Question

让这个小片段：

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
from PyQt5.QtWidgets import QGraphicsObject
from PyQt5.QtCore import QRectF
from PyQt5.QtGui import QBrush
from PyQt5.QtCore import QPoint
from PyQt5.QtGui import QLinearGradient
from PyQt5.QtGui import QColor
from PyQt5.QtGui import QPen
from PyQt5.QtGui import QPainter
from PyQt5.QtWidgets import QGraphicsTextItem
from PyQt5.QtWidgets import QGraphicsItem


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 = 32
    NUM_BLOCKS_Y = 16


class CI(QGraphicsTextItem):

    def __init__(self, text, pos):
        QGraphicsTextItem.__init__(self)

        self.content = text
        self.setPlainText(text)

        self.setPos(pos)
        self.setTextInteractionFlags(Qt.TextEditorInteraction)
        self.setDefaultTextColor(Qt.black)
        self.setFlags(
            self.flags() | QGraphicsItem.ItemIsMovable | QGraphicsItem.ItemIsSelectable)
        self.setZValue(-1)

    def paint(self, painter, option, widget):
        painter.save()
        painter.setBrush(QBrush(Qt.white))
        painter.drawRect(self.boundingRect())
        painter.restore()

        super().paint(painter, option, widget)

    def keyPressEvent(self, event):
        super().keyPressEvent(event)
        self.content = self.toPlainText()

    def focusInEvent(self, event):
        self.scene().writing_comment = True
        # self.setPlainText(self.content)
        # print("Focusinevent")

    def focusOutEvent(self, event):
        self.scene().writing_comment = False
        # self.setHtml(self.content)
        # print("FocusOutevent")

    def contextMenuEvent(self, scme):
        super().contextMenuEvent(scme)


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)

        pos = QPoint(
            5 * Settings.WIDTH,
            2 * Settings.HEIGHT
        )
        content = """<!DOCTYPE html>
<html>
<body>

<h1>This is heading 1</h1>
<h2>This is heading 2</h2>
<h3>This is heading 3</h3>
<h4>This is heading 4</h4>
<h5>This is heading 5</h5>
<h6>This is heading 6</h6>

</body>
</html>
"""
        self.addItem(CI(content, pos))


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):
        painter.setRenderHint(QPainter.Antialiasing, True)

        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()

        for index, x in enumerate(range(start_x, gr.right(), Settings.WIDTH)):
            if index == Settings.NUM_BLOCKS_X:
                painter.setPen(QtGui.QColor(255, 70, 80).lighter(90))
                painter.setOpacity(0.7)
            else:
                painter.setPen(QtGui.QColor(60, 70, 80).lighter(90))
                painter.setOpacity(0.7)

            painter.drawLine(x, gr.top(), x, gr.bottom())

        for index, y in enumerate(range(start_y, gr.bottom(), Settings.HEIGHT)):
            if index == Settings.NUM_BLOCKS_Y:
                painter.setPen(QtGui.QColor(255, 70, 80).lighter(90))
                painter.setOpacity(0.7)
            else:
                painter.setPen(QtGui.QColor(60, 70, 80).lighter(90))
                painter.setOpacity(0.7)

            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)
    print(b.mapToScene(b.rect()))
    b.show()
    sys.exit(app.exec_())

如果我们运行它，我们会看到它正在创建一个带有网格和QGraphicsTextItem的小场景，如下所示：

我试图弄清楚的是如何在网格交叉点上捕捉QGraphicsTextItem 每次移动它或调整其大小（当我写一些文字时），我该怎样保证？这里有一张小图片可以更好地解释我想要的东西：

Answer 1

要设置QGraphicsTextItem的新宽度和高度，您可以覆盖boundingRect()，setPos()可以使用任何适当的事件，例如MouseReleaseEvent或MouseMoveEvent ，并计算上一个pos()的下一个左上角网格交叉点：

class CI(QGraphicsTextItem):

    def __init__(self, text, pos):
        QGraphicsTextItem.__init__(self)

        self.content = text
        self.setPlainText(text)

        self.setPos(pos)
        self.setTextInteractionFlags(Qt.TextEditorInteraction)
        self.setDefaultTextColor(Qt.black)
        self.setFlags(
            self.flags() | QGraphicsItem.ItemIsMovable | QGraphicsItem.ItemIsSelectable)
        self.setZValue(-1)

