Question

I have created a image button for my apps on windows mobile. There is a small problem though, when i have different screen resolutions,bigger for example, the image isn’t automatic resized to fit in the control. How can this be done?

thanks in advance.

this is my code for the onPaint function

        Dim gxOff As Graphics
        'Offscreen graphics
        Dim imgRect As Rectangle
        'image rectangle
        Dim backBrush As Brush
        'brush for filling a backcolor
        If m_bmpOffscreen Is Nothing Then
            'Bitmap for doublebuffering
            m_bmpOffscreen = New Bitmap(Me.Width, Me.Height)
        End If

        gxOff = Graphics.FromImage(m_bmpOffscreen)

        gxOff.Clear(Me.BackColor)

        If Not bPushed Then
            backBrush = New SolidBrush(Parent.BackColor)
        Else
            backBrush = New SolidBrush(Color.Black)
            'change the background when it's pressed
        End If

        gxOff.FillRectangle(backBrush, Me.ClientRectangle)

        If m_image IsNot Nothing Then
            'Center the image relativelly to the control
            Dim imageLeft As Integer = (Me.Width - m_image.Width) / 2
            Dim imageTop As Integer = (Me.Height - m_image.Height) / 2

            If Not bPushed Then
                imgRect = New Rectangle(imageLeft, imageTop, m_image.Width, m_image.Height)
            Else
                'The button was pressed
                'Shift the image by one pixel
                imgRect = New Rectangle(imageLeft + 1, imageTop + 1, m_image.Width, m_image.Height)
            End If
            'Set transparent key
            Dim imageAttr As New Imaging.ImageAttributes()
            imageAttr.SetColorKey(BackgroundImageColor(m_image), BackgroundImageColor(m_image))
            'Draw image
            gxOff.DrawImage(m_image, imgRect, 0, 0, m_image.Width, m_image.Height, GraphicsUnit.Pixel, imageAttr)
        End If

        If bPushed Then
            'The button was pressed
            'Prepare rectangle
            Dim rc As Rectangle = Me.ClientRectangle
            rc.Width -= 1
            rc.Height -= 1
            'Draw rectangle
            gxOff.DrawRectangle(New Pen(Color.Black), rc)
        End If

        'Draw from the memory bitmap
        e.Graphics.DrawImage(m_bmpOffscreen, 0, 0)

        MyBase.OnPaint(e)

Answer 1

You need to scale image during OnPaint e.g.:

if (this._image != null)
{                    
  int x = (this.Width - this._image.Width) / 2;
  int y = (this.Height - this._image.Height) / 2;
  var imgRect = new Rectangle(x, y, this._image.Width, this._image.Height);

  var imageAttr = new ImageAttributes();

  Color clr = this._image.GetPixel(0, 0);
  imageAttr.SetColorKey(clr, clr);

  gr2.DrawImage(this._image, imgRect, 0, 0, this._image.Width, this._image.Height, GraphicsUnit.Pixel, imageAttr);
}

Above example is how to draw image with transparent color based on first pixel. Now you need to ammend second 3 lines:

bool qvga = Screen.PrimaryScreen.Bounds.Height == 240 || Screen.PrimaryScreen.Bounds.Width == 240; 
int x = (this.Width - (qvga ? this._image.Width : this._image.Width * 2)) / 2;
int y = (this.Height - (qvga ? this._image.Height : this._image.Height * 2)) / 2;
var imgRect = new Rectangle(x, y, (qvga ? this._image.Width : this._image.Width * 2), (qvga ? this._image.Height : this._image.Height * 2));

[Edit]

Seeing your code change is straight forward. Like I described in comment: For two main windows mobile resolutions, QVGA and VGA, we assuming that image is for QVGA size. Please convert my code to VB by yourself. So set qvga flag as I written:

bool qvga = Screen.PrimaryScreen.Bounds.Height == 240 || Screen.PrimaryScreen.Bounds.Width == 240; 

now based on flag ammend following based on my above code:

Dim imageLeft As Integer = (Me.Width - m_image.Width) / 2
Dim imageTop As Integer = (Me.Height - m_image.Height) / 2

and then this ones:

If Not bPushed Then
     imgRect = New Rectangle(imageLeft, imageTop, m_image.Width, m_image.Height)
Else
     'The button was pressed
     'Shift the image by one pixel
imgRect = New Rectangle(imageLeft + 1, imageTop + 1, m_image.Width, m_image.Height)

End If