GDI+ and Fat API

I am trying to figure out how to call a GDI+ Flat Api function, but cannot get anything working.

Here is my code:

Code:

---

#include <windows.h>
#include <objidl.h>
#include <gdiplus.h>
#include <GdiplusFlat.h>
using namespace Gdiplus;
#pragma comment (lib,"Gdiplus.lib")

VOID OnPaint(HDC hdc)
{
        Graphics graphics(hdc);
        Pen      pen(Color(255, 0, 0, 255));
        //graphics.DrawLine(&pen, 0, 0, 200, 100);
        GdipDrawLine(&graphics, &pen, 0, 0, 200, 0); //Flat Api version
}

---

Here I am trying to call only one flat function GdipDrawLine.

Any suggestions?

• Once included Gdiplus, use DllExports namespace i.e. DllExports::GdipDrawLine.
• First two arguments of DllExports::GdipDrawLine are not of type Gdilpus::Graphics and Gdiplus::Pen, but GpGraphics and GpPen.
  
  Code:

  ---

  GpStatus WINGDIPAPI
GdipDrawLine(GpGraphics *graphics, GpPen *pen, REAL x1, REAL y1,
                      REAL x2, REAL y2);

  ---

  None has implicit conversion from one to another.
• It has no sense in a C++ program to directly use flat GDI+ APIs.
  Generally, GDI+ classes methods are simple inline wrappers, e.g.
  
  Code:

  ---

      Status DrawLine(IN const Pen* pen,
                    IN INT x1,
                    IN INT y1,
                    IN INT x2,
                    IN INT y2)
    {
        return SetStatus(DllExports::GdipDrawLineI(nativeGraphics,
                                                  pen->nativePen,
                                                  x1,
                                                  y1,
                                                  x2,
                                                  y2));
    }

  ---

• Given the above points, you have to choose one of two:
  
  1. Use only GDI+ classes, recommended in C++ code;
  2. Use GDI+ flat API only in C code (as well as in other languages, except C++).

So are you are saying the Flat Api functions cannot be used in C++,
or just that using the wrapper method is easier?

I added

using namespace Gdiplus:: DllExports;

to my code and I now get this error:

error C2664: 'Gdiplus::DllExports::GdipDrawLine' : cannot convert parameter 1 from 'Gdiplus::Graphics *__w64 ' to 'Gdiplus::GpGraphics *'

Quote:

---

Originally Posted by mmscg

So are you are saying the Flat Api functions cannot be used in C++,
or just that using the wrapper method is easier?

---

I have never said "cannot". You can use flat GDI+ API in C++ code but it's like scratching with the foot.
Yes, the (wrapper) C++ classes are easier to use in C++ code. For that purpose they have been designed.

Quote:

---

Originally Posted by mmscg

I added

using namespace Gdiplus:: DllExports;

to my code and I now get this error:

error C2664: 'Gdiplus::DllExports::GdipDrawLine' : cannot convert parameter 1 from 'Gdiplus::Graphics *__w64 ' to 'Gdiplus::GpGraphics *'

---

Have you ever read this?

Quote:

---

Originally Posted by ME

• First two arguments of DllExports::GdipDrawLine are not of type Gdilpus::Graphics and Gdiplus::Pen, but GpGraphics and GpPen.
  
  Code:

  ---

  GpStatus WINGDIPAPI
GdipDrawLine(GpGraphics *graphics, GpPen *pen, REAL x1, REAL y1,
                      REAL x2, REAL y2);

  ---

  None has implicit conversion from one to another.
  ...

---

Yes, I had read that, but still being fairly new to C++ I find this very confusing.

Can one type be cast to another then?

I have been using GDI+ in my VB6 projects for the last year, and have become fairly proficient with the Flat Apis.

As I continue to learn C++, and start to port some of my projects from VB6 to C++,
I thought it might be easier for me to continue to use the Flat Api methodology for the GDI+ conversion.

Also now, even for just curiosity sake, I would like to see how to draw a line in C++ using flat GDI+ api.

Well, here is an example of using GDI+ flat API.

Code:

---

  using namespace DllExports;

  GpPen* pen = NULL;
  GpGraphics* graphics = NULL;
  ARGB color = 255 << ALPHA_SHIFT | 255 << BLUE_SHIFT;
  GpUnit unit = UnitPixel;
  REAL width = 1.0;

  GdipCreatePen1(color, width, unit, &pen);
  GdipCreateFromHDC(hdc, &graphics);
  GdipDrawLine(graphics, pen, 0, 0, 100, 50);
  // ...
  GdipDeletePen(pen);
  GdipDeleteGraphics(graphics);

---

Resources

• [MSDN] GDI+ Flat API

Thank you... you C++ guys are amazing!!

This works perfectly for me, and should be enough to get me on my way.
(I'm sure I'll hit a few stumbling blocks, and might have to ask more questions).