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SWT is an open source widget toolkit for Java designed to provide efficient, portable access to the user-interface facilities of the operating systems on which it is implemented.

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/*******************************************************************************
 * Copyright (c) 2000, 2012 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.widgets;


import org.eclipse.swt.internal.win32.*;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;

/**
 * This class is the abstract superclass of all classes which
 * represent controls that have standard scroll bars.
 * 

 * 
Styles:

 * 
H_SCROLL, V_SCROLL

 * 
Events:
 * 
(none)

 * 

 * 

 * IMPORTANT: This class is intended to be subclassed only
 * within the SWT implementation.
 * 

 *
 * @see Sample code and further information
 * @noextend This class is not intended to be subclassed by clients.
 */

public abstract class Scrollable extends Control {
	ScrollBar horizontalBar, verticalBar;

/**
 * Prevents uninitialized instances from being created outside the package.
 */
Scrollable () {
}

/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * 

 * The style value is either one of the style constants defined in
 * class SWT which is applicable to instances of this
 * class, or must be built by bitwise OR'ing together 
 * (that is, using the int "|" operator) two or more
 * of those SWT style constants. The class description
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * 

 *
 * @param parent a composite control which will be the parent of the new instance (cannot be null)
 * @param style the style of control to construct
 *
 * @exception IllegalArgumentException 
    
 *    
  • ERROR_NULL_ARGUMENT - if the parent is null
    • 
 * 

 * @exception SWTException 
    
 *    
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
    • 
 *    
  • ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass
    • 
 * 

 *
 * @see SWT#H_SCROLL
 * @see SWT#V_SCROLL
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public Scrollable (Composite parent, int style) {
	super (parent, style);
}

int /*long*/ callWindowProc (int /*long*/ hwnd, int msg, int /*long*/ wParam, int /*long*/ lParam) {
	if (handle == 0) return 0;
	return OS.DefWindowProc (hwnd, msg, wParam, lParam);
}

/**
 * Given a desired client area for the receiver
 * (as described by the arguments), returns the bounding
 * rectangle which would be required to produce that client
 * area.
 * 

 * In other words, it returns a rectangle such that, if the
 * receiver's bounds were set to that rectangle, the area
 * of the receiver which is capable of displaying data
 * (that is, not covered by the "trimmings") would be the
 * rectangle described by the arguments (relative to the
 * receiver's parent).
 * 

 * 
 * @param x the desired x coordinate of the client area
 * @param y the desired y coordinate of the client area
 * @param width the desired width of the client area
 * @param height the desired height of the client area
 * @return the required bounds to produce the given client area
 *
 * @exception SWTException 
    
 *    
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
    • 
 *    
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
    • 
 * 

 *
 * @see #getClientArea
 */
public Rectangle computeTrim (int x, int y, int width, int height) {
	checkWidget ();
	int /*long*/ scrolledHandle = scrolledHandle ();
	RECT rect = new RECT ();
	OS.SetRect (rect, x, y, x + width, y + height);
	int bits1 = OS.GetWindowLong (scrolledHandle, OS.GWL_STYLE);
	int bits2 = OS.GetWindowLong (scrolledHandle, OS.GWL_EXSTYLE);
	OS.AdjustWindowRectEx (rect, bits1, false, bits2);
	if (horizontalBar != null) rect.bottom += OS.GetSystemMetrics (OS.SM_CYHSCROLL);
	if (verticalBar != null) rect.right += OS.GetSystemMetrics (OS.SM_CXVSCROLL);
	int nWidth = rect.right - rect.left, nHeight = rect.bottom - rect.top;
	return new Rectangle (rect.left, rect.top, nWidth, nHeight);
}

ScrollBar createScrollBar (int type) {
	ScrollBar bar = new ScrollBar (this, type);
	if ((state & CANVAS) != 0) {
		bar.setMaximum (100);
		bar.setThumb (10);
	}
	return bar;
}

void createWidget () {
	super.createWidget ();
	if ((style & SWT.H_SCROLL) != 0) horizontalBar = createScrollBar (SWT.H_SCROLL);
	if ((style & SWT.V_SCROLL) != 0) verticalBar = createScrollBar (SWT.V_SCROLL);
}

void destroyScrollBar (int type) {
	int /*long*/ hwnd = scrolledHandle ();
	int bits = OS.GetWindowLong (hwnd, OS.GWL_STYLE);
	if ((type & SWT.HORIZONTAL) != 0) {
		style &= ~SWT.H_SCROLL;
		bits &= ~OS.WS_HSCROLL;
	}
	if ((type & SWT.VERTICAL) != 0) {
		style &= ~SWT.V_SCROLL;
		bits &= ~OS.WS_VSCROLL;
	}
	OS.SetWindowLong (hwnd, OS.GWL_STYLE, bits);
}

