TextEditor: Animate navigation within file

Change-Id: I490d70a785c947cd41809503e15a317152126641
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

8 files changed, 89 insertions, 13 deletions

diff --git a/src/plugins/cppeditor/cppoutline.cpp b/src/plugins/cppeditor/cppoutline.cpp
index 3b1209c1c8..def7d11a6e 100644
--- a/src/plugins/cppeditor/cppoutline.cpp
+++ b/src/plugins/cppeditor/cppoutline.cpp
@@ -173,7 +173,7 @@ void CppOutlineWidget::updateTextCursor(const QModelIndex &proxyIndex)
         Core::EditorManager::addCurrentPositionToNavigationHistory();
 
         // line has to be 1 based, column 0 based!
-        m_editor->gotoLine(symbol->line(), symbol->column() - 1);
+        m_editor->gotoLine(symbol->line(), symbol->column() - 1, true, true);
         m_blockCursorSync = false;
     }
 }
diff --git a/src/plugins/cpptools/cppeditoroutline.cpp b/src/plugins/cpptools/cppeditoroutline.cpp
index a5192f4441..8bd16ac98b 100644
--- a/src/plugins/cpptools/cppeditoroutline.cpp
+++ b/src/plugins/cpptools/cppeditoroutline.cpp
@@ -252,7 +252,7 @@ void CppEditorOutline::gotoSymbolInEditor()
 
     Core::EditorManager::cutForwardNavigationHistory();
     Core::EditorManager::addCurrentPositionToNavigationHistory();
-    m_editorWidget->gotoLine(link.targetLine, link.targetColumn);
+    m_editorWidget->gotoLine(link.targetLine, link.targetColumn, true, true);
     m_editorWidget->activateEditor();
 }
 
diff --git a/src/plugins/texteditor/displaysettings.cpp b/src/plugins/texteditor/displaysettings.cpp
index a2a06eff78..d15cf52dca 100644
--- a/src/plugins/texteditor/displaysettings.cpp
+++ b/src/plugins/texteditor/displaysettings.cpp
@@ -42,6 +42,8 @@ static const char centerCursorOnScrollKey[] = "CenterCursorOnScroll";
 static const char openLinksInNextSplitKey[] = "OpenLinksInNextSplitKey";
 static const char displayFileEncodingKey[] = "DisplayFileEncoding";
 static const char scrollBarHighlightsKey[] = "ScrollBarHighlights";
+static const char animateNavigationWithinFileKey[] = "AnimateNavigationWithinFile";
+static const char animateWithinFileTimeMaxKey[] = "AnimateWithinFileTimeMax";
 static const char groupPostfix[] = "DisplaySettings";
 
 namespace TextEditor {
@@ -66,6 +68,7 @@ void DisplaySettings::toSettings(const QString &category, QSettings *s) const
     s->setValue(QLatin1String(openLinksInNextSplitKey), m_openLinksInNextSplit);
     s->setValue(QLatin1String(displayFileEncodingKey), m_displayFileEncoding);
     s->setValue(QLatin1String(scrollBarHighlightsKey), m_scrollBarHighlights);
+    s->setValue(QLatin1String(animateNavigationWithinFileKey), m_animateNavigationWithinFile);
     s->endGroup();
 }
 
@@ -92,6 +95,8 @@ void DisplaySettings::fromSettings(const QString &category, const QSettings *s)
     m_openLinksInNextSplit = s->value(group + QLatin1String(openLinksInNextSplitKey), m_openLinksInNextSplit).toBool();
     m_displayFileEncoding = s->value(group + QLatin1String(displayFileEncodingKey), m_displayFileEncoding).toBool();
     m_scrollBarHighlights = s->value(group + QLatin1String(scrollBarHighlightsKey), m_scrollBarHighlights).toBool();
+    m_animateNavigationWithinFile = s->value(group + QLatin1String(animateNavigationWithinFileKey), m_animateNavigationWithinFile).toBool();
+    m_animateWithinFileTimeMax = s->value(group + QLatin1String(animateWithinFileTimeMaxKey), m_animateWithinFileTimeMax).toInt();
 }
 
 bool DisplaySettings::equals(const DisplaySettings &ds) const
@@ -111,6 +116,8 @@ bool DisplaySettings::equals(const DisplaySettings &ds) const
         && m_forceOpenLinksInNextSplit == ds.m_forceOpenLinksInNextSplit
         && m_displayFileEncoding == ds.m_displayFileEncoding
         && m_scrollBarHighlights == ds.m_scrollBarHighlights
+        && m_animateNavigationWithinFile == ds.m_animateNavigationWithinFile
+        && m_animateWithinFileTimeMax == ds.m_animateWithinFileTimeMax
         ;
 }
 
