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/*******************************************************************************
 * Copyright (c) 2000, 2016 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.custom;

import org.eclipse.swt.*;
import org.eclipse.swt.dnd.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

/**
 * This adapter class provides a default drag under effect (eg. select and scroll)
 * when a drag occurs over a StyledText.
 *
 * 

Classes that wish to provide their own drag under effect for a StyledText * can extend this class, override the StyledTextDropTargetEffect.dragOver * method and override any other applicable methods in StyledTextDropTargetEffect to * display their own drag under effect.

* * Subclasses that override any methods of this class should call the corresponding * super method to get the default drag under effect implementation. * *

The feedback value is either one of the FEEDBACK constants defined in * class DND which is applicable to instances of this class, * or it must be built by bitwise OR'ing together * (that is, using the int "|" operator) two or more * of those DND effect constants. *

*
*
Feedback:
*
FEEDBACK_SELECT, FEEDBACK_SCROLL
*
* * @see DropTargetAdapter * @see DropTargetEvent * @see Sample code and further information * * @since 3.3 */ public class StyledTextDropTargetEffect extends DropTargetEffect { static final int CARET_WIDTH = 2; static final int SCROLL_HYSTERESIS = 100; // milli seconds static final int SCROLL_TOLERANCE = 20; // pixels int currentOffset = -1; long scrollBeginTime; int scrollX = -1, scrollY = -1; Listener paintListener; /** * Creates a new StyledTextDropTargetEffect to handle the drag under effect on the specified * StyledText. * * @param styledText the StyledText over which the user positions the cursor to drop the data */ public StyledTextDropTargetEffect(StyledText styledText) { super(styledText); paintListener = event -> { if (currentOffset != -1) { StyledText text = (StyledText) getControl(); Point position = text.getLocationAtOffset(currentOffset); int height = text.getLineHeight(currentOffset); event.gc.setBackground(event.display.getSystemColor (SWT.COLOR_BLACK)); event.gc.fillRectangle(position.x, position.y, CARET_WIDTH, height); } }; } /** * This implementation of dragEnter provides a default drag under effect * for the feedback specified in event.feedback. * * For additional information see DropTargetAdapter.dragEnter. * * Subclasses that override this method should call super.dragEnter(event) * to get the default drag under effect implementation. * * @param event the information associated with the drag start event * * @see DropTargetAdapter * @see DropTargetEvent */ @Override public void dragEnter(DropTargetEvent event) { currentOffset = -1; scrollBeginTime = 0; scrollX = -1; scrollY = -1; getControl().removeListener(SWT.Paint, paintListener); getControl().addListener (SWT.Paint, paintListener); } /** * This implementation of dragLeave provides a default drag under effect * for the feedback specified in event.feedback. * * For additional information see DropTargetAdapter.dragLeave. * * Subclasses that override this method should call super.dragLeave(event) * to get the default drag under effect implementation. * * @param event the information associated with the drag leave event * * @see DropTargetAdapter * @see DropTargetEvent */ @Override public void dragLeave(DropTargetEvent event) { StyledText text = (StyledText) getControl(); if (currentOffset != -1) { refreshCaret(text, currentOffset, -1); } text.removeListener(SWT.Paint, paintListener); scrollBeginTime = 0; scrollX = -1; scrollY = -1; } /** * This implementation of dragOver provides a default drag under effect * for the feedback specified in event.feedback. * * For additional information see DropTargetAdapter.dragOver. * * Subclasses that override this method should call super.dragOver(event) * to get the default drag under effect implementation. * * @param event the information associated with the drag over event * * @see DropTargetAdapter * @see DropTargetEvent * @see DND#FEEDBACK_SELECT * @see DND#FEEDBACK_SCROLL */ @Override public void dragOver(DropTargetEvent event) { int effect = event.feedback; StyledText text = (StyledText) getControl(); Point pt = text.getDisplay().map(null, text, event.x, event.y); if ((effect & DND.FEEDBACK_SCROLL) == 0) { scrollBeginTime = 0; scrollX = scrollY = -1; } else { if (text.getCharCount() == 0) { scrollBeginTime = 0; scrollX = scrollY = -1; } else { if (scrollX != -1 && scrollY != -1 && scrollBeginTime != 0 && (pt.x >= scrollX && pt.x <= (scrollX + SCROLL_TOLERANCE) || pt.y >= scrollY && pt.y <= (scrollY + SCROLL_TOLERANCE))) { if (System.currentTimeMillis() >= scrollBeginTime) { Rectangle area = text.getClientArea(); GC gc = new GC(text); FontMetrics fm = gc.getFontMetrics(); gc.dispose(); double charWidth = fm.getAverageCharacterWidth(); int scrollAmount = (int) (10*charWidth); if (pt.x < area.x + 3*charWidth) { int leftPixel = text.getHorizontalPixel(); text.setHorizontalPixel(leftPixel - scrollAmount); } if (pt.x > area.width - 3*charWidth) { int leftPixel = text.getHorizontalPixel(); text.setHorizontalPixel(leftPixel + scrollAmount); } int lineHeight = text.getLineHeight(); if (pt.y < area.y + lineHeight) { int topPixel = text.getTopPixel(); text.setTopPixel(topPixel - lineHeight); } if (pt.y > area.height - lineHeight) { int topPixel = text.getTopPixel(); text.setTopPixel(topPixel + lineHeight); } scrollBeginTime = 0; scrollX = scrollY = -1; } } else { scrollBeginTime = System.currentTimeMillis() + SCROLL_HYSTERESIS; scrollX = pt.x; scrollY = pt.y; } } } if ((effect & DND.FEEDBACK_SELECT) != 0) { int[] trailing = new int [1]; int newOffset = text.getOffsetAtPoint(pt.x, pt.y, trailing, false); newOffset += trailing [0]; if (newOffset != currentOffset) { refreshCaret(text, currentOffset, newOffset); currentOffset = newOffset; } } } void refreshCaret(StyledText text, int oldOffset, int newOffset) { if (oldOffset != newOffset) { if (oldOffset != -1) { Point oldPos = text.getLocationAtOffset(oldOffset); int oldHeight = text.getLineHeight(oldOffset); text.redraw (oldPos.x, oldPos.y, CARET_WIDTH, oldHeight, false); } if (newOffset != -1) { Point newPos = text.getLocationAtOffset(newOffset); int newHeight = text.getLineHeight(newOffset); text.redraw (newPos.x, newPos.y, CARET_WIDTH, newHeight, false); } } } /** * This implementation of dropAccept provides a default drag under effect * for the feedback specified in event.feedback. * * For additional information see DropTargetAdapter.dropAccept. * * Subclasses that override this method should call super.dropAccept(event) * to get the default drag under effect implementation. * * @param event the information associated with the drop accept event * * @see DropTargetAdapter * @see DropTargetEvent */ @Override public void dropAccept(DropTargetEvent event) { if (currentOffset != -1) { StyledText text = (StyledText) getControl(); text.setSelection(currentOffset); currentOffset = -1; } } }




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