Scratchpad:Layer Mechanism

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Contents

1 Closed
2 Why use Layers
3 Schematic
4 Description
5 Advantages
6 Open Issues
7 Further Ideas
8 Example Application

Closed

I tried to adapt the code to play video in the background, but it doesn't work :-(

Why use Layers

Because of we have different plugins which partially use different widgets for displaying content

Schematic

alt text

Description

There will exist some special widgets: 1. "back" for actual theme image 2. "shield" is in front of other widget because it should hide any displayed items without changing the related content 3. "alarm" is in front of all widgets because the alarm should be possible to display in every situation

Now there are two special widgets for handling backgrounds and foreground items The QStackedWidget Object provide the possibility to switch easily between different backgrounds, whereat the other backgrounds will be hided automatically.

Examples are:

Phonon widget
Future VLC widget
maybe a widget for optimized image display

The other QStackedWidget Object manage different foreground widgets, these widgets should be transparent in the most cases.

Examples are:

webView widget (this is a special one, because of it can be transparent or not)
maybe widgets for displaying flashs, of graphic objects, ...

Advantages

Hide and Show mechanism is easier
it is not necessary anymore to cache the actual content while hiding (shield) is active
provide possiblity for more display widgets (optimized widgets for different content)

Open Issues

add mechanism to select the right foreground/background for different plugins

Further Ideas

We should use the same display classes for the preview widgets as for the main Display, because of I have had the effect, that I opened a little movie in the preview -> this works, but after going to live the movie doesn't appeared :-(

Example Application

from PyQt4 import QtCore, QtGui, QtWebKit

```
 
```
```
try:
```
```
    _fromUtf8 = QtCore.QString.fromUtf8
```
```
except AttributeError:
```
```
    _fromUtf8 = lambda s: s
```
```
 
```
```
class Ui_MainWindow(object):
```
```
    def setupUi(self, MainWindow):
```

        MainWindow.setObjectName(_fromUtf8("MainWindow"))

```
        MainWindow.resize(800, 600)
```
```
        self.frameSize = 400
```

        self.centralwidget = QtGui.QWidget(MainWindow)

        self.centralwidget.setObjectName(_fromUtf8("centralwidget"))

        #self.display = QtGui.QGraphicsView(self.centralwidget)

        self.display = QtGui.QFrame(self.centralwidget)

```
        #self.display = QtGui.QFrame()
```

        self.display.setGeometry(QtCore.QRect(360, 40, self.frameSize, self.frameSize))

        self.display.setFrameShape(QtGui.QFrame.Box)

        self.display.setFrameShadow(QtGui.QFrame.Raised)

        self.display.setObjectName(_fromUtf8("display"))

```
 
```

        self.back = self.display#QtGui.QWidget(self.display)

```
 
```

        #self.back.setGeometry(QtCore.QRect(5, 5, self.frameSize, self.frameSize))

        self.back.setObjectName(_fromUtf8("back"))

```
        color = QtGui.QColor(0, 0, 0)
```

        self.back.setAutoFillBackground(True)

        self.back.setPalette(QtGui.QPalette(color))

        self.name = QtGui.QLabel(self.back)

        self.name.setGeometry(QtCore.QRect(10, 10, 46, 13))

        self.name.setObjectName(_fromUtf8("name"))

```
 
```
```
        self.layer = Layer(self.back)
```

        self.bg_image = self.layer.new_widget(LayerTyp.Background, 'bg_First', QtGui.QColor(0, 200, 0))

        self.bg_video = self.layer.new_widget(LayerTyp.Background, 'bg_Second', QtGui.QColor(170, 0, 0))

        self.bg_songs = self.layer.new_widget(LayerTyp.Background, 'bg_Third', QtGui.QColor(0, 0, 255))

        self.bg_other = self.layer.new_widget(LayerTyp.Background, 'bg_Fourth', QtGui.QColor(100, 100, 100))

```
 
