Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2012 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.widgets; import org.eclipse.swt.*; import org.eclipse.swt.events.*; import org.eclipse.swt.graphics.*; import org.eclipse.swt.internal.win32.*; /** * Instances of the receiver represent a selectable user * interface object that present a range of continuous * numeric values. * <dl> * <dt><b>Styles:</b></dt> * <dd>HORIZONTAL, VERTICAL</dd> * <dt><b>Events:</b></dt> * <dd>Selection</dd> * </dl> * <p> * Note: Only one of the styles HORIZONTAL and VERTICAL may be specified. * </p> * <p> * IMPORTANT: This class is <em>not</em> intended to be subclassed. * </p> * * @see <a href="http://www.eclipse.org/swt/snippets/#scale">Scale snippets</a> * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ControlExample</a> * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> * @noextend This class is not intended to be subclassed by clients. */ public class Scale extends Control { boolean ignoreResize, ignoreSelection; static final long TrackBarProc; static final TCHAR TrackBarClass = new TCHAR(0, OS.TRACKBAR_CLASS, true); boolean createdAsRTL; static { WNDCLASS lpWndClass = new WNDCLASS(); OS.GetClassInfo(0, TrackBarClass, lpWndClass); TrackBarProc = lpWndClass.lpfnWndProc; /* * Feature in Windows. The track bar window class * does not include CS_DBLCLKS. This means that these * controls will not get double click messages such as * WM_LBUTTONDBLCLK. The fix is to register a new * window class with CS_DBLCLKS. * * NOTE: Screen readers look for the exact class name * of the control in order to provide the correct kind * of assistance. Therefore, it is critical that the * new window class have the same name. It is possible * to register a local window class with the same name * as a global class. Since bits that affect the class * are being changed, it is possible that other native * code, other than SWT, could create a control with * this class name, and fail unexpectedly. */ lpWndClass.hInstance = OS.GetModuleHandle(null); lpWndClass.style &= ~OS.CS_GLOBALCLASS; lpWndClass.style |= OS.CS_DBLCLKS; OS.RegisterClass(TrackBarClass, lpWndClass); } /** * Constructs a new instance of this class given its parent * and a style value describing its behavior and appearance. * <p> * The style value is either one of the style constants defined in * class <code>SWT</code> which is applicable to instances of this * class, or must be built by <em>bitwise OR</em>'ing together * (that is, using the <code>int</code> "|" operator) two or more * of those <code>SWT</code> style constants. The class description * lists the style constants that are applicable to the class. * Style bits are also inherited from superclasses. * </p> * * @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 <ul> * <li>ERROR_NULL_ARGUMENT - if the parent is null</li> * </ul> * @exception SWTException <ul> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li> * <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li> * </ul> * * @see SWT#HORIZONTAL * @see SWT#VERTICAL * @see Widget#checkSubclass * @see Widget#getStyle */ public Scale(Composite parent, int style) { super(parent, checkStyle(style)); } /** * Adds the listener to the collection of listeners who will * be notified when the user changes the receiver's value, by sending * it one of the messages defined in the <code>SelectionListener</code> * interface. * <p> * <code>widgetSelected</code> is called when the user changes the receiver's value. * <code>widgetDefaultSelected</code> is not called. * </p> * * @param listener the listener which should be notified * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the listener is null</li> * </ul> * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> * * @see SelectionListener * @see #removeSelectionListener */ public void addSelectionListener(SelectionListener listener) { checkWidget(); if (listener == null) error(SWT.ERROR_NULL_ARGUMENT); TypedListener typedListener = new TypedListener(listener); addListener(SWT.Selection, typedListener); addListener(SWT.DefaultSelection, typedListener); } @Override long callWindowProc(long hwnd, int msg, long wParam, long