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问PyQt5 QGraphicsView绘图分辨率
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Stack Overflow用户

提问于 2022-09-11 00:16:30

回答 1查看 149关注 0票数 3

我是Qt的新手，我正在尝试使用QGraphicsScene和QGraphicsView开发一个油漆应用程序。我发现的唯一绘制方法是在QGraphicsScene上mouseMoveEvent上添加圆圈和线条。它工作得很好，但是有没有一种方法可以像在FabricJS中那样绘制(当添加的项具有与图像相同的分辨率时)？

PyQt绘图：

fabricJS绘图：

我的代码：

import sys
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *


class QDMWorkingAreaScene(QGraphicsScene):
    def __init__(self, parent=None):
        super().__init__(parent)
        self._color_background = QColor("#393939")

        self.textItems = []
        self.drawingItems = []

        self.empty = True
        self.mainImage = QGraphicsPixmapItem()
        self.mainImage.setTransformationMode(Qt.SmoothTransformation)
        self.dirtySpeechBubbles = []
        self.setBackgroundBrush(self._color_background)


    def setImage(self, pixmap=None):
        if pixmap and not pixmap.isNull():
            self.empty = False
            self.mainImage.setPixmap(pixmap)
        else:
            self.empty = True
            self.mainImage.setPixmap(QPixmap())
        self.addItem(self.mainImage)
        #self.fitInView()

    def hasPhoto(self):
        return not self.empty

    def drawCircle(self, x, y, brushSize, pen, brush):
        self.drawingItems.append(self.addEllipse(x, y, brushSize, brushSize, pen, brush))
        print(len(self.drawingItems))

    def drawLine(self, start_x, start_y, x, y, pen):
        self.drawingItems.append(self.addLine(start_x, start_y, x, y, pen))
        print(len(self.drawingItems))


class QDMGraphicsView(QGraphicsView):
    def __init__(self, grScene, parent = None):
        super().__init__(parent)
        self.empty = True

        #brush drawing settings
        self.drawingMode = True
        self.brushSize = 10
        self.brushColor = Qt.black
        self.lastPoint = QPoint()
        self.brush_line_pen = QPen(self.brushColor, self.brushSize, Qt.SolidLine, Qt.RoundCap)

        #scene settings
        self.grScene = grScene
        self.initUI()
        self.setScene(self.grScene)

        #pan settings
        self.setDragMode(QGraphicsView.RubberBandDrag)
        self._isPanning = False
        self._mousePressed = False

        #zoom settings
        self.zoomInFactor = 1.25
        self.zoomOutFactor = 0.8
        self.zoomClamp = False
        self.zoom = 10
        self.zoomStep = 1
        self.zoomRange = [0, 20]
        if self.drawingMode:
            self.brush = self.grScene.addEllipse(0, 0, self.brushSize, self.brushSize, QPen(Qt.NoPen), self.brushColor)
            self.brush.setFlag(QGraphicsItem.ItemIsMovable)
            self.brush.setZValue(100)

    def initUI(self):
        self.setRenderHints(QPainter.Antialiasing | QPainter.HighQualityAntialiasing | QPainter.TextAntialiasing | QPainter.SmoothPixmapTransform)
        self.setViewportUpdateMode(QGraphicsView.FullViewportUpdate)

    def setMainImage(self, pixmapItem):
        self.grScene.setImage(pixmapItem)

    def mousePressEvent(self,  event):
        if self.drawingMode and (event.button() == Qt.LeftButton):
            x = self.mapToScene(event.pos()).x()
            y = self.mapToScene(event.pos()).y()
            self.grScene.drawCircle(x - self.brushSize / 2, y - self.brushSize / 2, self.brushSize, QPen(Qt.NoPen), self.brushColor)
            self.lastPoint = self.mapToScene(event.pos())
        elif event.button() == Qt.LeftButton:
            self._mousePressed = True
            if self._isPanning:
                self.setCursor(Qt.ClosedHandCursor)
                self._dragPos = event.pos()
                event.accept()
            else:
                super(QDMGraphicsView, self).mousePressEvent(event)

