wxImage并绘制原始的rgb字节 [英] wxImage and draw raw rgb bytes

问题描述

我正在将图像查看器编程为学校的任务，并且不能使用任何库来读取或处理图像。首先，我从bmp格式开始。我已经创建了用于处理此类文件的类。作为GUI框架，我正在使用wxWidgets。

I am programming image viewer as school task and I cant use any libraries for reading or manipulating images. First I started with bmp format. I have created class for handle this type of file. As GUI framework I am using wxWidgets.

所以我有普通的rgb字节数组，为wxImage构造函数准备了

So I have plain rgb bytes array, prepared for wxImage constructor

wxImage(int width, int height, unsigned char* data, bool static_data = false).

问题是，当我将其转换为wxBitmap并绘制为dc时，它忽略了rgb值，仅绘制黑色图片。我真的不知道可能是什么问题。这是我绘制图像的代码：

Problem is that when I convert it to wxBitmap and draw to dc it's ignoring rgb values a draw only black picture. I really do not know what could be a problem. This is my code for draw image:

DrawImage(wxDC &dc)
{
  BYTE *rgbArray = bmpFile->GetRGB();
  wxSize imageSize = wxSize(bmpFile->GetSize().w,bmpFile->GetSize().h);
  wxImage image = wxImage(imageSize, &rgbArray);
  wxBitmap bitmap = wxBitmap(image);
  dc.DrawBitmap(bitmap,5,5, false);
}

这是绘画事件：

void OnPaint(wxPaintEvent& event)
{
   wxAutoBufferedPaintDC dc(canvas);
   dc.SetBackground( wxBrush(canvas->GetBackgroundColour()));
   dc.Clear();
   DrawImage(dc);
}

rgbArray填充了正确的值，我检查了多次。

rgbArray is filled with right values, I checked it multiple times.

感谢您的帮助：）

推荐答案

那是因为您可能在称呼它

Thats because you are probably calling this function, because you are passing a BYTE**.

wxImage (const wxSize &sz, bool clear=true)

调用另一个重载，删除&可能有帮助

to call the other overload, removing the & might help

wxImage image = wxImage(imageSize, rgbArray);

为了使代码异常安全，必须对其稍做重写。我不知道bmpFile是返回新缓冲区还是指向其自身数据缓冲区的指针。如果它不返回新的缓冲区，则必须创建自己的副本，因为wxImage拥有该缓冲区的所有权。参见 wxImage

To make the code exception safe, it must be rewritten slightly. I don't know whether bmpFile returns a new buffer or a pointer to its own data buffer. If it doesn't return a new buffer then you must make your own copy because wxImage takes ownership of the buffer. see wxImage

DrawImage(wxDC &dc)
{
  wxSize imageSize = wxSize(bmpFile->GetSize().w,bmpFile->GetSize().h);
  wxImage image = wxImage(imageSize, bmpFile->GetRGB() );
  wxBitmap bitmap = wxBitmap(image);
  dc.DrawBitmap(bitmap,5,5, false);
}

或

DrawImage(wxDC &dc)
{
  std::unique_ptr<BYTE> rgbData( bmpFile->GetRGB() );
  wxSize imageSize = wxSize(bmpFile->GetSize().w,bmpFile->GetSize().h);
  wxImage image = wxImage(imageSize, rgbData.release()) );
  wxBitmap bitmap = wxBitmap(image);
  dc.DrawBitmap(bitmap,5,5, false);
}

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