Revision [15525]
This is an old revision of KeyPgImageInfo made by CountingPine on 2011-11-25 09:40:56.
IMAGEINFO
Retrieves information about an image
Syntax:
KeyPgDeclare declare KeyPgFunction function Imageinfo ( KeyPgByval byval image KeyPgAs as KeyPgAny any KeyPgPtr ptr, KeyPgByref byref width KeyPgAs as KeyPgInteger integer = 0, KeyPgByref byref height KeyPgAs as KeyPgInteger integer = 0, KeyPgByref byref bypp KeyPgAs as KeyPgInteger integer = 0, KeyPgByref byref pitch KeyPgAs as KeyPgInteger integer = 0, KeyPgByref byref pixdata KeyPgAs as KeyPgAny any KeyPgPtr ptr = 0, KeyPgByref byref size KeyPgAs as KeyPgInteger integer = 0 ) KeyPgAs as KeyPgInteger integer
Usage:
result = Imageinfo( image [, [width] [, [height] [, [bypp] [, [pitch] [, [pixdata] [, size]]]]]] )
Parameters:
image
The address of the image.
width
Stores the width of the image, in pixels.
height
Stores the height of the image, in pixels.
bypp
Stores the bytes per pixel of the image - i.e. the size of a single pixel, in bytes.
pitch
Stores the pitch of the image - i.e. the size of each scanline (row), in bytes. Note that this may be more than just width * bypp, because the scanlines may be padded to allow them to be aligned better in memory.
pixdata
Stores the address of the start of the first scanline of the image.
size
Stores the size of the image in memory, in bytes.
Return Value:
If image doesn't point to a valid image, one (1) is returned. Otherwise, width, height, bypp, pitch, pixdata and size are assigned appropriate values, and zero (0) is returned.
Description:
ImageInfo provides various information about an image, such as its dimensions and color depth, but also provides you with the information you need to directly access all the pixel data in the pixel buffer.
It can also provide the size of the image in memory, which is useful for allocating memory to copy the existing image, or to write the image to a file.
Examples:
'' pixelptr(): use imageinfo() to find the pointer to a pixel in the image
'' returns null on error or x,y out of bounds
Function pixelptr(ByVal img As Any Ptr, ByVal x As Integer, ByVal y As Integer) As Any Ptr
Dim As Integer w, h, bypp, pitch
Dim As Any Ptr pixdata
Dim As Integer success
success = (imageinfo(img, w, h, bypp, pitch, pixdata) = 0)
If success Then
If x < 0 Or x >= w Then Return 0
If y < 0 Or y >= h Then Return 0
Return pixdata + y * pitch + x * bypp
Else
Return 0
End If
End Function
'' usage example:
'' 320*200 graphics screen, 8 bits per pixel
ScreenRes 320, 200, 8
Dim As Any Ptr ip '' image pointer
Dim As Byte Ptr pp '' pixel pointer (use byte for 8 bits per pixel)
ip = ImageCreate(32, 32) '' create an image (32*32, 8 bits per pixel)
If ip <> 0 Then
'' draw a pattern on the image
For y As Integer = 0 To 31
For x As Integer = y - 5 To y + 5 Step 5
'' find the pointer to pixel at x,y position
'' note: this is inefficient to do for every pixel!
pp = pixelptr(ip, x, y)
'' if success, plot a value at the pixel
If (pp <> 0) Then *pp = 15
Next x
Next y
'' put the image and draw a border around it
Put (10, 10), ip, PSet
Line (9, 9)-Step(33, 33), 4, b
'' destroy the image to reclaim memory
ImageDestroy ip
Else
Print "Error creating image!"
End If
Sleep
'' returns null on error or x,y out of bounds
Function pixelptr(ByVal img As Any Ptr, ByVal x As Integer, ByVal y As Integer) As Any Ptr
Dim As Integer w, h, bypp, pitch
Dim As Any Ptr pixdata
Dim As Integer success
success = (imageinfo(img, w, h, bypp, pitch, pixdata) = 0)
If success Then
If x < 0 Or x >= w Then Return 0
If y < 0 Or y >= h Then Return 0
Return pixdata + y * pitch + x * bypp
Else
Return 0
End If
End Function
'' usage example:
'' 320*200 graphics screen, 8 bits per pixel
ScreenRes 320, 200, 8
Dim As Any Ptr ip '' image pointer
Dim As Byte Ptr pp '' pixel pointer (use byte for 8 bits per pixel)
ip = ImageCreate(32, 32) '' create an image (32*32, 8 bits per pixel)
If ip <> 0 Then
'' draw a pattern on the image
For y As Integer = 0 To 31
For x As Integer = y - 5 To y + 5 Step 5
'' find the pointer to pixel at x,y position
'' note: this is inefficient to do for every pixel!
pp = pixelptr(ip, x, y)
'' if success, plot a value at the pixel
If (pp <> 0) Then *pp = 15
Next x
Next y
'' put the image and draw a border around it
Put (10, 10), ip, PSet
Line (9, 9)-Step(33, 33), 4, b
'' destroy the image to reclaim memory
ImageDestroy ip
Else
Print "Error creating image!"
End If
Sleep
'' Create 32-bit graphics screen and image.
ScreenRes 320, 200, 32
Dim image As Any Ptr = ImageCreate( 64, 64 )
Dim pitch As Integer
Dim pixels As Any Ptr
'' Get enough information to iterate through the pixel data.
If 0 <> imageinfo( image, ,,, pitch, pixels ) Then
Print "unable to retrieve image information."
Sleep
End
End If
'' Draw a pattern on the image by directly manipulating pixel memory.
For y As Integer = 0 To 63
Dim row As UInteger Ptr = pixels + y * pitch
For x As Integer = 0 To 63
row[x] = RGB(x * 4, y * 4, (x Xor y) * 4)
Next x
Next y
'' Draw the image onto the screen.
Put (10, 10), image
ImageDestroy( image )
Sleep
ScreenRes 320, 200, 32
Dim image As Any Ptr = ImageCreate( 64, 64 )
Dim pitch As Integer
Dim pixels As Any Ptr
'' Get enough information to iterate through the pixel data.
If 0 <> imageinfo( image, ,,, pitch, pixels ) Then
Print "unable to retrieve image information."
Sleep
End
End If
'' Draw a pattern on the image by directly manipulating pixel memory.
For y As Integer = 0 To 63
Dim row As UInteger Ptr = pixels + y * pitch
For x As Integer = 0 To 63
row[x] = RGB(x * 4, y * 4, (x Xor y) * 4)
Next x
Next y
'' Draw the image onto the screen.
Put (10, 10), image
ImageDestroy( image )
Sleep
Dialect Differences:
- Not available in the CompilerOptlang -lang qb dialect unless referenced with the alias __Imageinfo.
Differences from QB:
- New to FreeBASIC
See also:
- KeyPgImagecreate ImageCreate
- KeyPgImageDestroy ImageDestroy
- KeyPgImageConvertRow ImageConvertRow
- KeyPgGetgraphics Get (Graphics)
- KeyPgPutgraphics Put (Graphics)
- GfxInternalFormats Internal pixel formats
Back to 2D Drawing Functions
