Module: FreeImage::Information

Included in:
Bitmap
Defined in:
lib/free-image/modules/information.rb

Overview

Once a bitmap is loaded into memory, you can use the following methods to retrieve information about is type, dimensions, colors, etc.

Instance Method Summary collapse

Instance Method Details

#background_color ⇒ Object

Returns the background color of a bitmap. For 8-bit images, the color index in the palette is returned in the rgbReserved member of the bkcolor parameter.



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# File 'lib/free-image/modules/information.rb', line 80

def background_color
  ptr = FFI::MemoryPointer.new(:pointer)
  FreeImage.FreeImage_GetBackgroundColor(self, ptr)
  FreeImage.check_last_error
  RGBQuad.new(ptr)
end

#background_color=(value) ⇒ Object

Set the background color of a bitmap. The color should be an instance of RGBQuad.

When saving an image to PNG, this background color is transparently saved to the PNG file. When the bkcolor parameter is nil, the background color is removed from the image.



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# File 'lib/free-image/modules/information.rb', line 93

def background_color=(value)
  result = FreeImage.FreeImage_GetBackgroundColor(self, value)
  FreeImage.check_last_error
  if !result
    raise(RuntimeError, "Could not save background color")
  end
end

#bits_per_pixel ⇒ Object Also known as: bpp

Returns the size of one pixel in the bitmap in bits. For example if each pixel takes 32-bits of space in the bitmap, this function returns 32. Possible bit depths are 1, 4, 8, 16, 24, 32 for standard bitmaps and 16-, 32-, 48-, 64-, 96- and 128-bit for non standard bitmaps



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# File 'lib/free-image/modules/information.rb', line 105

def bits_per_pixel
  result = FreeImage.FreeImage_GetBPP(self)
  FreeImage.check_last_error
  result
end

#blue_mask ⇒ Object

Returns a bit pattern describing the blue color component of a pixel in a bitmap.



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# File 'lib/free-image/modules/information.rb', line 113

def blue_mask
  result = FreeImage.FreeImage_GetBlueMask(self)
  FreeImage.check_last_error
  result
end

#color_type ⇒ Object 



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# File 'lib/free-image/modules/information.rb', line 119

def color_type
  result = FreeImage.FreeImage_GetColorType(self)
  FreeImage.check_last_error
  result
end

#dib_size ⇒ Object

Returns the size of the DIB-element of a bitmap in memory, which is the header size + palette size + data bits. Note that this is not the real size of a bitmap, just the size of its DIB-element.



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# File 'lib/free-image/modules/information.rb', line 128

def dib_size
  result = FreeImage.FreeImage_GetDIBSize(self)
  FreeImage.check_last_error
  result
end

#dots_per_meter_x ⇒ Object

Returns the horizontal resolution, in pixels-per-meter, of the target device for the bitmap.



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# File 'lib/free-image/modules/information.rb', line 136

def dots_per_meter_x
  result = FreeImage.FreeImage_GetDotsPerMeterX(self)
  FreeImage.check_last_error
  result
end

#dots_per_meter_x=(value) ⇒ Object

Sets the horizontal resolution, in pixels-per-meter, of the target device for the bitmap.



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# File 'lib/free-image/modules/information.rb', line 144

def dots_per_meter_x=(value)
  result = FreeImage.FreeImage_SetDotsPerMeterX(self, value)
  FreeImage.check_last_error
  result
end

#dots_per_meter_y ⇒ Object

Returns the vertical resolution, in pixels-per-meter, of the target device for the bitmap.



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# File 'lib/free-image/modules/information.rb', line 152

def dots_per_meter_y
  result = FreeImage.FreeImage_GetDotsPerMeterY(self)
  FreeImage.check_last_error
  result
end

#dots_per_meter_y=(value) ⇒ Object

Sets the vertical resolution, in pixels-per-meter, of the target device for the bitmap.



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# File 'lib/free-image/modules/information.rb', line 160

def dots_per_meter_y=(value)
  result = FreeImage.FreeImage_SetDotsPerMeterY(self, value)
  FreeImage.check_last_error
  result
end

#green_mask ⇒ Object

Returns a bit pattern describing the green color component of a pixel in a bitmap.



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# File 'lib/free-image/modules/information.rb', line 167

def green_mask
  result = FreeImage.FreeImage_GetGreenMask(self)
  FreeImage.check_last_error
  result
end

#has_background_color ⇒ Object

Returns true when the image has a file background color, false otherwise



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# File 'lib/free-image/modules/information.rb', line 174

def has_background_color
  result = FreeImage.FreeImage_HasBackgroundColor(self)
  FreeImage.check_last_error
  result
end

#has_pixels ⇒ Object

Returns true if the bitmap contains pixel data, otherwise false. Bitmaps can be loaded using the FIF_LOAD_NOPIXELS load flag whic tells the decoder to read header data and available metadata and skip pixel data decoding. This reduces memory usage and load speed.



