从HDC句柄创建QPaintDevice [英] Create a QPaintDevice from HDC handle

问题描述

我有一个来自外部库的Windows HDC句柄，我想使用QPainter功能来绘制。在Qt中有什么办法从HDC句柄创建QPaintDevice？

解决方案

使用Windows API从HDC获取HWND。

  HWND handle = WindowFromDC（hdc）; 
 assert（handle！= NULL）; 
  

然后再子类化QWidget以访问受保护的成员convert。使用此，使用此成员如此解决方案中所述创建QWidget：如何创建一个带有hwnd作为父类的qwidget 。在这个例子中，我为QWidgetWrapper调用了子类。

  QWidgetWrapper * w = new QWidgetWrapper 
 w-> create（（Wld）main_window）; 
 

注意，Wld是平台相关窗口标识符的Qt中的typedef。

I have a Windows HDC handle from an external library that I'd like to use QPainter functionality to draw on. Is there any way in Qt to create a QPaintDevice from a HDC handle?

解决方案

One way of doing this:

Using the Windows API, get the HWND from the HDC.

HWND handle = WindowFromDC(hdc);
assert(handle != NULL);

Then subclass QWidget to get access to the protected member convert. Using this, create the QWidget using this member as described in this solution: How to create a qwidget with a hwnd as parent. In this example, I've called the subclass for QWidgetWrapper.

QWidgetWrapper *w = new QWidgetWrapper();
w->create((Wld)main_window);

Note that Wld is a typedef in Qt for "Platform dependent window identifier".

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