GradientFillRect

  • Thread starter Thread starter NickP
  • Start date Start date
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NickP

Hi there,

I am trying to use GradientFillRect in a VB.NET application.

Does anyone have any examples of the correct PInvoke signature and
marshaling that I need to perform in order to achieve this?

BTW, I do not want to use .Nets gradient fill capabilities, and so far I
have this.

----------------------------------------------

Private Const GRADIENT_FILL_RECT_H As Long = &H0
Private Const GRADIENT_FILL_RECT_V As Long = &H1

<StructLayout(LayoutKind.Sequential)> _
Public Structure TRIVERTEX
Public x As Int32
Public y As Int32
Public Red As Int16
Public Green As Int16
Public Blue As Int16
Public Alpha As Int16
End Structure

<StructLayout(LayoutKind.Sequential)> _
Public Structure GRADIENT_RECT
Public UpperLeft As Integer
Public LowerRight As Integer
End Structure

<DllImport("msimg32.dll", EntryPoint:="GradientFill")> _
Public Shared Function GradientFillRect(ByVal hdc As IntPtr, _
ByVal pVertex As IntPtr, _
ByVal dwNumVertex As Integer, _
ByRef pMesh As GRADIENT_RECT, _
ByVal dwNumMesh As Integer, _
ByVal dwMode As Long) As Integer
End Function

Private Sub doGradientFill(ByVal iGraphics As Graphics, _
ByVal iSize As Size)
'//--------------------------------------------------
With iGraphics
Dim pTVxVert(2) As TRIVERTEX
Dim pGRtRect As GRADIENT_RECT
pTVxVert(0).x = 0
pTVxVert(0).y = 0
pTVxVert(0).Red = (Color.Green.R)
pTVxVert(0).Green = (Color.Green.G)
pTVxVert(0).Blue = (Color.Green.B)
pTVxVert(0).Alpha = (Color.Green.A)
pTVxVert(1).x = iSize.Width
pTVxVert(1).y = iSize.Height
pTVxVert(1).Red = (Color.Red.R)
pTVxVert(1).Green = (Color.Red.G)
pTVxVert(1).Blue = (Color.Red.B)
pTVxVert(1).Alpha = (Color.Red.A)
pGRtRect.UpperLeft = 0
pGRtRect.LowerRight = 1

Dim pIPrVert As IntPtr =
Marshal.AllocHGlobal(Marshal.SizeOf(pTVxVert))
Call Marshal.StructureToPtr(pTVxVert, pIPrVert, False)
Dim pIPrHDC As IntPtr = iGraphics.GetHdc()
GradientFillRect(pIPrHDC, pIPrVert, 2, pGRtRect, 1,
GRADIENT_FILL_RECT_H)
'GradientFillRect(pIPrHDC, pTVxVert, 2, pGRtRect, 1,
GRADIENT_FILL_RECT_V)
Call iGraphics.ReleaseHdc(pIPrHDC)
End With
End Sub

----------------------------------------------

Unfortunately this does not work as pTVxVert is an array and the size
cannot be calculated correctly. Any ideas?

Many thanks in advance.

Nick.
 
Just noticed 2 things but still can't get it working, just getting a solid
black block rather than gradient.

My API declaration for GradientFillRect includes a "Long" parameter, should
be Integer. Also I was not converting the RGB values to shorts, this is now
being done but still no luck :-(

Oh yeah and my array was 1 too big, not that this shoud effect the output.

Nick.
 
I now have this.... (which doesn't work also)... Even after hardcoding some
colours!

------------------

Private Const GRADIENT_FILL_RECT_H As Long = &H0
Private Const GRADIENT_FILL_RECT_V As Long = &H1

<StructLayout(LayoutKind.Sequential)> _
Public Structure TRIVERTEX
Public x As Int32
Public y As Int32
Public Red As UInt16
Public Green As UInt16
Public Blue As UInt16
Public Alpha As UInt16
End Structure

<StructLayout(LayoutKind.Sequential)> _
Public Structure GRADIENT_RECT
Public UpperLeft As Integer
Public LowerRight As Integer
End Structure

<DllImport("msimg32.dll", EntryPoint:="GradientFill")> _
Public Shared Function GradientFill(ByVal hdc As IntPtr, _
<MarshalAs(UnmanagedType.LPArray, ArraySubType:=UnmanagedType.Struct)> _
ByRef pVertex() As TRIVERTEX, _
ByVal dwNumVertex As Integer, _
ByRef pMesh As GRADIENT_RECT, _
ByVal dwNumMesh As Integer, _
ByVal dwMode As Integer) As Boolean
End Function

