texteditor: add a hover handler which shows color preview tooltips

This adds a new hover handler which matches stand-alone color strings
like "#112233" or "Qt::yellow" or function argument tuples for colors
such as "QColor(0x11, 0x22, 0x33)". When matching against function
arguments, the function name must correspond to a recognized color
function (setRgb, etc. This is biased towards cpp text, but not limited
to such). The matching occurs when hovering over the arguments, not the
function.
If a match is identified, the hover handler gives it a relatively high
ranking.

Change-Id: Ied2927399cb19d6f562185a8b087f0ce118157db
Reviewed-by: David Schulz <david.schulz@theqtcompany.com>

src/plugins/texteditor/colorpreviewhoverhandler.cpp

+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://www.qt.io/licensing.  For further information
+** use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file.  Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+
+#include "colorpreviewhoverhandler.h"
+#include "texteditor.h"
+
+#include <coreplugin/icore.h>
+#include <utils/tooltip/tooltip.h>
+#include <utils/qtcassert.h>
+
+#include <QPoint>
+#include <QColor>
+#include <QTextBlock>
+
+using namespace Core;
+
+namespace TextEditor {
+
+/*
+ * Attempts to find a color string such as "#112233" from the word at
+ * the given position in the string. Also looks for "Qt::" for recognizing
+ * Qt::GlobalColor types (although there cannot be any spaces such as
+ * "Qt:: yellow")
+ */
+static QString extractColorString(const QString s, int pos)
+{
+    if (s.length() < 3 || pos < 0 || pos >= s.length())
+        return QString();
+
+    int firstPos = pos;
+    do {
+        QChar c = s[firstPos];
+        if (c == QLatin1Char('#'))
+            break;
+
+        if (c == QLatin1Char(':')
+                && (firstPos > 3)
+                && (s.mid(firstPos-3, 4) == QLatin1String("Qt::"))) {
+            firstPos -= 3;
+            break;
+        }
+
+        if (!c.isLetterOrNumber())
+            return QString();
+
+        --firstPos;
+    } while (firstPos >= 0);
+
+    if (firstPos < 0)
+        return QString();
+
+    int lastPos = firstPos + 1;
+    do {
+        QChar c = s[lastPos];
+        if (!(c.isLetterOrNumber() || c == QLatin1Char(':')))
+            break;
+        lastPos++;
+    } while (lastPos < s.length());
+
+    return s.mid(firstPos, lastPos - firstPos);
+}
+
+static QColor fromEnumString(const QString &s)
+{
+    const struct EnumColorMap {
+        QLatin1String name;
+        QColor color;
+    } table[] = {
+        {QLatin1String("white") , QColor(Qt::white)},
+        {QLatin1String("black"), QColor(Qt::black)},
+        {QLatin1String("red"), QColor(Qt::red)},
+        {QLatin1String("darkRed"), QColor(Qt::darkRed)},
+        {QLatin1String("green"), QColor(Qt::green)},
+        {QLatin1String("darkGreen"), QColor(Qt::darkGreen)},
+        {QLatin1String("blue"), QColor(Qt::blue)},
+        {QLatin1String("darkBlue"), QColor(Qt::darkBlue)},
+        {QLatin1String("cyan"), QColor(Qt::cyan)},
+        {QLatin1String("darkCyan"), QColor(Qt::darkCyan)},
+        {QLatin1String("magenta"), QColor(Qt::magenta)},
+        {QLatin1String("darkMagenta"), QColor(Qt::darkMagenta)},
+        {QLatin1String("yellow"), QColor(Qt::yellow)},
+        {QLatin1String("darkYellow"), QColor(Qt::darkYellow)},
+        {QLatin1String("gray"), QColor(Qt::gray)},
+        {QLatin1String("darkGray"), QColor(Qt::darkGray)},
+        {QLatin1String("lightGray"), QColor(Qt::lightGray)},
+        {QLatin1String("transparent"), QColor(Qt::transparent)}
+    };
+
+    for (uint ii = 0; ii < sizeof(table) / sizeof(table[0]); ++ii) {
+        if (s == table[ii].name)
+            return table[ii].color;
+    }
+
+    return QColor();
+}
+
+static QColor checkColorText(const QString &str)
+{
+    if (str.startsWith(QLatin1Char('#')))
+        return QColor(str);
+
+    if (str.startsWith(QLatin1String("Qt::"))) {
+        QString colorStr = str;
+        colorStr.remove(0, 4);
+        return fromEnumString(colorStr);
+    }
+
+    return QColor();
+}
+
+// looks backwards through a string for the opening brace of a function
+static int findOpeningBrace(const QString &s, int startIndex)
+{
+    QTC_ASSERT(startIndex >= 0 && startIndex < s.length(), return -1);
+
+    int index = startIndex;
+    while (index > 0) {
+        const QChar c = s[index];
+        if (c == QLatin1Char('(') || c == QLatin1Char('{'))
+            return index;
+
+        --index;
+    }
+
+    return index;
+}
+
+static int findClosingBrace(const QString &s, int startIndex)
+{
+    QTC_ASSERT(startIndex >= 0 && startIndex < s.length(), return -1);
+
+    int index = startIndex;
+    const int len = s.length();
+    while (index < len) {
+        const QChar c = s[index];
+        if (c == QLatin1Char(')') || c == QLatin1Char('}'))
+            return index;
+
+        ++index;
+    }
+
+    return -1;
+}
+
+// returns the index of the first character of the func, or negative if not valid
+static int findFuncStart(const QString &s, int startIndex)
+{
+    QTC_ASSERT(startIndex >= 0 && startIndex < s.length(), return -1);
+
+    int index = startIndex;
+    while (index >= 0) {
+        const QChar c = s[index];
+        if (!c.isLetterOrNumber()) {
+            if (index == startIndex)
+                return -1;
+
+            return qMin(index + 1, startIndex);
+        }
+        --index;
+    }
+
+    return index;
+}
+
