在PyQt中绘制具有高程和降低效果的3D矩形/多边形

Question

在Java中，您可以使用（参见https://way2java.com/awt-graphics/4891/）绘制三维矩形：

void fill3DRect(int x, int y, int width, int height, boolean raised)

这里，最后一个参数“raise”用于相对于绘图表面降低/提升3d矩形。

如何在PyQt中实现这种效果？

Answer 1

据我所知，没有内置的PyQt 3D绘制小部件/功能，因为您只能绘制2D多边形。但我们可以创建一个自定义类来模拟3D绘画。从您的Java链接reference：

Java支持3D矩形，但第三维的效果不是很明显。由于海拔较低，效果可以忽略不计。 Java设计师通过沿矩形边框绘制更亮和更暗的线条来实现3D效果。

我们可以模拟Java的3D绘图功能的效果：

void fill3DRect(int x, int y, int width, int height, boolean raised)

此方法使用上面指定的参数绘制实心3D矩形。最后一个布尔参数true表示高于绘图表面的高程，false表示蚀刻到表面。

为了在Python中获得3D效果，我们基本上可以通过使用两种颜色的颜色然后变暗并照亮某些边来做同样的事情。

from PyQt5 import QtCore, QtGui, QtWidgets
import sys

class Rectangle3D(QtWidgets.QWidget):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)

        # Elevated 3D rectangle color settings
        self.elevated_border_color = QtGui.QColor(111,211,111)
        self.elevated_fill_color = QtGui.QColor(0,255,0)
        self.elevated_pen_width = 2.5

        # Lowered 3D rectangle color settings
        self.lowered_border_color = QtGui.QColor(0,235,0)
        self.lowered_fill_color = QtGui.QColor(0,178,0)
        self.lowered_pen_width = 2.5

    def draw3DRectangle(self, x, y, w, h, raised=True):
        # Specify the border/fill colors depending on raised or lowered
        if raised:
            # Line color (border)
            self.pen = QtGui.QPen(self.elevated_border_color, self.elevated_pen_width)
            # Fill color
            self.fill = QtGui.QBrush(self.elevated_fill_color)
        else:
            # Line color (border)
            self.pen = QtGui.QPen(self.lowered_border_color, self.lowered_pen_width)
            # Fill color
            self.fill = QtGui.QBrush(self.lowered_fill_color)

        painter = QtGui.QPainter(self)

        # Draw border color of rectangle
        painter.setPen(self.pen)
        painter.setBrush(self.fill)  
        painter.drawRect(x, y, w, h)

        # Cover up the top and left sides with filled color using lines
        if raised:
            painter.setPen(QtGui.QPen(self.elevated_fill_color, self.elevated_pen_width))
        else:
            painter.setPen(QtGui.QPen(self.lowered_fill_color, self.lowered_pen_width))

        painter.drawLine(x, y, x + w, y) 
        painter.drawLine(x, y, x, y + h)

    def paintEvent(self, event):
        self.draw3DRectangle(50,50,300,150,True)
        self.draw3DRectangle(50,250,300,150,False)

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv) 

    widget = Rectangle3D()
    widget.show()

    sys.exit(app.exec_())

Answer 2

这取决于您想要使用的油漆等级：

有两种选择：

• 使用QPainter：

这种效果可以通过绘制2个移位的矩形来实现，其中背景矩形的颜色比前面的颜色更暗：

from PyQt5 import QtCore, QtGui, QtWidgets


def draw3DRect(painter, rect, color, raised=False, offset=QtCore.QPoint(4, 4)):
    if raised:
        painter.fillRect(rect.translated(offset), color.darker())
    painter.fillRect(rect, color)


class Widget(QtWidgets.QWidget):
    def paintEvent(self, event):
        painter = QtGui.QPainter(self)
        r = QtCore.QRect(
            self.width() / 4,
            self.height() / 4,
            self.width() / 2,
            self.height() / 2,
        )
        draw3DRect(painter, r, QtGui.QColor("green"), raised=True)

    def sizeHint(self):
        return QtCore.QSize(320, 240)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())

• 使用QGraphicsDropShadowEffect：

在这种情况下，QWidget和QGraphicsItem支持这种效果：

from PyQt5 import QtCore, QtGui, QtWidgets


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = QtWidgets.QWidget()
    lay = QtWidgets.QHBoxLayout(w)
    scene = QtWidgets.QGraphicsScene()
    view = QtWidgets.QGraphicsView(scene)
    rect_item = QtWidgets.QGraphicsRectItem(QtCore.QRectF(0, 0, 200, 100))
    rect_item.setBrush(QtGui.QColor("green"))
    effect_item = QtWidgets.QGraphicsDropShadowEffect(
        offset=QtCore.QPointF(3, 3), blurRadius=5
    )
    rect_item.setGraphicsEffect(effect_item)
    scene.addItem(rect_item)

    rect_widget = QtWidgets.QWidget()
    rect_widget.setFixedSize(320, 240)
    rect_widget.setStyleSheet("background-color:green;")
    effect_widget = QtWidgets.QGraphicsDropShadowEffect(
        offset=QtCore.QPointF(3, 3), blurRadius=5
    )
    rect_widget.setGraphicsEffect(effect_widget)

    lay.addWidget(view)
    lay.addWidget(rect_widget)
    w.resize(640, 480)
    w.show()
    sys.exit(app.exec_())