[FEATURE] Better UI for embedding SVG files

Adds a common widget for SVG sources, with a tool button with
some handy options:
- select file (old behaviour), pick a file from disk
- embed file (pick a file from disk, is embedded into project/symbol)
- extract embedded file (for embedded files, allows you to save these
back to a disk based svg file)
- from url (opens a dialog prompting for a url, exposing
the previously hidden functionality that svgs can be retrieved
from a remote url (eg github))

Sponsored by SMEC/SJ

python/gui/auto_generated/qgssvgsourcelineedit.sip.in

@@ -0,0 +1,71 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/gui/qgssvgsourcelineedit.h                                       *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+
+class QgsSvgSourceLineEdit : QWidget
+{
+%Docstring
+A line edit widget with toolbutton for setting an SVG image path.
+
+.. versionadded:: 3.4
+%End
+
+%TypeHeaderCode
+#include "qgssvgsourcelineedit.h"
+%End
+  public:
+
+    QgsSvgSourceLineEdit( QWidget *parent /TransferThis/ = 0 );
+%Docstring
+Constructor for QgsSvgSourceLineEdit, with the specified ``parent`` widget.
+%End
+
+    QString source() const;
+%Docstring
+Returns the current SVG source.
+
+.. seealso:: :py:func:`setSource`
+
+.. seealso:: :py:func:`sourceChanged`
+%End
+
+    void setLastPathSettingsKey( const QString &key );
+%Docstring
+Sets a specific settings ``key`` to use when storing the last
+used path for the SVG source.
+%End
+
+  public slots:
+
+    void setSource( const QString &source );
+%Docstring
+Sets a new ``source`` to show in the widget.
+
+.. seealso:: :py:func:`source`
+
+.. seealso:: :py:func:`sourceChanged`
+%End
+
+  signals:
+
+    void sourceChanged( const QString &source );
+%Docstring
+Emitted whenever the SVG source is changed in the widget.
+%End
+
+};
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/gui/qgssvgsourcelineedit.h                                       *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/

python/gui/gui_auto.sip

@@ -195,6 +195,7 @@
 %Include auto_generated/qgsstatusbar.sip
 %Include auto_generated/qgssublayersdialog.sip
 %Include auto_generated/qgssubstitutionlistwidget.sip
+%Include auto_generated/qgssvgsourcelineedit.sip
 %Include auto_generated/qgssymbolbutton.sip
 %Include auto_generated/qgstablewidgetbase.sip
 %Include auto_generated/qgstabwidget.sip

src/gui/CMakeLists.txt

@@ -359,6 +359,7 @@ SET(QGIS_GUI_SRCS
   qgssubstitutionlistwidget.cpp
   qgssqlcomposerdialog.cpp
   qgsstatusbar.cpp
+  qgssvgsourcelineedit.cpp
   qgssymbolbutton.cpp
   qgstablewidgetbase.cpp
   qgstabwidget.cpp
@@ -526,6 +527,7 @@ SET(QGIS_GUI_MOC_HDRS
   qgsstatusbar.h
   qgssublayersdialog.h
   qgssubstitutionlistwidget.h
+  qgssvgsourcelineedit.h
   qgssymbolbutton.h
   qgstablewidgetbase.h
   qgstabwidget.h