lParam) { if (handle == 0) return 0; return OS.CallWindowProc(TrackBarProc, hwnd, msg, wParam, lParam); } static int checkStyle(int style) { return checkBits(style, SWT.HORIZONTAL, SWT.VERTICAL, 0, 0, 0, 0); } @Override Point computeSizeInPixels(int wHint, int hHint, boolean changed) { checkWidget(); int border = getBorderWidthInPixels(); int width = border * 2, height = border * 2; RECT rect = new RECT(); OS.SendMessage(handle, OS.TBM_GETTHUMBRECT, 0, rect); if ((style & SWT.HORIZONTAL) != 0) { width += OS.GetSystemMetrics(OS.SM_CXHSCROLL) * 10; int scrollY = OS.GetSystemMetrics(OS.SM_CYHSCROLL); height += (rect.top * 2) + scrollY + (scrollY / 3); } else { int scrollX = OS.GetSystemMetrics(OS.SM_CXVSCROLL); width += (rect.left * 2) + scrollX + (scrollX / 3); height += OS.GetSystemMetrics(OS.SM_CYVSCROLL) * 10; } if (wHint != SWT.DEFAULT) width = wHint + (border * 2); if (hHint != SWT.DEFAULT) height = hHint + (border * 2); return new Point(width, height); } @Override void createHandle() { super.createHandle(); state |= THEME_BACKGROUND | DRAW_BACKGROUND; OS.SendMessage(handle, OS.TBM_SETRANGEMAX, 0, 100); OS.SendMessage(handle, OS.TBM_SETPAGESIZE, 0, 10); OS.SendMessage(handle, OS.TBM_SETTICFREQ, 10, 0); createdAsRTL = (style & SWT.RIGHT_TO_LEFT) != 0; } @Override int defaultForeground() { return OS.GetSysColor(OS.COLOR_BTNFACE); } /** * Returns the amount that the receiver's value will be * modified by when the up/down (or right/left) arrows * are pressed. * * @return the increment * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public int getIncrement() { checkWidget(); return (int) OS.SendMessage(handle, OS.TBM_GETLINESIZE, 0, 0); } /** * Returns the maximum value which the receiver will allow. * * @return the maximum * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public int getMaximum() { checkWidget(); return (int) OS.SendMessage(handle, OS.TBM_GETRANGEMAX, 0, 0); } /** * Returns the minimum value which the receiver will allow. * * @return the minimum * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public int getMinimum() { checkWidget(); return (int) OS.SendMessage(handle, OS.TBM_GETRANGEMIN, 0, 0); } /** * Returns the amount that the receiver's value will be * modified by when the page increment/decrement areas * are selected. * * @return the page increment * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public int getPageIncrement() { checkWidget(); return (int) OS.SendMessage(handle, OS.TBM_GETPAGESIZE, 0, 0); } /** * Returns the 'selection', which is the receiver's position. * * @return the selection * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public int getSelection() { checkWidget(); return (int) OS.SendMessage(handle, OS.TBM_GETPOS, 0, 0); } /** * Removes the listener from the collection of listeners who will * be notified when the user changes the receiver's value. * * @param listener the listener which should no longer be notified * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the listener is null</li> * </ul> * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> * * @see SelectionListener * @see #addSelectionListener */ public void removeSelectionListener(SelectionListener listener) { checkWidget(); if (listener == null) error(SWT.ERROR_NULL_ARGUMENT); if (eventTable == null) return; eventTable.unhook(SWT.Selection, listener); eventTable.unhook(SWT.DefaultSelection, listener); } @Override void setBackgroundImage(long hImage) { super.setBackgroundImage(hImage); /* * Bug in Windows. Changing the background color of the Scale * widget and calling InvalidateRect() still draws with the old * color. The fix is to send a fake WM_SIZE event to cause * it to redraw with the new background color. */ ignoreResize = true; OS.SendMessage(handle, OS.WM_SIZE, 0, 0); ignoreResize = false; } @Override void setBackgroundPixel(int pixel) { super.setBackgroundPixel(pixel); /* * Bug in Windows. Changing the background color of the Scale * widget and calling InvalidateRect() still draws with the old * color. The fix is to send a fake WM_SIZE event to cause * it to redraw with the new background color. */ ignoreResize = true; OS.SendMessage(handle, OS.WM_SIZE, 0, 0); ignoreResize = false; } @Override void setBoundsInPixels(int x, int y, int width, int height, int flags, boolean defer) { /* * Bug in Windows. If SetWindowPos() is called on a * track bar with either SWP_DRAWFRAME, a new size, * or both during mouse down, the track bar posts a * WM_MOUSEMOVE message when the mouse has not moved. * The window proc for the track bar uses WM_MOUSEMOVE * to issue WM_HSCROLL or WM_SCROLL events to notify * the application that the slider has changed. The * end result is that when the user requests a page * scroll and the application resizes the track bar * during the change notification, continuous stream * of WM_MOUSEMOVE messages are generated and the * thumb moves to the mouse position rather than * scrolling by a page. The fix is to clear the * SWP_DRAWFRAME flag. * * NOTE: There is no fix for the WM_MOUSEMOVE that * is generated by a new size. Clearing SWP_DRAWFRAME * does not fix the problem. However, it is unlikely * that the programmer will resize the control during * mouse down. */ flags &= ~OS.SWP_DRAWFRAME; super.setBoundsInPixels(x, y, width, height, flags, true); } /** * Sets the amount that the receiver's value will be * modified by when the up/down (or right/left) arrows * are pressed to the argument, which must be at least * one. * * @param increment the new increment (must be greater than zero) * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public void setIncrement(int increment) { checkWidget(); if (increment < 1) return; int minimum = (int) OS.SendMessage(handle, OS.TBM_GETRANGEMIN, 0, 0); int maximum = (int) OS.SendMessage(handle, OS.TBM_GETRANGEMAX, 0, 0); if (increment > maximum - minimum) return; OS.SendMessage(handle, OS.TBM_SETLINESIZE, 0, increment); } /** * Sets the maximum value that the receiver will allow. This new * value will be ignored if it is not greater than the receiver's current * minimum value. If the new maximum is applied then the receiver's * selection value will be adjusted if necessary to fall within its new range. * * @param value the new maximum, which must be greater than the current minimum * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public void setMaximum(int value) { checkWidget(); int minimum = (int) OS.SendMessage(handle, OS.TBM_GETRANGEMIN, 0, 0); if (0 <= minimum && minimum < value) { OS.SendMessage(handle, OS.TBM_SETRANGEMAX, 1, value); } } /** * Sets the minimum value that the receiver will allow. This new * value will be ignored if it is negative or is not less than the receiver's * current maximum value. If the new minimum is applied then the receiver's * selection value will be adjusted if necessary to fall within its new range. * * @param value the new minimum, which must be nonnegative and less than the current maximum * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public void setMinimum(int value) { checkWidget(); int maximum = (int) OS.SendMessage(handle, OS.TBM_GETRANGEMAX, 0, 0); if (0 <= value && value < maximum) { OS.SendMessage(handle, OS.TBM_SETRANGEMIN, 1, value); } } /** * Sets the amount that the receiver's value will be * modified by when the page increment/decrement areas * are selected to the argument, which must be at least * one. * * @param pageIncrement the page increment (must be greater than zero) * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public void setPageIncrement(int pageIncrement) { checkWidget(); if (pageIncrement < 1) return; int minimum = (int) OS.SendMessage(handle, OS.TBM_GETRANGEMIN, 0, 0); int maximum = (int) OS.SendMessage(handle, OS.TBM_GETRANGEMAX, 0, 0); if (pageIncrement > maximum - minimum) return; OS.SendMessage(handle, OS.TBM_SETPAGESIZE, 0, pageIncrement); OS.SendMessage(handle, OS.TBM_SETTICFREQ, pageIncrement, 0); } /** * Sets the 'selection', which is the receiver's value, * to the argument which must be greater than or equal to zero. * * @param value the new selection (must be zero or greater) * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public void setSelection(int value) { checkWidget(); OS.SendMessage(handle, OS.TBM_SETPOS, 1, value); } @Override int widgetStyle() { int bits = super.widgetStyle() | OS.WS_TABSTOP | OS.TBS_BOTH | OS.TBS_AUTOTICKS; if ((style & SWT.HORIZONTAL) != 0) return bits | OS.TBS_HORZ | OS.TBS_DOWNISLEFT; return bits | OS.TBS_VERT; } @Override TCHAR windowClass() { return TrackBarClass; } @Override long windowProc() { return TrackBarProc; } @Override LRESULT WM_KEYDOWN(long wParam, long lParam) { LRESULT result = super.WM_KEYDOWN(wParam, lParam); if (result != null) return result; switch ((int) wParam) { case OS.VK_LEFT: case OS.VK_RIGHT: /* * Bug in Windows. The behavior for the left and right keys is not * changed if the orientation changes after the control was created. * The fix is to replace VK_LEFT by VK_RIGHT and VK_RIGHT by VK_LEFT * when the current orientation differs from the orientation used to * create the control. */ boolean isRTL = (style & SWT.RIGHT_TO_LEFT) != 0; if (isRTL != createdAsRTL) { long code = callWindowProc(handle, OS.WM_KEYDOWN, wParam == OS.VK_RIGHT ? OS.VK_LEFT : OS.VK_RIGHT, lParam); return new LRESULT(code); } break; } return result; } @Override LRESULT WM_MOUSEWHEEL(long wParam, long lParam) { LRESULT result = super.WM_MOUSEWHEEL(wParam, lParam); if (result != null) return result; /* * Bug in Windows. When a track bar slider is changed * from WM_MOUSEWHEEL, it does not always send either * a WM_VSCROLL or M_HSCROLL to notify the application * of the change. The fix is to detect that the selection * has changed and that notification has not been issued * and send the selection event. */ int oldPosition = (int) OS.SendMessage(handle, OS.TBM_GETPOS, 0, 0); ignoreSelection = true; long code = callWindowProc(handle, OS.WM_MOUSEWHEEL, wParam, lParam); ignoreSelection = false; int newPosition = (int) OS.SendMessage(handle, OS.TBM_GETPOS, 0, 0); if (oldPosition != newPosition) { /* * Send the event because WM_HSCROLL and WM_VSCROLL * are sent from a modal message loop in windows that * is active when the user is scrolling. */ sendSelectionEvent(SWT.Selection, null, true); // widget could be disposed at this point } return new LRESULT(code); } @Override LRESULT WM_PAINT(long wParam, long lParam) { if ((state & DISPOSE_SENT) != 0) return LRESULT.ZERO; /* * Bug in Windows. For some reason, when WM_CTLCOLORSTATIC * is used to implement transparency and returns a NULL brush, * Windows doesn't always draw the track bar. It seems that * it is drawn correctly the first time. It is possible that * Windows double buffers the control and the double buffer * strategy fails when WM_CTLCOLORSTATIC returns unexpected * results. The fix is to send a fake WM_SIZE to force it * to redraw every time there is a WM_PAINT. */ boolean fixPaint = findBackgroundControl() != null; if (!fixPaint) { if (OS.IsAppThemed()) { Control control = findThemeControl(); fixPaint = control != null; } } if (fixPaint) { boolean redraw = getDrawing() && OS.IsWindowVisible(handle); if (redraw) OS.SendMessage(handle, OS.WM_SETREDRAW, 0, 0); ignoreResize = true; OS.SendMessage(handle, OS.WM_SIZE, 0, 0); ignoreResize = false; if (redraw) { OS.SendMessage(handle, OS.WM_SETREDRAW, 1, 0); OS.InvalidateRect(handle, null, false); } } return super.WM_PAINT(wParam, lParam); } @Override LRESULT WM_SIZE(long wParam, long lParam) { if (ignoreResize) return null; return super.WM_SIZE(wParam, lParam); } @Override LRESULT wmScrollChild(long wParam, long lParam) { /* Do nothing when scrolling is ending */ int code = OS.LOWORD(wParam); switch (code) { case OS.TB_ENDTRACK: case OS.TB_THUMBPOSITION: return null; } if (!ignoreSelection) { Event event = new Event(); /* * This code is intentionally commented. The event * detail field is not currently supported on all * platforms. */ // switch (code) { // case OS.TB_TOP: event.detail = SWT.HOME; break; // case OS.TB_BOTTOM: event.detail = SWT.END; break; // case OS.TB_LINEDOWN: event.detail = SWT.ARROW_DOWN; break; // case OS.TB_LINEUP: event.detail = SWT.ARROW_UP; break; // case OS.TB_PAGEDOWN: event.detail = SWT.PAGE_DOWN; break; // case OS.TB_PAGEUP: event.detail = SWT.PAGE_UP; break; // } /* * Send the event because WM_HSCROLL and WM_VSCROLL * are sent from a modal message loop in windows that * is active when the user is scrolling. */ sendSelectionEvent(SWT.Selection, event, true); // widget could be disposed at this point } return null; } }