超载还是不超载？ [英] To overload, or not to overload?
问题描述
这就是问题了。
在一个非托管的C ++ DLL中我正在调用，其中一个函数原型是
/////
GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_DrawLayerList
（
HDC aDC，//要绘制的设备上下文
GM_LayerHandle_t32 * aLayerList，//要绘制的图层列表或所有的NULL值
uint32 aLayerCount，//列表中的图层数（0表示所有）
GM_DrawFlags_t32 aDrawFlags，//标志控制绘制的执行方式
const GM_Rectangle_t * aWorldBounds，//全局绘制界限或所有空值为
sint32 aLeftPixel，//左像素坐标绘制
sint32 aTopPixel，//要绘制的顶部像素坐标
sint32 aPixelWidth，//绘制的宽度（以像素为单位）
）;
/////
我最初翻译为
/////
公共声明函数GM_DrawLa yerList Lib" GlobalMapperInterface" _
（_
ByVal aDC As IntPtr，_
ByRef aLayerList As GM_LayerHandle_t32，_
ByVal aLayerCount As Int32，_
ByVal aDrawFlags为GM_DrawFlags_t32，_
ByRef aWorldBounds为GM_Rectangle_t，_
ByVal aLeftPixel为Int32，_
ByVal aTopPixel为Int32，_
ByVal aPixelWidth为Int32，_
ByVal aPixelHeight为Int32 _
）为GM_Error_t32
/////
但我无法弄清楚如何让它接收NULL（我发送IntPtr.Zero到
函数以表示NULL）当第5个参数期望
GM_Rectangle_t结构时。需要将NULL发送到函数，以便它绘制
所有图层。所以，我这样重载了这个函数
/////
公共声明函数GM_DrawLayerList Lib" GlobalMapperInterface" _
（_
ByVal aDC As IntPtr，_
ByRef aLayerList As GM_LayerHandle_t32，_
ByVal aLayerCount As Int32，_
ByVal aDrawFlags作为GM_DrawFlags_t32，_
ByVal aWorldBounds作为IntPtr，_
ByVal aLeftPixel作为Int32，_
ByVal aTopPixel为Int32，_
ByVal aPixelWidth为Int32，_
ByVal aPixelHeight为Int32 _
）为GM_Error_t32
/////
注意对ByVal的更改和IntPtr为第五个论点。现在它接受第5个参数的NULL
参数，以便获得绘制所有图层的函数。我想
一切都很好，而且一切似乎都运行正常，但DLL的开发者 -
谁也不是VB专家 - 认为在VB中应该有一个更好的方法
这样我就不必复制函数原型了（我会想象一些函数
原型需要更多只有1个重载。例如，我想我需要
重载上面的函数声明了几次才能占第二个
参数 - 这也可以接收NULL或结构 - 然后是
两个可以接收NULL或结构的参数的任意组合。）有没有更有效的方法来关于这个我的b $ b结束？
谢谢，
Lance
更改为ByVal aWorldBounds作为第一个版本中的GM_Rectangle_t。没有
需要通过ref传递它，因为它是一个in参数。然后只需将Nothing传递给
吧。
/ claes
" Lance" < nu *** @ business.comwrote in message
news：uG ************** @ TK2MSFTNGP04.phx.gbl ...
