Snowbound Software’s RasterMasterTM for Windows includes the ability to display transparent GIF images. To display a transparent GIF image, you can use the IMG_display_bitmap_transp() and the IMGLOW_get_transp_color() functions. The IMG_display_bitmap_transp() function displays the foreground color for a GIF image. The IMGLOW_get_transp_color() returns the background color for GIF images if this information is available in the header.
IMG_display_bitmap_transp()
This function displays transparent GIF images. It only draws the foreground color when displaying. It does not draw the background color. To get the background color from an image, use the IMGLOW_get_transp_color() function. See the IMGLOW_get_transp_color() function below for more information.
The IMG_display_bitmap_transp() function compares each pixel to the background color passed in and does not draw foreground pixels that are identical.
Note: A negative value indicates an error. See the imgerr.h file.
Syntax
int IMG_display_bitmap_transp (int imghandle, IMGPORT hdc, int xpos, int ypos, int width, int height, int tcolor);
Remark
The table below lists the IMG_display_bitmap_transp function variable descriptions.
| Variable | Description |
| imghandle | Standard image handle obtained from a decompress function such asIMG_decompress_bitmap() |
| hdc | Windows device context to display |
| hwnd | Handle of window within which to enable scroll bars |
| xpos | Starting X coordinate for display of image |
| ypos | Starting Y coordinate for display of image |
| width | Horizontal width to display image |
| height | Vertical height to display image |
| tcolor | Background color of image to ignore |
Returns
Integer
IMGLOW_get_transp_color ()
This function returns the background color for GIF images if this information is available in the header. It returns 1 byte or a NO_TCOLOR_FOUND error message if not available.
Note: A negative value indicates an error. See the imgerr.h file.
Syntax
int IMGLOW_get_transp_color (int imghandle);
Remark
The table below lists the IMGLOW_get_transp_color function variable description.
| Variable | Description |
| imghandle | Standard image handle obtained from a decompress function such asIMG_decompress_bitmap() |
Returns
Integer