Draw it Symmetrically (Resolved)

[Tec-Nico]

I am drawing a trapezoid using regions... But the problem is that it isn't symmetrical.. What am I doing wrong?

Option Explicit
 
Private Type COORD
 x As Long
 y As Long
End Type
 
Dim Region() As COORD
Dim iXBorder As Long
Dim iYBorder As Long
 
Private Declare Function CreatePolygonRgn Lib "gdi32" (lpPoint As Any, ByVal nCount As Long, ByVal nPolyFillMode As Long) As Long
Private Declare Function SetWindowRgn Lib "user32" (ByVal hWnd As Long, ByVal hRgn As Long, ByVal bRedraw As Boolean) As Long
Private Declare Function Polygon Lib "gdi32" (ByVal hdc As Long, lpPoint As Any, ByVal nCount 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.
 
Private Sub drawTrapezoid(x As Long, y As Long, Width As Long, Height As Long)
 Width = Width - iXBorder
 
 ReDim Preserve Region(1 To 4)
 Dim NumCoords As Long, hBrush As Long, hRgn As Long
 
 ' Number of vertices in polygon.
 NumCoords = 4
 
 With Region(1)
  .x = x + iXBorder
  .y = y
 End With
 With Region(2)
  .x = x
  .y = y + Height
 End With
 With Region(3)
  .x = x + iXBorder + Width
  .y = y + Height
 End With
 With Region(4)
  .x = x + Width
  .y = y
 End With
 
 hBrush = GetStockObject(BLACKBRUSH)
 ' Creates region to fill with color.
 hRgn = CreatePolygonRgn(Region(1), NumCoords, ALTERNATE)
 ' If the creation of the region was successful then color.
 If hRgn Then
  Dim Ret As Long
  Ret = SetWindowRgn(Me.hWnd, hRgn, True)
 End If
   
 DeleteObject hRgn
End Sub
 
Private Sub Form_Load()
 iXBorder = 10
 drawTrapezoid 40, 40, ScaleX(1995, vbTwips, vbPixels), ScaleX(285, vbTwips, vbPixels)
End Sub

Let me show what i mean:

[xjake88x]

Its where you have the -0.5. I don't see anywhere that xBorder is equal to 1.

[Tec-Nico]

Thank you for your reply. I am sorry, I was desperate and so I was changing the code before posting it... Please copy it to a form and run it.. You will see the trapezoid that appears is not symmetric even when the points tell it should be.

Also, iXBorder is set to 10 in FormLoad.

[dglienna]

do you mean to have 2 ScaleX, not X and Y???

[xjake88x]

With Region(1)
  .x = x + iXBorder
  .y = y
 End With
 With Region(2)
  .x = x
  .y = y + Height
 End With
 With Region(3)
  .x = x + Width
  .y = y + Height
 End With
 With Region(4)
  .x = (x + Width) - iXBorder
  .y = y
 End With

works for me.

[xjake88x]

Originally posted by dglienna
do you mean to have 2 ScaleX, not X and Y???

It really doesn't matter. Twips are the same per pixel x and y.

[Vishalgiri]

wow it is very nice custom type cord and arry of cord makes Region!! realy impressive

[Tec-Nico]

dglienna, I am using twips for all, that's why I make the conversions... xjake, I will try your code... It is strange because it gets symmetrical if you add a 1 to the last coordinate.

[Tec-Nico]

Thanks, Vishalgiri... But the credit is for si_geek, I found a skelleton of the code that is like the one I am using and I just adapted it to my needs.

I just added the coordinates for a trapezoid and the API for making the form have the shape of the region. And I also made it a call for drawing (I think I will generalize it later when I have time)

[Tec-Nico]

xjake, your code has the same problem my original does... Let me show you:

[Tec-Nico]

This code works... But.. Why?

(My old version):

With Region(1)
  .x = x + iXBorder
  .y = y
 End With
 With Region(2)
  .x = x
  .y = y + Height
 End With
 With Region(3)
  .x = x + iXBorder + Width
  .y = y + Height
 End With
 With Region(4)
  .x = x + Width [B]+ 1[/B]
  .y = y [B]+ 1[/B]
 End With

xjake's version

With Region(1)
  .x = x + iXBorder
  .y = y
 End With
 With Region(2)
  .x = x
  .y = y + Height
 End With
 With Region(3)
  .x = x + Width
  .y = y + Height
 End With
 With Region(4)
  .x = (x + Width) - iXBorder [B]+ 1[/B]
  .y = y [B]+ 1[/B]
 End With

[Tec-Nico]

No idea? This is about to be solved... I just want to know why I have to add 1 to both of the coordinates..

[Merri]

Hmm, well, what comes to mind is: if the coordinates were exact same and you were trying to draw something of 1 x 1 pixel, nothing would appear because the size would be 0 x 0. So you have to add one to the coordinates so that the size would be 1 x 1.

Does this make sense? I'm just about to go to sleep so the quality of the explanation is what it is...

[Tec-Nico]

Thanks Merri, now it makes perfect sense to me.

We need to add one more to delimitate it properly and thus be able to make regions that will be 1 x 1 pixels, if it wasn't like that we would have them of 0 x 0 instead.