这就是问题。
在一个非托管的C ++ DLL中我正在调用，其中一个函数
原型是
/////
GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_DrawLayerList
（
HDC aDC，//要绘制的设备上下文
GM_LayerHandle_t32 * aLayerList，//要绘制的图层列表或所有空的NULL
uint32 aLayerCount，//列表中的图层（0表示所有）
GM_DrawFlags_t32 aDrawFlags，//控制绘制方式的标志
执行
const GM_Rectangle_t * aWorldBounds，/ /世界界限绘制或NULL为
所有
sint32 aLeftPixel，//绘制的左像素坐标
sint32 aTopPixel，// Top要绘制的像素坐标
sint32 aPixelWidth，//绘制的宽度（以像素为单位）
）;
/////
我最初翻译为
/////
公共声明函数GM_DrawLayerList Lib" GlobalMapperInterface" _
（_
ByVal aDC As IntPtr，_
ByRef aLayerList As GM_LayerHandle_t32，_
ByVal aLayerCount As Int32，_
ByVal aDrawFlags为GM_DrawFlags_t32，_
ByRef aWorldBounds为GM_Rectangle_t，_
ByVal aLeftPixel为Int32，_
ByVal aTopPixel为Int32，_
ByVal aPixelWidth为Int32，_
ByVal aPixelHeight为Int32 _
）为GM_Error_t32
/////
但是我无法弄清楚如何让它接收NULL（我发送了
IntPtr。当第5个
参数期望GM_Rectangle_t结构时，为函数零以表示NULL。 NULL需要发送到函数的
才能绘制所有图层。所以，我这个函数超载了
/////
公共声明函数GM_DrawLayerList Lib" GlobalMapperInterface" _
（_
ByVal aDC As IntPtr，_
ByRef aLayerList As GM_LayerHandle_t32，_
ByVal aLayerCount As Int32，_
ByVal aDrawFlags作为GM_DrawFlags_t32，_
ByVal aWorldBounds作为IntPtr，_
ByVal aLeftPixel作为Int32，_
ByVal aTopPixel为Int32，_
ByVal aPixelWidth为Int32，_
ByVal aPixelHeight为Int32 _
）为GM_Error_t32
/////
注意对ByVal的更改和IntPtr为第五个论点。现在它
为第5个参数接受一个NULL参数，以便获得绘制所有图层的函数
。我认为'一切都很好，所有的东西
似乎工作得很好，但DLL的开发者 - 不可否认的是，不是一个VB
VB专家 - 认为在VB中应该有一个更好的方法，这样我就不需要复制函数原型（我会想象一些
函数原型需要更多只有1个重载。例如，
我想我需要重载上面的函数声明几次
多次来计算第二个参数 - 这也可以接收
NULL或结构 - 然后两个参数的任意组合
可以接收NULL或结构。）是否有更有效的方法去
关于这个我的结局？
谢谢，
Lance
将其更改为
/////
公共声明函数GM_DrawLayerList Lib" GlobalMapperInterface" _
（_
ByVal aDC As IntPtr，_
ByRef aLayerList As GM_LayerHandle_t32，_
ByVal aLayerCount As Int32，_
ByVal aDrawFlags为GM_DrawFlags_t32，_
ByVal aWorldBounds为GM_Rectangle_t，_
ByVal aLeftPixel为Int32，_
ByVal aTopPixel为Int32，_
ByVal aPixelWidth为Int32，_
ByVal aPixelHeight为Int32 _
）为GM_Error_t32
/////
然后发送Nothing （当然没有引号）因为第五个参数导致了一个p
PInvokeStackImbalance。
Lance
Claes Bergefall ; < lo ***** @ nospam.nospamwrote in message
news：uL ************** @ TK2MSFTNGP04.phx.gbl ...
在第一个版本中更改为ByVal aWorldBounds为GM_Rectangle_t。不需要传递它
by ref，因为它是一个in参数。然后只需传递任何东西。
/ claes
" Lance" < nu *** @ business.comwrote in message
news：uG ************** @ TK2MSFTNGP04.phx.gbl ...
>这就是问题。
在一个非托管的C ++ DLL中，我正在调用，其中一个函数原型是
/////
GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_DrawLayerList
（
HDC aDC，//要绘制的设备上下文
GM_LayerHandle_t32 * aLayerList，//层列表到所有的绘制或NULL
uint32 aLayerCount，//列表中的层数（0表示所有）
GM_DrawFlags_t32 aDrawFlags，//控制绘制方式的标志
const GM_Rectangle_t * aWorldBounds，/ / world为所有
sint32 aLeftPixel绘制或为NULL，//左边的像素坐标绘制为
sint32 aTopPixel，//绘制的顶部像素坐标为
sint32 aPixelWidth，//宽度为要绘制的像素
sint32 aPixelHeight //高度（以像素为单位）绘制
）;
/////
我最初翻译为
// /// <无线电通信公共声明函数GM_DrawLayerList Lib" GlobalMapperInterface" _
（_
ByVal aDC As IntPtr，_
