視窗的透視變換效果
?? 當我們點擊Win10的UWP應用中的小部件時，會發現小部件會朝著滑鼠點擊位置凹陷下去，而且不同的點擊位置對應著不同的凹陷情況，看起來就好像小部件在螢屏上不只有x軸和y軸，甚至還有一個z軸，要做到這一點，其實只要對視窗進行透視變換即可，下面是對Qt的視窗和按鈕進行透視變換的效果：
具體代碼
?? 1.下面先定義一個類，它的作用是將傳入的 QPixmap 轉換為numpy 陣列，然后用 opencv 的 warpPerspective 對陣列進行透視變換，最后再將 numpy 陣列轉為 QPixmap 并回傳；
# coding:utf-8
import cv2 as cv
import numpy
from PyQt5.QtGui import QImage, QPixmap
class PixmapPerspectiveTransform:
""" 透視變換基類 """
def __init__(self, pixmap=None):
""" 實體化透視變換物件\n
Parameter
---------
src : numpy陣列 """
self.pixmap = pixmap
def setPixmap(self, pixmap: QPixmap):
""" 設定被變換的QPixmap """
self.pixmap = QPixmap
self.src=self.transQPixmapToNdarray(pixmap)
self.height, self.width = self.src.shape[:2]
# 變換前后的邊角坐標
self.srcPoints = numpy.float32(
[[0, 0], [self.width - 1, 0], [0, self.height - 1],
[self.width - 1, self.height - 1]])
def setDstPoints(self, leftTop: list, rightTop, leftBottom, rightBottom):
""" 設定變換后的邊角坐標 """
self.dstPoints = numpy.float32(
[leftTop, rightTop, leftBottom, rightBottom])
def getPerspectiveTransform(self, imWidth, imHeight, borderMode=cv.BORDER_CONSTANT, borderValue=[255, 255, 255, 0]) -> QPixmap:
""" 透視變換影像，回傳QPixmap\n
Parameters
----------
imWidth : 變換后的影像寬度\n
imHeight : 變換后的影像高度\n
borderMode : 邊框插值方式\n
borderValue : 邊框顏色
"""
# 如果是jpg需要加上一個透明通道
if self.src.shape[-1] == 3:
self.src = cv.cvtColor(self.src, cv.COLOR_BGR2BGRA)
# 透視變換矩陣
perspectiveMatrix = cv.getPerspectiveTransform(
self.srcPoints, self.dstPoints)
# 執行變換
self.dst = cv.warpPerspective(self.src, perspectiveMatrix, (
imWidth, imHeight), borderMode=borderMode, borderValue=borderValue)
# 將ndarray轉換為QPixmap
return self.transNdarrayToQPixmap(self.dst)
def transQPixmapToNdarray(self, pixmap: QPixmap):
""" 將QPixmap轉換為numpy陣列 """
width, height = pixmap.width(), pixmap.height()
channels_count = 4
image = pixmap.toImage() # type:QImage
s = image.bits().asstring(height * width * channels_count)
# 得到BGRA格式陣列
array = numpy.fromstring(s, numpy.uint8).reshape(
(height, width, channels_count))
return array
def transNdarrayToQPixmap(self, array):
""" 將numpy陣列轉換為QPixmap """
height, width, bytesPerComponent = array.shape
bytesPerLine = 4 * width
# 默認陣列維度為 m*n*4
dst = cv.cvtColor(array, cv.COLOR_BGRA2RGBA)
pix = QPixmap.fromImage(
QImage(dst.data, width, height, bytesPerLine, QImage.Format_RGBA8888))
return pix
??2.接下來就是這篇博客的主角——PerspectiveWidget，當我們的滑鼠單擊這個類實體化出來的視窗時，視窗會先通過 self.grab() 被渲染為QPixmap，然后呼叫 PixmapPerspectiveTransform 中的方法對QPixmap進行透視變換，拿到透視變換的結果后只需隱藏視窗內的小部件并通過 PaintEvent 將結果繪制到視窗上即可，雖然思路很通順，但是實際操作起來會發現對于透明背景的視窗進行透視變換時，與透明部分交界的部分會被插值上半透明的像素，對于本來就屬于深色的像素來說這沒什么，但是如果像素是淺色的就會帶來很大的視覺干擾，你會發現這些淺色部分旁邊被描上了一圈黑邊，我們先將這個影像記為img_1，img_1差不多長這個樣子，可以很明顯看出白色的文字圍繞著一圈黑色的描邊，
為了解決這個煩人的問題，我又對桌面上的視窗進行截屏，再次透視變換，注意是桌面上看到的視窗，這時的視窗肯定是會有背景的，這時的透視變換就不會存在上述問題，記這個透視變換完的影像為img_2，但實際上我們本來是不想要img_2中的背景的，所以只要將img_2中的背景替換完img_1中的透明背景，下面是具體代碼：
# coding:utf-8
import numpy as np
from PyQt5.QtCore import QPoint, Qt
from PyQt5.QtGui import QPainter, QPixmap, QScreen, QImage
from PyQt5.QtWidgets import QApplication, QWidget
from my_functions.get_pressed_pos import getPressedPos
from my_functions.perspective_transform_cv import PixmapPerspectiveTransform
