C / C++ / MFC

Re: How to build bitmaps from the scratch?

11-Aug-04 3:01

A Beginners Guide to Bitmaps[^]

and

Bitmaps and Palette Manipulation[^]

are just a couple of randomly picked examples when you use Google and search for Bitmaps! Wink | ;)

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

Anonymous11-Aug-04 7:47

Anonymous

11-Aug-04 7:47

Oh the google way Smile | :)

Thanks both of you Wink | ;)

SDI Different Views

Rassul Yunussov10-Aug-04 22:51

Rassul Yunussov

10-Aug-04 22:51

I tried to make a project with one Document and 2 views. But I had a problem - i can't switch between them. How to do it?
In InitInstance i did this:

CSingleDocTemplate* pDocTemplate;
	CSingleDocTemplate* pDocTemplate1;
	pDocTemplate = new CSingleDocTemplate(
		IDR_MAINFRAME,
		RUNTIME_CLASS(CSDIMultiViewDoc),
		RUNTIME_CLASS(CMainFrame),       // main SDI frame window
		RUNTIME_CLASS(CSDIMultiViewView));
	AddDocTemplate(pDocTemplate);
	pDocTemplate1	= new CSingleDocTemplate(
		IDR_MAINFRAME,
		RUNTIME_CLASS(CSDIMultiViewDoc),
		RUNTIME_CLASS(CMainFrame),       // main SDI frame window
		RUNTIME_CLASS(CSDIMultiViewListView));
	AddDocTemplate(pDocTemplate1);

Re: SDI Different Views

Michael P Butler10-Aug-04 23:37

Michael P Butler

10-Aug-04 23:37

Have a read of

INFO: Switching Views in a Single Document Interface Program[^]

Michael

CP Blog [^]

Re: SDI Different Views

Joel Holdsworth10-Aug-04 23:43

Joel Holdsworth

10-Aug-04 23:43

I don't think that's the correct way... I think you want to kepp only one doc template. Have a look at http://www.codeproject.com/docview/switchingviews.asp[^]

Joel Holdsworth

Lists of a class : where to put a typedef

Jerome Conus10-Aug-04 22:50

Jerome Conus

10-Aug-04 22:50

Hi !

Here is a coding design question.

I defined a class in my application, let's call it CPoint.

In many other classes of my application, I have to manipulate lists of pointeurs on CPoint objects. I need to pass such lists by parameters.

For now, I defined, in each class using a list of CPoint a typedef like this :

typedef vector<CPoint*> PointList_t;

I'm now wondering if, instead of declaring such typedef in each class using a list of CPoint*, if it would be better coding practice to define such typedef in the CPoint class itselt :

class CPoint
{
public:
typedef vector<CPoint*> PointList_t;

...
};

and, in classes using a list of CPoint*, I would do (for example) :

void Foo(CPoint::PointList_t MyPointList)
{
CPoint::PointList_t::iterator It = MyPointList.begin();
...
...
}

The advantage of this new way of doing would be to avoid multiple declaration of the same typedef, the drawback is that I have to put CPoint:: each time I need a PointList_t and that I have to include the CPoint.h in the header of the classes using such typedef where a simple declaration of the class was enough with my first way of doing things.

What is your suggestion ?
Thanks !
Jerome

Re: Lists of a class : where to put a typedef

Antony M Kancidrowski11-Aug-04 0:04

Bits Fields - How to Use them

11-Aug-04 0:04

I would always put the typedef where it fits best. In your example the best fit is within the CPoint class.

This way as you have stated it is defined only once. This also means that there is one point of maintenance.

IMO the drawbacks you have stated are not really drawbacks, just a little more typing!

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

sweep12310-Aug-04 22:24

10-Aug-04 22:24

I have been trying to define a structure and use it with a union, but the bit fields seem to cause the structure to be bigger than I expected.

e.g. ( 4 x 4 bit fileds + 2 float fields + short = 11 bytes)
But what I get is 28 bytes.

// Data1	w03_second_10_s_;<br />
typedef struct <br />
{<br />
	unsigned	 data 	:	4	;	<br />
}W03_SECOND_10_S_;<br />
<br />
// Data2	w03_second_1_s_;<br />
typedef struct <br />
{<br />
	unsigned	 data 	:	4	;	<br />
}W03_SECOND_1_S_;<br />
<br />
// Data3	w03_second_0_1_s_;<br />
typedef struct <br />
{<br />
	unsigned	 data 	:	4	;	<br />
}W03_SECOND_0_1_S_;<br />
<br />
// Data4	w03_second_0_01_s_;<br />
typedef struct <br />
{<br />
	unsigned	 data 	:	4	;	<br />
}W03_SECOND_0_01_S_;<br />
<br />
// Data5	w05_price;<br />
typedef struct <br />
{<br />
	float		data; <br />
}W05_PRICE;<br />
<br />
// Data6	w07_netCost;<br />
typedef struct <br />
{<br />
	float		data; <br />
}W07_NETCOST;<br />
<br />
// Data7	w08_index;<br />
typedef struct <br />
{<br />
	unsigned short		data; <br />
}W08_INDEX;<br />
// All the fields into a sigle structure<br />
typedef struct{<br />
W03_SECOND_10_S_	w03_second_10_s_;<br />
W03_SECOND_1_S_		w03_second_1_s_;<br />
W03_SECOND_0_1_S_	w03_second_0_1_s_;<br />
W03_SECOND_0_01_S_	w03_second_0_01_s_;<br />
W05_PRICE			w05_price;<br />
W07_NETCOST			w07_netCost;<br />
W08_INDEX			w08_index;<br />
}TEST1_10;