ByRef aLayerList As GM_LayerHandle_t32，_
ByVal aLayerCount As Int32，_
ByVal aDrawFlags As GM_DrawFlags_t32，_
ByRef aWorldBounds为GM_Rectangle_t，_
ByVal aLeftPixel为Int32，_
ByVal aTopPixel为Int32，_
ByVal aPixelWidth为Int32，_
ByVal aPixelHeight为Int32 _
）作为GM_Error_t32
/////
但我无法弄清楚如何让它接收NULL（我正在按顺序发送IntPtr.Zero到
函数当第5个参数期待
GM_Rectangle_t结构时表示NULL。需要将NULL发送到函数，以便它可以绘制所有图层。所以，我重载了这个函数
/////
Public Declare Function GM_DrawLayerList Lib" GlobalMapperInterface" _
（_
ByVal aDC As IntPtr，_
ByRef aLayerList As GM_LayerHandle_t32，_
ByVal aLayerCount As Int32，_
ByVal aDrawFlags As GM_DrawFlags_t32，_
ByVal aWorldBounds As IntPtr，_
ByVal aLeftPixel As Int32，_
ByVal aTopPixel As Int32，_
ByVal aPixelWidth As Int32，_
ByVal aPixelHeight As Int32 _
）作为GM_Error_t32
/////
请注意对ByVal的更改和IntPtr为第五个论点。现在它接受第5个参数的NULL
参数，以便获得绘制所有图层的函数。我认为这一切都很好，而且一切似乎都运行良好，但DLL的开发人员 - 不可否认的是他不是VB专家 - 认为应该有更好的在VB中使用它以便我不必复制函数原型（我会想象一些函数原型需要的不仅仅是1次重载。例如，
我想我需要重载上面的函数多次声明第二个参数 - 也可以接收NULL或结构 - 然后
两个参数的任意组合可以接收NULL或结构。）有没有更有效的方法来解决这个问题？
谢谢，
Lance
嗯...如果Claes和其他少数几个A在这里被难倒，那么我猜它是'
安全到假设比过载更好的解决方案可能不存在。我知道，
它只是自原始发布以来只有5或6个小时，但我可以告诉我们什么时候没有人b / b
咬人！那就是超载了。
Lance
" Lance" < nu *** @ business.comwrote in message
news：uG ************** @ TK2MSFTNGP04.phx.gbl ...
这就是问题。
在一个非托管的C ++ DLL中我正在调用，其中一个函数原型是
/////
GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_DrawLayerList
（
HDC aDC，//设备要绘制的上下文
GM_LayerHandle_t32 * aLayerList，//要绘制的图层列表或所有的NULL值
uint32 aLayerCount，//列表中的图层数（0表示全部）
GM_DrawFlags_t32 aDrawFlags，//控制绘制方式的标志
const GM_Rectangle_t * aWorldBounds，//全局绘制范围或所有空值
sint32 aLeftPixel，//要绘制的左像素坐标
sint32 aTopPixel，//要绘制的顶部像素坐标
sint32 aPixelWidth，//绘制的宽度（以像素为单位） br />
sint32 aPixelHeight //用于绘制的高度（以像素为单位） />
）;
/////
我最初翻译为
//// /
公共声明函数GM_DrawLayerList Lib" GlobalMapperInterface" _
（_
ByVal aDC As IntPtr，_
ByRef aLayerList As GM_LayerHandle_t32，_
ByVal aLayerCount As Int32，_
ByVal aDrawFlags为GM_DrawFlags_t32，_
ByRef aWorldBounds为GM_Rectangle_t，_
ByVal aLeftPixel为Int32，_
ByVal aTopPixel为Int32，_
ByVal aPixelWidth为Int32，_
ByVal aPixelHeight为Int32 _
）为GM_Error_t32
/////
但我无法弄清楚如何让它接收NULL（我发送IntPtr.Zero到
函数以表示NULL）当第5个参数期望
GM_Rectangle_t结构时。需要将NULL发送到函数，以便它绘制
所有图层。所以，我这样重载了这个函数
/////
公共声明函数GM_DrawLayerList Lib" GlobalMapperInterface" _
（_
ByVal aDC As IntPtr，_
ByRef aLayerList As GM_LayerHandle_t32，_
ByVal aLayerCount As Int32，_
ByVal aDrawFlags作为GM_DrawFlags_t32，_
ByVal aWorldBounds作为IntPtr，_
ByVal aLeftPixel作为Int32，_
ByVal aTopPixel为Int32，_
ByVal aPixelWidth为Int32，_
ByVal aPixelHeight为Int32 _
）为GM_Error_t32
/////
注意对ByVal的更改和IntPtr为第五个论点。现在它接受第5个参数的NULL
参数，以便获得绘制所有图层的函数。我认为'一切都很好，而且一切似乎都运行良好，但是这个DLL的开发人员 - 无可否认的是，他不是VB专家 - 认为在VB中应该有一个更好的方式
，这样我就不必复制函数原型（我会想象
一些函数原型需要更多只有1个重载。例如，我认为
我需要重载上面的函数多次声明为第二个参数的帐户
- 这也可以接收NULL或结构 - 然后是可以接收NULL或结构的两个参数的任何
组合。）是否有更多的
有效的方法来解决这个问题结束？
谢谢，
Lance
That is the question.
