PyQt5 第六章拖拽和绘画（四）

忘是亡心i 2023-01-12 10:27 176阅读 0赞

### 6.3.5 笔刷 ###

## 《[零基础入门玩转 PyQt5][PyQt5]》 邀请码： LWskm3AS ##

`QBrush`也是图像的一个基本元素，用来填充一些物体的背景图，比如矩形，椭圆，多边形等。有三种类型：预定义、渐变和纹理

**程序展示**

本例中，画了9个不同的矩形

import sys
    
    from PyQt5.QtWidgets import QWidget, QApplication
    from PyQt5.QtGui import QPainter, QBrush
    from PyQt5.QtCore import Qt
    
    class 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, event):
            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)
        e = Example()
        sys.exit(app.exec_())

程序预览：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pseTcxNzIxNg_size_16_color_FFFFFF_t_70_pic_center]

**代码解释**

创建笔刷对象，添加笔刷样式，然后调用`drawRect()`方法画图

brush = QBrush(Qt.SolidPattern)
    qp.setBrush(brush)
    qp.drawRect(10, 15, 90, 60)

### 6.3.6 贝塞尔曲线 ###

**程序展示**

本例中，画了一个贝塞尔曲线

import sys
    
    from PyQt5.QtWidgets import QWidget, QApplication
    from PyQt5.QtGui import QPainter, QPainterPath
    from PyQt5.QtCore import Qt
    
    class 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, event):
            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)
        e = Example()
        sys.exit(app.exec_())

程序预览：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pseTcxNzIxNg_size_16_color_FFFFFF_t_70_pic_center 1]

**代码解释**

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

path = QPainterPath()
    path.moveTo(30, 30)
    path.cubicTo(30, 30, 200, 350, 350, 30)

`drawPath()`绘制最后的图像

qp.drawPath(path)

[目录][Link 1]   [下一篇 第七章 综合篇（一）][Link 2]

[PyQt5]: https://www.lanqiao.cn/courses/3841
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pseTcxNzIxNg_size_16_color_FFFFFF_t_70_pic_center]: /images/20221119/09d86b714a284a14bc8589618858643c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pseTcxNzIxNg_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221119/c6133d8d8fc14113b2f14486c3d4236f.png
[Link 1]: https://blog.csdn.net/zly717216/article/details/113332916
[Link 2]: https://blog.csdn.net/zly717216/article/details/113330410