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# File 'lib/free-image/modules/information.rb', line 184

def has_pixels
  result = FreeImage.FreeImage_HasPixels(self)
  FreeImage.check_last_error
  result
end

#height ⇒ Object

Returns the height of the bitmap in pixel units



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# File 'lib/free-image/modules/information.rb', line 191

def height
  result = FreeImage.FreeImage_GetHeight(self)
  FreeImage.check_last_error
  result
end

#image_type ⇒ Object

Returns the image type of a bitmap.



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# File 'lib/free-image/modules/information.rb', line 198

def image_type
  result = FreeImage.FreeImage_GetImageType(self)
  FreeImage.check_last_error
  result
end

#line ⇒ Object

Returns the width of the bitmap in bytes. See also FreeImage::Information.pitch. There has been some criticism on the name of this function. Some people expect it to return a scanline in the pixel data, while it actually returns the width of the bitmap in bytes. As far as I know the term Line is common terminology for the width of a bitmap in bytes. It is at least used by Microsoft DirectX.



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# File 'lib/free-image/modules/information.rb', line 209

def line
  result = FreeImage.FreeImage_GetLine(self)
  FreeImage.check_last_error
  result
end

#palette ⇒ Object

Returns a bitmap’s palette. If the bitmap doesn’t have a palette (i.e. when the pixel bit depth is greater than 8), this return nil.



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# File 'lib/free-image/modules/information.rb', line 217

def palette
  @palette ||= Palette.new(self)
end

#pitch ⇒ Object

Returns the width of the bitmap in bytes, rounded to the next 32-bit boundary, also known as pitch or stride or scan width. In FreeImage each scanline starts at a 32-bit boundary for performance reasons. This accessor is essential when using low level pixel manipulation functions.



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# File 'lib/free-image/modules/information.rb', line 226

def pitch
  result = FreeImage.FreeImage_GetPitch(self)
  FreeImage.check_last_error
  result
end

#red_mask ⇒ Object

Returns a bit pattern describing the red color component of a pixel in a bitmap.



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# File 'lib/free-image/modules/information.rb', line 233

def red_mask
  result = FreeImage.FreeImage_GetRedMask(self)
  FreeImage.check_last_error
  result
end

#transparency_count ⇒ Object

Returns the number of transparent colors in a palletized bitmap, otherwise returns 0.



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# File 'lib/free-image/modules/information.rb', line 241

def transparency_count
  result = FreeImage.FreeImage_GetTransparencyCount(self)
  FreeImage.check_last_error
  result
end

#transparent ⇒ Object

Returns true if the transparency table is enabled (1-, 4- or 8-bit images) or when the input dib contains alpha values (32-bit images, RGBA16 or RGBAF images). Returns false otherwise.



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# File 'lib/free-image/modules/information.rb', line 250

def transparent
  result = FreeImage.FreeImage_IsTransparent(self)
  FreeImage.check_last_error
  result
end

#transparent=(value) ⇒ Object

Tells FreeImage if it should make use of the transparency table or the alpha channel that may accompany a bitmap. When calling this function with a bitmap whose bitdepth is different from 1-, 4-, 8- or 32-bit, transparency is disabled whatever the value of the Boolean parameter.



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# File 'lib/free-image/modules/information.rb', line 260

def transparent=(value)
  result = FreeImage.FreeImage_SetTransparent(self, value)
  FreeImage.check_last_error
  result
end

#transparent_index ⇒ Object

Returns the palette entry used as transparent color for the image specified. Works for palletised images only and returns -1 for high color images or if the image has no color set to be transparent. Although it is possible for palletised images to have more than one transparent color, this function always returns the index of the first palette entry, set to be transparent.



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# File 'lib/free-image/modules/information.rb', line 272

def transparent_index
  result = FreeImage.FreeImage_GetTransparentIndex(self)
  FreeImage.check_last_error
  result
end

#transparent_index=(value) ⇒ Object

Sets the index of the palette entry to be used as transparent color for the image specified. This works on palletised images only and does nothing for high color images.

Although it is possible for palletised images to have more than one transparent color, this method sets the palette entry specified as the single transparent color for the image. All other colors will be set to be non-transparent by this method.

As with FreeImage::Bitmap.transparency_table=, this method also sets the image’s transparency property to true for palletised images.



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# File 'lib/free-image/modules/information.rb', line 288

def transparent_index=(value)
  result = FreeImage.FreeImage_SetTransparentIndex(self, value)
  FreeImage.check_last_error
  result
end

#width ⇒ Object

Returns the width of the bitmap in pixel units



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# File 'lib/free-image/modules/information.rb', line 299

def width
  result = FreeImage.FreeImage_GetWidth(self)
  FreeImage.check_last_error
  result
end