In an unmanaged C++ DLL I''m making calls to, one of the function prototypes is
/////
GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_DrawLayerList
(
HDC aDC, // Device context to draw to
GM_LayerHandle_t32* aLayerList, // List of layers to draw or NULL for all
uint32 aLayerCount, // Number of layers in list (0 for all)
GM_DrawFlags_t32 aDrawFlags, // Flags controlling how the draw is performed
const GM_Rectangle_t* aWorldBounds, // World bounds to draw or NULL for all
sint32 aLeftPixel, // Left pixel coordinate to draw to
sint32 aTopPixel, // Top pixel coordinate to draw to
sint32 aPixelWidth, // Width in pixels to draw
sint32 aPixelHeight // Height in pixels to draw
);
/////
which I originally translated to
/////
Public Declare Function GM_DrawLayerList Lib "GlobalMapperInterface" _
( _
ByVal aDC As IntPtr, _
ByRef aLayerList As GM_LayerHandle_t32, _
ByVal aLayerCount As Int32, _
ByVal aDrawFlags As GM_DrawFlags_t32, _
ByRef aWorldBounds As GM_Rectangle_t, _
ByVal aLeftPixel As Int32, _
ByVal aTopPixel As Int32, _
ByVal aPixelWidth As Int32, _
ByVal aPixelHeight As Int32 _
) As GM_Error_t32
/////
but I couldn''t figure out how get it to receive NULL (I was sending IntPtr.Zero to the
function in order to represent NULL) when the 5th argument was expecting the
GM_Rectangle_t structure. NULL needs to be sent to the function in order for it to draw
all layers. So, I overloaded the function as such
/////
Public Declare Function GM_DrawLayerList Lib "GlobalMapperInterface" _
( _
ByVal aDC As IntPtr, _
ByRef aLayerList As GM_LayerHandle_t32, _
ByVal aLayerCount As Int32, _
ByVal aDrawFlags As GM_DrawFlags_t32, _
ByVal aWorldBounds As IntPtr, _
ByVal aLeftPixel As Int32, _
ByVal aTopPixel As Int32, _
ByVal aPixelWidth As Int32, _
ByVal aPixelHeight As Int32 _
) As GM_Error_t32
/////
Note the change to "ByVal" and "IntPtr" for the 5th argument. Now it accepts a NULL
argument for the 5th parameter in order to get the function to draw all layers. I suppose
that''s all well and good and everything seems to work fine, but the developer of the DLL -
who admittedly is not a VB expert - thinks that there should be a better way to it in VB
so that I don''t have to duplicate the function prototypes (I would imagine some function
prototypes would require more than just 1 overload. For example, I think I would need to
overload the above function declare a couple of more times to account for the second
argument - which can also receive NULL or a structure - and then any combination of the
two arguments that can receive a NULL or structure.) Is there a more efficient way to go
about this on my end?
Thanks,
Lance
Change to ByVal aWorldBounds As GM_Rectangle_t in your first version. No
need to pass it by ref since it''s an in parameter. Then just pass Nothing to
it.
/claes
"Lance" <nu***@business.comwrote in message
news:uG**************@TK2MSFTNGP04.phx.gbl...That is the question.
