我刚刚开始用 Python 编程，因此尝试了一个简单的 GUI，它由一个仪表（转速计数器）和一个条形图组成。这一切都有效（代码附在下面）。但是，由于屏幕刷新（Windows XP），我的闪烁非常严重。我知道我需要使用缓冲 DC，但是我无法从所有帖子中找出我实际需要做的事情。
但是我的假设是：
- 最初为缓冲图像创建一个内存 DC 以“驻留在”其中，然后
- 实例化缓冲 DC
- 将 On Paint 绑定到缓冲 DC。
为了提供相关的仪表面（比例），我在 Autocad 中将其全部绘制出来，然后将其转换为 jpg (HMIV0.2.bmp)，条形图和仪表指针叠加在上面。
正如您会注意到的，我在循环结束时使用了 Refresh，我想知道这是否是“不好的做法”。然而，我的目的是让程序自由运行并在每次循环时“获取”相关值（转速）。因此没有外部事件来触发绘制。
任何正确方向的建议或指针都非常感谢......我购买了 Cody Precord 的“Wx.Python 2.8 Application Development Cookbook”，希望能得到一些启发，但唉。
import wx
import random
import time
import math
def Data():
data_value =random.randint(0,400)
return data_value
def Pointer():
meter_value =float(random.randint(0,260))
Needle_centre_x = 253
Needle_centre_y = 239
Needle_length = float(125)
Needle_sweep = math.radians(214) #Number of degrees (converted to radians) that the needle is to deflect through
Meter_max_scale = 260 # maximum value on the meter scale
lo_reflect = float(20) # Meter reading that are less than this value are below the horizontal-Lo
Angle_per_digit = Needle_sweep / Meter_max_scale # Angle_per_digit is in radians
print '*******************NEW CYCLE*****************************'
print 'The meter value is ' +str(meter_value)
Start_displac = Angle_per_digit * lo_reflect
needle_ang = -1*(Start_displac -(meter_value * Angle_per_digit))
Needle_x = Needle_length * (math.cos(needle_ang))
Needle_y = Needle_length * (math.sin(needle_ang))
needle_degrees = math.degrees(needle_ang)
anglea = needle_ang - math.pi/2
angleb = needle_ang + math.pi/2
base_x = 10*(math.cos(anglea))
base_y = 10*(math.sin(anglea))
print 'The needle angle is' + str(needle_degrees)
print 'Angle A is ' + str(math.degrees(anglea))
print 'Angle B is ' + str(math.degrees(angleb))
print 'The needle deflection angle is ' + str(math.degrees(needle_ang))
basea_y = int(Needle_centre_y- base_y)
basea_x = int(Needle_centre_x - base_x)
baseb_y = int(Needle_centre_y + base_y)
baseb_x = int(Needle_centre_x + base_x)
needle_y = int(Needle_centre_y - Needle_y)
needle_x = int(Needle_centre_x - Needle_x)
Needle = [Needle_centre_x,Needle_centre_y,needle_x,needle_y,basea_x,basea_y,baseb_x,baseb_y] #Needle = [x1,y1,x2,y2,pointa_y,pointa_x,pointb_y,pointb_x]
return Needle
class MyPanel(wx.Panel):
def __init__(self, parent):
wx.Panel.__init__(self, parent,pos = (0,0), size = (800,500))
self.Bind(wx.EVT_PAINT, self.OnPaint)
def OnPaint(self, data_value):
data_value = Data()
dc = wx.PaintDC(self)
bmp = wx.Bitmap("HMIV0.2.bmp")
dc.DrawBitmap(bmp, 0, 0)
if data_value > 300:
dc.SetBrush(wx.RED_BRUSH)
dc.DrawRoundedRectangle(12,450,40,-1*(data_value),2)
dc.SetBrush(wx.BLUE_BRUSH)
dc.DrawRoundedRectangle(12,450,40,-1*300,2)
dc.SetBrush(wx.GREEN_BRUSH)
dc.DrawRoundedRectangle(12,450,40,-1*200,2)
if data_value < 300 and data_value > 200 :
dc.SetBrush(wx.BLUE_BRUSH)
dc.DrawRoundedRectangle(12,450,40,-1*(data_value),2)
dc.SetBrush(wx.GREEN_BRUSH)
dc.DrawRoundedRectangle(12,450,40,-1*200,2)
if data_value < 200:
dc.SetBrush(wx.GREEN_BRUSH)
dc.DrawRoundedRectangle(12,450,40,-1*(data_value),2)
dc.SetBrush(wx.BLUE_BRUSH)
HMI_needle = Pointer()
print 'the contents of HMI needle are' + str(HMI_needle)
print 'Needle_centre_x,Needle_centre_y,needle_x,needle_y,basea_x,basea_y,baseb_x,baseb_y'
print type(HMI_needle)
Points = [(HMI_needle[2],HMI_needle[3]),(HMI_needle[4],HMI_needle[5]),(HMI_needle[6],HMI_needle[7])]
dc.DrawPolygon(Points)
dc.DrawCircle(253,239,20)
time.sleep(0.1)
self.Refresh()
class MyFrame(wx.Frame):
def __init__(self, parent, title, size):
wx.Frame.__init__(self, parent, wx.ID_ANY, title, wx.DefaultPosition, size,)
bitmap = wx.Bitmap("Background.jpg", type=wx.BITMAP_TYPE_JPEG)
self.bitmap =wx.StaticBitmap(self,bitmap =bitmap)
self.Panel = MyPanel(self)
app = wx.PySimpleApp(redirect=False, filename = "C:\output.txt", clearSigInt=True)
frame = MyFrame(None,"WxPaint", size=(800,500))#size=(800,480))
frame.Show()
app.SetTopWindow(frame)
app.MainLoop()