使用Wx和PyAutoGui从Python制作“剪裁工具”

Question

I am trying to make a snipping tool using the Wx and PyAutoGui modules, I am stuck at a certain problem: The saved image file is at wrong position (see image below)

Picture Link

As you can see I am trying to grab a specific region, that is the red rectangle, and save those pixels in that region to the file "my_screenshot.png". However, the position/coordinates seems to be off (you can see the rectangles, which was supposed to be the region of the screenshot)

Here are the codes:

import wx
import pyautogui

class SelectableFrame(wx.Frame):

    c1 = None
    c2 = None

    def __init__(self, parent=None, id=-1, title=""):
        wx.Frame.__init__(self, parent, id, title, size=wx.DisplaySize())

        self.panel = wx.Panel(self, size=self.GetSize())

        self.panel.Bind(wx.EVT_MOTION, self.OnMouseMove)
        self.panel.Bind(wx.EVT_LEFT_DOWN, self.OnMouseDown)
        self.panel.Bind(wx.EVT_LEFT_UP, self.OnMouseUp)
        self.panel.Bind(wx.EVT_PAINT, self.OnPaint)

        self.SetCursor(wx.Cursor(wx.CURSOR_CROSS))

        self.SetTransparent(50)

    def OnMouseMove(self, event):
        if event.Dragging() and event.LeftIsDown():
            self.c2 = event.GetPosition()
            self.Refresh()

    def OnMouseDown(self, event):
        self.c1 = event.GetPosition()

    def OnMouseUp(self, event):
        self.SetCursor(wx.Cursor(wx.CURSOR_ARROW))
        region = (self.c1.x, self.c1.y, self.c2.x - self.c1.x, self.c2.y - self.c1.y)
        pyautogui.screenshot('my_screenshot.png', region=region)
        print("MouseUp: " + str(region))
        self.Hide()

    def OnPaint(self, event):
        if self.c1 is None or self.c2 is None: return

        dc = wx.PaintDC(self.panel)
        dc.SetPen(wx.Pen('red', 1))
        dc.SetBrush(wx.Brush(wx.Colour(0, 0, 0), wx.TRANSPARENT))

        region = (self.c1.x, self.c1.y, self.c2.x - self.c1.x, self.c2.y - self.c1.y)
        dc.DrawRectangle(self.c1.x, self.c1.y, self.c2.x - self.c1.x, self.c2.y - self.c1.y)
        print("Draw: " + str(region))


    def PrintPosition(self, pos):
        return str(pos.x) + " " + str(pos.y)


class MyApp(wx.App):

    def OnInit(self):
        frame = SelectableFrame()
        frame.Show(True)
        self.SetTopWindow(frame)

        return True


app = MyApp(0)
app.MainLoop()

From what I've gathered that, it took the width and height, but wrong x and y position, how can I fix that? Thank you

EDIT: There seems to be values difference between these functions

    def OnMouseDown(self, event):
        self.c1 = event.GetPosition()
        print("MouseDown[event]: " + str(self.c1))
        print("MouseDown[gui]: "+  str(pyautogui.position()))

Output:

MouseDown[event]: (729, 484)
MouseDown[gui]: Point(x=737, y=515)

The offset is +8 for x, and +31 for y. How did this incontinence happen? My hotfix would be to add those offsets to the pyautogui.screenshot command but I don't think that is the right fix and would not be guaranteed to be the same offset values for other screen sizes..

Answer 1

The wxpython MouseEvent doc tells

The position associated with a mouse event is expressed in the window coordinates of the window which generated the event, you can use wx.Window.ClientToScreen to convert it to screen coordinates and possibly call wx.Window.ScreenToClient next to convert it to window coordinates of another window.

pyautogui' screenshot() works with screen coordinates .

So, use wx.Window.ClientToScreen with both your c1 and c2 .

BTW, you should update c2 also at OnMouseUp and check it not to be 'None' nor equal to c1 .