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Transparent control in .net (currently using picturebox)

Posted on 2004-04-09
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Last Modified: 2012-06-21
Hello!

I have transparent gif. I load my gif into my picturebox

pb.image = image

The picturebox will not be transparent, it will get the parent forms background color.
How can I make it be transparent?

I have tried alot of things, for example:

Dim bm As New Bitmap(pb.Image)
bm.MakeTransparent(pb.BackColor)
MyBase.Image = bm

I tried to rewrite the Paint-event in the picturebox and trying to paint my picturebox with the graphic-object and using ColorMatrix to get an alpha on the background but I only succeed changing the alpha for the whole picture.

I have also tried using a panel but nothing seems to work.
If you have an idea of a form control that can hold a picture and have transparent background and that will solve my problem I will give you the points!

Nothing I have tried works...

Any suggestions?
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Question by:Brimba
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14 Comments
 
LVL 4

Expert Comment

by:zinno
ID: 10794125
Private pbImg As New PictureBox
Private bitmap As Bitmap


bitmap = New Bitmap("WaterDropsTransparent.gif")
With pbImg
.SizeMode = PictureBoxSizeMode.AutoSize
.Location = New Point(724, 96)
.Image = bitmap
.BackColor = System.Drawing.Color.Transparent
End With
Me.Controls.Add(pbImg )

be sure that u have a transparent image. "bm.MakeTransparent(pb.BackColor)" works if have the exact color, in RGB aka blue background is bm.MakeTransparent(0,0,255)
0
 
LVL 4

Author Comment

by:Brimba
ID: 10804360
That is what I have already tried. It will only set the picturebox background to the forms background color. And that is not transparent, since I have different pictures on the form and my picturebox will move over the form and over the other pictures (road, grass, bridges). But all that it will show is my character and he is inside a grey box.
The grey color is the default forms color.

I really need to get rid of that box...

Suggestions?
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LVL 85

Accepted Solution

by:
Mike Tomlinson earned 250 total points
ID: 10807977
Place your transparent gif into a PictureBox (PictureBox1) as you have done before, and set its BackColor property to Transparent as zinno has shown you.

    PictureBox1.BackColor = System.Drawing.Color.Transparent

On your form place a Panel Object (Panel1).  Now set the parent property of your PictureBox to your Panel.

    PictureBox1.Parent = Panel1

Now load up your map tiles into Images.

    Dim grass As Image = Image.FromFile("c:\maps\grass.gif") ' or something like that
    Dim road1 As Image = Image.FromFile("c:\maps\road1.gif")

In your Paint event for your panel, draw the tiles onto the panel to build your map:

    Private Sub Panel1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Panel1.Paint
        e.Graphics.DrawImage(grass, 50, 50)
        e.Graphics.DrawImage(road1, 100, 50)
        ' etc.....
    End Sub

Now you can move your PictureBox around the Panel like this
 
    PictureBox1.Left = 65
    PictureBox1.Top = 71

The transparent portions of your gif will take on the background colors of its parent container (the panel) that are directly below it.  Since you painted your map tiles directly onto the panel with DrawImage(), you gif will appear above your map tiles correctly since it will take the backgound color of what ever it is above on the panel.

Regards,

Idle_Mind
0
 
LVL 4

Author Comment

by:Brimba
ID: 10830380
Thank you!

I have a problem though...
Now it will paint my background everytime I move my character or a computer character is moving.
Is there any good way to get some speed in this? Or do I need to think in another way when trying to build a tile-based-game with vb.net/c# ?
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LVL 85

Expert Comment

by:Mike Tomlinson
ID: 10832615
You are probably repainting the entire visible portion of your map in the Paint event of your Panel.  The "e" argument to the Paint event actually tells you which part of the Panel needs to be repainted.  You can access this information like this:

    Dim r As Rectangle = e.ClipRectangle

Now you can use "r" to figure out which part of the map has been invalidated and just repaint those tiles that are affected instead of the whole map.

Idle_Mind
0
 
LVL 4

Author Comment

by:Brimba
ID: 10834898
Works perfect!

There is only one small thing.

If I dont override the paint-method then everything is good (except the transparency).

But when I override the paint-method I get some weird error..

I have this code:

---
Dim pb As PictureBox
Dim r As Rectangle
r = e.ClipRectangle

For Each pb In p.Controls
        If r.IntersectsWith(New Rectangle(pb.Left, pb.Top, pb.Image.Width, pb.Image.Height)) Then
                e.Graphics.DrawImageUnscaled(pb.Image, pb.Location)I
        End If
Next
---

When the form is loaded all obstacles (pb) are 1½ of the original size. But when I walk on that ½ obstacle that shouldnt be there it disappears.. So after I have walked around the whole map it looks good again but to start with it looks a bit weird.
I have tried to change locations and tried to paint all controls but it doesnt matter.
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LVL 85

Expert Comment

by:Mike Tomlinson
ID: 10834921
Not sure I understand the 1 1/2 starting size vs. walking over 1/2 an obstacle.  Can you explain that part in a different way?

=)
Idle_Mind
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LVL 85

Expert Comment

by:Mike Tomlinson
ID: 10834923
Not sure I understand the 1 1/2 starting size vs. walking over 1/2 an obstacle.  Can you explain that part in a different way?

=)
Idle_Mind
0
 
LVL 4

Author Comment

by:Brimba
ID: 10835077
Sure...

Look at this picture: http://nix.brimba.nu/one_and_half.gif

Before: I am using my own paint-method now and my obstacle will look like this
 
After: I have walked near the obstacle. As you can see it will remove some of the stone since the stone isnt really there (i am doing a hittest on the picturebox, and that is why I can walk on some of the stone)

Orignal: This is what the stone should look like. And it looks like this if i dont override the paint-method of the panel.

Thanks!
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LVL 85

Expert Comment

by:Mike Tomlinson
ID: 10835777
Well,

Your using this in your Paint Method:

   e.Graphics.DrawImageUnscaled(pb.Image, pb.Location)

What are you using to draw the 1 1/2 starting size?  Can't you use that same code in your Paint Method to put it back the way it was before?

Idle_Mind
0
 
LVL 4

Author Comment

by:Brimba
ID: 10836079
What I do is that I have an arraylist. and add all my obstacles to that.. like this:

aListObstacles.Add(New Stone(100, 100))

Stone inherits a picturebox.
The constructor of stone takes one x and one y parameter.

What I do then is that I add all the controls in the arraylist to my panel like this:

Dim itm As Obstacle
For Each itm In aListObstacles
        gameBoard.Controls.Add(itm)
Next

gameBoard is of type panel

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LVL 85

Expert Comment

by:Mike Tomlinson
ID: 10836130
Is the code to paint the initial map tiles at 1 1/2 size any different from that used to repaint a tile after it has been touched?

Idle_Mind
0
 
LVL 4

Author Comment

by:Brimba
ID: 10836913
I only have one paint-method and that is the one for the panel.

I believe it will call my paint-method first thing to do when I add my controls (pictureboxes(stones)).

So I dont know why it paint my obstacles 1½ times... since the width and height of the control really is 25*25 but the first time it is like 37*37 or something like that. (like you saw)...

0
 
LVL 85

Expert Comment

by:Mike Tomlinson
ID: 10837029
Yeah...that is what I was trying to figure out as well...do you have an initial size for your Picturebox?  Do you have the SizeMode set to AutoSize maybe?
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