#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
Created on 2020/11/12
@author: Irony
@site: https://pyqt.site , https://github.com/PyQt5
@email: 892768447@qq.com
@file: ImageView
@description: 图片查看控件，支持移动、放大、缩小
"""

import os

try:
    from PyQt5.QtCore import QPointF, Qt, QRectF, QSizeF
    from PyQt5.QtGui import QPainter, QColor, QImage, QPixmap
    from PyQt5.QtWidgets import QApplication, QGraphicsView, QGraphicsPixmapItem, QGraphicsScene
except ImportError:
    from PySide2.QtCore import QPointF, Qt, QRectF, QSizeF
    from PySide2.QtGui import QPainter, QColor, QImage, QPixmap
    from PySide2.QtWidgets import QApplication, QGraphicsView, QGraphicsPixmapItem, QGraphicsScene


class ImageView(QGraphicsView):
    """图片查看控件"""

    def __init__(self, *args, **kwargs):
        image = kwargs.pop('image', None)
        background = kwargs.pop('background', None)
        super(ImageView, self).__init__(*args, **kwargs)
        self.setCursor(Qt.OpenHandCursor)
        self.setBackground(background)
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setRenderHints(QPainter.Antialiasing | QPainter.HighQualityAntialiasing |
                            QPainter.SmoothPixmapTransform)
        self.setCacheMode(self.CacheBackground)
        self.setViewportUpdateMode(self.SmartViewportUpdate)
        self._item = QGraphicsPixmapItem()  # 放置图像
        self._item.setFlags(QGraphicsPixmapItem.ItemIsFocusable |
                            QGraphicsPixmapItem.ItemIsMovable)
        self._scene = QGraphicsScene(self)  # 场景
        self.setScene(self._scene)
        self._scene.addItem(self._item)
        rect = QApplication.instance().desktop().availableGeometry(self)
        self.resize(int(rect.width() * 2 / 3), int(rect.height() * 2 / 3))

        self.pixmap = None
        self._delta = 0.1  # 缩放
        self.setPixmap(image)

    def setBackground(self, color):
        """设置背景颜色
        :param color: 背景颜色
        :type color: QColor or str or GlobalColor
        """
        if isinstance(color, QColor):
            self.setBackgroundBrush(color)
        elif isinstance(color, (str, Qt.GlobalColor)):
            color = QColor(color)
            if color.isValid():
                self.setBackgroundBrush(color)

    def setPixmap(self, pixmap, fitIn=True):
        """加载图片
        :param pixmap: 图片或者图片路径
        :param fitIn: 是否适应
        :type pixmap: QPixmap or QImage or str
        :type fitIn: bool
        """
        if isinstance(pixmap, QPixmap):
            self.pixmap = pixmap
        elif isinstance(pixmap, QImage):
            self.pixmap = QPixmap.fromImage(pixmap)
        elif isinstance(pixmap, str) and os.path.isfile(pixmap):
            self.pixmap = QPixmap(pixmap)
        else:
            return
        self._item.setPixmap(self.pixmap)
        self._item.update()
        self.setSceneDims()
        if fitIn:
            self.fitInView(QRectF(self._item.pos(), QSizeF(
                self.pixmap.size())), Qt.KeepAspectRatio)
        self.update()

    def setSceneDims(self):
        if not self.pixmap:
            return
        self.setSceneRect(QRectF(QPointF(0, 0), QPointF(self.pixmap.width(), self.pixmap.height())))

    def fitInView(self, rect, flags=Qt.IgnoreAspectRatio):
        """剧中适应
        :param rect: 矩形范围
        :param flags:
        :return:
        """
        if not self.scene() or rect.isNull():
            return
        unity = self.transform().mapRect(QRectF(0, 0, 1, 1))
        self.scale(1 / unity.width(), 1 / unity.height())
        viewRect = self.viewport().rect()
        sceneRect = self.transform().mapRect(rect)
        x_ratio = viewRect.width() / sceneRect.width()
        y_ratio = viewRect.height() / sceneRect.height()
        if flags == Qt.KeepAspectRatio:
            x_ratio = y_ratio = min(x_ratio, y_ratio)
        elif flags == Qt.KeepAspectRatioByExpanding:
            x_ratio = y_ratio = max(x_ratio, y_ratio)
        self.scale(x_ratio, y_ratio)
        self.centerOn(rect.center())

    def wheelEvent(self, event):
        if event.angleDelta().y() > 0:
            self.zoomIn()
        else:
            self.zoomOut()

    def zoomIn(self):
        """放大"""
        self.zoom(1 + self._delta)

    def zoomOut(self):
        """缩小"""
        self.zoom(1 - self._delta)

    def zoom(self, factor):
        """缩放
        :param factor: 缩放的比例因子
        """
        _factor = self.transform().scale(
            factor, factor).mapRect(QRectF(0, 0, 1, 1)).width()
        if _factor < 0.07 or _factor > 100:
            # 防止过大过小
            return
        self.scale(factor, factor)


if __name__ == '__main__':
    import sys
    import cgitb

    cgitb.enable(format='text')

    app = QApplication(sys.argv)
    w = ImageView(image='Data/bg.jpg', background=Qt.black)
    w.show()
    sys.exit(app.exec_())