPos ? ScrollAmount.SmallDecrement : ScrollAmount.SmallIncrement;
do
{
ScrollAmount amount = si.nPos > newPos ? ScrollAmount.SmallDecrement : ScrollAmount.SmallIncrement;
// If we were moving in one direction and overshoot, break to prevent getting into infant loop.
// If ScrollCursor() can not set the new position, also break to prevent infant loop.
if (prevAmount != amount || prevPos == si.nPos)
{
break;
}
prevPos = si.nPos;
fRet = ScrollCursor(hwnd, amount, sbFlag, forceResults);
} while (fRet && Misc.GetScrollInfo(hwnd, sbFlag, ref si) && si.nPos != newPos);
}
return fRet;
}
// Scroll control by a given amount
static private bool ScrollCursor(IntPtr hwnd, ScrollAmount amount, int sbFlag, bool fForceResults)
{
// Check Param
if (amount == ScrollAmount.NoAmount)
{
return true;
}
if (!Scrollable(hwnd, sbFlag))
{
return false;
}
// Get Max & min
NativeMethods.ScrollInfo si = new NativeMethods.ScrollInfo ();
si.fMask = NativeMethods.SIF_ALL;
si.cbSize = Marshal.SizeOf (si.GetType ());
// if no scroll bar return false
// on Win 6.0 success is false
// on other system check through the scroll info is a scroll bar is there
if ((!Misc.GetScrollInfo(hwnd, sbFlag, ref si) ||
!((si.nMax != si.nMin && si.nPage != si.nMax - si.nMin + 1))))
{
return false;
}
// Get Action to perform
int nAction;
if (sbFlag == NativeMethods.SB_HORZ)
{
switch (amount)
{
case ScrollAmount.SmallDecrement :
nAction = NativeMethods.SB_LINELEFT;
break;
case ScrollAmount.LargeDecrement :
nAction = NativeMethods.SB_PAGELEFT;
break;
case ScrollAmount.SmallIncrement :
nAction = NativeMethods.SB_LINERIGHT;
break;
case ScrollAmount.LargeIncrement :
nAction = NativeMethods.SB_PAGERIGHT;
break;
default :
return false;
}
}
else
{
switch (amount)
{
case ScrollAmount.SmallDecrement :
nAction = NativeMethods.SB_LINEUP;
break;
case ScrollAmount.LargeDecrement :
nAction = NativeMethods.SB_PAGEUP;
break;
case ScrollAmount.SmallIncrement :
nAction = NativeMethods.SB_LINEDOWN;
break;
case ScrollAmount.LargeIncrement :
nAction = NativeMethods.SB_PAGEDOWN;
break;
default :
return false;
}
}
// Set position
int wParam = NativeMethods.Util.MAKELONG (nAction, 0);
int message = sbFlag == NativeMethods.SB_HORZ ? NativeMethods.WM_HSCROLL : NativeMethods.WM_VSCROLL;
int result = Misc.ProxySendMessageInt(hwnd, message, (IntPtr)wParam, IntPtr.Zero);
return result == 0 || fForceResults;
}
#endregion
}
}
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