```
```
        self.add_web_view()
```

        self.layer.add_widget(self.webView, LayerTyp.Foreground, 'fg_First(webView)')

        self.fg_image = self.layer.new_widget(LayerTyp.Foreground, 'fg_Second')

        self.fg_video = self.layer.new_widget(LayerTyp.Foreground, 'fg_Third')

        self.fg_songs = self.layer.new_widget(LayerTyp.Foreground, 'fg_Fourth')

```
 
```

        self.Foreground = QtGui.QGroupBox(self.centralwidget)

        self.Foreground.setGeometry(QtCore.QRect(20, 200, 120, 121))

        self.Foreground.setObjectName(_fromUtf8("Foreground"))

        self.rf_First = QtGui.QRadioButton(self.Foreground)

        self.rf_First.setGeometry(QtCore.QRect(20, 20, 82, 17))

        self.rf_First.setObjectName(_fromUtf8("rf_First"))

        self.rf_Second = QtGui.QRadioButton(self.Foreground)

        self.rf_Second.setGeometry(QtCore.QRect(20, 40, 82, 17))

        self.rf_Second.setObjectName(_fromUtf8("rf_Second"))

        self.rf_Third = QtGui.QRadioButton(self.Foreground)

        self.rf_Third.setGeometry(QtCore.QRect(20, 60, 82, 17))

        self.rf_Third.setObjectName(_fromUtf8("rf_Third"))

        self.rf_Fourth = QtGui.QRadioButton(self.Foreground)

        self.rf_Fourth.setGeometry(QtCore.QRect(20, 80, 82, 17))

        self.rf_Fourth.setObjectName(_fromUtf8("rf_Fourth"))

        self.bg_foreground = QtGui.QButtonGroup(self.Foreground)

        self.bg_foreground.addButton(self.rf_First, 0)

        self.bg_foreground.addButton(self.rf_Second, 1)

        self.bg_foreground.addButton(self.rf_Third, 2)

        self.bg_foreground.addButton(self.rf_Fourth, 3)

        self.Background = QtGui.QGroupBox(self.centralwidget)

        self.Background.setGeometry(QtCore.QRect(180, 200, 120, 121))

        self.Background.setObjectName(_fromUtf8("Background"))

        self.rb_First = QtGui.QRadioButton(self.Background)

        self.rb_First.setGeometry(QtCore.QRect(20, 20, 82, 17))

        self.rb_First.setObjectName(_fromUtf8("rb_First"))

        self.rb_Second = QtGui.QRadioButton(self.Background)

        self.rb_Second.setGeometry(QtCore.QRect(20, 40, 82, 17))

        self.rb_Second.setObjectName(_fromUtf8("rb_Second"))

        self.rb_Third = QtGui.QRadioButton(self.Background)

        self.rb_Third.setGeometry(QtCore.QRect(20, 60, 82, 17))

        self.rb_Third.setObjectName(_fromUtf8("rb_Third"))

        self.rb_Fourth = QtGui.QRadioButton(self.Background)

        self.rb_Fourth.setGeometry(QtCore.QRect(20, 80, 82, 17))

        self.rb_Fourth.setObjectName(_fromUtf8("rb_Fourth"))

        self.bg_background = QtGui.QButtonGroup(self.Background)

        self.bg_background.addButton(self.rb_First, 0)

        self.bg_background.addButton(self.rb_Second, 1)

        self.bg_background.addButton(self.rb_Third, 2)

        self.bg_background.addButton(self.rb_Fourth, 3)

        self.bHide = QtGui.QPushButton(self.centralwidget)

        self.bHide.setGeometry(QtCore.QRect(30, 140, 75, 23))

        self.bHide.setObjectName(_fromUtf8("bHide"))

        self.bShield = QtGui.QPushButton(self.centralwidget)

        self.bShield.setGeometry(QtCore.QRect(120, 140, 75, 23))

        self.bShield.setObjectName(_fromUtf8("bShield"))

        self.bAlarm = QtGui.QPushButton(self.centralwidget)

        self.bAlarm.setGeometry(QtCore.QRect(210, 140, 75, 23))

        self.bAlarm.setObjectName(_fromUtf8("bAlarm"))

        MainWindow.setCentralWidget(self.centralwidget)

        self.menubar = QtGui.QMenuBar(MainWindow)

        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 20))

        self.menubar.setObjectName(_fromUtf8("menubar"))

        MainWindow.setMenuBar(self.menubar)

        self.statusbar = QtGui.QStatusBar(MainWindow)

        self.statusbar.setObjectName(_fromUtf8("statusbar"))