diff --git a/src/plugins/texteditor/displaysettings.h b/src/plugins/texteditor/displaysettings.h
index 08d2077768..fabebd96d8 100644
--- a/src/plugins/texteditor/displaysettings.h
+++ b/src/plugins/texteditor/displaysettings.h
@@ -56,6 +56,8 @@ public:
     bool m_forceOpenLinksInNextSplit = false;
     bool m_displayFileEncoding = false;
     bool m_scrollBarHighlights = true;
+    bool m_animateNavigationWithinFile = false;
+    int m_animateWithinFileTimeMax = 333; // read only setting
 
     bool equals(const DisplaySettings &ds) const;
 };
diff --git a/src/plugins/texteditor/displaysettingspage.cpp b/src/plugins/texteditor/displaysettingspage.cpp
index 946234c0ec..147fa97080 100644
--- a/src/plugins/texteditor/displaysettingspage.cpp
+++ b/src/plugins/texteditor/displaysettingspage.cpp
@@ -118,6 +118,7 @@ void DisplaySettingsPage::settingsFromUI(DisplaySettings &displaySettings,
     displaySettings.m_openLinksInNextSplit = d->m_page->openLinksInNextSplit->isChecked();
     displaySettings.m_displayFileEncoding = d->m_page->displayFileEncoding->isChecked();
     displaySettings.m_scrollBarHighlights = d->m_page->scrollBarHighlights->isChecked();
+    displaySettings.m_animateNavigationWithinFile = d->m_page->animateNavigationWithinFile->isChecked();
 }
 
 void DisplaySettingsPage::settingsToUI()
@@ -140,6 +141,7 @@ void DisplaySettingsPage::settingsToUI()
     d->m_page->openLinksInNextSplit->setChecked(displaySettings.m_openLinksInNextSplit);
     d->m_page->displayFileEncoding->setChecked(displaySettings.m_displayFileEncoding);
     d->m_page->scrollBarHighlights->setChecked(displaySettings.m_scrollBarHighlights);
+    d->m_page->animateNavigationWithinFile->setChecked(displaySettings.m_animateNavigationWithinFile);
 }
 
 const DisplaySettings &DisplaySettingsPage::displaySettings() const
diff --git a/src/plugins/texteditor/displaysettingspage.ui b/src/plugins/texteditor/displaysettingspage.ui
index ee8b15cfdf..b91965a192 100644
--- a/src/plugins/texteditor/displaysettingspage.ui
+++ b/src/plugins/texteditor/displaysettingspage.ui
@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>501</width>
-    <height>331</height>
+    <height>339</height>
    </rect>
   </property>
   <layout class="QGridLayout" name="gridLayout_3">
@@ -174,6 +174,13 @@
         </property>
        </widget>
       </item>
+      <item row="7" column="1">
+       <widget class="QCheckBox" name="animateNavigationWithinFile">
+        <property name="text">
+         <string>Animate navigation within file</string>
+        </property>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>
diff --git a/src/plugins/texteditor/texteditor.cpp b/src/plugins/texteditor/texteditor.cpp
index 2eed90f3c7..86d74f28ad 100644
--- a/src/plugins/texteditor/texteditor.cpp
+++ b/src/plugins/texteditor/texteditor.cpp
@@ -99,7 +99,9 @@
 #include <QPainter>
 #include <QPrintDialog>
 #include <QPrinter>
+#include <QPropertyAnimation>
 #include <QDrag>
+#include <QSequentialAnimationGroup>
 #include <QScrollBar>
 #include <QShortcut>
 #include <QStyle>
@@ -457,6 +459,8 @@ public:
     bool m_assistRelevantContentAdded = false;
     QList<BaseHoverHandler *> m_hoverHandlers; // Not owned
 
+    QPointer<QSequentialAnimationGroup> m_navigationAnimation;
+
     QPointer<TextEditorAnimator> m_bracketsAnimator;
 
     // Animation and highlighting of auto completed text
@@ -2515,7 +2519,7 @@ void TextEditorWidget::doSetTextCursor(const QTextCursor &cursor)
     doSetTextCursor(cursor, false);
 }
 
-void TextEditorWidget::gotoLine(int line, int column, bool centerLine)
+void TextEditorWidget::gotoLine(int line, int column, bool centerLine, bool animate)
 {
     d->m_lastCursorChangeWasInteresting = false; // avoid adding the previous position to history
     const int blockNumber = qMin(line, document()->blockCount()) - 1;
@@ -2531,12 +2535,61 @@ void TextEditorWidget::gotoLine(int line, int column, bool centerLine)
             }
             cursor.setPosition(pos);
         }
-        setTextCursor(cursor);
 