/**
 * Returns a rectangle which describes the area of the
 * receiver which is capable of displaying data (that is,
 * not covered by the "trimmings").
 * 
 * @return the client area
 *
 * @exception SWTException 
    
 *    
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
    • 
 *    
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
    • 
 * 

 *
 * @see #computeTrim
 */
public Rectangle getClientArea () {
	checkWidget ();
	forceResize ();
	RECT rect = new RECT ();
	int /*long*/ scrolledHandle = scrolledHandle ();
	OS.GetClientRect (scrolledHandle, rect);
	int x = rect.left, y = rect.top;
	int width = rect.right - rect.left;
	int height = rect.bottom - rect.top;
	if (scrolledHandle != handle) {
		OS.GetClientRect (handle, rect);
		OS.MapWindowPoints(handle, scrolledHandle, rect, 2);
		x = -rect.left;
		y = -rect.top;
	}
	return new Rectangle (x, y, width, height);
}

/**
 * Returns the receiver's horizontal scroll bar if it has
 * one, and null if it does not.
 *
 * @return the horizontal scroll bar (or null)
 *
 * @exception SWTException 
    
 *    
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
    • 
 *    
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
    • 
 * 

 */
public ScrollBar getHorizontalBar () {
	checkWidget ();
	return horizontalBar;
}

/**
 * Returns the mode of the receiver's scrollbars. This will be
 * bitwise OR of one or more of the constants defined in class
 * SWT.

 * 
  • SWT.SCROLLBAR_OVERLAY - if receiver
 * uses overlay scrollbars
    • 
 * 
  • SWT.NONE - otherwise
    • 
 * 
 * @return the mode of scrollbars
 * 
 * @exception SWTException 
      
 * 
    • ERROR_WIDGET_DISPOSED - if the receiver has been
 * disposed
      • 
 * 
    • ERROR_THREAD_INVALID_ACCESS - if not called from the
 * thread that created the receiver
      • 
 * 
    
 * 
 * @see SWT#SCROLLBAR_OVERLAY
 * 
 * @since 3.8
 */
public int getScrollbarsMode () {
	checkWidget();
	return SWT.NONE;
}

/**
 * Returns the receiver's vertical scroll bar if it has
 * one, and null if it does not.
 *
 * @return the vertical scroll bar (or null)
 *
 * @exception SWTException 
      
 *    
    • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
      • 
 *    
    • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
      • 
 * 
    
 */
public ScrollBar getVerticalBar () {
	checkWidget ();
	return verticalBar;
}

void releaseChildren (boolean destroy) {
	if (horizontalBar != null) {
		horizontalBar.release (false);
		horizontalBar = null;
	}
	if (verticalBar != null) {
		verticalBar.release (false);
		verticalBar = null;
	}
	super.releaseChildren (destroy);
}

void reskinChildren (int flags) {
	if (horizontalBar != null) horizontalBar.reskin (flags);
	if (verticalBar != null) verticalBar.reskin (flags);
	super.reskinChildren (flags);
}

int /*long*/ scrolledHandle () {
	return handle;
}

int widgetExtStyle () {
	return super.widgetExtStyle ();
	/*
	* This code is intentionally commented.  In future,
	* we may wish to support different standard Windows
	* edge styles.  The issue here is that not all of
	* these styles are available on the other platforms
	* this would need to be a hint.
	*/
//	if ((style & SWT.BORDER) != 0) return OS.WS_EX_CLIENTEDGE;
//	if ((style & SWT.SHADOW_IN) != 0) return OS.WS_EX_STATICEDGE;
//	return super.widgetExtStyle ();
}

int widgetStyle () {
	int bits = super.widgetStyle () | OS.WS_TABSTOP;
	if ((style & SWT.H_SCROLL) != 0) bits |= OS.WS_HSCROLL;
	if ((style & SWT.V_SCROLL) != 0) bits |= OS.WS_VSCROLL;
	return bits;
}

