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fix: reduce LSPTextHover resize flicker #1449

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fix: reduce LSPTextHover resize flicker #1449

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b6d0459
fix: reduce LSPTextHover resize flicker
sebthom Dec 3, 2025
94e637f
fix: harden FocusableBrowserInformationControl.updateBrowserSize
sebthom Dec 3, 2025
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71 changes: 48 additions & 23 deletions ...ipse.lsp4e/src/org/eclipse/lsp4e/operations/hover/FocusableBrowserInformationControl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -94,57 +94,79 @@ protected void createContent(Composite parent) {
}

private void updateBrowserSize(final Browser browser) {
updateBrowserSize(browser, 1);
}

private void updateBrowserSize(final Browser browser, final int attempt) {
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@rubenporras rubenporras Dec 15, 2025

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@sebthom , can you rebase your PR? Now that I think I have solved the problem with safeEvaluate returning exceptions, I think you can go back to your original attempt which was much simpler.

if (attempt > 100) // ~1s total
return;

if (getShell().isDisposed() || browser.isDisposed() || getInput() == null)
return;

@Nullable
Point constraints = getSizeConstraints();
Point hint = computeSizeHint();
final @Nullable Point constraints = getSizeConstraints();
final Point hint = computeSizeHint();
setSize(hint.x, hint.y);

if (!"complete".equals(safeEvaluate(browser, "return document.readyState"))) { //$NON-NLS-1$ //$NON-NLS-2$
UI.getDisplay().timerExec(200, () -> updateBrowserSize(browser));
final var docReadyState = safeEvaluate(browser, "return document.readyState"); //$NON-NLS-1$
if (!"complete".equals(docReadyState)) { //$NON-NLS-1$
retryUpdateBrowserSize(browser, attempt);
return;
}

safeExecute(browser, "document.getElementsByTagName('html')[0].style.whiteSpace = 'nowrap'"); //$NON-NLS-1$
final Object widthObj = safeEvaluate(browser, "var b = document.body; return b && b.scrollWidth"); //$NON-NLS-1$
if (!(widthObj instanceof final Number widthValue)) {
retryUpdateBrowserSize(browser, attempt);
return;
}
double width = 20 + widthValue.doubleValue();
setSize((int) width, hint.y);

safeExecute(browser, "document.getElementsByTagName('html')[0].style.whiteSpace = 'normal'"); //$NON-NLS-1$
final Object heightObj = safeEvaluate(browser, "var b = document.body; return b && b.scrollHeight"); //$NON-NLS-1$
if (!(heightObj instanceof final Number heightValue)) {
retryUpdateBrowserSize(browser, attempt);
return;
}

safeExecute(browser, "document.getElementsByTagName(\"html\")[0].style.whiteSpace = \"nowrap\""); //$NON-NLS-1$
Double width = 20
+ (safeEvaluate(browser, "return document.body.scrollWidth;") instanceof Double evaluated ? evaluated //$NON-NLS-1$
: 0);
setSize(width.intValue(), hint.y);

safeExecute(browser, "document.getElementsByTagName(\"html\")[0].style.whiteSpace = \"normal\""); //$NON-NLS-1$
Double height = safeEvaluate(browser, "return document.body.scrollHeight;") instanceof Double evaluated //$NON-NLS-1$
? evaluated
: 0d;
Object marginTop = safeEvaluate(browser, "return window.getComputedStyle(document.body).marginTop;"); //$NON-NLS-1$
Object marginBottom = safeEvaluate(browser, "return window.getComputedStyle(document.body).marginBottom;"); //$NON-NLS-1$
double height = heightValue.doubleValue();
if (Platform.getPreferencesService().getBoolean(EditorsUI.PLUGIN_ID,
AbstractDecoratedTextEditorPreferenceConstants.EDITOR_SHOW_TEXT_HOVER_AFFORDANCE, true, null)) {
FontData[] fontDatas = JFaceResources.getDialogFont().getFontData();
final FontData[] fontDatas = JFaceResources.getDialogFont().getFontData();
height += fontDatas[0].getHeight();
}

width = width * 1.5;
if (Util.isWin32()) {
Object marginTop = safeEvaluate(browser,
"var b = document.body; return b && window.getComputedStyle(b).marginTop"); //$NON-NLS-1$
Object marginBottom = safeEvaluate(browser,
"var b = document.body; return b && window.getComputedStyle(b).marginBottom"); //$NON-NLS-1$
height = adjust(height, marginTop);
height = adjust(height, marginBottom);
}
if (constraints != null && constraints.x < width) {
width = (double) constraints.x;
width = constraints.x;
}
if (constraints != null && constraints.y < height) {
height = (double) constraints.y;
height = constraints.y;
}

