pyqt5——绘图

绘图PyQt5绘图系统能渲染矢量图像、位图图像和轮廓字体文本。一般会使用在修改或者提高现有组件的功能，或者创建自己的组件。使用PyQt5的绘图API进行操作。绘图由paintEvent()方法完成，绘图的代码要放在QPainter对象的begin()和end()方法之间。是低级接口。文本涂鸦我们从画一些Unicode文本开始。#!/usr/bin/python3# -- coding: utf-8 --“““ZetCode PyQt5 tutorial 欢迎加入我的QQ群923 414 804与我一起学习In this example, we draw text in Russian Cylliric.Author: Jan BodnarWebsite: zetcode.com Last edited: August 2017"““import sysfrom PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainter, QColor, QFontfrom PyQt5.QtCore import Qtclass Example(QWidget): def init(self): super().init() self.initUI() def initUI(self): self.text = " \n " self.setGeometry(300, 300, 280, 170) self.setWindowTitle(‘Drawing text’) self.show() def paintEvent(self, event): qp = QPainter() qp.begin(self) self.drawText(event, qp) qp.end() def drawText(self, event, qp): qp.setPen(QColor(168, 34, 3)) qp.setFont(QFont(‘Decorative’, 10)) qp.drawText(event.rect(), Qt.AlignCenter, self.text) if name == ‘main’: app = QApplication(sys.argv) ex = Example() sys.exit(app.exec_())写了一些文本上下居中对齐的俄罗斯Cylliric语言的文字。def paintEvent(self, event):…在绘画事件内完成绘画动作。qp = QPainter()qp.begin(self)self.drawText(event, qp)qp.end()QPainter是低级的绘画类。所有的绘画动作都在这个类的begin()和end()方法之间完成，绘画动作都封装在drawText()内部了。qp.setPen(QColor(168, 34, 3))qp.setFont(QFont(‘Decorative’, 10))为文字绘画定义了笔和字体。qp.drawText(event.rect(), Qt.AlignCenter, self.text)drawText()方法在窗口里绘制文本，rect()方法返回要更新的矩形区域。程序展示：点的绘画点是最简单的绘画了。#!/usr/bin/python3# -- coding: utf-8 --“““ZetCode PyQt5 tutorial In the example, we draw randomly 1000 red points on the window.Author: Jan BodnarWebsite: zetcode.com Last edited: August 2017"““from PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainterfrom PyQt5.QtCore import Qtimport sys, randomclass Example(QWidget): def init(self): super().init() self.initUI() def initUI(self): self.setGeometry(300, 300, 300, 190) self.setWindowTitle(‘Points’) self.show() def paintEvent(self, e): qp = QPainter() qp.begin(self) self.drawPoints(qp) qp.end() def drawPoints(self, qp): qp.setPen(Qt.red) size = self.size() for i in range(1000): x = random.randint(1, size.width()-1) y = random.randint(1, size.height()-1) qp.drawPoint(x, y) if name == ‘main’: app = QApplication(sys.argv) ex = Example() sys.exit(app.exec_())我们在窗口里随机的画出了1000个点。qp.setPen(Qt.red)设置笔的颜色为红色，使用的是预定义好的颜色。size = self.size()每次更改窗口大小，都会产生绘画事件，从size()方法里获得当前窗口的大小，然后把产生的点随机的分配到窗口的所有位置上。qp.drawPoint(x, y)drawPoint()方法绘图。程序展示：颜色颜色是一个物体显示的RGB的混合色。RBG值的范围是0~~255。我们有很多方式去定义一个颜色，最常见的方式就是RGB和16进制表示法，也可以使用RGBA，增加了一个透明度的选项，透明度值的范围是0~~1，0代表完全透明。#!/usr/bin/python3# -- coding: utf-8 --“““ZetCode PyQt5 tutorial This example draws three rectangles in three#different colours. Author: Jan BodnarWebsite: zetcode.com Last edited: August 2017"““from PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainter, QColor, QBrushimport sysclass Example(QWidget): def init(self): super().init() self.initUI() def initUI(self): self.setGeometry(300, 300, 350, 100) self.setWindowTitle(‘Colours’) self.show() def paintEvent(self, e): qp = QPainter() qp.begin(self) self.drawRectangles(qp) qp.end() def drawRectangles(self, qp): col = QColor(0, 0, 0) col.setNamedColor(’#d4d4d4’) qp.setPen(col) qp.setBrush(QColor(200, 0, 0)) qp.drawRect(10, 15, 90, 60) qp.setBrush(QColor(255, 80, 0, 160)) qp.drawRect(130, 15, 90, 60) qp.setBrush(QColor(25, 0, 90, 200)) qp.drawRect(250, 15, 90, 60) if name == ‘main’: app = QApplication(sys.argv) ex = Example() sys.exit(app.exec_())我们画出了三个颜色的矩形。color = QColor(0, 0, 0)color.setNamedColor(’#d4d4d4’)使用16进制的方式定义一个颜色。qp.setBrush(QColor(200, 0, 0))qp.drawRect(10, 15, 90, 60)定义了一个笔刷，并画出了一个矩形。笔刷是用来画一个物体的背景。drawRect()有四个参数，分别是矩形的x、y、w、h。然后用笔刷和矩形进行绘画。程序展示：QPenQPen是基本的绘画对象，能用来画直线、曲线、矩形框、椭圆、多边形和其他形状。#!