TCHAR windowClass () {
	return display.windowClass;
}

int /*long*/ windowProc () {
	return display.windowProc;
}

LRESULT WM_HSCROLL (int /*long*/ wParam, int /*long*/ lParam) {
	LRESULT result = super.WM_HSCROLL (wParam, lParam);
	if (result != null) return result;
	
	/*
	* Bug on WinCE.  lParam should be NULL when the message is not sent
	* by a scroll bar control, but it contains the handle to the window.
	* When the message is sent by a scroll bar control, it correctly
	* contains the handle to the scroll bar.  The fix is to check for
	* both.
	*/
	if (horizontalBar != null && (lParam == 0 || lParam == handle)) {
		return wmScroll (horizontalBar, (state & CANVAS) != 0, handle, OS.WM_HSCROLL, wParam, lParam);
	}
	return result;
}

LRESULT WM_MOUSEWHEEL (int /*long*/ wParam, int /*long*/ lParam) {
	return wmScrollWheel ((state & CANVAS) != 0, wParam, lParam);
}

LRESULT WM_SIZE (int /*long*/ wParam, int /*long*/ lParam) {
	int /*long*/ code = callWindowProc (handle, OS.WM_SIZE, wParam, lParam);
	super.WM_SIZE (wParam, lParam);
	// widget may be disposed at this point
	if (code == 0) return LRESULT.ZERO;
	return new LRESULT (code);
}

LRESULT WM_VSCROLL (int /*long*/ wParam, int /*long*/ lParam) {
	LRESULT result = super.WM_VSCROLL (wParam, lParam);
	if (result != null) return result;
	/*
	* Bug on WinCE.  lParam should be NULL when the message is not sent
	* by a scroll bar control, but it contains the handle to the window.
	* When the message is sent by a scroll bar control, it correctly
	* contains the handle to the scroll bar.  The fix is to check for
	* both.
	*/
	if (verticalBar != null && (lParam == 0 || lParam == handle)) {
		return wmScroll (verticalBar, (state & CANVAS) != 0, handle, OS.WM_VSCROLL, wParam, lParam);
	}
	return result;
}

LRESULT wmNCPaint (int /*long*/ hwnd, int /*long*/ wParam, int /*long*/ lParam) {
	LRESULT result = super.wmNCPaint (hwnd, wParam, lParam);
	if (result != null) return result;
	/*
	* Bug in Windows.  On XP only (not Vista), Windows sometimes
	* does not redraw the bottom right corner of a window that
	* has scroll bars, causing pixel corruption.  The fix is to
	* always draw the corner.
	*/
	if (OS.COMCTL32_MAJOR >= 6 && OS.IsAppThemed ()) {
		if (!OS.IsWinCE && OS.WIN32_VERSION < OS.VERSION (6, 0)) {
			int bits1 = OS.GetWindowLong (hwnd, OS.GWL_STYLE);
			if ((bits1 & (OS.WS_HSCROLL | OS.WS_VSCROLL)) != 0) {
				RECT windowRect = new RECT ();
				OS.GetWindowRect (hwnd, windowRect);
				RECT trimRect = new RECT ();
				int bits2 = OS.GetWindowLong (hwnd, OS.GWL_EXSTYLE);
				OS.AdjustWindowRectEx (trimRect, bits1, false, bits2);
				boolean hVisible = false, vVisible = false;
				SCROLLBARINFO psbi = new SCROLLBARINFO ();
				psbi.cbSize = SCROLLBARINFO.sizeof;
				if (OS.GetScrollBarInfo (hwnd, OS.OBJID_HSCROLL, psbi)) {
					hVisible = (psbi.rgstate [0] & OS.STATE_SYSTEM_INVISIBLE) == 0;
				}
				if (OS.GetScrollBarInfo (hwnd, OS.OBJID_VSCROLL, psbi)) {
					vVisible = (psbi.rgstate [0] & OS.STATE_SYSTEM_INVISIBLE) == 0;
				}
				RECT cornerRect = new RECT ();
				cornerRect.bottom = windowRect.bottom - windowRect.top - trimRect.bottom;
				cornerRect.top = cornerRect.bottom - (vVisible ? OS.GetSystemMetrics (OS.SM_CYHSCROLL) : 0);
				if ((bits2 & OS.WS_EX_LEFTSCROLLBAR) != 0) {
					cornerRect.left = trimRect.left;
					cornerRect.right = cornerRect.left + (hVisible ? OS.GetSystemMetrics (OS.SM_CXVSCROLL) : 0);
				} else {
					cornerRect.right = windowRect.right - windowRect.left - trimRect.right;
					cornerRect.left = cornerRect.right - (hVisible ? OS.GetSystemMetrics (OS.SM_CXVSCROLL) : 0);
				}
				if (cornerRect.left != cornerRect.right && cornerRect.top != cornerRect.bottom) {
					int /*long*/ hDC = OS.GetWindowDC (hwnd);
					OS.FillRect (hDC, cornerRect, OS.COLOR_BTNFACE + 1);
					Decorations shell = menuShell ();
					if ((shell.style & SWT.RESIZE) != 0) {
						int /*long*/ hwndScroll = shell.scrolledHandle ();
						boolean drawGripper = hwnd == hwndScroll;
						if (!drawGripper) {
							RECT shellRect = new RECT ();
							OS.GetClientRect (hwndScroll, shellRect);
							OS.MapWindowPoints (hwndScroll, 0, shellRect, 2);
							drawGripper = shellRect.right == windowRect.right && shellRect.bottom == windowRect.bottom;
						}
						if (drawGripper) {
							OS.DrawThemeBackground (display.hScrollBarTheme(), hDC, OS.SBP_SIZEBOX, 0, cornerRect, null);
						}
					}
					OS.ReleaseDC (hwnd, hDC);
				}
			}
		}
	}
	return result;
}

