Trapezoid and Click?

[Tec-Nico]

Hello, I am trying to draw a couple of trapezoids on an OCX control... I am using the following code:

Private Type COORD
 x As Long
 y As Long
End Type
 
Private Declare Function CreatePolygonRgn Lib "gdi32" (lpPoint As Any, ByVal nCount As Long, ByVal nPolyFillMode As Long) As Long
Private Declare Function Polygon Lib "gdi32" (ByVal hdc As Long, lpPoint As Any, ByVal nCount As Long) As Long
Private Declare Function FillRgn Lib "gdi32" (ByVal hdc As Long, ByVal hRgn As Long, ByVal hBrush As Long) As Long
Private Declare Function GetStockObject Lib "gdi32" (ByVal nIndex As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
 
Const ALTERNATE = 1 ' ALTERNATE and WINDING are
Const WINDING = 2 ' constants for FillMode.
Const BLACKBRUSH = 4 ' Constant for brush type.
Const WHITEBRUSH = 1
 
Private Sub dibujaTrapecio(x As Long, y As Long, width As Long, height As Long, color As Long)
 Dim iXBorder As Long
 Dim iYBorder As Long
 
 iXBorder = 10
 iYBorder = 1
 
 x = x - iXBorder
 width = width + iXBorder
 
 y = y - iYBorder
 height = height + iYBorder
 
 Dim poly(1 To 4) As COORD, NumCoords As Long, hBrush As Long, hRgn As Long
 UserControl.Cls
 ' Number of vertices in polygon.
 NumCoords = 4
 ' Set scalemode to pixels to set up points of trapezoid.
 UserControl.ScaleMode = vbPixels
 ' Assign values to points.
 poly(1).x = x + iXBorder
 poly(1).y = y
 poly(2).x = x
 poly(2).y = y + height
 poly(3).x = x + iXBorder + width
 poly(3).y = y + height
 poly(4).x = x + width
 poly(4).y = y
 ' Polygon function creates unfilled polygon on screen.
 ' Remark FillRgn statement to see results.
 Polygon UserControl.hdc, poly(1), NumCoords
 ' Gets stock black brush.
 hBrush = GetStockObject(color)
 ' Creates region to fill with color.
 hRgn = CreatePolygonRgn(poly(1), NumCoords, ALTERNATE)
 ' If the creation of the region was successful then color.
 If hRgn Then FillRgn UserControl.hdc, hRgn, hBrush
 DeleteObject hRgn
End Sub

(I took the code from si_geek and changed it a little for my own needs, thank you, si_geek)

As you can imagine, I am trying to emulate the behavior Frontpage has with its different files.

I wonder if there is a way to get the WindowBackground color for the brush... And also how could I redraw an array... Meaning I have to have something like a ZOrder... I am just starting and I would like some help.

Thanks in advance.

[krtxmrtz]

Originally posted by Tec-Nico
...
hBrush = GetStockObject(color)
...

Hola Tec-Nico,

I'm using code similar to yours to draw a filled polygon. Do you happen to know how it could be filled with a custom colour like, for example, black border and blue inside?

Saludos desde el otro lado del Atlantico...

[si_the_geek]

Originally posted by Tec-Nico
(I took the code from si_geek and changed it a little for my own needs, thank you, si_geek)

thanks, I'm glad it helped!


Anyway, time to see if I can help some more!

From the title of this thread I guessed you wanted to know how to detect a click in a polygon, if that is the case try searching this site for PtInRegion, hopefully there will be some good examples/explantions.


No ideas about the Brush questions I'm afraid - I've neve needed to use them.

Originally posted by Tec-Nico
And also how could I redraw an array... Meaning I have to have something like a ZOrder... .

If you are drawing directly onto a form you can just do formname.cls, then re-draw everything (in the new order, the shapes at the "back" first).

I think usercontrols might have the cls method too, in which case you can use the same method.

[Tec-Nico]

¡Hola krtxmrtz!

I am so ashamed I can't help you with the brushes either... Yet I solved it in another way... I will show you how I did it.

si_the_geek, thanks for your suggestions... But I ended up making a control that would be like the shape control but that would know when you click on it... I haven't finished it yet, but so far I have done what I need so far.

