PiConvertImage()

Convert an image from one type to another

Synopsis:

PhImage_t *PiConvertImage( PhImage_t *image,
                           PhRect_t const *bounds,
                           int type,
                           int flags )

Arguments:

image

A pointer to a PhImage_t structure that defines the image to be converted.

bounds

A pointer to a PhRect_t structure specifying a rectangle within image to convert, effectively cropping the image before converting. Pass as NULL to convert the whole image.

type

The type of image to convert to. This must be one of the Pg_IMAGE_* types defined for PhImage_t. See Image types for a list of defined types.

You can pass 0 for no type conversion.

flags

Flags that dictate special behavior of the conversion process and can take on the following values:

Pi_FREE

Free the original image if the conversion succeeds. The function frees the old image by setting all its release flags and calling PhReleaseImage() on it.

Pi_DITHER

Not currently supported.

Pi_CALC_PALETTE

calculate an optimum palette during quantization. If this flag bit isn't set, the function uses the current Photon palette.

Library:

ph

Description:

This function converts a Photon image from one type to another. It allocates space for the resulting image, leaving the original image untouched. If you set the Pi_FREE flag bit, the function frees the old image by setting all its release flags and calling PhReleaseImage() on it.

Returns:

A pointer to the new, converted image on success, or NULL if an error occurred.

Examples:

This example loads a file, resizes it to 200 x 200 thumbnail, and then converts it to a palette-based image before displaying it in a PtLabel:

#include <stdlib.h>
#include <stdio.h>

/* Toolkit headers */
#include <Pt.h>
#include <photon/PxImage.h>


int main(int argc, char *argv[]) {

    PtWidget_t *window;
    PtArg_t    args[2];
    PhImage_t *img, *resized_img, *new_img;
    short width = 200;
    short height = 200;

   if (PtInit(NULL) == -1)
      PtExit(EXIT_FAILURE);

    printf("Loading file: %s\n", argv[1]);      
  
    // load the image
    if ( NULL== (img = PxLoadImage(argv[1], NULL ))){
        printf("PxLoadImage() error.\n");
    }       
    
    // resize the image
    if ( NULL== (resized_img  = PiResizeImage( img, NULL, width,
                                               height, 0 ))){
        printf("PiResizeImage() error.\n");
    }
    
    // convert the image to the current Photon palette:
    if (NULL == (new_img = PiConvertImage( resized_img, NULL,
                               Pg_IMAGE_PALETTE_BYTE,
                               Pi_CALC_PALETTE | Pi_DITHER ))){
        printf("PiConvertImage() error.\n");
    }
    
    // setting these flags ensures the image is released 
    // when the widget is destroyed:
    new_img->flags |= Ph_RELEASE_IMAGE|Ph_RELEASE_PALETTE|
        Ph_RELEASE_TRANSPARENCY_MASK|Ph_RELEASE_GHOST_BITMAP;
    
    window = PtCreateWidget(PtWindow, Pt_NO_PARENT, 0, NULL);   
    PtSetArg(&args[0], Pt_ARG_LABEL_IMAGE, new_img, 0);  
    PtSetArg(&args[1], Pt_ARG_LABEL_TYPE, Pt_IMAGE,0);
    PtCreateWidget(PtLabel, window, 2, args);
    PtRealizeWidget(window);
    
    PtMainLoop();   
    return (EXIT_SUCCESS);
}

Classification:

Photon

See also:

PhCreateImage(), PhImage_t, PhRect_t, PiDuplicateImage(), PiFlipImage(), PiResizeImage()

“Images” in the Raw Drawing and Animation chapter of the Photon Programmer's Guide