class PerspectiveWidget(QWidget):
""" 可進行透視變換的視窗 """
def __init__(self, parent=None, isTransScreenshot=False):
super().__init__(parent)
self.__visibleChildren = []
self.__isTransScreenshot = isTransScreenshot
self.__perspectiveTrans = PixmapPerspectiveTransform()
self.__screenshotPix = None
self.__pressedPix = None
self.__pressedPos = None
@property
def pressedPos(self) -> str:
""" 回傳滑鼠點擊位置 """
return self.__pressedPos
def mousePressEvent(self, e):
""" 滑鼠點擊視窗時進行透視變換 """
super().mousePressEvent(e)
self.grabMouse()
pixmap = self.grab()
self.__perspectiveTrans.setPixmap(pixmap)
# 根據滑鼠點擊位置的不同設定背景封面的透視變換
self.__setDstPointsByPressedPos(getPressedPos(self,e))
# 獲取透視變換后的QPixmap
self.__pressedPix = self.__getTransformPixmap()
# 對桌面上的視窗進行截圖
if self.__isTransScreenshot:
self.__adjustTransformPix()
# 隱藏本來看得見的小部件
self.__visibleChildren = [
child for child in self.children() if hasattr(child, 'isVisible') and child.isVisible()]
for child in self.__visibleChildren:
if hasattr(child, 'hide'):
child.hide()
self.update()
def mouseReleaseEvent(self, e):
""" 滑鼠松開時顯示小部件 """
super().mouseReleaseEvent(e)
self.releaseMouse()
self.__pressedPos = None
self.update()
# 顯示小部件
for child in self.__visibleChildren:
if hasattr(child, 'show'):
child.show()
def paintEvent(self, e):
""" 繪制背景 """
super().paintEvent(e)
painter = QPainter(self)
painter.setRenderHints(QPainter.Antialiasing | QPainter.HighQualityAntialiasing |
QPainter.SmoothPixmapTransform)
painter.setPen(Qt.NoPen)
# 繪制背景圖片
if self.__pressedPos:
painter.drawPixmap(self.rect(), self.__pressedPix)
def __setDstPointsByPressedPos(self,pressedPos:str):
""" 通過滑鼠點擊位置設定透視變換的四個邊角坐標 """
self.__pressedPos = pressedPos
if self.__pressedPos == 'left':
self.__perspectiveTrans.setDstPoints(
[5, 4], [self.__perspectiveTrans.width - 2, 1],
[3, self.__perspectiveTrans.height - 3],
[self.__perspectiveTrans.width - 2, self.__perspectiveTrans.height - 1])
elif self.__pressedPos == 'left-top':
self.__perspectiveTrans.setDstPoints(
[6, 5], [self.__perspectiveTrans.width - 1, 1],
[1, self.__perspectiveTrans.height - 2],
[self.__perspectiveTrans.width - 2, self.__perspectiveTrans.height - 1])
elif self.__pressedPos == 'left-bottom':
self.__perspectiveTrans.setDstPoints(
[2, 3], [self.__perspectiveTrans.width - 3, 0],
[4, self.__perspectiveTrans.height - 4],
[self.__perspectiveTrans.width - 2, self.__perspectiveTrans.height - 2])
elif self.__pressedPos == 'top':
self.__perspectiveTrans.setDstPoints(
[3, 5], [self.__perspectiveTrans.width - 4, 5],
[1, self.__perspectiveTrans.height - 2],
[self.__perspectiveTrans.width - 2, self.__perspectiveTrans.height - 2])
elif self.__pressedPos == 'center':
self.__perspectiveTrans.setDstPoints(
[3, 4], [self.__perspectiveTrans.width - 4, 4],
[3, self.__perspectiveTrans.height - 3],
[self.__perspectiveTrans.width - 4, self.__perspectiveTrans.height - 3])
elif self.__pressedPos == 'bottom':
self.__perspectiveTrans.setDstPoints(
[2, 2], [self.__perspectiveTrans.width - 3, 3],
[3, self.__perspectiveTrans.height - 3],
[self.__perspectiveTrans.width - 4, self.__perspectiveTrans.height - 3])
elif self.__pressedPos == 'right-bottom':