// Form a union between the message structure and a buffer<br />
union<br />
{<br />
	TEST1_10			message_data;		// I expect this to be = 14 bytes<br />
	unsigned short		buffer[32];			// Max buffer size<br />
}messageStructData;<br />
<br />
int sizeStruct = sizeof(messageStructData);

The size if 64 bytes, but the size of the TEST1_10 structure is 28 bytes (not 11 bytes)so each field of 4 bits is taking up 4 bytes

TEST1_10			message_data1;<br />
int sizeStruct1 = sizeof(message_data1);

sizeStruct1 = 28 bytes.

The short is being padded to 4 bytes as is each 4 bit field.

Is it possible to map bit fields onto a structure and then a union in C++.

Antony M Kancidrowski10-Aug-04 23:45

10-Aug-04 23:45

The best you will get is to set the byte alignment for structures to a single byte. Currently you must have it set to 4 bytes.

Look in the Project Settings under Code Generation

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

sweep12311-Aug-04 1:24

11-Aug-04 1:24

Thanks for your post, I set it to 1 byte and that reduced the count from 28 to 26.

Are they no way that I can used bit fields in the way I intended; i.e.

overlay these bit field and other fileds (short, float etc) with a buffer.

I did remove the wrapping of the bit fields from a struct:

typedef struct{<br />
	unsigned	 data1 	:	4	;	<br />
	unsigned	 data2 	:	4	;	<br />
	unsigned	 data3 	:	4	;	<br />
	unsigned	 data4 	:	4	;	<br />
	W05_PRICE			w05_price;<br />
	W07_NETCOST			w07_netCost;<br />
	W08_INDEX			w08_index;<br />
}TEST1_10;

this gave a size of 14 (2 floats, 1 short and 4 x 4 bit fields = 11 bytes)

But each 4 bit field is taking a byte; hence 14 bytes.

Any suggestions to get this scheme working?

Antony M Kancidrowski11-Aug-04 2:03

11-Aug-04 2:03

Without combining the fields in the struct I can not see how you can do this.

e.g.

typedef struct{<br />
BYTE data1and2; <br />
BYTE data3and4;<br />
W05_PRICE w05_price;<br />
W07_NETCOST w07_netCost;<br />
W08_INDEX w08_index;<br />
}TEST1_10;

Downside is that will have to do the bit manipulation on data1and2 and data3and4 in order to get the appropriate 4bit values however. Though a couple of functions should be enough to get and set the values.

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

David Crow11-Aug-04 5:25

David Crow

11-Aug-04 5:25

Contrast what you have with:

#pragma pack(1)
typedef struct
{
    unsigned data1 : 4; 
    unsigned data2 : 4;
    unsigned data3 : 4;
    unsigned data4 : 4;
    float data5;
    float data6;
    unsigned short data7;
} TEST1_10;
#pragma pack()

TEST1_10 message_data1;
int sizeStruct1 = sizeof(message_data1);

What is the value of sizeStruct1?

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

sweep12311-Aug-04 6:12

11-Aug-04 6:12

The size of the structure is 14 bytes.
I assume this is (8 for 2 floats + 2 for the short and 4 for the 4 bit fields)

I am after a size of 11 bytes.

Are they any settings that I have not made?

David Crow11-Aug-04 7:23

David Crow

11-Aug-04 7:23

You do know that sizeof() cannot be used on bit fields, don't you?

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

sweep12311-Aug-04 21:58

11-Aug-04 21:58

If I use the following code:-

typedef struct<br />
{ <br />
	unsigned short data1;<br />
//	unsigned data1 : 4;<br />
//	unsigned data2 : 4;<br />
//	unsigned data3 : 4;<br />
//	unsigned data4 : 4;<br />
	float data5;<br />
	float data6;<br />
	unsigned short data7;<br />
}TEST1_101;<br />
#pragma pack()<br />
TEST1_101 message_data1;<br />
int sizeStruct1 = sizeof(message_data1

);

I get size = 12 bytes, which I understand (8 for floats + 2 x 2 for shorts = 12 bytes. But why dont I get 12 for the following:-

typedef struct<br />
{ <br />
	unsigned data1 : 4;<br />
	unsigned data2 : 4;<br />
	unsigned data3 : 4;<br />
	unsigned data4 : 4;<br />
	float data5;<br />
	float data6;<br />
	unsigned short data7;<br />
}TEST1_101;<br />
#pragma pack()<br />
TEST1_101 message_data1;<br />
int sizeStruct1 = sizeof(message_data1);

David Crow12-Aug-04 2:58

David Crow

12-Aug-04 2:58

sweep123 wrote:
But why dont I get 12 for the following:-

I hinted at the fact that you cannot use sizeof() with bit fields. Did you miss that earlier?

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

sweep12312-Aug-04 4:17