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Improve logic for auto-enable/-disable of scroll lock in TextConsoleV…
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…iewer #669

Fixes #669
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@sagarrohat @jukzi
sagarrohat authored and jukzi committed Mar 8, 2024
1 parent 31e1ef4 commit 7782daa
Showing 1 changed file with 29 additions and 39 deletions.
68 changes: 29 additions & 39 deletions debug/org.eclipse.ui.console/src/org/eclipse/ui/console/TextConsoleViewer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
Expand Down Expand Up @@ -63,6 +62,7 @@
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.ScrollBar;
import org.eclipse.ui.internal.console.ConsoleDocumentAdapter;
import org.eclipse.ui.internal.console.ConsoleHyperlinkPosition;
import org.eclipse.ui.progress.WorkbenchJob;
Expand Down Expand Up @@ -124,10 +124,7 @@ public void documentChanged(DocumentEvent event) {
}
};

// to store to user scroll lock action
private final AtomicBoolean userHoldsScrollLock = new AtomicBoolean(false);

WorkbenchJob revealJob = new WorkbenchJob("Reveal End of Document") {//$NON-NLS-1$
WorkbenchJob revealJob = new WorkbenchJob("Reveal End of Document") { //$NON-NLS-1$
@Override
public IStatus runInUIThread(IProgressMonitor monitor) {
scrollToEndOfDocument();
Expand All @@ -147,51 +144,41 @@ private void scrollToEndOfDocument() {

// set the scroll Lock setting for Console Viewer and Console View
private void setScrollLock(boolean lock) {
userHoldsScrollLock.set(lock);
if (scrollLockStateProvider != null && scrollLockStateProvider.getAutoScrollLock() != lock) {
scrollLockStateProvider.setAutoScrollLock(lock);
}
}

/*
* Checks if at the end of document
* Checks if last visible line is same as line count, implying end of the
* document.
*/
private boolean checkEndOfDocument() {
private boolean isAtEndOfDocument() {
StyledText textWidget = getTextWidget();
if (textWidget != null && !textWidget.isDisposed()) {
int partialBottomIndex = JFaceTextUtil.getPartialBottomIndex(textWidget);
int lastVisibleLineIndex = JFaceTextUtil.getPartialBottomIndex(textWidget);
int lineCount = textWidget.getLineCount();
int delta = textWidget.getVerticalBar().getIncrement();
return lineCount - partialBottomIndex < delta;
return lineCount == lastVisibleLineIndex + 1;
}
return false;
}

/*
* Check if user preference is enabled for auto scroll lock and the document is empty or the line count is smaller than each
* vertical scroll
* Checks if user preference is enabled for auto scroll lock. and if the view is
* empty or the content is minimal, implying no need for scrolling.
*/
private boolean isAutoScrollLockNotApplicable() {
if (!consoleAutoScrollLock) {
return true;
}
StyledText textWidget = getTextWidget();
if (textWidget != null && !textWidget.isDisposed()) {
return (textWidget.getLineCount() <= textWidget.getVerticalBar().getIncrement());
}
return false;
}

/*
* Checks if at the start of document
*/
private boolean checkStartOfDocument() {
StyledText textWidget = getTextWidget();
if (textWidget != null && !textWidget.isDisposed()) {
int partialTopIndex = JFaceTextUtil.getPartialTopIndex(textWidget);
int lineCount = textWidget.getLineCount();
int delta = textWidget.getVerticalBar().getIncrement();
return lineCount - partialTopIndex < delta;
ScrollBar scrollBar = textWidget.getVerticalBar();
/**
* Value for pageIncrement is only set when lines exceed one page, otherwise it
* is 1
*/
return scrollBar.getPageIncrement() == 1;
}
return false;
}
Expand Down Expand Up @@ -253,30 +240,30 @@ public TextConsoleViewer(Composite parent, TextConsole console) {
styledText.addListener(SWT.MouseUp, mouseUpListener);
// event listener used to send event to vertical scroll bar
styledText.getVerticalBar().addSelectionListener(new SelectionAdapter() {

@Override
public void widgetSelected(SelectionEvent e) {
if (isAutoScrollLockNotApplicable()) {
return;
}
// scroll lock if vertical scroll bar dragged, OR selection on
// vertical bar used
if (e.detail == SWT.TOP || e.detail == SWT.HOME) {
if (e.detail == SWT.HOME || e.detail == SWT.TOP) {
// selecting TOP or HOME should lock
setScrollLock(true);
}
if (e.detail == SWT.ARROW_UP || e.detail == SWT.PAGE_UP) {
} else if (e.detail == SWT.PAGE_UP || e.detail == SWT.ARROW_UP) {
setScrollLock(true);
} else if (e.detail == SWT.END || e.detail == SWT.BOTTOM) {
// selecting BOTTOM or END from vertical scroll makes it
// reveal the end
setScrollLock(false);
} else if (e.detail == SWT.DRAG) {
if (checkEndOfDocument()) {
if (isAtEndOfDocument()) {
setScrollLock(false);
} else {
setScrollLock(true);
}
} else if ((e.detail == SWT.PAGE_DOWN || e.detail == SWT.ARROW_DOWN) && checkEndOfDocument()) {
} else if ((e.detail == SWT.PAGE_DOWN || e.detail == SWT.ARROW_DOWN) && isAtEndOfDocument()) {
// unlock if Down at the end of document
setScrollLock(false);
}
Expand All @@ -291,12 +278,12 @@ public void keyPressed(KeyEvent e) {
// lock the scroll if PAGE_UP ,HOME or TOP selected
if (e.keyCode == SWT.HOME || e.keyCode == SWT.TOP) {
setScrollLock(true);
} else if ((e.keyCode == SWT.PAGE_UP || e.keyCode == SWT.ARROW_UP) && !checkStartOfDocument()) {
} else if ((e.keyCode == SWT.PAGE_UP || e.keyCode == SWT.ARROW_UP)) {
setScrollLock(true);
} else if ((e.keyCode == SWT.END && (e.stateMask & SWT.CTRL) != 0) || e.keyCode == SWT.BOTTOM) {
// pressing CTRL+END reveals the end
setScrollLock(false);
} else if ((e.keyCode == SWT.PAGE_DOWN || e.keyCode == SWT.ARROW_DOWN) && checkEndOfDocument()) {
} else if ((e.keyCode == SWT.PAGE_DOWN || e.keyCode == SWT.ARROW_DOWN) && isAtEndOfDocument()) {
// unlock if Down at the end of document
setScrollLock(false);
}
Expand All @@ -306,11 +293,13 @@ public void keyPressed(KeyEvent e) {
if (isAutoScrollLockNotApplicable()) {
return;
}
if (e.count < 0) { // Mouse dragged down
if (checkEndOfDocument()) {
if (e.count < 0) { // Mouse scroll down
if (isAtEndOfDocument()) {
setScrollLock(false);
} else {
setScrollLock(true);
}
} else if (!userHoldsScrollLock.get()) {
} else if (e.count > 0) { // Mouse scroll up
setScrollLock(true);
}
});
Expand All @@ -331,6 +320,7 @@ public void keyPressed(KeyEvent e) {
document.addPositionUpdater(positionUpdater);
}


/**
* Sets the tab width used by this viewer.
*
Expand Down Expand Up @@ -854,4 +844,4 @@ protected void internalRevealRange(int start, int end) {
}


}
}

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