如何做 dregradê在 wx.Panel 背景上？

Question

我想将 wx.Panel 的背景（SetBackgroundColour）着色为蓝色到黑色的渐变。

我怎样才能做到呢？

Answer 1

改编自 DaniWeb：

import wx

class MyFrame(wx.Frame):
    def __init__(self, parent=None, title=None):
        wx.Frame.__init__(self, parent, wx.ID_ANY, title)
        self.panel = wx.Panel(self, size=(350, 450))
        # this sets up the painting canvas
        self.panel.Bind(wx.EVT_PAINT, self.on_paint)
        # set frame size to fit panel
        self.Fit()

    def on_paint(self, event):
        # establish the painting canvas
        dc = wx.PaintDC(self.panel)
        x = 0
        y = 0
        w, h = self.GetSize()
        dc.GradientFillLinear((x, y, w, h), 'blue', 'black')


app = wx.App(0)
MyFrame(title='Gradient Test').Show()
app.MainLoop()

以及使用 NumPy 生成渐变位图的另一种方法（来自 wxpython.org）：

import numpy as np

def GetBitmap( self, width=640, height=480, leftColour=(255,128,0), rightColour=(64,0,255) ):
        ## Create a horizontal gradient
        array = np.zeros( (height, width, 3),'uint8')
        # alpha is a one dimensional array with a linear gradient from 0.0 to 1.0
        alpha = np.linspace( 0., 1., width )
        # This uses alpha to linearly interpolate between leftColour and rightColour
        colourGradient = np.outer(alpha, leftColour) + np.outer((1.-alpha), rightColour)
        # NumPy's broadcasting rules will assign colourGradient to every row of the destination array
        array[:,:,:] = colourGradient
        image = wx.EmptyImage(width,height)
        image.SetData( array.tostring())
        return image.ConvertToBitmap()# wx.BitmapFromImage(image)