GAMBAS BOOK 3.19.1

The Image class of the gb.image.imlib component adds image processing methods from the imlib2 library to the Image class in the gb.image component and thus extends its methods.

The Image class in the gb.image.imlib component has these methods:

Table 23.4.2.9.1 : Methods of the Image class (gb.image.imlib)

Notes

• Blur(…): Note that the Blur() function is used in practice to blur or blur parts of the image - not the entire image.
• PaintImage(…): If Width and Height differ from SrcWidth, SrcHeight, the source image is scaled. SrcX, SrcY, SrcWidth, SrcHeight determine the part of the image to be copied. By default, the entire image is copied. In contrast to DrawImage, the source image is blended with the current image background. Pre-multiplied pixel formats are currently not supported.
• The Tile() method creates an image that is heavily distorted by horizontal and vertical tiling.

An example is presented for each method of the Image class (gb.image.imlib). If the methods use parameters, these and the images - the original and the modified one - are displayed. The source code used in each case is also shown in extracts.

Example 1 - Image.Blur(…) method

The method returns a blurred image. A value of 5 is used here as the parameter (blur radius), which can be set using the slider:

Figure 23.4.2.9.1: Blur(5) method Source code snippet

' Gambas class file
 
Public imgOriginal As Image
Public sImagePath As String
 
Public Sub Form_Open()
 
    FMain.Resizable = False
 
    sImagePath = "images/augentrost_355x242.png"
 
'-- Display of original and modified image
    imgOriginal = Image.Load(sImagePath)
    pboxOriginal.Picture = imgOriginal.Picture
    pboxChanged.Picture = imgOriginal.Copy().Picture
 
    pboxOriginal.Stretch = True
    pboxChanged.Stretch = True
 
'-- Slider configuration
    hSliderV.Visible = True
    hSliderV.MinValue = 0
    hSliderV.MaxValue = 8
    hSliderV.PageStep = 2
    hSliderV.Step = 1
    hSliderV.Mark = False
    hSliderV.Value = 5
    lblValue.Visible = True
 
End
 
Public Sub hSliderV_Change()
 
    lblChanged.Text = "C H A N G E D  —>  " & "B L U R (...)"
    lblValue.Text = hSliderV.Value
    pboxChanged.Picture = imgOriginal.Blur(hSliderV.Value).Picture
 
End

Example 2 - Image.PaintImage(…) method

You can use this method to insert an image with a specified width and height into the original at a specific position:

Figure 23.4.2.9.2: PaintImage(…) method

Source code snippet

Public Sub btnDoPaintImage_Click()
 
    lblChanged.Text = "C H A N G E D  >>  " & "P A I N T I M A G E (...)"
 
    imgExtern = Image.Load("images/augentrost_355x242.png")
 
    imgOriginal.PaintImage(imgExtern, 200, 150, imgExtern.W / 3, imgExtern.H / 3)
 
    pboxChanged.Picture = imgOriginal.Picture
 
End

Example 3 - Image.Rotate(φ) method

The method rotates an image by a certain angle φ. If the value is positive, the image is rotated clockwise - otherwise it is rotated anti-clockwise. Note the resulting (white) border that is automatically added so that the rotated image is always displayed in full. Due to the fixed size of the picturebox for the rotated image, you will only see part of the image in the project!

Figure 23.4.2.9.3: Rotate(arc(63°)) method

Source code snippet

  lblChanged.Text = "C H A N G E D  >>  " & "R O T A T E ( φ )"
 
  lblValue.Text = hSliderV.Value & "°"
  imgChanged = imgCurrent.Rotate(Rad(hSliderV.Value))

Example 4 - Image.Scroll(…) method

The method moves (!) a defined image section to a specific position in the original if the 4 optional parameters are set:

Figure 23.4.2.9.4: Scroll(…) method

Source code snippet

Public Sub btnDoShift_Click()
 
  imgOriginal.Scroll(50, 60, 115, 80, 230, 120)
  pboxChanged.Picture = imgOriginal.Picture
 
End
<code>
 
By the way: If you do not use the optional parameters and add a slider to the project, you can move the entire image:
 
<code gambas>
Public Sub btnDoShift_Click()
 
   imgOriginal.Scroll(160, 130)
   pboxChanged.Picture = imgOriginal.Picture
 
End

Example 5 - Image.Sharpen(…) method

The method returns a sharper image. A parameter value of 2 appears to produce an optimally sharpened image, as values higher than 2 do not show any significant change:

Figure 23.4.2.9.5: Sharpen(2) method

Source code snippet

  lblChanged.Text = "C H A N G E D  >>  " & "S H A R P E N (...)"
  lblValue.Text = hSliderV.Value
  imgChanged = imgOriginal.Sharpen(hSliderV.Value)

Example 6 - Image.Stretch(…) method

The method creates an image in the project in which the width and height are set proportionally. The image can only be reduced with the set min-max values (0 < p ⇐ 1) for the slider:

Figure 23.4.2.9.6: Stretch(0.67) method

Source code snippet

  Dim W, H As Integer
 
  lblChanged.Text = "C H A N G E D  >>  " & "S T R E T C H (...)"
  lblValue.Text = hSliderV.Value & "%"
 
  W = Int(imgOriginal.W * (hSliderV.Value / 100))
  H = Int(imgOriginal.H * (hSliderV.Value / 100))
 
  pboxChanged.Picture = imgOriginal.Stretch(W, H).Picture

Example 7 - Image.Tile() method

The method creates a new version of the image, which is seamlessly tiled horizontally and vertically and therefore appears very alienated:

Figure 23.4.2.9.7: Tile() method

Source code snippet

  lblChanged.Text = "C H A N G E D  >>  " & "T I L E ( )"
  pboxChanged.Picture = imgOriginal.Tile().Picture