    def mouseMoveEvent(self, event):
        if self.drawingMode:
            x = self.mapToScene(event.pos()).x()
            y = self.mapToScene(event.pos()).y()
            self.brush.setPos(x - self.brushSize / 2, y - self.brushSize / 2)
        if(event.buttons() & Qt.LeftButton) & self.drawingMode:
            x = self.mapToScene(event.pos()).x()
            y = self.mapToScene(event.pos()).y()
            self.grScene.drawLine(self.lastPoint.x(), self.lastPoint.y(), x, y, self.brush_line_pen)
            self.lastPoint = self.mapToScene(event.pos())

        elif self._mousePressed and self._isPanning:
            newPos = event.pos()
            diff = newPos - self._dragPos
            self._dragPos = newPos
            self.horizontalScrollBar().setValue(self.horizontalScrollBar().value() - diff.x())
            self.verticalScrollBar().setValue(self.verticalScrollBar().value() - diff.y())
            event.accept()
        else:
            super(QDMGraphicsView, self).mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            if event.modifiers() & Qt.ControlModifier:
                self.setCursor(Qt.OpenHandCursor)
            else:
                self._isPanning = False
                self.setCursor(Qt.ArrowCursor)
            self._mousePressed = False
        super(QDMGraphicsView, self).mouseReleaseEvent(event)

    def keyPressEvent(self, event):
        if event.key() == Qt.Key_Control and not self._mousePressed:
            self._isPanning = True
            self.setCursor(Qt.OpenHandCursor)
        else:
            super(QDMGraphicsView, self).keyPressEvent(event)

    def keyReleaseEvent(self, event):
        if event.key() == Qt.Key_Control:
            if not self._mousePressed:
                self._isPanning = False
                self.setCursor(Qt.ArrowCursor)
        elif event.key() == Qt.Key_Delete:
            self.deleteSelected()
        else:
            super(QDMGraphicsView, self).keyPressEvent(event)

    def deleteSelected(self):
        for item in self.grScene.selectedItems():
            self.grScene.removeItem(item)

    def getZoomStep(self, mode):
        if mode == "+":
            if self.zoom + self.zoomStep not in range(self.zoomRange[0], self.zoomRange[1]):
                return self.zoom, 1
            else:
                return self.zoom + self.zoomStep, self.zoomInFactor
        elif mode == "-":
            if self.zoom - self.zoomStep not in range(self.zoomRange[0], self.zoomRange[1]):
                return self.zoom, 1
            else:
                return self.zoom - self.zoomStep, self.zoomOutFactor
        return 10, 1

    def wheelEvent(self, event):
        if event.angleDelta().y() > 0:
            self.zoom, zoomFactor = self.getZoomStep("+")
        else:
            self.zoom, zoomFactor = self.getZoomStep("-")
        self.scale(zoomFactor, zoomFactor)

    def fitInView(self, scale=True):
        rect = QRectF(self.grScene.mainImage.pixmap().rect())
        if not rect.isNull():
            self.setSceneRect(rect)
            if self.grScene.hasPhoto():
                unity = self.transform().mapRect(QRectF(0, 0, 1, 1))
                self.scale(1 / unity.width(), 1 / unity.height())
            self.zoom = 5

class WorkingArea(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.initUI()

    def loadImage(self):
        self.view.setMainImage(QPixmap('roi.jpg'))

    def initUI(self):
        self.layout = QVBoxLayout()
        self.layout.setContentsMargins(0, 0, 0, 0)
        self.setLayout(self.layout)
        self.grScene = QDMWorkingAreaScene()
        self.view = QDMGraphicsView(self.grScene, self)
        self.layout.addWidget(self.view)
        gl = QOpenGLWidget()
        gl.setMouseTracking(True)
        format = QSurfaceFormat()
        format.setSamples(4)
        gl.setFormat(format)
        self.view.setViewport(gl)
        self.setWindowTitle("AutoMangaCleaner")
        self.loadImage()
        self.show()
        #self.showMaximized()