        MainWindow.setStatusBar(self.statusbar)

```
 
```
```
        self.retranslateUi(MainWindow)
```

        QtCore.QMetaObject.connectSlotsByName(MainWindow)

        self.bHide.clicked.connect(self.switch_hide)

        self.bAlarm.clicked.connect(self.resizing)

        self.bShield.clicked.connect(self.switch_shield)

        self.bg_foreground.buttonClicked.connect(self.switch_foregrounds)

        self.bg_background.buttonClicked.connect(self.switch_backgrounds)

```
 
```

    def retranslateUi(self, MainWindow):

        MainWindow.setWindowTitle(QtGui.QApplication.translate("MainWindow", "MainWindow", None, QtGui.QApplication.UnicodeUTF8))

        self.name.setText(QtGui.QApplication.translate("MainWindow", "back", None, QtGui.QApplication.UnicodeUTF8))

        self.Foreground.setTitle(QtGui.QApplication.translate("MainWindow", "Foreground", None, QtGui.QApplication.UnicodeUTF8))

        self.rf_First.setText(QtGui.QApplication.translate("MainWindow", "First", None, QtGui.QApplication.UnicodeUTF8))

        self.rf_Second.setText(QtGui.QApplication.translate("MainWindow", "Second", None, QtGui.QApplication.UnicodeUTF8))

        self.rf_Third.setText(QtGui.QApplication.translate("MainWindow", "Third", None, QtGui.QApplication.UnicodeUTF8))

        self.rf_Fourth.setText(QtGui.QApplication.translate("MainWindow", "Fourth", None, QtGui.QApplication.UnicodeUTF8))

        self.Background.setTitle(QtGui.QApplication.translate("MainWindow", "Background", None, QtGui.QApplication.UnicodeUTF8))

        self.rb_First.setText(QtGui.QApplication.translate("MainWindow", "First", None, QtGui.QApplication.UnicodeUTF8))

        self.rb_Second.setText(QtGui.QApplication.translate("MainWindow", "Second", None, QtGui.QApplication.UnicodeUTF8))

        self.rb_Third.setText(QtGui.QApplication.translate("MainWindow", "Third", None, QtGui.QApplication.UnicodeUTF8))

        self.rb_Fourth.setText(QtGui.QApplication.translate("MainWindow", "Fourth", None, QtGui.QApplication.UnicodeUTF8))

        self.bHide.setText(QtGui.QApplication.translate("MainWindow", "Hide", None, QtGui.QApplication.UnicodeUTF8))

        self.bShield.setText(QtGui.QApplication.translate("MainWindow", "Shield", None, QtGui.QApplication.UnicodeUTF8))

        self.bAlarm.setText(QtGui.QApplication.translate("MainWindow", "Grow", None, QtGui.QApplication.UnicodeUTF8))

```
 
```
```
    def add_web_view(self):
```

        self.webView = QtWebKit.QWebView(self.back)

        self.webView.setGeometry(QtCore.QRect(0, 0, self.back.size().width(), self.back.size().height()))

```
        self.page = self.webView.page()
```

        self.frame = self.page.mainFrame()

```
 
```
```
    def switch_shield(self):
```

      self.layer.shield.setVisible(not self.layer.shield.isVisible())

```
 
```
```
    def switch_hide(self):
```

      self.display.setVisible(not self.display.isVisible())

```
 
```

    def switch_backgrounds(self, button):

      self.layer.activate_layer_index(self.layer.foregrounds.currentIndex(), self.bg_background.id(button))

```
 
```

    def switch_foregrounds(self, button):

      self.layer.activate_layer_index(self.bg_foreground.id(button), self.layer.backgrounds.currentIndex())

```
 
```
```
    def resizing(self):
```

      self.frameSize = self.frameSize + 50

      self.display.setGeometry(QtCore.QRect(360, 40, self.frameSize, self.frameSize))

```
      self.layer.resize_widget()
```
```
 
```
```
class LayerTyp(object):
```
```
  """
```

  This class defines the different types of Layers

```
  """
```
```
  Foreground = 1
```
```
  Background = 2
```
```
 
```
```
class Layer(object):
```
```
  """
```

  This class provide a mechanism to store widget in a multi layer environment

  So new foregrounds or backgrounds for other plugins can added and managed easely

```
  """
```
```
  def __init__(self, parent):
```
```
    self.parent = parent
```

    self.size = QtCore.QRect(0, 0, self.parent.size().width(), self.parent.size().height())

```
 
