The _p_i_x_e_l_P_t_r field points to the first pixel, that is, the top-left pixel
in the block. The _w_i_d_t_h and _h_e_i_g_h_t fields specify the dimensions of the
block of pixels. The _p_i_x_e_l_S_i_z_e field specifies the address difference
between two horizontally adjacent pixels. Often it is 3 or 4, but it can
have any value. The _p_i_t_c_h field specifies the address difference between
two vertically adjacent pixels. The _o_f_f_s_e_t array contains the offsets
from the address of a pixel to the addresses of the bytes containing the
red, green and blue components. These are normally 0, 1 and 2, but can
have other values, e.g., for images that are stored as separate red,
green and blue planes.
The value given for the _w_i_d_t_h and _h_e_i_g_h_t parameters to TTTTkkkk____PPPPhhhhoooottttooooPPPPuuuuttttBBBBlllloooocccckkkk
do not have to correspond to the values specified in _b_l_o_c_k. If they are
smaller, TTTTkkkk____PPPPhhhhoooottttooooPPPPuuuuttttBBBBlllloooocccckkkk extracts a sub-block from the image data
supplied. If they are larger, the data given are replicated (in a tiled
fashion) to fill the specified area. These rules operate independently
in the horizontal and vertical directions.
TTTTkkkk____PPPPhhhhoooottttooooPPPPuuuuttttZZZZoooooooommmmeeeeddddBBBBlllloooocccckkkk works like TTTTkkkk____PPPPhhhhoooottttooooPPPPuuuuttttBBBBlllloooocccckkkk except that the image
can be reduced or enlarged for display. The _s_u_b_s_a_m_p_l_e_X and _s_u_b_s_a_m_p_l_e_Y
parameters allow the size of the image to be reduced by subsampling.
TTTTkkkk____PPPPhhhhoooottttooooPPPPuuuuttttZZZZoooooooommmmeeeeddddBBBBlllloooocccckkkk will use only pixels from the input image whose X
coordinates are multiples of _s_u_b_s_a_m_p_l_e_X, and whose Y coordinates are
multiples of _s_u_b_s_a_m_p_l_e_Y. For example, an image of 512x512 pixels can be
reduced to 256x256 by setting _s_u_b_s_a_m_p_l_e_X and _s_u_b_s_a_m_p_l_e_Y to 2.
The _z_o_o_m_X and _z_o_o_m_Y parameters allow the image to be enlarged by pixel
replication. Each pixel of the (possibly subsampled) input image will be
written to a block _z_o_o_m_X pixels wide and _z_o_o_m_Y pixels high of the
displayed image. Subsampling and zooming can be used together for
special effects.
TTTTkkkk____PPPPhhhhoooottttooooGGGGeeeettttIIIImmmmaaaaggggeeee can be used to retrieve image data from a photo image.
TTTTkkkk____PPPPhhhhoooottttooooGGGGeeeettttIIIImmmmaaaaggggeeee fills in the structure pointed to by the _b_l_o_c_k_P_t_r
parameter with values that describe the address and layout of the image
data that the photo image has stored internally. The values are valid
until the image is destroyed or its size is changed. TTTTkkkk____PPPPhhhhoooottttooooGGGGeeeettttIIIImmmmaaaaggggeeee
returns 1 for compatibility with the corresponding procedure in the old
photo widget.
TTTTkkkk____PPPPhhhhoooottttooooBBBBllllaaaannnnkkkk blanks the entire area of the photo image. Blank areas of
a photo image are transparent.
TTTTkkkk____PPPPhhhhoooottttooooEEEExxxxppppaaaannnndddd requests that the widget's image be expanded to be at
least _w_i_d_t_h x _h_e_i_g_h_t pixels in size. The width and/or height are
unchanged if the user has specified an explicit image width or height
with the ----wwwwiiiiddddtttthhhh and/or ----hhhheeeeiiiigggghhhhtttt configuration options, respectively. If
the image data are being supplied in many small blocks, it is more
efficient to use TTTTkkkk____PPPPhhhhoooottttooooEEEExxxxppppaaaannnndddd or TTTTkkkk____PPPPhhhhoooottttooooSSSSeeeettttSSSSiiiizzzzeeee at the beginning
rather than allowing the image to expand in many small increments as
image blocks are supplied.
TTTTkkkk____PPPPhhhhoooottttooooSSSSeeeettttSSSSiiiizzzzeeee specifies the size of the image, as if the user had
specified the given _w_i_d_t_h and _h_e_i_g_h_t values to the ----wwwwiiiiddddtttthhhh and ----hhhheeeeiiiigggghhhhtttt
configuration options. A value of zero for _w_i_d_t_h or _h_e_i_g_h_t does not
change the image's width or height, but allows the width or height to be
changed by subsequent calls to TTTTkkkk____PPPPhhhhoooottttooooPPPPuuuuttttBBBBlllloooocccckkkk, TTTTkkkk____PPPPhhhhoooottttooooPPPPuuuuttttZZZZoooooooommmmeeeeddddBBBBlllloooocccckkkk
or TTTTkkkk____PPPPhhhhoooottttooooEEEExxxxppppaaaannnndddd.
TTTTkkkk____PPPPhhhhoooottttooooGGGGeeeettttSSSSiiiizzzzeeee returns the dimensions of the image in *_w_i_d_t_h_P_t_r and
*_h_e_i_g_h_t_P_t_r.
CCCCRRRREEEEDDDDIIIITTTTSSSS
The code for the photo image type was developed by Paul Mackerras, based