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

    window = WorkingArea()

    sys.exit(app.exec_())

编辑:我最近发现了另一种绘画方法：

from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import sys


class Canvas(QGraphicsPixmapItem):
    def __init__(self, image=None):
        super().__init__()
        self.last_pos = QPoint()

    def setImage(self, image):
        self.pixmap = image
        self.pixmap_clone = self.pixmap.copy()
        self.last_pos = QPoint()
        self.setPixmap(self.pixmap)

    def mousePressEvent(self,  event):
        pos = self.mapToParent(event.pos())
        p = QPainter(self.pixmap_clone)
        p.setBrush(Qt.black)
        p.drawEllipse(pos, 5, 5)
        self.last_pos = pos
        self.setPixmap(self.pixmap_clone)

    def mouseMoveEvent(self, event):
        pos = self.mapToScene(event.pos())
        if(event.buttons() & Qt.LeftButton):
            p = QPainter(self.pixmap_clone)
            p.setPen(QPen(Qt.black, 10, Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
            p.drawLine(self.last_pos, event.pos())
            self.last_pos = pos
            self.setPixmap(self.pixmap_clone)



class QDMWorkingAreaScene(QGraphicsScene):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.empty = True
        self._color_background = QColor("#393939")
        self.mainImage = Canvas()
        self.mainImage.setTransformationMode(Qt.SmoothTransformation)
        self.dirtySpeechBubbles = []
        self.setBackgroundBrush(self._color_background)

    def mouseMoveEvent(self, event):
        super().mouseMoveEvent(event)

    def setImage(self, pixmap=None):
        if pixmap and not pixmap.isNull():
            self.empty = False
            self.mainImage.setImage(pixmap)
        else:
            self.empty = True
            self.mainImage.setPixmap(QPixmap())
        self.addItem(self.mainImage)
        #self.fitInView()

    def hasPhoto(self):
        return not self.empty


class QDMGraphicsView(QGraphicsView):
    def __init__(self, grScene, parent = None):
        super().__init__(parent)

        self.empty = True
        self.photo = QGraphicsPixmapItem()

        #text settings
        #fonts, color, outline etc.

        #brush drawing settings
        #self.brush = QGraphicsEllipseItem
        self.drawingMode = True
        self.is_drawing = True
        self.brushSize = 10
        self.brushColor = Qt.black
        self.lastPoint = QPoint()
        self.brush_line_pen = QPen(self.brushColor, self.brushSize, Qt.SolidLine, Qt.RoundCap)
        # self.brush = self.grScene.addEllipse(0, 0, self.brushSize, self.brushSize, QPen(Qt.NoPen), self.brushColor)
        #scene settings
        self.grScene = grScene
        self.initUI()
        self.setScene(self.grScene)

        #pan settings
        self.setDragMode(QGraphicsView.RubberBandDrag)
        self.setDragMode(QGraphicsView.NoDrag)
        self._isPanning = False
        self._mousePressed = False

        #zoom settings
        self.zoomInFactor = 1.25
        self.zoomOutFactor = 0.8
        self.zoomClamp = False
        self.zoom = 10
        self.zoomStep = 1
        self.zoomRange = [0, 20]
        if self.drawingMode:
            self.setDragMode(QGraphicsView.NoDrag)
            self.brush = self.grScene.addEllipse(0, 0, self.brushSize, self.brushSize, QPen(Qt.NoPen), self.brushColor)
            self.brush.setAcceptedMouseButtons(Qt.NoButton)
            self.brush.setFlag(QGraphicsItem.ItemIsMovable)
            self.brush.setZValue(100)

    def initUI(self):
        self.setRenderHints(QPainter.Antialiasing | QPainter.HighQualityAntialiasing | QPainter.TextAntialiasing | QPainter.SmoothPixmapTransform)
        self.setViewportUpdateMode(QGraphicsView.FullViewportUpdate)