+static QString removeWhitespace(const QString &s)
+{
+    QString ret;
+    ret.reserve(s.size());
+    for (int ii = 0; ii < s.length(); ++ii) {
+        const QChar c = s[ii];
+        if (!c.isSpace())
+            ret += c;
+
+    }
+    return ret;
+}
+
+/*
+ * Parses the string looking for a function and its arguments.
+ * The starting position is assumed to be within the braces.
+ */
+static bool extractFuncAndArgs(const QString &s,
+                               int pos,
+                               QString &retFuncName,
+                               QStringList &retArgs)
+{
+    int openBrace = findOpeningBrace(s, pos);
+    if (openBrace <= 0)
+        return false;
+
+    int closeBrace = findClosingBrace(s, openBrace + 1);
+    if (closeBrace < 0)
+        return false;
+
+    int funcEnd = openBrace - 1;
+    int funcStart = findFuncStart(s, funcEnd);
+
+    if (funcStart < 0 || funcEnd <= funcStart)
+        return false;
+
+    retFuncName = removeWhitespace(s.mid(funcStart, funcEnd - funcStart + 1));
+
+    QString argStr = s.mid(openBrace + 1, closeBrace - openBrace - 1);
+    retArgs = argStr.split(QLatin1Char(','), QString::KeepEmptyParts);
+
+    return true;
+}
+
+static QColor::Spec specForFunc(const QString &func)
+{
+    if ((func == QLatin1String("QColor"))
+            || (func == QLatin1String("QRgb"))
+            || (func == QLatin1String("rgb"))
+            || func.startsWith(QLatin1String("setRgb"))
+            || func.startsWith(QLatin1String("setRgba"))){
+        return QColor::Rgb;
+    }
+
+    if (func.startsWith(QLatin1String("setCmyk")))
+        return QColor::Cmyk;
+
+    if (func.startsWith(QLatin1String("setHsv")))
+        return QColor::Hsv;
+
+    if (func.startsWith(QLatin1String("setHsl")))
+        return QColor::Hsv;
+
+    return QColor::Invalid;
+}
+
+static QColor colorFromArgs(const QStringList &args, QColor::Spec spec)
+{
+    const int maxArgs = 5;
+    int vals[maxArgs];
+    vals[3] = 0xff;
+    vals[4] = 0xff;
+
+    bool allOk = true;
+    for (int ii = 0; ii < qMin(args.size(), maxArgs); ++ii) {
+         bool ok;
+         vals[ii] = args[ii].toInt(&ok, 0);
+         allOk &= ok;
+    }
+
+    if (!allOk)
+        return QColor();
+
+    QColor c;
+    switch (spec) {
+    case QColor::Rgb:
+        c.setRgb(vals[0], vals[1], vals[2], vals[3]);
+        break;
+    case QColor::Cmyk:
+        c.setCmyk(vals[0], vals[1], vals[2], vals[3], vals[4]);
+        break;
+    case QColor::Hsv:
+        c.setHsv(vals[0], vals[1], vals[2], vals[3]);
+        break;
+    case QColor::Hsl:
+        c.setHsl(vals[0], vals[1], vals[2], vals[3]);
+        break;
+    default:
+        break;
+    }
+    return c;
+}
+
+static QColor colorFromArgsF(const QStringList &args, QColor::Spec spec)
+{
+    const int maxArgs = 5;
+    qreal vals[maxArgs];
+    vals[3] = 1.0;
+    vals[4] = 1.0;
+
+    bool allOk = true;
+    for (int ii = 0; ii < qMin(args.size(), maxArgs); ++ii) {
+        bool ok;
+        vals[ii] = args[ii].toDouble(&ok);
+        allOk &= ok;
+    }
+    if (!allOk)
+        return QColor();
+
+    QColor c;
+    switch (spec) {
+    case QColor::Rgb:
+        c.setRgbF(vals[0], vals[1], vals[2], vals[3]);
+        break;
+    case QColor::Cmyk:
+        c.setCmykF(vals[0], vals[1], vals[2], vals[3], vals[4]);
+        break;
+    case QColor::Hsv:
+        c.setHsvF(vals[0], vals[1], vals[2], vals[3]);
+        break;
+    case QColor::Hsl:
+        c.setHslF(vals[0], vals[1], vals[2], vals[3]);
+        break;
+    default:
+        break;
+    }
+    return c;
+}
+
+static QColor colorFromFuncAndArgs(const QString &func, const QStringList &args)
+{
+    if (args.isEmpty())
+        return QColor();
+
+    if (args.size() < 3) {
+        QString arg0 = removeWhitespace(args[0]);
+        arg0.remove(QLatin1Char('\"'));
+        if (func == QLatin1String("setNamedColor"))
+            return QColor(arg0);
+
+        if (arg0.startsWith(QLatin1Char('#')))
+            return QColor(arg0);
+
+        if (arg0.startsWith(QLatin1String("Qt::"))) {
+            arg0.remove(0, 4);
+            return fromEnumString(arg0);
+        }
+
+        return QColor();
+    }
+
+    QColor::Spec spec = specForFunc(func);
+    if (spec == QColor::Invalid)
+        return QColor();
+
+    if (func.endsWith(QLatin1Char('F')))
+        return colorFromArgsF(args, spec);
+
+    return colorFromArgs(args, spec);
+}
+
+void ColorPreviewHoverHandler::identifyMatch(TextEditorWidget *editorWidget, int pos)
+{
+    if (editorWidget->extraSelectionTooltip(pos).isEmpty()) {
+        const QTextBlock tb = editorWidget->document()->findBlock(pos);
+        const int tbpos = pos - tb.position();
+        const QString tbtext = tb.text();
+
+        QString colorString = extractColorString(tbtext, tbpos);
+        m_colorTip = checkColorText(colorString);
+
+        if (!m_colorTip.isValid()) {
+            QString funcName;
+            QStringList args;
+            if (extractFuncAndArgs(tbtext, tbpos, funcName, args))
+                m_colorTip = colorFromFuncAndArgs(funcName, args);
+        }
+
+        setPriority(m_colorTip.isValid() ? Priority_Help - 1 : Priority_None);
+    }
+}
+
+void ColorPreviewHoverHandler::operateTooltip(TextEditorWidget *editorWidget, const QPoint &point)
+{
+    if (m_colorTip.isValid())
+        Utils::ToolTip::show(point, m_colorTip, editorWidget);
+    else
+        Utils::ToolTip::hide();
+}
+
+} // namespace TextEditor

