ImageInfo - FreeBASIC Documentation

Declare Function ImageInfo ( ByVal image As Any Ptr, ByRef width As Integer = 0, ByRef height As Integer = 0, ByRef bypp As Integer = 0, ByRef pitch As Integer = 0, ByRef pixdata As Any Ptr = 0, ByRef size As Integer = 0 ) As Long

result = ImageInfo( image [, [width] [, [height] [, [bypp] [, [pitch] [, [pixdata] [, size]]]]]] )

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.

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.

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.

'' 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

'' 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 ulong 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

Not available in the -lang qb dialect unless referenced with the alias __Imageinfo.

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