Private Sub doGradientFill(ByVal iGraphics As Graphics, _
ByVal iSize As Size)
'//--------------------------------------------------
With iGraphics
Dim pTVxVert(1) As TRIVERTEX
Dim pGRtRect As GRADIENT_RECT
pTVxVert(0).x = 0
pTVxVert(0).y = 0
pTVxVert(0).Red = 0 'ByteToUShort(255)
pTVxVert(0).Green = &HFF00 'ByteToUShort(0)
pTVxVert(0).Blue = 0 'ByteToUShort(0)
pTVxVert(0).Alpha = 0 'ByteToUShort(0)
pTVxVert(1).x = iSize.Width
pTVxVert(1).y = iSize.Height
pTVxVert(1).Red = &HFF00 'ByteToUShort(0)
pTVxVert(1).Green = 0 'ByteToUShort(255)
pTVxVert(1).Blue = 0 'ByteToUShort(0)
pTVxVert(1).Alpha = &HFF00 'ByteToUShort(0)
pGRtRect.UpperLeft = 0
pGRtRect.LowerRight = 1
Dim pIPrHDC As IntPtr = iGraphics.GetHdc()
Console.WriteLine(GradientFill(pIPrHDC, pTVxVert, 2, pGRtRect, 1,
GRADIENT_FILL_RECT_V).ToString)
Call iGraphics.ReleaseHdc(pIPrHDC)
End With
End Sub
------------------

I've tried to add as much marshaling information as I can think of as well
as assuring the signatures are correct but the lack of information with
regard to this method and .NET is upsetting :-(

If anyone else has done this, some info would be great. I'll post this on
the graphics one too just incase.

Nick.
 
Hi Jay,
NOTE: I have not used the API, as I find using .NET's simply & very
flexible.
Click to expand...

And also very slow in comparrison. All .net graphics methods are slow in
comparrison. Currently I have a drawing routine that has 1 bottle neck, it
is the drawing of this gradient unfortunately.

I'll check that link out, many thanks :-)

Nick.

Jay B. Harlow said:
Nick,
BTW, I do not want to use .Nets gradient fill capabilities, and so far
I have this.
Click to expand...
As Stuart asked: Why not??????

.NET has already done all the hard work for you.


If you have an actual need to call the API itself, I would recommend you
start here:

http://pinvoke.net/search.aspx?search=GradientFill&namespace=[All]

NOTE: I have not used the API, as I find using .NET's simply & very
flexible.

--
Hope this helps
Jay B. Harlow [MVP - Outlook]
.NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net


NickP said:
Hi there,

I am trying to use GradientFillRect in a VB.NET application.

Does anyone have any examples of the correct PInvoke signature and
marshaling that I need to perform in order to achieve this?

BTW, I do not want to use .Nets gradient fill capabilities, and so far
I have this.

----------------------------------------------

Private Const GRADIENT_FILL_RECT_H As Long = &H0
Private Const GRADIENT_FILL_RECT_V As Long = &H1

<StructLayout(LayoutKind.Sequential)> _
Public Structure TRIVERTEX
Public x As Int32
Public y As Int32
Public Red As Int16
Public Green As Int16
Public Blue As Int16
Public Alpha As Int16
End Structure

<StructLayout(LayoutKind.Sequential)> _
Public Structure GRADIENT_RECT
Public UpperLeft As Integer
Public LowerRight As Integer
End Structure

<DllImport("msimg32.dll", EntryPoint:="GradientFill")> _
Public Shared Function GradientFillRect(ByVal hdc As IntPtr, _
ByVal pVertex As IntPtr, _
ByVal dwNumVertex As Integer, _
ByRef pMesh As GRADIENT_RECT, _
ByVal dwNumMesh As Integer, _
ByVal dwMode As Long) As Integer
End Function

Private Sub doGradientFill(ByVal iGraphics As Graphics, _
ByVal iSize As Size)
'//--------------------------------------------------
With iGraphics
Dim pTVxVert(2) As TRIVERTEX
Dim pGRtRect As GRADIENT_RECT
pTVxVert(0).x = 0
pTVxVert(0).y = 0
pTVxVert(0).Red = (Color.Green.R)
pTVxVert(0).Green = (Color.Green.G)
pTVxVert(0).Blue = (Color.Green.B)
pTVxVert(0).Alpha = (Color.Green.A)
pTVxVert(1).x = iSize.Width
pTVxVert(1).y = iSize.Height
pTVxVert(1).Red = (Color.Red.R)
pTVxVert(1).Green = (Color.Red.G)
pTVxVert(1).Blue = (Color.Red.B)
pTVxVert(1).Alpha = (Color.Red.A)
pGRtRect.UpperLeft = 0
pGRtRect.LowerRight = 1

