dtk_create_image man page
dtk_create_image — Create and modify a shape displaying an image
dtk_hshape dtk_create_image(dtk_hshape shp,
float x, float y, float width, float height,
const float* color, dtk_htex image);
dtk_create_image() creates a rectangle of size (height,width) centered at (cx,cy) containing the image loaded in texture image. The image will by stretched to fit the size of the rectangle disregarding the dimension of the image. The color argument modulates the pixel values of the image, i.e. to display the image the same way it exist in the image file, color should be white.
shp and color have the same usage and meaning as for other shape creation function:
shp can be used to modify a previously created shape. If it is non-null, the handle will be used to modify the shape referenced by shp: no new shape is created and the returned value is ensured to be shp in case of success, NULL otherwise. If shp is NULL, the function will attempt to create a new shape.
color should point to a 4 float array containing a normalized RGBA value (i.e. each component is between 0.0 and 1.0).
In case of success these functions return the handle to the newly created or modified shape. If the shp argument is non-null, the handle returned is the same value. In case of error, NULL is returned.