I will add that control here (the code and the OCX, of course), it is still in testing mode.. For example, when it is disabled in Windows XP it won't get the colors it should... Also when you try changing the BackColor (I commented this code) it will make all of it go black.

Why? I don't know...

Anyway, here is the code...

Oh, saludos desde este lado del charco, krtxmrtz

[krtxmrtz]

Originally posted by Tec-Nico

Hi,

I'll take a look at the control... For now I've solved it differently: I draw my polygon on a picturebox with black brush and then I use an API function to change black for another colour.

Still I'd like to know if this step could be avoided by using the SetDCBrushColor or SetDCPenColor function. The explanation in the Microsoft pages was not too informative -I couldn't set the functions to work properly- and I haven't found any references to them neither searching the forum nor in Allapi.

[krtxmrtz]

What I haven't figured out yet is how to have a border colour different from the fill colour...

[Tec-Nico]

What I did was to draw a line per edge of the polygon of the color I wanted. That's how I personally solved it.

I am afraid I know how to work with Brushes but with .NET which seems to be a little different (in the management of them) than VB 6.

[krtxmrtz]

I don't have VB.NET so I'll have to make do with VB6.

I have been experimenting with various values of the parameter in GetStockObject but can't get it to plot a black border and the interior area of a different color, for example unfilled.

Further, I can't erase the polygon -which I draw in a picturebox- after I'm done with it, the picturebox.cls instruction is ignored altogether!!! Thereafter, if I draw a polygon of a different shape it overlaps with the previous image.

Would someone have pity on me and fish me out of this deadlock? Please...

[Tec-Nico]

Just a couple of ideas... I haven't tried them (Well, I tried the first one) but I hope they can help you.

The first one is to draw two polygons... One will be the border and the other one will be the polygon inside.

So you first draw the black polygon and then the blue one to give the sensation there is a blue polygon with a black border.

The trick here would be to add a quantity in the left and on the top and substract it from the right and the bottom.

And for erasing it, you could try setting the autoRedraw of the PictureBox to be False, then try .cls and then setting it to True again.

[krtxmrtz]

Originally posted by Tec-Nico
The trick here would be to add a quantity in the left and on the top and substract it from the right and the bottom.

And for erasing it, you could try setting the autoRedraw of the PictureBox to be False, then try .cls and then setting it to True again.

The first idea may work, probably I should add/substract one or two pixels but I thought the CreatePolygonRgn, GetStockObject and FillRgn functions would be more flexible and allow the trick directly.

As for erasing the picturebox, it didn't work. I don't know what else to try, I'm stuck.

[Wokawidget]

if you look at the tootip text link it my sig then you will see a class called clsDraw. This class is used to simplify API drawing.
You can fill with custom cothers, you can even fill with a bitmap.
It allows you to draw text in any font or style.

All you would ned to do is add the class into your project, and away you go

Hope that helps.

Woof

[krtxmrtz]

Originally posted by Wokawidget
if you look at the tootip text link it my sig...

You mean the Graph control, I assume... I'll take a look. What kind of bugs are those you mention in the page linked to?

[krtxmrtz]

Originally posted by Tec-Nico
¡Hola krtxmrtz!

I am so ashamed I can't help you with the brushes either...

I finally found the answer:

'(In a sub...)
        Dim hBrush As Long
        Dim hPen As Long
 
        hBrush = CreateSolidBrush(MyColour)
        SelectObject myBuffer, hBrush
        hPen = CreatePen(PS_SOLID, 1, vbBlack)
        SelectObject myBuffer, hRPen
 
        'Poly2Buffer is a sub which does exactly
        'what its name suggests by means of the
        'CreatePolygonRgn API function. After the
        'polygon region has been created to a buffer
        'this buffer is BitBlt'd to a picturebox
        Poly2Buffer myBuffer, xIon, yIon, nIon
 
        DeleteObject hBrush
        DeleteObject hPen

So this plots a polygon with black border and fills it with any colour you like. I've tried this out with back buffering, don't know if it would work when plotting directly to a PictureBox (no time to check it now)