src/gui/qgssvgsourcelineedit.cpp

@@ -0,0 +1,212 @@
+/***************************************************************************
+ qgssvgsourcelineedit.cpp
+ -----------------------
+ begin                : July 2018
+ copyright            : (C) 2018 by Nyall Dawson
+ email                : nyall dot dawson at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgssvgsourcelineedit.h"
+#include "qgssettings.h"
+#include <QMenu>
+#include <QLineEdit>
+#include <QToolButton>
+#include <QHBoxLayout>
+#include <QFileDialog>
+#include <QInputDialog>
+
+QgsSvgSourceLineEdit::QgsSvgSourceLineEdit( QWidget *parent )
+  : QWidget( parent )
+{
+  QHBoxLayout *layout = new QHBoxLayout( this );
+  mFileLineEdit = new QLineEdit( this );
+  mFileToolButton = new QToolButton( this );
+  mFileToolButton->setText( tr( "…" ) );
+  layout->addWidget( mFileLineEdit, 1 );
+  layout->addWidget( mFileToolButton );
+  setLayout( layout );
+
+  QMenu *sourceMenu = new QMenu( mFileToolButton );
+
+  QAction *selectFileAction = new QAction( tr( "Select File…" ), sourceMenu );
+  connect( selectFileAction, &QAction::triggered, this, &QgsSvgSourceLineEdit::selectFile );
+  sourceMenu->addAction( selectFileAction );
+
+  QAction *embedFileAction = new QAction( tr( "Embed File…" ), sourceMenu );
+  connect( embedFileAction, &QAction::triggered, this, &QgsSvgSourceLineEdit::embedFile );
+  sourceMenu->addAction( embedFileAction );
+
+  QAction *extractFileAction = new QAction( tr( "Extract Embedded File…" ), sourceMenu );
+  connect( extractFileAction, &QAction::triggered, this, &QgsSvgSourceLineEdit::extractFile );
+  sourceMenu->addAction( extractFileAction );
+
+  connect( sourceMenu, &QMenu::aboutToShow, this, [this, extractFileAction]
+  {
+    extractFileAction->setEnabled( mFileLineEdit->text().startsWith( QStringLiteral( "base64:" ), Qt::CaseInsensitive ) );
+  } );
+
+  QAction *enterUrlAction = new QAction( tr( "From URL…" ), sourceMenu );
+  connect( enterUrlAction, &QAction::triggered, this, &QgsSvgSourceLineEdit::selectUrl );
+  sourceMenu->addAction( enterUrlAction );
+
+  mFileToolButton->setMenu( sourceMenu );
+  mFileToolButton->setPopupMode( QToolButton::MenuButtonPopup );
+  connect( mFileToolButton, &QToolButton::clicked, this, &QgsSvgSourceLineEdit::selectFile );
+
+  connect( mFileLineEdit, &QLineEdit::textEdited, this, &QgsSvgSourceLineEdit::mFileLineEdit_textEdited );
+  connect( mFileLineEdit, &QLineEdit::editingFinished, this, &QgsSvgSourceLineEdit::mFileLineEdit_editingFinished );
+}
+
+QString QgsSvgSourceLineEdit::source() const
+{
+  return mFileLineEdit->text();
+}
+
+void QgsSvgSourceLineEdit::setLastPathSettingsKey( const QString &key )
+{
+  mLastPathKey = key;
+}
+
+void QgsSvgSourceLineEdit::setSource( const QString &source )
+{
+  if ( source == mFileLineEdit->text() )
+    return;
+
+  mFileLineEdit->setText( source );
+  emit sourceChanged( source );
+}
+
+void QgsSvgSourceLineEdit::selectFile()
+{
+  QgsSettings s;
+  QString file = QFileDialog::getOpenFileName( nullptr,
+                 tr( "Select SVG file" ),
+                 defaultPath(),
+                 tr( "SVG files" ) + " (*.svg)" );
+  QFileInfo fi( file );
+  if ( file.isEmpty() || !fi.exists() || file == source() )
+  {
+    return;
+  }
+  mFileLineEdit->setText( file );
+  s.setValue( settingsKey(), fi.absolutePath() );
+  emit sourceChanged( mFileLineEdit->text() );
+}
+
+void QgsSvgSourceLineEdit::selectUrl()
+{
+  bool ok = false;
+  const QString path = QInputDialog::getText( this, tr( "SVG From URL" ), tr( "Enter SVG URL" ), QLineEdit::Normal, mFileLineEdit->text(), &ok );
+  if ( ok && path != source() )
+  {
+    mFileLineEdit->setText( path );
+    emit sourceChanged( mFileLineEdit->text() );
+  }
+}
+
+void QgsSvgSourceLineEdit::embedFile()
+{
+  QgsSettings s;
+  QString file = QFileDialog::getOpenFileName( nullptr,
+                 tr( "Embed SVG File" ),
+                 defaultPath(),
+                 tr( "SVG files" ) + " (*.svg)" );
+  QFileInfo fi( file );
+  if ( file.isEmpty() || !fi.exists() )
+  {
+    return;
+  }
+
+  s.setValue( settingsKey(), fi.absolutePath() );
+
+  // encode file as base64
+  QFile fileSource( file );
+  if ( !fileSource.open( QIODevice::ReadOnly ) )
+  {
+    return;
+  }
+
+  QByteArray blob = fileSource.readAll();
+  QByteArray encoded = blob.toBase64();
+
+  QString path( encoded );
+  path.prepend( QLatin1String( "base64:" ) );
+  if ( path == source() )
+    return;
+
+  mFileLineEdit->setText( path );
+  emit sourceChanged( mFileLineEdit->text() );
+}
+
+void QgsSvgSourceLineEdit::extractFile()
+{
+  QgsSettings s;
+  QString file = QFileDialog::getSaveFileName( nullptr,
+                 tr( "Extract SVG File" ),
+                 defaultPath(),
+                 tr( "SVG files" ) + " (*.svg)" );
+  if ( file.isEmpty() )
+  {
+    return;
+  }
+
+  QFileInfo fi( file );
+  s.setValue( settingsKey(), fi.absolutePath() );
+
+  // decode current base64 embedded file
+  QString path = mFileLineEdit->text().trimmed();
+  if ( path.startsWith( QLatin1String( "base64:" ), Qt::CaseInsensitive ) )
+  {
+    QByteArray base64 = path.mid( 7 ).toLocal8Bit(); // strip 'base64:' prefix
+    QByteArray decoded = QByteArray::fromBase64( base64, QByteArray::OmitTrailingEquals );
+
+    QFile fileOut( file );
+    fileOut.open( QIODevice::WriteOnly );
+    fileOut.write( decoded );
+    fileOut.close();
+  }
+}
+
+void QgsSvgSourceLineEdit::mFileLineEdit_textEdited( const QString &text )
+{
+  if ( !QFileInfo::exists( text ) )
+  {
+    return;
+  }
+  emit sourceChanged( text );
+}
+
+void QgsSvgSourceLineEdit::mFileLineEdit_editingFinished()
+{
+  if ( !QFileInfo::exists( mFileLineEdit->text() ) )
+  {
+    QUrl url( mFileLineEdit->text() );
+    if ( !url.isValid() )
+    {
+      return;
+    }
+  }
+
+  emit sourceChanged( mFileLineEdit->text() );
+}
+
+QString QgsSvgSourceLineEdit::defaultPath() const
+{
+  if ( QFileInfo::exists( source() ) )
+    return source();
+
+  return QgsSettings().value( settingsKey(), QDir::homePath() ).toString();
+}
+
+QString QgsSvgSourceLineEdit::settingsKey() const
+{
+  return mLastPathKey.isEmpty() ? QStringLiteral( "/UI/lastSVGDir" ) : mLastPathKey;
+}
+