LRESULT wmScrollWheel (boolean update, int /*long*/ wParam, int /*long*/ lParam) {
	int scrollRemainder = display.scrollRemainder;
	LRESULT result = super.WM_MOUSEWHEEL (wParam, lParam);
	if (result != null) return result;
	/*
	* Translate WM_MOUSEWHEEL to WM_VSCROLL or WM_HSCROLL.
	*/
	if (update) {
		if ((wParam & (OS.MK_SHIFT | OS.MK_CONTROL)) != 0) return result;
		boolean vertical = verticalBar != null && verticalBar.getEnabled ();
		boolean horizontal = horizontalBar != null && horizontalBar.getEnabled ();
		int msg = vertical ? OS.WM_VSCROLL : horizontal ? OS.WM_HSCROLL : 0;
		if (msg == 0) return result;
		int [] linesToScroll = new int [1];
		OS.SystemParametersInfo (OS.SPI_GETWHEELSCROLLLINES, 0, linesToScroll, 0);
		int delta = OS.GET_WHEEL_DELTA_WPARAM (wParam);
		boolean pageScroll = linesToScroll [0] == OS.WHEEL_PAGESCROLL;
		if (!OS.IsWinCE && OS.WIN32_VERSION >= OS.VERSION (5, 1)) {
			ScrollBar bar = vertical ? verticalBar : horizontalBar;
			SCROLLINFO info = new SCROLLINFO ();
			info.cbSize = SCROLLINFO.sizeof;
			info.fMask = OS.SIF_POS;
			OS.GetScrollInfo (handle, bar.scrollBarType (), info);
			if (vertical && !pageScroll) delta *= linesToScroll [0];
			int increment = pageScroll ? bar.getPageIncrement () : bar.getIncrement ();
			info.nPos -=  increment * delta / OS.WHEEL_DELTA;
			OS.SetScrollInfo (handle, bar.scrollBarType (), info, true);
			OS.SendMessage (handle, msg, OS.SB_THUMBPOSITION, 0);
		} else {
			int code = 0;
	  		if (pageScroll) {
	   			code = delta < 0 ? OS.SB_PAGEDOWN : OS.SB_PAGEUP;
	  		} else {
	  			code = delta < 0 ? OS.SB_LINEDOWN : OS.SB_LINEUP;
	  			if (msg == OS.WM_VSCROLL) delta *= linesToScroll [0];
	  		}
	  		/* Check if the delta and the remainder have the same direction (sign) */
	  		if ((delta ^ scrollRemainder) >= 0) delta += scrollRemainder;
			int count = Math.abs (delta) / OS.WHEEL_DELTA;
			for (int i=0; i




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