-        if (centerLine)
-            centerCursor();
-        else
-            ensureCursorVisible();
+        const DisplaySettings &ds = d->m_displaySettings;
+        if (animate && ds.m_animateNavigationWithinFile) {
+            const QScrollBar *scrollBar = verticalScrollBar();
+            const int start = scrollBar->value();
+
+            setTextCursor(cursor);
+            ensureBlockIsUnfolded(block);
+
+            const int visibleLines = lastVisibleLine() - firstVisibleLine();
+
+            int end = 0;
+            auto it = document()->firstBlock();
+            while (it.isValid() && it != block) {
+                if (it.isVisible())
+                    ++end;
+                it = it.next();
+            }
+
+            if (centerLine)
+                end = qMin(scrollBar->maximum(), qMax(scrollBar->minimum(), end - visibleLines / 2));
+
+            const int delta = end - start;
+            // limit the number of steps for the animation otherwise you wont be able to tell
+            // the direction of the animantion for large delta values
+            const int steps = qMax(-ds.m_animateWithinFileTimeMax,
+                                   qMin(ds.m_animateWithinFileTimeMax, delta));
+            // limit the duration of the animation to at least 4 pictures on a 60Hz Monitor and
+            // at most to the number of absolute steps
+            const int durationMinimum = int (4 // number of pictures
+                                             * float(1) / 60 // on a 60 Hz Monitor
+                                             * 1000); // milliseconds
+            const int duration = qMax(durationMinimum, qAbs(steps));
+
+            d->m_navigationAnimation = new QSequentialAnimationGroup(this);
+            auto startAnimation = new QPropertyAnimation(verticalScrollBar(), "value");
+            startAnimation->setEasingCurve(QEasingCurve::InExpo);
+            startAnimation->setStartValue(start);
+            startAnimation->setEndValue(start + steps / 2);
+            startAnimation->setDuration(duration / 2);
+            d->m_navigationAnimation->addAnimation(startAnimation);
+            auto endAnimation = new QPropertyAnimation(verticalScrollBar(), "value");
+            endAnimation->setEasingCurve(QEasingCurve::OutExpo);
+            endAnimation->setStartValue(end - steps / 2);
+            endAnimation->setEndValue(end);
+            endAnimation->setDuration(duration / 2);
+            d->m_navigationAnimation->addAnimation(endAnimation);
+            d->m_navigationAnimation->start(QAbstractAnimation::DeleteWhenStopped);
+        } else {
+            setTextCursor(cursor);
+            if (centerLine)
+                centerCursor();
+            else
+                ensureCursorVisible();
+        }
     }
     d->saveCurrentCursorPositionForNavigation();
 }
@@ -5224,7 +5277,12 @@ void TextEditorWidget::extraAreaMouseEvent(QMouseEvent *e)
 
 void TextEditorWidget::ensureCursorVisible()
 {
-    QTextBlock block = textCursor().block();
+    ensureBlockIsUnfolded(textCursor().block());
+    QPlainTextEdit::ensureCursorVisible();
+}
+
+void TextEditorWidget::ensureBlockIsUnfolded(QTextBlock block)
+{
     if (!block.isVisible()) {
         TextDocumentLayout *documentLayout = qobject_cast<TextDocumentLayout*>(document()->documentLayout());
         QTC_ASSERT(documentLayout, return);
@@ -5246,7 +5304,6 @@ void TextEditorWidget::ensureCursorVisible()
         documentLayout->requestUpdate();
         documentLayout->emitDocumentSizeChanged();
     }
-    QPlainTextEdit::ensureCursorVisible();
 }
 
 void TextEditorWidgetPrivate::toggleBlockVisible(const QTextBlock &block)
@@ -5493,7 +5550,7 @@ bool TextEditorWidget::openLink(const Link &link, bool inNextSplit)
 
     if (!inNextSplit && textDocument()->filePath().toString() == link.targetFileName) {
         EditorManager::addCurrentPositionToNavigationHistory();
-        gotoLine(link.targetLine, link.targetColumn);
+        gotoLine(link.targetLine, link.targetColumn, true, true);
         setFocus();
         return true;
     }
diff --git a/src/plugins/texteditor/texteditor.h b/src/plugins/texteditor/texteditor.h
index 9b996dd61b..841324891c 100644
--- a/src/plugins/texteditor/texteditor.h
+++ b/src/plugins/texteditor/texteditor.h
@@ -183,7 +183,7 @@ public:
     // IEditor
     QByteArray saveState() const;
     bool restoreState(const QByteArray &state);
-    void gotoLine(int line, int column = 0, bool centerLine = true);
+    void gotoLine(int line, int column = 0, bool centerLine = true, bool animate = false);
     int position(TextPositionOperation posOp = CurrentPosition,
          int at = -1) const;
     void convertPosition(int pos, int *line, int *column) const;
@@ -297,6 +297,7 @@ public:
     const BehaviorSettings &behaviorSettings() const;
 
     void ensureCursorVisible();
+    void ensureBlockIsUnfolded(QTextBlock block);
 
     static Core::Id FakeVimSelection;
     static Core::Id SnippetPlaceholderSelection;