        #self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        #self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)


    def setMainImage(self, pixmapItem):
        self.grScene.setImage(pixmapItem)
        self.fitInView()

    def mousePressEvent(self,  event):
        #print("view pos:", self.mapToScene(event.pos()))
        if self.drawingMode and (event.button() == Qt.LeftButton):
            super(QDMGraphicsView, self).mousePressEvent(event)
            #self.grScene.mainImage.mousePressEvent(event)
        if event.button() == Qt.LeftButton:
            self._mousePressed = True
            if self._isPanning:
                self.setCursor(Qt.ClosedHandCursor)
                self._dragPos = event.pos()
                event.accept()
            else:
                super(QDMGraphicsView, self).mousePressEvent(event)


    def mouseMoveEvent(self, event):
        if self.drawingMode:
            x = self.mapToScene(event.pos()).x()
            y = self.mapToScene(event.pos()).y()
            self.brush.setPos(x - self.brushSize / 2, y - self.brushSize / 2)
        if(event.buttons() == Qt.LeftButton) & self.drawingMode:
            super(QDMGraphicsView, self).mouseMoveEvent(event)
        elif self._mousePressed and self._isPanning:
            newPos = event.pos()
            diff = newPos - self._dragPos
            self._dragPos = newPos
            self.horizontalScrollBar().setValue(self.horizontalScrollBar().value() - diff.x())
            self.verticalScrollBar().setValue(self.verticalScrollBar().value() - diff.y())
            event.accept()
        else:
            super(QDMGraphicsView, self).mouseMoveEvent(event)
        super().mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            if event.modifiers() == Qt.ControlModifier:
                self.setCursor(Qt.OpenHandCursor)
            else:
                self._isPanning = False
                self.setCursor(Qt.ArrowCursor)
            self._mousePressed = False
        super(QDMGraphicsView, self).mouseReleaseEvent(event)

    def keyPressEvent(self, event):
        if event.key() == Qt.Key_Control and not self._mousePressed:
            self.drawingMode = False
            self._isPanning = True
            self.setCursor(Qt.OpenHandCursor)
        else:
            super(QDMGraphicsView, self).keyPressEvent(event)

    def keyReleaseEvent(self, event):
        if event.key() == Qt.Key_Control:
            if self.is_drawing:
                self.drawingMode = True
            if not self._mousePressed:
                self._isPanning = False
                self.setCursor(Qt.ArrowCursor)
        elif event.key() == Qt.Key_Delete:
            self.deleteSelected()
        else:
            super(QDMGraphicsView, self).keyPressEvent(event)

    def deleteSelected(self):
        for item in self.grScene.selectedItems():
            self.grScene.removeItem(item)

    def wheelEvent(self, event):
        if event.angleDelta().y() > 0:
            step = self.zoomStep
            fact = self.zoomInFactor
        else:
            step = -self.zoomStep
            fact = self.zoomOutFactor
        zoom = max(self.zoomRange[0], min(self.zoom + step, self.zoomRange[1]))
        if zoom != self.zoom:
            self.zoom = zoom
            self.scale(fact, fact)

    def fitInView(self, scale=True):
        rect = QRectF(self.grScene.mainImage.pixmap.rect())
        if not rect.isNull():
            self.setSceneRect(rect)
            if self.grScene.hasPhoto():
                unity = self.transform().mapRect(QRectF(0, 0, 1, 1))
                self.scale(1 / unity.width(), 1 / unity.height())
            self.zoom = 5


class WorkingArea(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.initUI()

    def loadImage(self):
        self.view.setMainImage(QPixmap('roi.jpg'))

    def initUI(self):
        self.setGeometry(0, 0, 800, 800)
        self.layout = QVBoxLayout()
        self.layout.setContentsMargins(0, 0, 0, 0)
        self.setLayout(self.layout)

        self.grScene = QDMWorkingAreaScene()

        self.view = QDMGraphicsView(self.grScene, self)
        self.layout.addWidget(self.view)
        gl = QOpenGLWidget()
        gl.setMouseTracking(True)
        format = QSurfaceFormat()
        format.setSamples(4)
        gl.setFormat(format)
        self.view.setViewport(gl)
        self.setWindowTitle("AutoMangaCleaner")
        self.loadImage()
        self.show()
        #self.view.setFocus()

    def mouseMoveEvent(self, event):
        self.view.mouseMoveEvent()


