lib/shared/spacer_widget.cpp

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Designer of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:GPL-EXCEPT$
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** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
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** $QT_END_LICENSE$
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#include "spacer_widget_p.h"
#include "layoutinfo_p.h"

#include <QtDesigner/abstractformwindow.h>
#include <QtDesigner/abstractformeditor.h>
#include <QtDesigner/propertysheet.h>
#include <QtDesigner/qextensionmanager.h>

#include <QtWidgets/qlayout.h>
#include <QtGui/qpainter.h>
#include <QtGui/qevent.h>
#include <QtCore/qdebug.h>

QT_BEGIN_NAMESPACE

// The Spacer widget is Designer representation of  QLayoutItem.
// It uses QLayoutItem's sizeHint property as QWidget
// sizeHint and the QLayoutItem's sizeType property as QWidget size policy.
// If it is not within a layout, it adds a margin (m_SizeOffset) around it
// to avoid being shrunk to an invisible state when the sizeHint is reset to 0,0
// and enables sizeHandle-resizing. In a layout, however, this m_SizeOffset
// should not be applied for  pixel-exact design.

Spacer::Spacer(QWidget *parent) :
    QWidget(parent)
{
    setAttribute(Qt::WA_MouseNoMask);
    m_formWindow = QDesignerFormWindowInterface::findFormWindow(this);
    setSizeType(QSizePolicy::Expanding);
}

bool Spacer::event(QEvent *e)
{
    switch (e->type()) {
    case QEvent::ToolTip:
        updateToolTip(); // Tooltip includes size, so, refresh on demand
        break;
    case QEvent::ParentChange: // Cache information about 'being in layout' which is expensive to calculate.
        m_layoutState = UnknownLayoutState;
        break;
    default:
        break;
    }
    return QWidget::event(e);
}

bool Spacer::isInLayout() const
{
    if (m_layoutState == UnknownLayoutState) {
        m_layoutState = OutsideLayout;
        if (m_formWindow)
            if (const QWidget *parent = parentWidget())
                if (qdesigner_internal::LayoutInfo::managedLayoutType(m_formWindow->core(), parent) != qdesigner_internal::LayoutInfo::NoLayout)
                    m_layoutState = InLayout;
    }
    return m_layoutState == InLayout;
}

void Spacer::paintEvent(QPaintEvent *)
{
    // Only draw spacers when we're editting widgets
    if (m_formWindow != nullptr && m_formWindow->currentTool() != 0)
        return;

    QPainter p(this);
    p.setPen(Qt::blue);
    const int w = width();
    const int h = height();
    if (w * h == 0)
        return;

    if (w <= m_SizeOffset.width() || h <= m_SizeOffset.height()) {
        const int lw = w - 1;
        const int lh = h - 1;
        switch (m_orientation) {
        case Qt::Horizontal:
            p.drawLine(0,  0, 0,  lh);
            p.drawLine(lw, 0, lw, lh);
            break;
        case Qt::Vertical:
            p.drawLine(0, 0,  lw, 0);
            p.drawLine(0, lh, lw, lh);
            break;
        }
        return;
    }
    if (m_orientation == Qt::Horizontal) {
        const int dist = 3;
        const int amplitude = qMin(3, h / 3);
        const int base = h / 2;
        int i = 0;
        p.setPen(Qt::white);
        for (i = 0; i < w / 3 +2; ++i)
            p.drawLine(i * dist, base - amplitude, i * dist + dist / 2, base + amplitude);
        p.setPen(Qt::blue);
        for (i = 0; i < w / 3 +2; ++i)
            p.drawLine(i * dist + dist / 2, base + amplitude, i * dist + dist, base - amplitude);
        const int y = h/2;
        p.drawLine(0, y-10, 0, y+10);
        p.drawLine(w - 1, y-10, w - 1, y+10);
    } else {
        const int dist = 3;
        const int amplitude = qMin(3, w / 3);
        const int base = w / 2;
        int i = 0;
        p.setPen(Qt::white);
        for (i = 0; i < h / 3 +2; ++i)
            p.drawLine(base - amplitude, i * dist, base + amplitude,i * dist + dist / 2);
        p.setPen(Qt::blue);
        for (i = 0; i < h / 3 +2; ++i)
            p.drawLine(base + amplitude, i * dist + dist / 2, base - amplitude, i * dist + dist);
        const int x = w/2;
        p.drawLine(x-10, 0, x+10, 0);
        p.drawLine(x-10, h - 1, x+10, h - 1);
    }
}

