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package org.eclipse.swt.widgets;
/*
* (c) Copyright IBM Corp. 2000, 2001.
* All Rights Reserved
*/
import org.eclipse.swt.internal.win32.*;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
/**
* Instances of this class provide a surface for drawing
* arbitrary graphics.
* <dl>
* <dt><b>Styles:</b></dt>
* <dd>(none)</dd>
* <dt><b>Events:</b></dt>
* <dd>(none)</dd>
* </dl>
* <p>
* This class may be subclassed by custom control implementors
* who are building controls that are <em>not</em> constructed
* from aggregates of other controls. That is, they are either
* painted using SWT graphics calls or are handled by native
* methods.
* </p>
*
* @see Composite
*/
public class Canvas extends Composite {
Caret caret;
/**
* Prevents uninitialized instances from being created outside the package.
*/
Canvas () {
}
/**
* 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
* for all SWT widget classes should include a comment which
* describes the style constants which are applicable to the class.
* </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
* @see Widget#checkSubclass
* @see Widget#getStyle
*/
public Canvas (Composite parent, int style) {
super (parent, style);
}
/*
* Not currently used.
*/
void clearArea (int x, int y, int width, int height) {
checkWidget ();
if (OS.IsWindowVisible (handle)) return;
RECT rect = new RECT ();
OS.SetRect (rect, x, y, x + width, y + height);
int hDC = OS.GetDCEx (handle, 0, OS.DCX_CACHE | OS.DCX_CLIPCHILDREN | OS.DCX_CLIPSIBLINGS);
drawBackground (hDC, rect);
OS.ReleaseDC (handle, hDC);
}
/**
* Returns the caret.
* <p>
* The caret for the control is automatically hidden
* and shown when the control is painted or resized,
* when focus is gained or lost and when an the control
* is scrolled. To avoid drawing on top of the caret,
* the programmer must hide and show the caret when
* drawing in the window any other time.
* </p>
*
* @return the caret
*
* @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 Caret getCaret () {
checkWidget ();
return caret;
}
void releaseWidget () {
if (caret != null) caret.releaseWidget ();
caret = null;
super.releaseWidget ();
}
/**
* Scrolls a rectangular area of the receiver by first copying
* the source area to the destination and then causing the area
* of the source which is not covered by the destination to
* be repainted. Children that intersect the rectangle are
* optionally moved during the operation. In addition, outstanding
* paint events are flushed before the source area is copied to
* ensure that the contents of the canvas are drawn correctly.
*
* @param destX the x coordinate of the destination
* @param destY the y coordinate of the destination
* @param x the x coordinate of the source
* @param y the y coordinate of the source
* @param width the width of the area
* @param height the height of the area
* @param all <code>true</code>if children should be scrolled, and <code>false</code> otherwise
*
* @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 scroll (int destX, int destY, int x, int y, int width, int height, boolean all) {
checkWidget ();
/* Remove the caret so it won't get scrolled */
boolean isFocus = caret != null && caret.isFocusCaret ();
if (isFocus) caret.killFocus ();
/* Flush outstanding WM_PAINT's and scroll the window */
OS.RedrawWindow (handle, null, 0, OS.RDW_UPDATENOW | OS.RDW_ALLCHILDREN);
RECT rect = new RECT ();
OS.SetRect (rect, x, y, x + width, y + height);
int deltaX = destX - x, deltaY = destY - y;
int flags = OS.SW_INVALIDATE | OS.SW_ERASE;
if (all) flags |= OS.SW_SCROLLCHILDREN;
OS.ScrollWindowEx (handle, deltaX, deltaY, rect, null, 0, null, flags);
/* Restore the caret */
if (isFocus) caret.setFocus ();
}
/**
* Sets the receiver's caret.
* <p>
* The caret for the control is automatically hidden
* and shown when the control is painted or resized,
* when focus is gained or lost and when an the control
* is scrolled. To avoid drawing on top of the caret,
* the programmer must hide and show the caret when
* drawing in the window any other time.
* </p>
* @param caret the new caret for the receiver
*
* @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 setCaret (Caret caret) {
checkWidget ();
Caret newCaret = caret;
Caret oldCaret = this.caret;
this.caret = newCaret;
if (isFocusControl ()) {
if (oldCaret != null) oldCaret.killFocus ();
if (newCaret != null) newCaret.setFocus ();
}
}
public void setFont (Font font) {
checkWidget ();
super.setFont (font);
if (caret != null) caret.setFont (font);
}
LRESULT WM_KILLFOCUS (int wParam, int lParam) {
LRESULT result = super.WM_KILLFOCUS (wParam, lParam);
if (result != null) return result;
if (caret != null) caret.killFocus ();
return result;
}
LRESULT WM_SETFOCUS (int wParam, int lParam) {
LRESULT result = super.WM_SETFOCUS (wParam, lParam);
if (result != null) return result;
if (caret != null) caret.setFocus ();
return result;
}
}
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