Class
RGBSurface
Description
Used for direct-color pixel manipulations. The RGBSurface property of a Picture object allows you to manipulate the picture at the pixel level. Can be used only for pictures created by the Picture constructor with no pixel depth or a depth of only 16 or 32.
Methods
Name |
Parameters |
Returns |
Shared |
|---|---|---|---|
map() As Integer |
|||
redMap() As Integer, greenMap() As Integer, blueMap() As Integer |
Method descriptions
RGBSurface.FloodFill
FloodFill(x As Double, y As Double, FillColor As Color)
Performs a "floodfill" (the action performed by a PaintBucket tool in an image editing program) on an RGBSurface.
The pixel at x, y and all adjacent pixels of the same color are changed to the passed FillColor.
Important
This method is not currently supported for Android.
The following code uses the FloodFill method to paint an RGBSurface object in a random color. It is in the MouseDown event of a DesktopCanvas control. The variable p is a Picture object.
Var randomColor As Color
randomColor = Color.RGB(Rnd * 255, Rnd * 255, Rnd * 255) ' create random color
p.RGBSurface.FloodFill(x, y, randomColor) ' fill the area with the color
Me.Graphics.DrawPicture(p, 0, 0) ' repaint the canvas control
RGBSurface.Pixel
Pixel(x As Double, y As Double) As Color
Returns the color of the object at location specified by the x and y parameters.
This example replaces all the black pixels in a Picture, somePicture, with white:
Var surf As RGBSurface = somePicture.RGBSurface
Var lastX As Integer = somePicture.Width - 1
Var lastY As Integer = somePicture.Height - 1
For y As Integer = 0 To lastY
For x As Integer = 0 To lastX
If surf.Pixel(x, y) = &c000000 Then
surf.Pixel(x, y) = &cFFFFFF
End if
Next
Next
Pixel(x As Double, y As Double, Assigns value As Color)
The color value is assigned to the location specified by the x and y parameters.
RGBSurface.Transform
Transform(map() As Integer)
Applies a one-to-one pixel transformation to all pixels of an RGBSurface.
Each map parameter is an 256 element array of integers. The transformation works as follows: For each pixel, the pixel's RGB value is used as an index into the map arrays and the value found becomes the new R, G, or B value for the pixel.
For example, if you set up a map such that map(i)=255-i, then calling Transform(Map) will invert the image.
Important
This method is not currently supported for Android.
The following example uses the Transform method to invert an image:
Const kMaxMapOffset = 255
Var map(kMaxMapOffset) As Integer
For i As Integer = 0 To kMaxMapOffset
map(i) = kMaxMapOffset - i
Next
somePicture.RGBSurface.Transform(map)
Transform(redMap() As Integer, greenMap() As Integer, blueMap() As Integer)
Applies a one-to-one pixel transformation by primary color (red, green, blue) of an RGBSurface.
Important
This method is not currently supported for Android.
Notes
Pixel manipulations using the RGBSurface property are faster than the same manipulations using the Graphics class methods.
32-bit RGBSurface objects are mapped to 24-bit objects on Windows.
RGBSurface supports alpha channels by taking them into account when rendering objects.
Sample code
This example replaces all the black pixels in a Picture, somePicture, with white. Put it in the Paint event handler of a Canvas and reference a picture you have added to the project.
Var surf As RGBSurface = somePicture.RGBSurface
Var lastX As Integer = somePicture.Width - 1
Var lastY As Integer = somePicture.Height - 1
For y As Integer = 0 To lastY
For x As Integer = 0 To lastX
If surf.Pixel(x, y) = &c000000 Then
surf.Pixel(x, y) = &cFFFFFF
End if
Next
Next
g.DrawPicture(somePicture, 0, 0, somePicture.Width, somePicture.Height)
The following example uses the FloodFill method to paint an RGBSurface object in a random color. You can put it in the Paint event handle of a Canvas.
' Create a random color
Var randomColor As Color
randomColor = Color.RGB(Rnd * 255, Rnd * 255, Rnd * 255) //create random color
' Starting in the top left, fill the picture with the color
somePicture.RGBSurface.FloodFill(0, 0, randomColor)
' Display the picture
g.DrawPicture(somePicture, 0, 0)
The following example uses the Transform method to invert an image. You can put it in the Paint event handle of a Canvas.
Const kMaxMapOffset = 255
Var map(kMaxMapOffset) As Integer
For i As Integer = 0 To kMaxMapOffset
map(i) = kMaxMapOffset - i
Next
somePicture.RGBSurface.Transform(map)
' Display the picture
g.DrawPicture(somePicture, 0, 0)
Compatibility
All project types on all supported operating systems.
See also
Object parent class; RGBSurface property of the Picture object.