load-file in bitmap%

Loads a bitmap from a file. If the bitmap is in use by a bitmap-dc% object or a control, the bitmap file is not loaded.

• (send a-bitmap load-file name kind bg-color) -> boolean
     name : string
     kind = 'unknown : symbol in '(unknown unknown/mask gif gif/mask jpeg png png/mask xbm xpm bmp pict)
   bg-color = #f : color% object or #f

  The kind parameter specifies the file's format:

  • 'unknown -- examine the file to determine its format

  • 'unknown/mask -- like 'unknown, but see get-loaded-mask

  • 'gif -- load a GIF bitmap file (X, Windows, Mac OS)

  • 'gif/mask -- like 'gif, but see get-loaded-mask (X, Windows, Mac OS)

  • 'jpeg -- load a JPEG bitmap file (X, Windows, Mac OS)

  • 'png -- load a PNG bitmap file (X, Windows, Mac OS)

  • 'png/mask -- like 'png, but see get-loaded-mask (X, Windows, Mac OS)

  • 'xbm -- load an X bitmap file (X, Windows, Mac OS); creates a monochrome bitmap

  • 'xpm -- load an XPM bitmap file (X, Windows, Mac OS)

  • 'bmp -- load a Windows bitmap file (X, Windows, Mac OS)

  • 'pict -- load a PICT bitmap file (Mac OS)

  An XBM image is always loaded as a monochrome bitmap. A 1-bit grayscale PNG without a mask or alpha channel is also loaded as a monochrome bitmap. An image in any other format is always loaded as a bitmap that matches the depth of the screen.

  For PNG loading, if bg-color is not #f, then it is combined with the file's alpha channel or mask (if any) while loading the image; in this case, no separate mask bitmap is generated, even if 'unknown/mask or 'png/mask is specified for the format. If the format is specified as 'unknown or 'png and bg-color is not specified, the PNG file is consulted for a background color to use for loading, and white is used if no background color is indicated in the file.

  In all PNG-loading modes, gamma correction is applied when the file provides a gamma value, otherwise gamma correction is not applied. The current display's gamma factor is determined by the '|MrEd:gamma| preference (see Preferences) if it is set, or else by the SCREEN_GAMMA environment variable if it is defined. If the preference and environment variable are both undefined, a platform-specific default is used.