Dim pIPrVert As IntPtr =
Marshal.AllocHGlobal(Marshal.SizeOf(pTVxVert))
Call Marshal.StructureToPtr(pTVxVert, pIPrVert, False)
Dim pIPrHDC As IntPtr = iGraphics.GetHdc()
GradientFillRect(pIPrHDC, pIPrVert, 2, pGRtRect, 1,
GRADIENT_FILL_RECT_H)
'GradientFillRect(pIPrHDC, pTVxVert, 2, pGRtRect, 1,
GRADIENT_FILL_RECT_V)
Call iGraphics.ReleaseHdc(pIPrHDC)
End With
End Sub

----------------------------------------------

Unfortunately this does not work as pTVxVert is an array and the size
cannot be calculated correctly. Any ideas?

Many thanks in advance.

Nick.
Click to expand...
Click to expand...
 
BTW,

I don't see Stuarts reply, I think my outlook express is borked :-(

Jay B. Harlow said:
Nick,
BTW, I do not want to use .Nets gradient fill capabilities, and so far
I have this.
Click to expand...
As Stuart asked: Why not??????

.NET has already done all the hard work for you.


If you have an actual need to call the API itself, I would recommend you
start here:

http://pinvoke.net/search.aspx?search=GradientFill&namespace=[All]

NOTE: I have not used the API, as I find using .NET's simply & very
flexible.

--
Hope this helps
Jay B. Harlow [MVP - Outlook]
.NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net


NickP said:
Hi there,

I am trying to use GradientFillRect in a VB.NET application.

Does anyone have any examples of the correct PInvoke signature and
marshaling that I need to perform in order to achieve this?

BTW, I do not want to use .Nets gradient fill capabilities, and so far
I have this.

----------------------------------------------

Private Const GRADIENT_FILL_RECT_H As Long = &H0
Private Const GRADIENT_FILL_RECT_V As Long = &H1

<StructLayout(LayoutKind.Sequential)> _
Public Structure TRIVERTEX
Public x As Int32
Public y As Int32
Public Red As Int16
Public Green As Int16
Public Blue As Int16
Public Alpha As Int16
End Structure

<StructLayout(LayoutKind.Sequential)> _
Public Structure GRADIENT_RECT
Public UpperLeft As Integer
Public LowerRight As Integer
End Structure

<DllImport("msimg32.dll", EntryPoint:="GradientFill")> _
Public Shared Function GradientFillRect(ByVal hdc As IntPtr, _
ByVal pVertex As IntPtr, _
ByVal dwNumVertex As Integer, _
ByRef pMesh As GRADIENT_RECT, _
ByVal dwNumMesh As Integer, _
ByVal dwMode As Long) As Integer
End Function

Private Sub doGradientFill(ByVal iGraphics As Graphics, _
ByVal iSize As Size)
'//--------------------------------------------------
With iGraphics
Dim pTVxVert(2) As TRIVERTEX
Dim pGRtRect As GRADIENT_RECT
pTVxVert(0).x = 0
pTVxVert(0).y = 0
pTVxVert(0).Red = (Color.Green.R)
pTVxVert(0).Green = (Color.Green.G)
pTVxVert(0).Blue = (Color.Green.B)
pTVxVert(0).Alpha = (Color.Green.A)
pTVxVert(1).x = iSize.Width
pTVxVert(1).y = iSize.Height
pTVxVert(1).Red = (Color.Red.R)
pTVxVert(1).Green = (Color.Red.G)
pTVxVert(1).Blue = (Color.Red.B)
pTVxVert(1).Alpha = (Color.Red.A)
pGRtRect.UpperLeft = 0
pGRtRect.LowerRight = 1

Dim pIPrVert As IntPtr =
Marshal.AllocHGlobal(Marshal.SizeOf(pTVxVert))
Call Marshal.StructureToPtr(pTVxVert, pIPrVert, False)
Dim pIPrHDC As IntPtr = iGraphics.GetHdc()
GradientFillRect(pIPrHDC, pIPrVert, 2, pGRtRect, 1,
GRADIENT_FILL_RECT_H)
'GradientFillRect(pIPrHDC, pTVxVert, 2, pGRtRect, 1,
GRADIENT_FILL_RECT_V)
Call iGraphics.ReleaseHdc(pIPrHDC)
End With
End Sub

----------------------------------------------

Unfortunately this does not work as pTVxVert is an array and the size
cannot be calculated correctly. Any ideas?