    def boundingRect(self):     
        # get the original width and height of boundingrect
        br = QGraphicsTextItem.boundingRect(self)
        brw = br.width()
        brh = br.height()
        # new width and height in "blocks"
        wblocks = int(brw/Settings.WIDTH) + 1
        hblocks = int(brh/Settings.HEIGHT) + 1
        w = wblocks*Settings.WIDTH
        h = hblocks*Settings.HEIGHT
        return QtCore.QRectF(0, 0, w, h)

    def mouseReleaseEvent(self, event):                         
        # QGraphicsItem.mouseReleaseEvent(self, event)
        QGraphicsTextItem.mouseReleaseEvent(self, event)
        self.setGridIntersection(self.pos())

    def mouseMoveEvent(self, event):
        QGraphicsTextItem.mouseMoveEvent(self, event)
        self.setGridIntersection(self.pos())

    def setGridIntersection(self, pos):
        # get the next grid intersection top left of items top-left corner
        grid_x = int(pos.x()/Settings.WIDTH)                        
        grid_y = int(pos.y()/Settings.HEIGHT)
        self.setPos(grid_x*Settings.WIDTH, grid_y*Settings.HEIGHT)

    def paint(self, painter, option, widget):
        painter.save()
        painter.setBrush(QBrush(Qt.white))
        painter.drawRect(self.boundingRect())
        painter.restore()

        super().paint(painter, option, widget)

    def keyPressEvent(self, event):
        super().keyPressEvent(event)
        self.content = self.toPlainText()

    def focusInEvent(self, event):
        self.scene().writing_comment = True
        # self.setPlainText(self.content)
        # print("Focusinevent")

    def focusOutEvent(self, event):
        self.scene().writing_comment = False
        # self.setHtml(self.content)
        # print("FocusOutevent")

    def contextMenuEvent(self, scme):
        super().contextMenuEvent(scme)

编辑01.02.17：上述解决方案仅适用于单选，单选和多选使用：

class CI(QGraphicsTextItem):

    def __init__(self, text, pos):
        QGraphicsTextItem.__init__(self)

        self.content = text
        self.setPlainText(text)

        self.setPos(pos)
        self.setTextInteractionFlags(Qt.TextEditorInteraction)
        self.setDefaultTextColor(Qt.black)
        self.setFlags(
            self.flags() | QGraphicsItem.ItemIsMovable | QGraphicsItem.ItemIsSelectable)
        self.setZValue(-1)
        self.setAcceptDrops(True)

    def boundingRect(self):
        # get the original width and height of boundingrect
        br = QGraphicsTextItem.boundingRect(self)
        brw = br.width()
        brh = br.height()
        # new width and height in "blocks"
        wblocks = int(brw / Settings.WIDTH) + 1
        hblocks = int(brh / Settings.HEIGHT) + 1
        w = wblocks * Settings.WIDTH
        h = hblocks * Settings.HEIGHT
        return QtCore.QRectF(0, 0, w, h)

    def setGridIntersection(self, pos):
        # get the next grid intersection top left of items top-left corner
        grid_x = int(pos.x() / Settings.WIDTH)
        grid_y = int(pos.y() / Settings.HEIGHT)
        self.setPos(grid_x * Settings.WIDTH, grid_y * Settings.HEIGHT)

    def paint(self, painter, option, widget):
        painter.save()
        painter.setBrush(QBrush(Qt.white))
        painter.drawRect(self.boundingRect())
        painter.restore()

        super().paint(painter, option, widget)

    def keyPressEvent(self, event):
        super().keyPressEvent(event)
        self.content = self.toPlainText()

    def focusInEvent(self, event):
        self.scene().writing_comment = True
        # self.setPlainText(self.content)
        # print("Focusinevent")

    def focusOutEvent(self, event):
        self.scene().writing_comment = False
        # self.setHtml(self.content)
        # print("FocusOutevent")

    def contextMenuEvent(self, scme):
        super().contextMenuEvent(scme)

并在课程QS中添加：

    def mouseMoveEvent(self, event):
        QtWidgets.QGraphicsScene.mouseMoveEvent(self, event)
        for i in self.selectedItems():
            if type(i) == CI:
                i.setGridIntersection(i.pos())

如何捕捉QGraphicsTextItem网格？

1 个答案: