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| - | Drawing is used, when we want to change or enhance an existing widget. Or if we are creating a custom widget from scratch.
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| - | To do the drawing, we use the drawing API provided by the PyQt4 toolkit.
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| - | The drawing is done within the <i>paintEvent()</i> method. The drawing code is placed between the <i>begin()</i> and <i>end()</i> methods of the <i>QPainter</i> object.
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| - | == Drawing text ==
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| - | We begin with drawing some unicode text onto the window client area.
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| - | <source lang="python">
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| - | #!/usr/bin/python
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| - | # drawtext.py
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| - |
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| - | import sys
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| - | from PyQt4 import QtGui, QtCore
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| - | class DrawText(QtGui.QWidget):
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| - | def __init__(self, parent=None):
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| - | QtGui.QWidget.__init__(self, parent)
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| - | self.setGeometry(300, 300, 250, 150)
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| - | self.setWindowTitle('Draw Text')
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| - | self.text = u'\u041b\u0435\u0432 \u041d\u0438\u043a\u043e\u043b\u0430\
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| - | \u0435\u0432\u0438\u0447 \u0422\u043e\u043b\u0441\u0442\u043e\u0439: \n\
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| - | \u0410\u043d\u043d\u0430 \u041a\u0430\u0440\u0435\u043d\u0438\u043d\u0430'
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| - | def paintEvent(self, event):
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| - | paint = QtGui.QPainter()
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| - | paint.begin(self)
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| - | paint.setPen(QtGui.QColor(168, 34, 3))
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| - | paint.setFont(QtGui.QFont('Decorative', 10))
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| - | paint.drawText(event.rect(), QtCore.Qt.AlignCenter, self.text)
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| - | paint.end()
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| - | app = QtGui.QApplication(sys.argv)
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| - | dt = DrawText()
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| - | dt.show()
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| - | app.exec_()
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| - | </source>
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| - | In our example, we draw some text in azbuka. The text is vertically and horizontally aligned.
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| - | <source lang="python">
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| - | def paintEvent(self, event):
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| - | </source>
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| - | Drawing is done within a paint event.
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| - | <source lang="python">
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| - | paint = QtGui.QPainter()
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| - | paint.begin(self)
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| - | ...
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| - | paint.end()
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| - | </source>
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| - | The <i>QPainter</i> class is responsible for all the low-level painting. All the painting methods go between <i>begin()</i> and <i>end()</i> methods.
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| - | <source lang="python">
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| - | paint.setPen(QtGui.QColor(168, 34, 3))
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| - | paint.setFont(QtGui.QFont('Decorative', 10))
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| - | </source>
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| - |
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| - | Here we define pen and font, which we use to draw the text.
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| - | <source lang="python">
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| - | paint.drawText(event.rect(), QtCore.Qt.AlignCenter, self.text)
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| - | </source>
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| - | The <i>drawText()</i> method actually draws text on the window.
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| - | [[image: pyqt_faq_drawtext.jpg | center]]
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| - |
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| - | == Drawing points ==
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| - | A point is the most simple graphics object, that can be drawn. It is a small spot on the window.
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| - | <source lang="python">
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| - | #!/usr/bin/python
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| - | # points.py
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| - |
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| - | import sys, random
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| - | from PyQt4 import QtGui, QtCore
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| - | class Points(QtGui.QWidget):
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| - | def __init__(self, parent=None):
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| - | QtGui.QWidget.__init__(self, parent)
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| - | self.setGeometry(300, 300, 250, 150)
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| - | self.setWindowTitle('Points')
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| - | def paintEvent(self, event):
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| - | paint = QtGui.QPainter()
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| - | paint.begin(self)
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| - | paint.setPen(QtCore.Qt.red)
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| - | size = self.size()
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| - | for i in range(1000):
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| - | x = random.randint(1, size.width()-1)
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| - | y = random.randint(1, size.height()-1)
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| - | paint.drawPoint(x, y)
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| - | paint.end()
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| - | app = QtGui.QApplication(sys.argv)
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| - | dt = Points()
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| - | dt.show()
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| - | app.exec_()
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| - | </source>
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| - | In our example, we draw randomly 1000 red points on the client area.
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| - | <source lang="python">
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| - | paint.setPen(QtCore.Qt.red)
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| - | </source>
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| - | We set the pen to red color. We use a predefined color constant.
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| - | <source lang="python">
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| - | size = self.size()
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| - | </source>
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| - | Each time we resize the window, a paint event is generated. We get the current size of the window with the <i>size()</i> method.
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| - | <source lang="python">
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| - | paint.drawPoint(x, y)
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| - | </source>
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| - | We draw the point with the <i>drawPoint()</i> method.