In an unmanaged C++ DLL I''m making calls to, one of the function
prototypes is
/////
GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_DrawLayerList
(
HDC aDC, // Device context to draw to
GM_LayerHandle_t32* aLayerList, // List of layers to draw or NULL for all
uint32 aLayerCount, // Number of layers in list (0 for all)
GM_DrawFlags_t32 aDrawFlags, // Flags controlling how the draw is
performed
const GM_Rectangle_t* aWorldBounds, // World bounds to draw or NULL for
all
sint32 aLeftPixel, // Left pixel coordinate to draw to
sint32 aTopPixel, // Top pixel coordinate to draw to
sint32 aPixelWidth, // Width in pixels to draw
sint32 aPixelHeight // Height in pixels to draw
);
/////
which I originally translated to
/////
Public Declare Function GM_DrawLayerList Lib "GlobalMapperInterface" _
( _
ByVal aDC As IntPtr, _
ByRef aLayerList As GM_LayerHandle_t32, _
ByVal aLayerCount As Int32, _
ByVal aDrawFlags As GM_DrawFlags_t32, _
ByRef aWorldBounds As GM_Rectangle_t, _
ByVal aLeftPixel As Int32, _
ByVal aTopPixel As Int32, _
ByVal aPixelWidth As Int32, _
ByVal aPixelHeight As Int32 _
) As GM_Error_t32
/////
but I couldn''t figure out how get it to receive NULL (I was sending
IntPtr.Zero to the function in order to represent NULL) when the 5th
argument was expecting the GM_Rectangle_t structure. NULL needs to be
sent to the function in order for it to draw all layers. So, I overloaded
the function as such
/////
Public Declare Function GM_DrawLayerList Lib "GlobalMapperInterface" _
( _
ByVal aDC As IntPtr, _
ByRef aLayerList As GM_LayerHandle_t32, _
ByVal aLayerCount As Int32, _
ByVal aDrawFlags As GM_DrawFlags_t32, _
ByVal aWorldBounds As IntPtr, _
ByVal aLeftPixel As Int32, _
ByVal aTopPixel As Int32, _
ByVal aPixelWidth As Int32, _
ByVal aPixelHeight As Int32 _
) As GM_Error_t32
/////
Note the change to "ByVal" and "IntPtr" for the 5th argument. Now it
accepts a NULL argument for the 5th parameter in order to get the function
to draw all layers. I suppose that''s all well and good and everything
seems to work fine, but the developer of the DLL - who admittedly is not a
VB expert - thinks that there should be a better way to it in VB so that I
don''t have to duplicate the function prototypes (I would imagine some
function prototypes would require more than just 1 overload. For example,
I think I would need to overload the above function declare a couple of
more times to account for the second argument - which can also receive
NULL or a structure - and then any combination of the two arguments that
can receive a NULL or structure.) Is there a more efficient way to go
about this on my end?
Thanks,
Lance
Changing it to
/////
Public Declare Function GM_DrawLayerList Lib "GlobalMapperInterface" _
( _
ByVal aDC As IntPtr, _
ByRef aLayerList As GM_LayerHandle_t32, _
ByVal aLayerCount As Int32, _
ByVal aDrawFlags As GM_DrawFlags_t32, _
ByVal aWorldBounds As GM_Rectangle_t, _
ByVal aLeftPixel As Int32, _
ByVal aTopPixel As Int32, _
ByVal aPixelWidth As Int32, _
ByVal aPixelHeight As Int32 _
) As GM_Error_t32
/////
then sending "Nothing" (without the quotes, of course) as the 5th argument results in a
PInvokeStackImbalance.
Lance
"Claes Bergefall" <lo*****@nospam.nospamwrote in message
news:uL**************@TK2MSFTNGP04.phx.gbl...Change to ByVal aWorldBounds As GM_Rectangle_t in your first version. No need to pass it
by ref since it''s an in parameter. Then just pass Nothing to it.
/claes
"Lance" <nu***@business.comwrote in message
news:uG**************@TK2MSFTNGP04.phx.gbl...>That is the question.
In an unmanaged C++ DLL I''m making calls to, one of the function prototypes is
/////
GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_DrawLayerList
(
HDC aDC, // Device context to draw to
GM_LayerHandle_t32* aLayerList, // List of layers to draw or NULL for all
uint32 aLayerCount, // Number of layers in list (0 for all)
GM_DrawFlags_t32 aDrawFlags, // Flags controlling how the draw is performed
const GM_Rectangle_t* aWorldBounds, // World bounds to draw or NULL for all
sint32 aLeftPixel, // Left pixel coordinate to draw to
sint32 aTopPixel, // Top pixel coordinate to draw to
sint32 aPixelWidth, // Width in pixels to draw
sint32 aPixelHeight // Height in pixels to draw
);
/////
which I originally translated to
/////
Public Declare Function GM_DrawLayerList Lib "GlobalMapperInterface" _
( _
ByVal aDC As IntPtr, _
ByRef aLayerList As GM_LayerHandle_t32, _
ByVal aLayerCount As Int32, _
ByVal aDrawFlags As GM_DrawFlags_t32, _
ByRef aWorldBounds As GM_Rectangle_t, _
ByVal aLeftPixel As Int32, _
ByVal aTopPixel As Int32, _
ByVal aPixelWidth As Int32, _
ByVal aPixelHeight As Int32 _
) As GM_Error_t32
/////
but I couldn''t figure out how get it to receive NULL (I was sending IntPtr.Zero to the
function in order to represent NULL) when the 5th argument was expecting the
GM_Rectangle_t structure. NULL needs to be sent to the function in order for it to
draw all layers. So, I overloaded the function as such
/////
Public Declare Function GM_DrawLayerList Lib "GlobalMapperInterface" _
( _
ByVal aDC As IntPtr, _
ByRef aLayerList As GM_LayerHandle_t32, _
ByVal aLayerCount As Int32, _
ByVal aDrawFlags As GM_DrawFlags_t32, _
ByVal aWorldBounds As IntPtr, _
ByVal aLeftPixel As Int32, _
ByVal aTopPixel As Int32, _
ByVal aPixelWidth As Int32, _
ByVal aPixelHeight As Int32 _
) As GM_Error_t32
/////
Note the change to "ByVal" and "IntPtr" for the 5th argument. Now it accepts a NULL
argument for the 5th parameter in order to get the function to draw all layers. I
suppose that''s all well and good and everything seems to work fine, but the developer
of the DLL - who admittedly is not a VB expert - thinks that there should be a better
way to it in VB so that I don''t have to duplicate the function prototypes (I would
imagine some function prototypes would require more than just 1 overload. For example,
I think I would need to overload the above function declare a couple of more times to
account for the second argument - which can also receive NULL or a structure - and then
any combination of the two arguments that can receive a NULL or structure.) Is there a
more efficient way to go about this on my end?
