GdipBitmapLockBits?

SDKs Plugins
1

Hi,

has someone an idea on how to use GdipBitmapLockBits right to get pixels from Windows pictures with GDI+?

Greetings
Christian

2

See my (possibly) related question here: https://forum.xojo.com/13042-picture-copyoshandle-on-win32-with-32-bit-pictures
I wonder if the object that’s begin returned by Xojo is not a GDI+ bitmap, but just a regular BITMAP object?

3

my code looks like this:

[code] REALpictureDescription des;
if (REALLockPictureDescriptionX(pic, &des, pictureGDIPlusBitmap))
{
DebugMessage(“pictureGDIPlusBitmap”);

	RBInteger w = des.width;
	RBInteger h = des.height;
			
	DebugMessage("w",w);
	DebugMessage("h",h);
	
	if (des.pictureType == pictureGDIPlusBitmap)
		{
		GpBitmap* g = (GpBitmap*) des.pictureData;
		DebugMessage("g",g);
		if (g)
			{
			if (LoadGDIPlus())
				{
				BitmapData* bitmapData = new BitmapData();
				DebugMessage("bitmapData", (void*)bitmapData);
				if (bitmapData )
					{
					RBInteger flags = ImageLockModeRead|ImageLockModeWrite;
						
					DebugMessage("flags",flags);
		
					GpRect r;
					
					r.left = 0;
					r.top = 0;
					r.right = w;
					r.bottom = h;
					
					GpStatus e = _GdipBitmapLockBits(g, &r, flags, PixelFormat32bppPARGB, bitmapData);
					DebugMessage("e",e);
					if (e == 2)
						{
						e = _GdipBitmapLockBits(g, &r, flags, PixelFormat32bppARGB, bitmapData);
						DebugMessage("e",e);
						}
					if (e != Ok)
						{
						DebugMessage("Lockbits failed");
						delete bitmapData;
						REALUnlockPictureDescription(pic);
						return;
						}

[/code]

4

from debug output I see that I got a GpBitmap with right pixel size.
Pixel format is PixelFormat32bppRGB and type is a ImageTypeBitmap.

5

passing rectangle was wrong! Passing NULL works :slight_smile:

6

I’m confused about the Rectangle here - in the Win32API we have

typedef struct _RECT {
  LONG left;
  LONG top;
  LONG right;
  LONG bottom;
} RECT, *PRECT;

but I also see places where gpRect is defined as { X,Y,width,height }.

The difference of course would be that right = X+width and bottom = Y + height?

Could you be passing a pointer to the wrong structure type?

7

[quote=101209:@Michael Diehr]I’m confused about the Rectangle here - in the Win32API we have

typedef struct _RECT {
  LONG left;
  LONG top;
  LONG right;
  LONG bottom;
} RECT, *PRECT;

but I also see places where gpRect is defined as { X,Y,width,height }.

The difference of course would be that right = X+width and bottom = Y + height?

Could you be passing a pointer to the wrong structure type?[/quote]

EDIT: no, I think you are correct, here’s where Rect is defined (which is not the same as RECT): http://msdn.microsoft.com/en-us/library/windows/desktop/ms534495(v=vs.85).aspx

8

for me it started working when I stopped passing a rect at all!

9

Have you tried passing in a buffer for the pixels and then using the imageLockModeUserInputBuf = &h0004 flag?

10

no