src/plugins/texteditor/colorpreviewhoverhandler.h

+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://www.qt.io/licensing.  For further information
+** use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file.  Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+
+#ifndef COLORPREVIEWHOVERHANDLER_H
+#define COLORPREVIEWHOVERHANDLER_H
+
+#include "texteditor_global.h"
+#include "basehoverhandler.h"
+
+#include <QColor>
+
+namespace Core { class IEditor; }
+
+namespace TextEditor {
+
+class TextEditorWidget;
+
+class TEXTEDITOR_EXPORT ColorPreviewHoverHandler : public BaseHoverHandler
+{
+    Q_OBJECT
+public:
+
+private:
+    virtual void identifyMatch(TextEditorWidget *editorWidget, int pos);
+    virtual void operateTooltip(TextEditorWidget *editorWidget, const QPoint &point);
+
+    QColor m_colorTip;
+};
+
+} // namespace TextEditor
+
+#endif // COLORPREVIEWHOVERHANDLER_H

src/plugins/texteditor/texteditor.pro

@@ -55,6 +55,7 @@ SOURCES += texteditorplugin.cpp \
     refactoroverlay.cpp \
     outlinefactory.cpp \
     basehoverhandler.cpp \
+    colorpreviewhoverhandler.cpp \
     helpitem.cpp \
     autocompleter.cpp \
     snippets/snippetssettingspage.cpp \
@@ -161,6 +162,7 @@ HEADERS += texteditorplugin.h \
     outlinefactory.h \
     ioutlinewidget.h \
     basehoverhandler.h \
+    colorpreviewhoverhandler.h \
     helpitem.h \
     autocompleter.h \
     snippets/snippetssettingspage.h \