void Spacer::resizeEvent(QResizeEvent* e)
{
    QWidget::resizeEvent(e);
    // When resized by widget handle dragging after a reset (QSize(0, 0)):
    // Mark the property as changed (geometry and sizeHint are in sync except for 'changed').
    if (m_formWindow) {
        const QSize oldSize = e->oldSize();
        if (oldSize.isNull() || oldSize.width() <= m_SizeOffset.width() || oldSize.height() <= m_SizeOffset.height())
            if (QDesignerPropertySheetExtension *sheet = qt_extension<QDesignerPropertySheetExtension*>(m_formWindow->core()->extensionManager(), this))
                sheet->setChanged(sheet->indexOf(QStringLiteral("sizeHint")), true);
    }

    updateMask();

    if (!m_interactive)
        return;

    if (!isInLayout()) { // Allow size-handle resize only if not in layout
        const QSize currentSize = size();
        if (currentSize.width() >= m_SizeOffset.width() && currentSize.height() >= m_SizeOffset.height())
            m_sizeHint = currentSize - m_SizeOffset;
    }
}

void Spacer::updateMask()
{
    QRegion r(rect());
    const int w = width();
    const int h = height();
    if (w > 1 && h > 1) {
        if (m_orientation == Qt::Horizontal) {
            const int amplitude = qMin(3, h / 3);
            const int base = h / 2;
            r = r.subtracted(QRect(1, 0, w - 2, base - amplitude));
            r = r.subtracted(QRect(1, base + amplitude, w - 2, h - base - amplitude));
        } else {
            const int amplitude = qMin(3, w / 3);
            const int base = w / 2;
            r = r.subtracted(QRect(0, 1, base - amplitude, h - 2));
            r = r.subtracted(QRect(base + amplitude, 1, w - base - amplitude, h - 2));
        }
    }
    setMask(r);
}

void Spacer::setSizeType(QSizePolicy::Policy t)
{
    const QSizePolicy sizeP = m_orientation == Qt::Vertical ? QSizePolicy(QSizePolicy::Minimum, t) : QSizePolicy(t, QSizePolicy::Minimum);
    setSizePolicy(sizeP);
}


QSizePolicy::Policy Spacer::sizeType() const
{
    return m_orientation == Qt::Vertical ? sizePolicy().verticalPolicy() : sizePolicy().horizontalPolicy();
}

Qt::Alignment Spacer::alignment() const
{
    // For grid layouts
    return m_orientation == Qt::Vertical ?  Qt::AlignHCenter : Qt::AlignVCenter;
}

QSize Spacer::sizeHint() const
{
    return isInLayout() ? m_sizeHint : m_sizeHint + m_SizeOffset;
}

QSize Spacer::sizeHintProperty() const
{
    return m_sizeHint;
}

void Spacer::setSizeHintProperty(const QSize &s)
{
    m_sizeHint = s;

    if (!isInLayout()) // Visible resize only if not in layout
        resize(s + m_SizeOffset);

    updateGeometry();
}

Qt::Orientation Spacer::orientation() const
{
    return m_orientation;
}

void Spacer::setOrientation(Qt::Orientation o)
{
    if (m_orientation == o)
        return;

    const QSizePolicy::Policy st = sizeType(); // flip size type
    m_orientation = o;
    setSizeType(st);

    if (m_interactive) {
        m_sizeHint = QSize(m_sizeHint.height(), m_sizeHint.width());
        if (!isInLayout())
            resize(m_sizeHint + m_SizeOffset);
    }

    updateMask();
    update();
    updateGeometry();
}

void Spacer::updateToolTip()
{
    const QString format = m_orientation == Qt::Horizontal ? tr("Horizontal Spacer '%1', %2 x %3") : tr("Vertical Spacer '%1', %2 x %3");
    QString msg = format.arg(objectName()).arg(m_sizeHint.width()).arg(m_sizeHint.height());
    setToolTip(msg);
}

QT_END_NAMESPACE