/usr/bin/python3# -- coding: utf-8 --“““ZetCode PyQt5 tutorial In this example we draw 6 lines usingdifferent pen styles. Author: Jan BodnarWebsite: zetcode.com Last edited: August 2017"““from PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainter, QPenfrom PyQt5.QtCore import Qtimport sysclass Example(QWidget): def init(self): super().init() self.initUI() def initUI(self): self.setGeometry(300, 300, 280, 270) self.setWindowTitle(‘Pen styles’) self.show() def paintEvent(self, e): qp = QPainter() qp.begin(self) self.drawLines(qp) qp.end() def drawLines(self, qp): pen = QPen(Qt.black, 2, Qt.SolidLine) qp.setPen(pen) qp.drawLine(20, 40, 250, 40) pen.setStyle(Qt.DashLine) qp.setPen(pen) qp.drawLine(20, 80, 250, 80) pen.setStyle(Qt.DashDotLine) qp.setPen(pen) qp.drawLine(20, 120, 250, 120) pen.setStyle(Qt.DotLine) qp.setPen(pen) qp.drawLine(20, 160, 250, 160) pen.setStyle(Qt.DashDotDotLine) qp.setPen(pen) qp.drawLine(20, 200, 250, 200) pen.setStyle(Qt.CustomDashLine) pen.setDashPattern([1, 4, 5, 4]) qp.setPen(pen) qp.drawLine(20, 240, 250, 240) if name == ‘main’: app = QApplication(sys.argv) ex = Example() sys.exit(app.exec_())在这个例子里，我们用不同的笔画了6条直线。PyQt5有五个预定义的笔，另外一个笔的样式使我们自定义的。pen = QPen(Qt.black, 2, Qt.SolidLine)新建一个QPen对象，设置颜色黑色，宽2像素，这样就能看出来各个笔样式的区别。Qt.SolidLine是预定义样式的一种。pen.setStyle(Qt.CustomDashLine)pen.setDashPattern([1, 4, 5, 4])qp.setPen(pen)这里我们自定义了一个笔的样式。定义为Qt.CustomDashLine然后调用setDashPattern()方法。数字列表是线的样式，要求必须是个数为奇数，奇数位定义的是空格，偶数位为线长，数字越大，空格或线长越大，比如本例的就是1像素线，4像素空格，5像素线，4像素空格。程序展示：QBrushQBrush也是图像的一个基本元素。是用来填充一些物体的背景图用的，比如矩形，椭圆，多边形等。有三种类型：预定义、渐变和纹理。#!/usr/bin/python3# -- coding: utf-8 --“““ZetCode PyQt5 tutorial This example draws nine rectangles in differentbrush styles.Author: Jan BodnarWebsite: zetcode.com Last edited: August 2017"““from PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainter, QBrushfrom PyQt5.QtCore import Qtimport sysclass Example(QWidget): def init(self): super().init() self.initUI() def initUI(self): self.setGeometry(300, 300, 355, 280) self.setWindowTitle(‘Brushes’) self.show() def paintEvent(self, e): qp = QPainter() qp.begin(self) self.drawBrushes(qp) qp.end() def drawBrushes(self, qp): brush = QBrush(Qt.SolidPattern) qp.setBrush(brush) qp.drawRect(10, 15, 90, 60) brush.setStyle(Qt.Dense1Pattern) qp.setBrush(brush) qp.drawRect(130, 15, 90, 60) brush.setStyle(Qt.Dense2Pattern) qp.setBrush(brush) qp.drawRect(250, 15, 90, 60) brush.setStyle(Qt.DiagCrossPattern) qp.setBrush(brush) qp.drawRect(10, 105, 90, 60) brush.setStyle(Qt.Dense5Pattern) qp.setBrush(brush) qp.drawRect(130, 105, 90, 60) brush.setStyle(Qt.Dense6Pattern) qp.setBrush(brush) qp.drawRect(250, 105, 90, 60) brush.setStyle(Qt.HorPattern) qp.setBrush(brush) qp.drawRect(10, 195, 90, 60) brush.setStyle(Qt.VerPattern) qp.setBrush(brush) qp.drawRect(130, 195, 90, 60) brush.setStyle(Qt.BDiagPattern) qp.setBrush(brush) qp.drawRect(250, 195, 90, 60) if name == ‘main’: app = QApplication(sys.argv) ex = Example() sys.exit(app.exec_())我们画了9个不同的矩形。brush = QBrush(Qt.SolidPattern)qp.setBrush(brush)qp.drawRect(10, 15, 90, 60)创建了一个笔刷对象，添加笔刷样式，然后调用drawRect()方法画图。程序展示：贝塞尔曲线噩梦可以使用PyQt5的QPainterPath创建贝塞尔曲线。绘画路径是由许多构建图形的对象，具体表现就是一些线的形状，比如矩形，椭圆，线和曲线。#!/usr/bin/python3# -- coding: utf-8 --“““ZetCode PyQt5 tutorial This program draws a Bézier curve with QPainterPath.Author: Jan BodnarWebsite: zetcode.com Last edited: August 2017"““from PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainter, QPainterPathfrom PyQt5.QtCore import Qtimport sysclass Example(QWidget): def init(self): super().init() self.initUI() def initUI(self): self.setGeometry(300, 300, 380, 250) self.setWindowTitle(‘Bézier curve’) self.show() def paintEvent(self, e): qp = QPainter() qp.begin(self) qp.setRenderHint(QPainter.Antialiasing) self.drawBezierCurve(qp) qp.end() def drawBezierCurve(self, qp): path = QPainterPath() path.moveTo(30, 30) path.cubicTo(30, 30, 200, 350, 350, 30) qp.drawPath(path) if name == ‘main’: app = QApplication(sys.argv) ex = Example() sys.exit(app.exec_())这个示例中，我们画出了一个贝塞尔曲线。path = QPainterPath()path.moveTo(30, 30)path.cubicTo(30, 30, 200, 350, 350, 30)用QPainterPath路径创建贝塞尔曲线。使用cubicTo()方法生成，分别需要三个点：起始点，控制点和终止点。qp.drawPath(path)drawPath()绘制最后的图像。