如何在PyQt上绘制一个合适的网格？

Question

让我们考虑一下这个小片段:

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块是正常的,如规定它是8x10:

现在,让我们说,我设置NUM_BLOCKS_X=3和NUM_BLOCKS_Y=2,输出将是这样:

那是错的!我绝对不希望这样,我希望QGraphicsView能够正确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的已发布片段然后让我们将QGraphicsWidget调整为800x600,输出将为:

但我想知道我如何才能绘制QGraphicsScene区域.现在我rect在drawBackground中使用.

所以我的第二个问题是:我怎样才能在QGraphicsScene的区域内绘制网格？

当我缩小时出现一个主要问题,在这种情况下,我只想看到QGraphicsScene的大小,因为我将仅在该区域添加项目,让我们称之为"可绘制"区域.正如您所看到的,现在它在"不可绘制"区域上绘制网格线,这确实令人困惑

Answer 1

我将在场景中绘制网格，如下所示：

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： 其他可见性/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)

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

EDIT2： 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)