self.__perspectiveTrans.setDstPoints(
[1, 0], [self.__perspectiveTrans.width - 3, 2],
[1, self.__perspectiveTrans.height - 2],
[self.__perspectiveTrans.width - 5, self.__perspectiveTrans.height - 4])
elif self.__pressedPos == 'right-top':
self.__perspectiveTrans.setDstPoints(
[0, 1], [self.__perspectiveTrans.width - 7, 5],
[2, self.__perspectiveTrans.height - 1],
[self.__perspectiveTrans.width - 2, self.__perspectiveTrans.height - 2])
elif self.__pressedPos == 'right':
self.__perspectiveTrans.setDstPoints(
[1, 1], [self.__perspectiveTrans.width - 6, 4],
[2, self.__perspectiveTrans.height - 1],
[self.__perspectiveTrans.width - 4, self.__perspectiveTrans.height - 3])
def __getTransformPixmap(self) -> QPixmap:
""" 獲取透視變換后的QPixmap """
pix = self.__perspectiveTrans.getPerspectiveTransform(
self.__perspectiveTrans.width, self.__perspectiveTrans.height).scaled(
self.size(), Qt.KeepAspectRatio, Qt.SmoothTransformation)
return pix
def __getScreenShot(self) -> QPixmap:
""" 對視窗口所在的桌面區域進行截圖 """
screen = QApplication.primaryScreen() # type:QScreen
pos = self.mapToGlobal(QPoint(0, 0)) # type:QPoint
pix = screen.grabWindow(
0, pos.x(), pos.y(), self.width(), self.height())
return pix
def __adjustTransformPix(self):
""" 對視窗截圖再次進行透視變換并將兩張圖融合，消除可能存在的黑邊 """
self.__screenshotPix = self.__getScreenShot()
self.__perspectiveTrans.setPixmap(self.__screenshotPix)
self.__screenshotPressedPix = self.__getTransformPixmap()
# 融合兩張透視圖
img_1 = self.__perspectiveTrans.transQPixmapToNdarray(self.__pressedPix)
img_2 = self.__perspectiveTrans.transQPixmapToNdarray(self.__screenshotPressedPix)
# 去除非透明背景部分
mask = img_1[:, :, -1] == 0
img_2[mask] = img_1[mask]
self.__pressedPix = self.__perspectiveTrans.transNdarrayToQPixmap(img_2)
在mousePressEvent中呼叫了一個全域函式 getPressedPos(widget,e) ，如果將視窗分為九宮格，它就是用來獲取判斷滑鼠的點擊位置落在九宮格的哪個格子的，因為我在其他地方有用到它，所以沒將其設定為PerspectiveWidget的方法成員，下面是這個函式的代碼：
# coding:utf-8
from PyQt5.QtGui import QMouseEvent
def getPressedPos(widget, e: QMouseEvent) -> str:
""" 檢測滑鼠并回傳按下的方位 """
pressedPos = None
width = widget.width()
height = widget.height()
leftX = 0 <= e.x() <= int(width / 3)
midX = int(width / 3) < e.x() <= int(width * 2 / 3)
rightX = int(width * 2 / 3) < e.x() <= width
topY = 0 <= e.y() <= int(height / 3)
midY = int(height / 3) < e.y() <= int(height * 2 / 3)
bottomY = int(height * 2 / 3) < e.y() <= height
# 獲取點擊位置
if leftX and topY:
pressedPos = 'left-top'
elif midX and topY:
pressedPos = 'top'
elif rightX and topY:
pressedPos = 'right-top'
elif leftX and midY:
pressedPos = 'left'
elif midX and midY:
pressedPos = 'center'
elif rightX and midY:
pressedPos = 'right'
elif leftX and bottomY:
pressedPos = 'left-bottom'
elif midX and bottomY:
pressedPos = 'bottom'
elif rightX and bottomY:
pressedPos = 'right-bottom'
return pressedPos
使用方法
?? 很簡單，只要將代碼中的QWidget替換為PerspectiveWidget就可以享受透視變換帶來的無盡樂趣，要想向gif中那樣對按鈕也進行透視變換，只要按代碼中所做的那樣重寫mousePressEvent、mouseReleaseEvent 和 paintEvent 即可，如果有對按鈕使用qss，記得在paintEvent中加上super().paintEvent(e)，這樣樣式表才會起作用，總之框架已經給出，具體操作取決于你，如果你喜歡這篇博客的話，記得點個贊哦(oﾟ▽ﾟ)o ，順便做個下期預告：在gif中可以看到界面切換時帶了彈入彈出的影片，在下一篇博客中我會對如何實作QStackedWidget的界面切換影片進行介紹，敬請期待~~
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