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| - | [[image: pyqt_faq_points.jpg | center]]
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| - | == Colors ==
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| - | A color is an object representing a combination of Red, Green, and Blue (RGB) intensity values. Valid RGB values are in the range 0 to 255. We can define a color in various ways. The most common are RGB decimal values or hexadecimal values.
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| - | We can also use an RGBA value, which stands for Red, Green, Blue, Alpha. Here we add some extra information, regarding transparency. Alpha value of 255 defines full opacity, 0 is for full transparency, eg the color is invisible.
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| - | <source lang="python">
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| - | #!/usr/bin/python
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| - | # colors.py
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| - | import sys, random
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| - | from PyQt4 import QtGui, QtCore
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| - | class Colors(QtGui.QWidget):
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| - | def __init__(self, parent=None):
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| - | QtGui.QWidget.__init__(self, parent)
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| - | self.setGeometry(300, 300, 350, 280)
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| - | self.setWindowTitle('Colors')
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| - | def paintEvent(self, event):
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| - | paint = QtGui.QPainter()
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| - | paint.begin(self)
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| - | color = QtGui.QColor(0, 0, 0)
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| - | color.setNamedColor('#d4d4d4')
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| - | paint.setPen(color)
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| - | paint.setBrush(QtGui.QColor(255, 0, 0, 80))
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| - | paint.drawRect(10, 15, 90, 60)
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| - | paint.setBrush(QtGui.QColor(255, 0, 0, 160))
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| - | paint.drawRect(130, 15, 90, 60)
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| - | paint.setBrush(QtGui.QColor(255, 0, 0, 255))
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| - | paint.drawRect(250, 15, 90, 60)
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| - | paint.setBrush(QtGui.QColor(10, 163, 2, 55))
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| - | paint.drawRect(10, 105, 90, 60)
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| - | paint.setBrush(QtGui.QColor(160, 100, 0, 255))
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| - | paint.drawRect(130, 105, 90, 60)
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| - | paint.setBrush(QtGui.QColor(60, 100, 60, 255))
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| - | paint.drawRect(250, 105, 90, 60)
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| - | paint.setBrush(QtGui.QColor(50, 50, 50, 255))
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| - | paint.drawRect(10, 195, 90, 60)
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| - | paint.setBrush(QtGui.QColor(50, 150, 50, 255))
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| - | paint.drawRect(130, 195, 90, 60)
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| - | paint.setBrush(QtGui.QColor(223, 135, 19, 255))
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| - | paint.drawRect(250, 195, 90, 60)
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| - | paint.end()
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| - | app = QtGui.QApplication(sys.argv)
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| - | dt = Colors()
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| - | dt.show()
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| - | app.exec_()
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| - | </source>
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| - | In our example, we draw 9 colored rectangles. The first row shows a red color, with different alpha values.
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| - | <source lang="python">
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| - | color = QtGui.QColor(0, 0, 0)
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| - | color.setNamedColor('#d4d4d4')
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| - | </source>
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| - | Here we define a color using hexadecimal notation.
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| - | <source lang="python">
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| - | paint.setBrush(QtGui.QColor(255, 0, 0, 80));
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| - | paint.drawRect(10, 15, 90, 60)
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| - | </source>
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| - | Here we define a brush and draw a rectangle. A <b>brush</b> is an elementary graphics object, which is used to draw the background of a shape. The <i>drawRect()</i> method accepts four parameter. The first two are x, y values on the axis. The third and fourth parameters are width and height of the rectangle. The method draws a rectangle using current pen and current brush.
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| - | [[image: pyqt_faq_colors.jpg | center]]
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| - | == QPen ==
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| - | QPen is an elementary graphics object. It is used to draw lines, curves and outlines of rectangles, ellipses, polygons or other shapes.
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| - | <source lang="python">
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| - | #!/usr/bin/python
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| - | # penstyles.py
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| - | import sys
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| - | from PyQt4 import QtGui, QtCore
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| - | class PenStyles(QtGui.QWidget):
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| - | def __init__(self, parent=None):
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| - | QtGui.QWidget.__init__(self, parent)
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| - | self.setGeometry(300, 300, 280, 270)
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| - | self.setWindowTitle('penstyles')
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| - | def paintEvent(self, event):
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| - | paint = QtGui.QPainter()
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| - | paint.begin(self)
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| - | pen = QtGui.QPen(QtCore.Qt.black, 2, QtCore.Qt.SolidLine)
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| - | paint.setPen(pen)
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| - | paint.drawLine(20, 40, 250, 40)
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| - | pen.setStyle(QtCore.Qt.DashLine)
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| - | paint.setPen(pen)
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| - | paint.drawLine(20, 80, 250, 80)
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| - | pen.setStyle(QtCore.Qt.DashDotLine)
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| - | paint.setPen(pen)
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| - | paint.drawLine(20, 120, 250, 120)
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| - | pen.setStyle(QtCore.Qt.DotLine)
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| - | paint.setPen(pen)
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| - | paint.drawLine(20, 160, 250, 160)
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| - | pen.setStyle(QtCore.Qt.DashDotDotLine)
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| - | paint.setPen(pen)
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| - | paint.drawLine(20, 200, 250, 200)
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| - | pen.setStyle(QtCore.Qt.CustomDashLine)
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| - | pen.setDashPattern([1, 4, 5, 4])
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| - | paint.setPen(pen)
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| - | paint.drawLine(20, 240, 250, 240)
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| - | paint.end()
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| - | app = QtGui.QApplication(sys.argv)
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| - | dt = PenStyles()
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| - | dt.show()
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| - | app.exec_()
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| - | </source>
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| - | In our example, we draw six lines. The lines are drawn in six different pen styles. There are five predefined pen styles.
