eric7/HelpViewer/HelpViewerImpl_qtb.py

# -*- coding: utf-8 -*-

# Copyright (c) 2021 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing the QTextBrowser based help viewer class.
"""

from PyQt6.QtCore import Qt, QByteArray, QUrl
from PyQt6.QtGui import QDesktopServices,  QImage
from PyQt6.QtWidgets import QTextBrowser

from .HelpViewerImpl import HelpViewerImpl


class HelpViewerImpl_qtb(HelpViewerImpl, QTextBrowser):
    """
    Class implementing the QTextBrowser based help viewer class.
    """
    def __init__(self, engine, parent=None):
        """
        Constructor
        
        @param engine reference to the help engine
        @type QHelpEngine
        @param parent reference to the parent widget
        @type QWidget
        """
        QTextBrowser.__init__(self,  parent=parent)
        HelpViewerImpl.__init__(self, engine)
        
        self.__zoomCount = 0
        
        self.sourceChanged.connect(self.titleChanged)
    
    def setUrl(self, url):
        """
        Public method to set the URL of the document to be shown.
        
        @param url source of the document
        @type QUrl
        """
        self.setSource(url)
    
    def doSetSource(self, url, type):
        """
        Public method to load the data and show it.
        
        @param url DESCRIPTION
        @type TYPE
        @param type DESCRIPTION
        @type TYPE
        """
        data = self.getData(url)
        if data is None:
            QDesktopServices.openUrl(url)
            return
        
        if url != QUrl("about:blank"):
            super().doSetSource(url, type)
        
        self.setHtml(data)
        self.sourceChanged.emit(url)
        self.loadFinished.emit(True)
    
    def title(self):
        """
        Public method get the page title.
        
        @return page title
        @rtype str
        """
        return self.documentTitle()
    
    def loadResource(self, type_,  name):
        """
        Public method to load data of the specified type from the resource with
        the given name.
        
        @param type_ resource type
        @type int
        @param name resource name
        @type QUrl
        """
        ba = QByteArray()
        
        if type_ < 4:     # QTextDocument.ResourceType.MarkdownResource
            url = self._engine.findFile(name)
            ba = self._engine.fileData(url)
            if url.toString().lower().endswith(".svg"):
                image = QImage()
                image.loadFromData(ba, "svg")
                if not image.isNull():
                    return image
        
        return ba
    
    def mousePressEvent(self, evt):
        """
        Protected method called by a mouse press event.
        
        @param evt reference to the mouse event
        @type QMouseEvent
        """
        if evt.button() == Qt.MouseButton.XButton1:
            self.backward()
        elif evt.button() == Qt.MouseButton.XButton2:
            self.forward()
        else:
            super().mousePressEvent(evt)
    
    def gotoHistory(self, index):
        """
        Public method to step through the history.
        
        @param index history index (<0 backward, >0 forward)
        @type int
        """
        if index < 0:
            # backward
            for ind in range(-index):
                self.backward()
        else:
            # forward
            for ind in range(index):
                self.forward()
    
    def scaleUp(self):
        """
        Public method to zoom in.
        """
        if self.__zoomCount < 10:
            self.__zoomCount += 1
            self.zoomIn()
            self.zoomChanged.emit()
    
    def scaleDown(self):
        """
        Public method to zoom out.
        """
        if self.__zoomCount > -5:
            self.__zoomCount -= 1
            self.zoomOut()
            self.zoomChanged.emit()
    
    def resetScale(self):
        """
        Public method to reset the zoom level.
        """
        if self.__zoomCount != 0:
            self.zoomOut(self.__zoomCount)
            self.zoomChanged.emit()
        self.__zoomCount = 0
    
    def scale(self):
        """
        Public method to get the zoom level.
        
        @return current zoom level
        @rtype int
        """
        return self.__zoomCount
    
    def isScaleUpAvailable(self):
        """
        Public method to check, if the max. zoom level is reached.
        
        @return flag indicating scale up is available
        @rtype bool
        """
        return self.__zoomCount < 10
    
    def isScaleDownAvailable(self):
        """
        Public method to check, if the min. zoom level is reached.
        
        @return flag indicating scale down is available
        @rtype bool
        """
        return self.__zoomCount > -5
    
    def wheelEvent(self, evt):
        """
        Public method to handle wheel event to zoom.
        
        @param evt reference to the event object
        @type QWheelEvent
        """
        if evt.modifiers() == Qt.KeyboardModifier.ControlModifier:
            if evt.angleDelta().y() > 0:
                self.scaleUp()
            else:
                self.scaleDown()
            evt.accept()
        else:
            QTextBrowser.wheelEvent(self, evt)
    
    # TODO: implement context menu 
    # TODO: add Ctrl+LMB action (open link in new page)