wximage_viewer.py

import wx

class ImagePanel(wx.Panel):
    
    def __init__(self, parent, image_size):
        super().__init__(parent)
        self.max_size = 240
        self.file_path = None
        
        img = wx.Image(*image_size)
        self.image_ctrl = wx.StaticBitmap(self, bitmap=wx.Bitmap(img))
        
        browse_btn = wx.Button(self, label='Browse')
        browse_btn.Bind(wx.EVT_BUTTON, self.on_browse)
        
        main_sizer = wx.BoxSizer(wx.VERTICAL)
        hsizer = wx.BoxSizer(wx.HORIZONTAL)
        
        main_sizer.Add(self.image_ctrl, 0, wx.ALL, 5)
        hsizer.Add(browse_btn, 0, wx.ALL, 5)
        main_sizer.Add(hsizer, 0, wx.ALL, 5)
        
        self.SetSizer(main_sizer)
        main_sizer.Fit(parent)
        self.Layout()
        
        
    def on_browse(self, event):
        wildcard = "JPEG files (*.jpg)|*.jpg"
        with wx.FileDialog(None, "Choose a file", 
                           wildcard=wildcard,
                           style=wx.ID_OPEN) as dialog:
            if dialog.ShowModal() == wx.ID_OK:
                self.file_path = dialog.GetPath()
                self.load_image()
                
    def load_image(self):
        if self.file_path is None:
            return
        
        img = wx.Image(self.file_path, wx.BITMAP_TYPE_ANY)
        
        W = img.GetWidth()
        H = img.GetHeight()
        
        if W > H:
            NewW = self.max_size
            NewH = self.max_size * H / W
        else:
            NewH = self.max_size
            NewW = self.max_size * W / H
            
        img = img.Scale(NewW, NewH)
        
        self.image_ctrl.SetBitmap(wx.Bitmap(img))
        self.Refresh()

class MainFrame(wx.Frame):
    
    def __init__(self):
        super().__init__(None, title='Image Viewer')
        panel = ImagePanel(self, image_size=(240, 240))
        self.Show()
        
if __name__ == '__main__':
    app = wx.App(redirect=False)
    frame = MainFrame()
    app.MainLoop()