让我们考虑这个小片段:

import sys
from PyQt5 import QtWidgets
from PyQt5 import QtCore
from PyQt5 import QtGui
from PyQt5.QtWidgets import QMenu
from PyQt5.QtGui import QKeySequence
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QCursor


def create_action(parent, text, slot=None,
                  shortcut=None, shortcuts=None, shortcut_context=None,
                  icon=None, tooltip=None,
                  checkable=False, checked=False):
    action = QtWidgets.QAction(text, parent)

    if icon is not None:
        action.setIcon(QIcon(':/%s.png' % icon))
    if shortcut is not None:
        action.setShortcut(shortcut)
    if shortcuts is not None:
        action.setShortcuts(shortcuts)
    if shortcut_context is not None:
        action.setShortcutContext(shortcut_context)
    if tooltip is not None:
        action.setToolTip(tooltip)
        action.setStatusTip(tooltip)
    if checkable:
        action.setCheckable(True)
    if checked:
        action.setChecked(True)
    if slot is not None:
        action.triggered.connect(slot)

    return action


class Settings():

    WIDTH = 20
    HEIGHT = 15
    NUM_BLOCKS_X = 10
    NUM_BLOCKS_Y = 14


class QS(QtWidgets.QGraphicsScene):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        width = Settings.NUM_BLOCKS_X * Settings.WIDTH
        height = Settings.NUM_BLOCKS_Y * Settings.HEIGHT
        self.setSceneRect(0, 0, width, height)
        self.setItemIndexMethod(QtWidgets.QGraphicsScene.NoIndex)


class QV(QtWidgets.QGraphicsView):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.view_menu = QMenu(self)
        self.create_actions()

    def create_actions(self):
        act = create_action(self.view_menu, "Zoom in",
                            slot=self.on_zoom_in,
                            shortcut=QKeySequence("+"), shortcut_context=Qt.WidgetShortcut)
        self.view_menu.addAction(act)

        act = create_action(self.view_menu, "Zoom out",
                            slot=self.on_zoom_out,
                            shortcut=QKeySequence("-"), shortcut_context=Qt.WidgetShortcut)
        self.view_menu.addAction(act)
        self.addActions(self.view_menu.actions())

    def on_zoom_in(self):
        if not self.scene():
            return

        self.scale(1.5, 1.5)

    def on_zoom_out(self):
        if not self.scene():
            return

        self.scale(1.0 / 1.5, 1.0 / 1.5)

    def drawBackground(self, painter, rect):
        gr = rect.toRect()
        start_x = gr.left() + Settings.WIDTH - (gr.left() % Settings.WIDTH)
        start_y = gr.top() + Settings.HEIGHT - (gr.top() % Settings.HEIGHT)
        painter.save()
        painter.setPen(QtGui.QColor(60, 70, 80).lighter(90))
        painter.setOpacity(0.7)

        for x in range(start_x, gr.right(), Settings.WIDTH):
            painter.drawLine(x, gr.top(), x, gr.bottom())

        for y in range(start_y, gr.bottom(), Settings.HEIGHT):
            painter.drawLine(gr.left(), y, gr.right(), y)

        painter.restore()

        super().drawBackground(painter, rect)


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    a = QS()
    b = QV()
    b.setScene(a)
    # b.resize(800,600)
    b.show()
    sys.exit(app.exec_())

如果我们运行它，我们可以看到网格的数字 block 是正确的，正如指定的那样，它是 8x10:

现在，假设我设置了 NUM_BLOCKS_X=3 和 NUM_BLOCKS_Y=2，输出将是这个:

错了!我绝对不希望那样，我希望 QGraphicsView 能够适本地缩小到我指定的网格设置。

第一个问题:我怎样才能做到这一点？

我想知道的另一件事是，让我们考虑网格为 10x8 的已发布代码段，然后让我们将 QGraphicsWidget 的大小调整为 800x600，输出将是:

但我想知道如何只绘制 QGraphicsScene 区域。现在我在 drawBackground 中使用 rect。

所以我的第二个问题是:如何只在 QGraphicsScene 的区域内绘制网格？

主要问题之一出现在我缩小时，在那种情况下我只想看到 QGraphicsScene 的大小，因为我将只在那个区域添加项目，我们称它为“可绘制”区域。如您所见，现在它正在“不可绘制”区域绘制网格线，这真的很令人困惑

最佳答案

我会像这样在场景中绘制网格:

class QS(QtWidgets.QGraphicsScene):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        width = Settings.NUM_BLOCKS_X * Settings.WIDTH
        height = Settings.NUM_BLOCKS_Y * Settings.HEIGHT
        self.setSceneRect(0, 0, width, height)
        self.setItemIndexMethod(QtWidgets.QGraphicsScene.NoIndex)

        for x in range(0,Settings.NUM_BLOCKS_X+1):
            xc = x * Settings.WIDTH
            self.addLine(xc,0,xc,height)

        for y in range(0,Settings.NUM_BLOCKS_Y+1):
            yc = y * Settings.HEIGHT
            self.addLine(0,yc,width,yc)

编辑: 额外的可见性/不透明度功能:

class QS(QtWidgets.QGraphicsScene):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.lines = []

        self.draw_grid()
        self.set_opacity(0.3)
        #self.set_visible(False)
        #self.delete_grid()

    def draw_grid(self):
        width = Settings.NUM_BLOCKS_X * Settings.WIDTH
        height = Settings.NUM_BLOCKS_Y * Settings.HEIGHT
        self.setSceneRect(0, 0, width, height)
        self.setItemIndexMethod(QtWidgets.QGraphicsScene.NoIndex)

        pen = QPen(QColor(255,0,100), 1, Qt.SolidLine)

        for x in range(0,Settings.NUM_BLOCKS_X+1):
            xc = x * Settings.WIDTH
            self.lines.append(self.addLine(xc,0,xc,height,pen))

        for y in range(0,Settings.NUM_BLOCKS_Y+1):
            yc = y * Settings.HEIGHT
            self.lines.append(self.addLine(0,yc,width,yc,pen))

    def set_visible(self,visible=True):
        for line in self.lines:
            line.setVisible(visible)

    def delete_grid(self):
        for line in self.lines:
            self.removeItem(line)
        del self.lines[:]

    def set_opacity(self,opacity):
        for line in self.lines:
            line.setOpacity(opacity)

需要添加导入:from PyQt5.QtGui import QPen, QColor

编辑 2: 在场景中绘制一个矩形:

def draw_insert_at_marker(self):
    w = Settings.WIDTH * 3
    h = Settings.HEIGHT

    r = QRectF(7 * Settings.WIDTH, 7 * Settings.HEIGHT, w, h)
    gradient = QLinearGradient(r.topLeft(), r.bottomRight())
    gradient.setColorAt(1, QColor(255, 255, 255, 0))
    gradient.setColorAt(0, QColor(255, 255, 255, 127))
    rect = self.addRect(r, Qt.white, gradient)

关于python - 如何在 PyQt 上绘制合适的网格？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39614777/