```

    self.alarm = QtGui.QWidget(self.parent)

```
    self.alarm.setGeometry(self.size)
```

    self.shield = QtGui.QWidget(self.parent)

```
    self.shield.setGeometry(self.size)
```

    self.shield.setAutoFillBackground(True)

    self.shield.setPalette(QtGui.QPalette(QtGui.QColor(0, 255, 0)))

    self.foregrounds = QtGui.QStackedWidget(self.parent)

    self.foregrounds.setGeometry(self.size)

    self.backgrounds = QtGui.QStackedWidget(self.parent)

    self.backgrounds.setGeometry(self.size)

```
 
```

  def new_widget(self, type, title, color=QtGui.QColor(0, 0, 0)):

```
    widget = QtGui.QWidget(self.parent)
```

    self.add_widget(widget, type, title, color)

```
    return widget
```
```
 
```

  def add_widget(self, widget, type, name, color=QtGui.QColor(0, 0, 0)):

```
    if type == LayerTyp.Foreground:
```

      widget.setAttribute(QtCore.Qt.WA_NoSystemBackground)

```
      widget.setGeometry(self.size)
```
```
      title = QtGui.QLabel(widget)
```

      title.setGeometry(QtCore.QRect(widget.size().width()/2-50, widget.size().height()/2, 100, 13))

```
      title.setObjectName(name)
```
```
      title.setText(name)
```

      self.foregrounds.addWidget(widget)

```
    else:
```
```
      widget.setGeometry(self.size)
```

      widget.setAutoFillBackground(True)

      widget.setPalette(QtGui.QPalette(color))

```
      title = QtGui.QLabel(widget)
```

      title.setGeometry(QtCore.QRect(widget.size().width()-100, 10, 100, 13))

```
      title.setObjectName(name)
```
```
      title.setText(name)
```

      self.backgrounds.addWidget(widget)

```
    self.arrange_widgets()
```
```
 
```

  def activate_layer_widget(self, fg_widget=None, bg_widget=None):

```
    if fg_widget:
```
```
      self.foregrounds.setVisible(True)
```

      self.foregrounds.setCurrentWidget(fg_widget)

```
    else:
```

      self.foregrounds.setVisible(False)

```
    if bg_widget:
```
```
      self.backgrounds.setVisible(True)
```

      self.backgrounds.setCurrentWidget(bg_widget)

```
    else:
```

      self.backgrounds.setVisible(False)

```
 
```

  def activate_layer_index(self, fg_index=-1, bg_index=-1):

```
    if fg_index > -1:
```
```
      self.foregrounds.setVisible(True)
```

      self.foregrounds.setCurrentIndex(fg_index)

```
    else:
```

      self.foregrounds.setVisible(False)

```
    if bg_index > -1:
```
```
      self.backgrounds.setVisible(True)
```

      self.backgrounds.setCurrentIndex(bg_index)

```
    else:
```

      self.backgrounds.setVisible(False)

```
 
```
```
  def arrange_widgets(self):
```
```
    self.alarm.raise_()
```
```
    self.shield.stackUnder(self.alarm)
```

    self.foregrounds.stackUnder(self.shield)

    self.backgrounds.stackUnder(self.foregrounds)

```
 
```
```
  def resize_widget(self):
```

    self.size = QtCore.QRect(0, 0, self.parent.size().width(), self.parent.size().height())

```
    #self.setGeometry(self.size)
```
```
    self.shield.setGeometry(self.size)
```

    self.shield.setAutoFillBackground(True)

    self.shield.setPalette(QtGui.QPalette(QtGui.QColor(0, 255, 0)))

    self.backgrounds.setGeometry(self.size)

    self.foregrounds.setGeometry(self.size)

```
 
```
```
 
```
```
if __name__ == "__main__":
```
```
    import sys
```
```
    app = QtGui.QApplication(sys.argv)
```
```
    MainWindow = QtGui.QMainWindow()
```
```
    ui = Ui_MainWindow()
```
```
    ui.setupUi(MainWindow)
```
```
    MainWindow.show()
```
```
    sys.exit(app.exec_())
```

Retrieved from "http://wiki.openlp.org/Scratchpad:Layer_Mechanism"

Category: Scratchpad

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