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.
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.
*
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;
}
}
}