Many thanks in advance.

Nick.
Click to expand...
Click to expand...
 
And also very slow in comparrison.
Slow is a user perception.

For where & how I'm using gradients I don't see/perceive that they are slow.

Although I realize there are places where high performant graphics is
important. Which is where having 3 systems to choose from; GDI, GDI+ or
DirectX is nice...

--
Hope this helps
Jay B. Harlow [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net


NickP said:
Hi Jay,
NOTE: I have not used the API, as I find using .NET's simply & very
flexible.
Click to expand...

And also very slow in comparrison. All .net graphics methods are slow in
comparrison. Currently I have a drawing routine that has 1 bottle neck,
it is the drawing of this gradient unfortunately.

I'll check that link out, many thanks :-)

Nick.

Jay B. Harlow said:
Nick,
BTW, I do not want to use .Nets gradient fill capabilities, and so
far I have this.
Click to expand...
As Stuart asked: Why not??????

.NET has already done all the hard work for you.


If you have an actual need to call the API itself, I would recommend you
start here:

http://pinvoke.net/search.aspx?search=GradientFill&namespace=[All]

NOTE: I have not used the API, as I find using .NET's simply & very
flexible.

--
Hope this helps
Jay B. Harlow [MVP - Outlook]
.NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net


NickP said:
Hi there,

I am trying to use GradientFillRect in a VB.NET application.

Does anyone have any examples of the correct PInvoke signature and
marshaling that I need to perform in order to achieve this?

BTW, I do not want to use .Nets gradient fill capabilities, and so
far I have this.

----------------------------------------------

Private Const GRADIENT_FILL_RECT_H As Long = &H0
Private Const GRADIENT_FILL_RECT_V As Long = &H1

<StructLayout(LayoutKind.Sequential)> _
Public Structure TRIVERTEX
Public x As Int32
Public y As Int32
Public Red As Int16
Public Green As Int16
Public Blue As Int16
Public Alpha As Int16
End Structure

<StructLayout(LayoutKind.Sequential)> _
Public Structure GRADIENT_RECT
Public UpperLeft As Integer
Public LowerRight As Integer
End Structure

<DllImport("msimg32.dll", EntryPoint:="GradientFill")> _
Public Shared Function GradientFillRect(ByVal hdc As IntPtr, _
ByVal pVertex As IntPtr, _
ByVal dwNumVertex As Integer, _
ByRef pMesh As GRADIENT_RECT, _
ByVal dwNumMesh As Integer, _
ByVal dwMode As Long) As Integer
End Function

Private Sub doGradientFill(ByVal iGraphics As Graphics, _
ByVal iSize As Size)
'//--------------------------------------------------
With iGraphics
Dim pTVxVert(2) As TRIVERTEX
Dim pGRtRect As GRADIENT_RECT
pTVxVert(0).x = 0
pTVxVert(0).y = 0
pTVxVert(0).Red = (Color.Green.R)
pTVxVert(0).Green = (Color.Green.G)
pTVxVert(0).Blue = (Color.Green.B)
pTVxVert(0).Alpha = (Color.Green.A)
pTVxVert(1).x = iSize.Width
pTVxVert(1).y = iSize.Height
pTVxVert(1).Red = (Color.Red.R)
pTVxVert(1).Green = (Color.Red.G)
pTVxVert(1).Blue = (Color.Red.B)
pTVxVert(1).Alpha = (Color.Red.A)
pGRtRect.UpperLeft = 0
pGRtRect.LowerRight = 1

Dim pIPrVert As IntPtr =
Marshal.AllocHGlobal(Marshal.SizeOf(pTVxVert))
Call Marshal.StructureToPtr(pTVxVert, pIPrVert, False)
Dim pIPrHDC As IntPtr = iGraphics.GetHdc()
GradientFillRect(pIPrHDC, pIPrVert, 2, pGRtRect, 1,
GRADIENT_FILL_RECT_H)
'GradientFillRect(pIPrHDC, pTVxVert, 2, pGRtRect, 1,
GRADIENT_FILL_RECT_V)
Call iGraphics.ReleaseHdc(pIPrHDC)
End With
End Sub

----------------------------------------------

Unfortunately this does not work as pTVxVert is an array and the size
cannot be calculated correctly. Any ideas?

Many thanks in advance.

Nick.
Click to expand...
Click to expand...
Click to expand...
 
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