绘图程序的通用缩放算法

问题描述

我的GUI工具箱wxPython提供了一些用于实现用户缩放系数的方法，但是质量不太好。我正在寻找有关如何创建缩放功能的想法，我知道这很复杂。

My GUI toolkit, wxPython provides some methods for implementing a user zoom factor, however the quality isn't too good. I'm looking for ideas on how to create a zooming feature, which I know is complicated.

我有一个位图，代表我的画布被绘制。它显示在滚动窗口内。

I have a bitmap representing my canvas which is drawn to. This is displayed inside a scrolled window.

我预见的问题：
-放大和在画布上平移时的性能
-真实坐标和放大坐标$ b的困难$ b-图像质量不会随缩放而降低

Problems I forsee: - performance when zoomed in and panning around the canvas - difficulties with "real" coordinates and zoomed in coordinates - image quality not degrading with the zoom

在其设备上下文中使用wxPython的SetUserScale（）会显示-这是一条1px的线，放大了30％。

Using wxPython's SetUserScale() on its device contexts presents image quality like this - this is with a 1px line, at 30% zoomed in.

我只是想知道我需要采取的一般步骤以及遇到的挑战。感谢您的任何建议

I'm just wondering the general steps I'll need to take and the challenges I'll encounter. Thanks for any suggestions

推荐答案

您是否尝试过使用？

Have you tried using GraphicsContext?

以下是一些示例码。使用包装器。您可能只需要以下行： dc = wx.GCDC（dc）

Here's some sample code. It should be easy to drop into your existing code using the GCDC wrapper. You may only need the line: dc = wx.GCDC(dc)

渲染速度会慢很多！您可以将此选项设置为可由用户启用/禁用的选项。

Rendering will be a lot slower! You could make this an option that could be enabled/disabled by the user.

import wx
import random

class Panel(wx.Panel):
    def __init__(self, parent):
        super(Panel, self).__init__(parent, -1)
        self.Bind(wx.EVT_PAINT, self.on_paint)
        self.lines = [[random.randint(0, 500) for i in range(4)] for j in range(100)]
    def on_paint(self, event):
        dc = wx.PaintDC(self)
        dc = wx.GCDC(dc)
        dc.SetUserScale(0.3, 0.3)
        for line in self.lines:
            dc.DrawLine(*line)

class Frame(wx.Frame):
    def __init__(self):
        super(Frame, self).__init__(None, -1, 'Test')
        Panel(self)

if __name__ == "__main__":
    app = wx.PySimpleApp()
    frame = Frame()
    frame.Show()
    app.MainLoop()

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