messageview.py

"""
Custom message viewer with support for switching between HTML and plain
text rendering, HTML sanitization, lazy rendering (as you scroll down),
zoom and URL click warning popup

"""

from PyQt4 import QtCore, QtGui

from .safehtmlparser import SafeHTMLParser
from tr import _translate


class MessageView(QtGui.QTextBrowser):
    """Message content viewer class, can switch between plaintext and HTML"""
    MODE_PLAIN = 0
    MODE_HTML = 1

    def __init__(self, parent=0):
        super(MessageView, self).__init__(parent)
        self.mode = MessageView.MODE_PLAIN
        self.html = None
        self.setOpenExternalLinks(False)
        self.setOpenLinks(False)
        self.anchorClicked.connect(self.confirmURL)
        self.out = ""
        self.outpos = 0
        self.document().setUndoRedoEnabled(False)
        self.rendering = False
        self.defaultFontPointSize = self.currentFont().pointSize()
        self.verticalScrollBar().valueChanged.connect(self.lazyRender)
        self.setWrappingWidth()

    def resizeEvent(self, event):
        """View resize event handler"""
        super(MessageView, self).resizeEvent(event)
        self.setWrappingWidth(event.size().width())

    def mousePressEvent(self, event):
        """Mouse press button event handler"""
        if event.button() == QtCore.Qt.LeftButton and self.html and self.html.has_html and self.cursorForPosition(
                event.pos()).block().blockNumber() == 0:
            if self.mode == MessageView.MODE_PLAIN:
                self.showHTML()
            else:
                self.showPlain()
        else:
            super(MessageView, self).mousePressEvent(event)

    def wheelEvent(self, event):
        """Mouse wheel scroll event handler"""
        # super will actually automatically take care of zooming
        super(MessageView, self).wheelEvent(event)
        if (
            QtGui.QApplication.queryKeyboardModifiers() & QtCore.Qt.ControlModifier
        ) == QtCore.Qt.ControlModifier and event.orientation() == QtCore.Qt.Vertical:
            zoom = self.currentFont().pointSize() * 100 / self.defaultFontPointSize
            QtGui.QApplication.activeWindow().statusBar().showMessage(_translate(
                "MainWindow", "Zoom level %1%").arg(str(zoom)))

    def setWrappingWidth(self, width=None):
        """Set word-wrapping width"""
        self.setLineWrapMode(QtGui.QTextEdit.FixedPixelWidth)
        if width is None:
            width = self.width()
        self.setLineWrapColumnOrWidth(width)

    def confirmURL(self, link):
        """Show a dialog requesting URL opening confirmation"""
        if link.scheme() == "mailto":
            window = QtGui.QApplication.activeWindow()
            window.ui.lineEditTo.setText(link.path())
            if link.hasQueryItem("subject"):
                window.ui.lineEditSubject.setText(
                    link.queryItemValue("subject"))
            if link.hasQueryItem("body"):
                window.ui.textEditMessage.setText(
                    link.queryItemValue("body"))
            window.setSendFromComboBox()
            window.ui.tabWidgetSend.setCurrentIndex(0)
            window.ui.tabWidget.setCurrentIndex(
                window.ui.tabWidget.indexOf(window.ui.send)
            )
            window.ui.textEditMessage.setFocus()
            return
        reply = QtGui.QMessageBox.warning(
            self,
            QtGui.QApplication.translate(
                "MessageView",
                "Follow external link"),
            QtGui.QApplication.translate(
                "MessageView",
                "The link \"%1\" will open in a browser. It may be a security risk, it could de-anonymise you"
                " or download malicious data. Are you sure?").arg(unicode(link.toString())),
            QtGui.QMessageBox.Yes,
            QtGui.QMessageBox.No)
        if reply == QtGui.QMessageBox.Yes:
            QtGui.QDesktopServices.openUrl(link)

    def loadResource(self, restype, name):
        """
        Callback for loading referenced objects, such as an image. For security reasons at the moment doesn't do
        anything)
        """
        pass

    def lazyRender(self):
        """
        Partially render a message. This is to avoid UI freezing when loading huge messages. It continues loading as
        you scroll down.
        """
        if self.rendering:
            return
        self.rendering = True
        position = self.verticalScrollBar().value()
        cursor = QtGui.QTextCursor(self.document())
        while self.outpos < len(self.out) and self.verticalScrollBar().value(
        ) >= self.document().size().height() - 2 * self.size().height():
            startpos = self.outpos
            self.outpos += 10240
            # find next end of tag
            if self.mode == MessageView.MODE_HTML:
                pos = self.out.find(">", self.outpos)
                if pos > self.outpos:
                    self.outpos = pos + 1
            cursor.movePosition(QtGui.QTextCursor.End, QtGui.QTextCursor.MoveAnchor)
            cursor.insertHtml(QtCore.QString(self.out[startpos:self.outpos]))
        self.verticalScrollBar().setValue(position)
        self.rendering = False

    def showPlain(self):
        """Render message as plain text."""
        self.mode = MessageView.MODE_PLAIN
        out = self.html.raw
        if self.html.has_html:
            out = "<div align=\"center\" style=\"text-decoration: underline;\"><b>" + unicode(
                QtGui.QApplication.translate(
                    "MessageView", "HTML detected, click here to display")) + "</b></div><br/>" + out
        self.out = out
        self.outpos = 0
        self.setHtml("")
        self.lazyRender()

    def showHTML(self):
        """Render message as HTML"""
        self.mode = MessageView.MODE_HTML
        out = self.html.sanitised
        out = "<div align=\"center\" style=\"text-decoration: underline;\"><b>" + unicode(
            QtGui.QApplication.translate("MessageView", "Click here to disable HTML")) + "</b></div><br/>" + out
        self.out = out
        self.outpos = 0
        self.setHtml("")
        self.lazyRender()

    def setContent(self, data):
        """Set message content from argument"""
        self.html = SafeHTMLParser()
        self.html.reset()
        self.html.reset_safe()
        self.html.allow_picture = True
        self.html.feed(data)
        self.html.close()
        self.showPlain()