setSize(width.intValue(), height.intValue());
setSize((int) width, (int) height);
}

private void retryUpdateBrowserSize(final Browser browser, final int currentAttempt) {
UI.getDisplay().timerExec(10, () -> updateBrowserSize(browser, currentAttempt + 1));
}

private static @Nullable Object safeEvaluate(Browser browser, String expression) {
try {
return browser.evaluate(expression);
} catch (Exception ex) {
LanguageServerPlugin.logError(ex);
if (LanguageServerPlugin.DEBUG || LanguageServerPlugin.isLogTraceEnabled()) {
LanguageServerPlugin.logError("Failed to evaluate browser expression: " + expression, ex); //$NON-NLS-1$
}
}
return null;
}
Expand All @@ -153,7 +175,9 @@ private static boolean safeExecute(Browser browser, String expression) {
try {
return browser.execute(expression);
} catch (Exception ex) {
LanguageServerPlugin.logError(ex);
if (LanguageServerPlugin.DEBUG || LanguageServerPlugin.isLogTraceEnabled()) {
LanguageServerPlugin.logError("Failed to execute browser expression: " + expression, ex); //$NON-NLS-1$
}
}
return false;
}
Expand Down Expand Up @@ -191,6 +215,7 @@ public void setInput(@Nullable Object input) {
}));
return;
}
this.currentAsyncToken = null;
if (input instanceof String html) {
input = styleHtml(html);
}
Expand Down
38 changes: 27 additions & 11 deletions org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/hover/LSPTextHover.java
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,8 @@
@SuppressWarnings("restriction")
public class LSPTextHover implements ITextHover, ITextHoverExtension, ITextHoverExtension2 {

private static final int GET_LEGACY_HOVER_INFO_TIMEOUT_MS = 1000;
private static final int GET_ASYNC_HOVER_INFO_TIMEOUT_MS = 100;
private static final int GET_HOVER_REGION_TIMEOUT_MS = 100;

private @Nullable IRegion lastRegion;
Expand All @@ -74,17 +76,17 @@ public class LSPTextHover implements ITextHover, ITextHoverExtension, ITextHover
private @Nullable CompletableFuture<@Nullable String> hoverInfoFuture;

@Override
@Deprecated
public @Nullable String getHoverInfo(ITextViewer textViewer, IRegion hoverRegion) {
// Non-blocking: only return immediately available content.
final var hoverInfoRequest_ = this.hoverInfoFuture = getHoverInfoFuture(textViewer, hoverRegion);
if (hoverInfoRequest_.isDone()) {
try {
return hoverInfoRequest_.getNow(null);
} catch (final Exception ex) {
if (CancellationUtil.isRequestCancelledException(ex)) {
// Hover was cancelled; ignore as this is an expected fast-mouse-move scenario.
return null;
}

try {
return hoverInfoRequest_.get(GET_LEGACY_HOVER_INFO_TIMEOUT_MS, TimeUnit.MILLISECONDS);
} catch (InterruptedException ex) {
LanguageServerPlugin.logError(ex);
Thread.currentThread().interrupt();
} catch (ExecutionException | TimeoutException ex) {
if (!CancellationUtil.isRequestCancelledException(ex)) {
LanguageServerPlugin.logError(ex);
}
}
Expand All @@ -94,8 +96,22 @@ public class LSPTextHover implements ITextHover, ITextHoverExtension, ITextHover
@Override
public @Nullable Object getHoverInfo2(ITextViewer textViewer, IRegion hoverRegion) {
final var hoverInfoRequest_ = this.hoverInfoFuture = getHoverInfoFuture(textViewer, hoverRegion);
final String placeholder = "<html><body>Loading…</body></html>"; //$NON-NLS-1$
return new AsyncHtmlHoverInput(hoverInfoRequest_, placeholder);

try {
return hoverInfoRequest_.get(GET_ASYNC_HOVER_INFO_TIMEOUT_MS, TimeUnit.MILLISECONDS);
} catch (InterruptedException ex) {
LanguageServerPlugin.logError(ex);
Thread.currentThread().interrupt();
return null;
} catch (ExecutionException ex) {
if (!CancellationUtil.isRequestCancelledException(ex)) {
LanguageServerPlugin.logError(ex);
}
return null;
} catch (TimeoutException ex) {
final String placeholder = "<html><body>Loading…</body></html>"; //$NON-NLS-1$
return new AsyncHtmlHoverInput(hoverInfoRequest_, placeholder);
}
}

public CompletableFuture<@Nullable String> getHoverInfoFuture(ITextViewer textViewer, IRegion hoverRegion) {
Expand Down