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| - | We can create also custom pen styles. The last line is drawn using custom pen style.
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| - | <source lang="python">
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| - | pen = QtGui.QPen(QtCore.Qt.black, 2, QtCore.Qt.SolidLine)
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| - | </source>
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| - | We create a <i>QPen</i> object. The color is black. The width is set to 2 pixels, so that we can see the differences between the pen styles. The <i>QtCore.Qt.SolidLine</i> is one of the predefined pen styles.
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| - | <source lang="python">
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| - | pen.setStyle(QtCore.Qt.CustomDashLine)
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| - | pen.setDashPattern([1, 4, 5, 4])
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| - | paint.setPen(pen)
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| - | </source>
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| - | Here we define a custom pen style. We set a <i>QtCore.Qt.CustomDashLine</i> pen style and call a <i>setDashPattern()</i> method. The list of numbers defines a style. There must be an even number of numbers. Odd numbers define a dash, even numbers space. The greater the number, the greater the space or the dash. Our pattern is 1px dash 4px space 5px dash 4px space etc.
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| - | [[image: pyqt_faq_penstyles.jpg | center]]
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| - | == QBrush ==
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| - | <i>QBrush</i> is an elementary graphics object. It is used to paint the background of graphics shapes, such as rectangles, ellipses or polygons. A brush can be of three different types. A predefined brush a gradien or a texture pattern.
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| - | <source lang="python">
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| - | #!/usr/bin/python
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| - | # brushes.py
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| - | import sys
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| - | from PyQt4 import QtGui, QtCore
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| - | class Brushes(QtGui.QWidget):
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| - | def __init__(self, parent=None):
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| - | QtGui.QWidget.__init__(self, parent)
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| - | self.setGeometry(300, 300, 355, 280)
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| - | self.setWindowTitle('Brushes')
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| - | def paintEvent(self, event):
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| - | paint = QtGui.QPainter()
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| - | paint.begin(self)
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| - | brush = QtGui.QBrush(QtCore.Qt.SolidPattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(10, 15, 90, 60)
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| - | brush.setStyle(QtCore.Qt.Dense1Pattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(130, 15, 90, 60)
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| - |
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| - | brush.setStyle(QtCore.Qt.Dense2Pattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(250, 15, 90, 60)
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| - | brush.setStyle(QtCore.Qt.Dense3Pattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(10, 105, 90, 60)
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| - | brush.setStyle(QtCore.Qt.DiagCrossPattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(10, 105, 90, 60)
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| - | brush.setStyle(QtCore.Qt.Dense5Pattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(130, 105, 90, 60)
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| - | brush.setStyle(QtCore.Qt.Dense6Pattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(250, 105, 90, 60)
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| - |
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| - | brush.setStyle(QtCore.Qt.Dense7Pattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(250, 105, 90, 60)
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| - |
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| - | brush.setStyle(QtCore.Qt.HorPattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(10, 195, 90, 60)
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| - | brush.setStyle(QtCore.Qt.VerPattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(130, 195, 90, 60)
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| - |
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| - | brush.setStyle(QtCore.Qt.BDiagPattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(250, 195, 90, 60)
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| - |
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| - | paint.end()
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| - | app = QtGui.QApplication(sys.argv)
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| - | dt = Brushes()
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| - | dt.show()
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| - | app.exec_()
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| - | </source>
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| - |
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| - | In our example, we draw six different rectangles.
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| - |
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| - | <source lang="python">
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| - | brush = QtGui.QBrush(QtCore.Qt.SolidPattern)
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| - | paint.setBrush(brush)
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| - | paint.drawRect(10, 15, 90, 60)
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| - | </source>
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| - |
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| - | We define a brush object. Set it to the painter object. And draw the rectangle calling the <i>drawRect()</i> method.
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| - |
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| - | [[image: pyqt_faq_brushes.jpg | center]]
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| - | [[Категория:Qt]]
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| - | [[Категория:Python]]
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