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

    window = WorkingArea()

    sys.exit(app.exec_())

python

pyqt5

qgraphicsview

qgraphicsscene

回答 1

Stack Overflow用户

回答已采纳

发布于 2022-09-11 16:51:23

这是因为形状项目总是矢量的，所以没有“分辨率”的概念:无论大小，圆总是一个圆，而不是使用像素概念的光栅图像。

由于用于缩放的平滑转换类似于模糊效果，因此有可能对项目使用QGraphicsBlurEffect，blurRadius值为1 (如"1像素“中的值)。

虽然您可以对每个项目设置效果，但出于性能原因，这并不是一个好的选择:您应该将所有这些项分组到一个单独的父项中。Qt提供了可以通过使用QGraphicsGroupItem轻松创建的scene.createItemGroup()类。

class QDMWorkingAreaScene(QGraphicsScene):
    def __init__(self, parent=None):
        # ...
        self.drawingGroup = self.createItemGroup([])
        blur = QGraphicsBlurEffect(blurRadius=1)
        self.drawingGroup.setGraphicsEffect(blur)
        self.drawingGroup.setZValue(100)

    # ...

    def drawCircle(self, x, y, brushSize, pen, brush):
        item = QGraphicsEllipseItem(
            round(x), round(y), 
            brushSize, brushSize, 
            self.drawingGroup
        )
        item.setPen(pen)
        item.setBrush(brush)

    def drawLine(self, start_x, start_y, x, y, pen):
        item = QGraphicsLineItem(
            round(start_x), round(start_y), 
            round(x), round(y), 
            self.drawingGroup
        )
        item.setPen(pen)

考虑一下，当您要导出图像时，您可能希望暂时禁用图形效果。

进一步说明：

同样，出于优化的原因，您应该在绘制连续线时使用QPainterPathItem，并在鼠标释放之前向其路径添加线条，然后在鼠标再次按下时创建一个新项；
在创建椭圆或启动新的行/路径时，您应该进行区分，否则您将始终两者兼备；
由于您可能希望始终使用非十进制值(这是使用原语构造函数addEllipse()时所发生的情况，因为它们总是使用整数值)，因此您应该始终围绕场景位置，就像上面所做的那样；或者，只需再次将场景点转换为QPoint和QPointF：

    scenePos = QPointF(self.mapToScene(event.pos()).toPoint())
    self.grScene.drawLine(self.lastPoint, scenePos, self.brush_line_pen)
    self.lastPoint = scenePos

为“画笔光标”使用图形项具有重要的副作用:首先，每当它靠近场景的边缘时，场景将增加其边框，因此您可能应该在self.setSceneRect(self.mainImage.sceneBoundingRect())中使用setImage() (而不是在fitInView()中)；然后，如果鼠标移动得非常快，则该项目仍将在场景的某个地方可见:考虑在视图的enterEvent和leaveEvent中切换其可见性；
如果您不够小心的话，为鼠标按钮和键使用标志可能会很危险；请使用正确的事件属性，这更简单、更清晰：

    if event.buttons() == Qt.LeftButton:
        # left mouse button pressed *during* a mouse move event
    if event.modifiers() == Qt.ControlModifier:
        # Ctrl key pressed

简化缩放功能：

    def wheelEvent(self, event):
        if event.angleDelta().y() > 0:
            step = self.zoomStep
            fact = self.zoomInFactor
        else:
            step = -self.zoomStep
            fact = self.zoomOutFactor
        zoom = max(self.zoomRange[0], min(self.zoom + step, self.zoomRange[1]))
        if zoom != self.zoom:
            self.zoom = zoom
            self.scale(fact, fact)

票数 1

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/73676005

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