Thanks,
Lance
Well drat...if Claes and the other handful of aces here are stumped, then I guess it''s
safe to assume that a better solution than overloading is likely non-existent. I know,
it''s only been about 5 or 6 hours since the original posting, but I can tell when no ones
biting! Overloading it is, then.
Lance
"Lance" <nu***@business.comwrote in message
news:uG**************@TK2MSFTNGP04.phx.gbl...That is the question.
In an unmanaged C++ DLL I''m making calls to, one of the function prototypes is
/////
GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_DrawLayerList
(
HDC aDC, // Device context to draw to
GM_LayerHandle_t32* aLayerList, // List of layers to draw or NULL for all
uint32 aLayerCount, // Number of layers in list (0 for all)
GM_DrawFlags_t32 aDrawFlags, // Flags controlling how the draw is performed
const GM_Rectangle_t* aWorldBounds, // World bounds to draw or NULL for all
sint32 aLeftPixel, // Left pixel coordinate to draw to
sint32 aTopPixel, // Top pixel coordinate to draw to
sint32 aPixelWidth, // Width in pixels to draw
sint32 aPixelHeight // Height in pixels to draw
);
/////
which I originally translated to
/////
Public Declare Function GM_DrawLayerList Lib "GlobalMapperInterface" _
( _
ByVal aDC As IntPtr, _
ByRef aLayerList As GM_LayerHandle_t32, _
ByVal aLayerCount As Int32, _
ByVal aDrawFlags As GM_DrawFlags_t32, _
ByRef aWorldBounds As GM_Rectangle_t, _
ByVal aLeftPixel As Int32, _
ByVal aTopPixel As Int32, _
ByVal aPixelWidth As Int32, _
ByVal aPixelHeight As Int32 _
) As GM_Error_t32
/////
but I couldn''t figure out how get it to receive NULL (I was sending IntPtr.Zero to the
function in order to represent NULL) when the 5th argument was expecting the
GM_Rectangle_t structure. NULL needs to be sent to the function in order for it to draw
all layers. So, I overloaded the function as such
/////
Public Declare Function GM_DrawLayerList Lib "GlobalMapperInterface" _
( _
ByVal aDC As IntPtr, _
ByRef aLayerList As GM_LayerHandle_t32, _
ByVal aLayerCount As Int32, _
ByVal aDrawFlags As GM_DrawFlags_t32, _
ByVal aWorldBounds As IntPtr, _
ByVal aLeftPixel As Int32, _
ByVal aTopPixel As Int32, _
ByVal aPixelWidth As Int32, _
ByVal aPixelHeight As Int32 _
) As GM_Error_t32
/////
Note the change to "ByVal" and "IntPtr" for the 5th argument. Now it accepts a NULL
argument for the 5th parameter in order to get the function to draw all layers. I
suppose that''s all well and good and everything seems to work fine, but the developer of
the DLL - who admittedly is not a VB expert - thinks that there should be a better way
to it in VB so that I don''t have to duplicate the function prototypes (I would imagine
some function prototypes would require more than just 1 overload. For example, I think
I would need to overload the above function declare a couple of more times to account
for the second argument - which can also receive NULL or a structure - and then any
combination of the two arguments that can receive a NULL or structure.) Is there a more
efficient way to go about this on my end?
Thanks,
Lance
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