NAME

XInitImage, XCreateImage, XGetPixel, XPutPixel, XSubImage, XAddPixel, XDestroyImage - image utilities

SYNTAX

Status XInitImage(XImage *_i_m_a_g_e); XImage *XCreateImage(Display *_d_i_s_p_l_a_y, Visual *_v_i_s_u_a_l, unsigned int _d_e_p_t_h, int _f_o_r_m_a_t, int _o_f_f_s_e_t, char *_d_a_t_a, unsigned int _w_i_d_t_h, unsigned int _h_e_i_g_h_t, int _b_i_t_m_a_p___p_a_d, int _b_y_t_e_s___p_e_r___l_i_n_e); unsigned long XGetPixel(XImage *_x_i_m_a_g_e, int _x, int _y); int XPutPixel(XImage *_x_i_m_a_g_e, int _x, int _y, unsigned long _p_i_x_e_l); XImage *XSubImage(XImage *_x_i_m_a_g_e, int _x, int _y, unsigned int _s_u_b_i_m_a_g_e___w_i_d_t_h, unsigned int _s_u_b_i_m_a_g_e___h_e_i_g_h_t); int XAddPixel(XImage *_x_i_m_a_g_e, long _v_a_l_u_e); int XDestroyImage(XImage *_x_i_m_a_g_e);

ARGUMENTS

_b_i_t_m_a_p___p_a_d Specifies the quantum of a scanline (8, 16, or 32).
In other words, the start of one scanline is separated in client memory from the start of the next scanline by an integer multiple of this many bits.
_b_y_t_e_s___p_e_r___l_i_n_e Specifies the number of bytes in the client image between
the start of one scanline and the start of the next.
_d_a_t_a Specifies the image data.
_d_e_p_t_h Specifies the depth of the image.
_d_i_s_p_l_a_y Specifies the connection to the X server.
_f_o_r_m_a_t Specifies the format for the image.
You can pass _X_Y_B_i_t_m_a_p, _X_Y_P_i_x_m_a_p, or _Z_P_i_x_m_a_p.
_h_e_i_g_h_t Specifies the height of the image, in pixels.
_o_f_f_s_e_t Specifies the number of pixels to ignore at the beginning of the scanline.
_p_i_x_e_l Specifies the new pixel value.
_s_u_b_i_m_a_g_e___h_e_i_g_h_t Specifies the height of the new subimage, in pixels.
_s_u_b_i_m_a_g_e___w_i_d_t_h Specifies the width of the new subimage, in pixels.
_v_a_l_u_e Specifies the constant value that is to be added.
_v_i_s_u_a_l Specifies the
_V_i_s_u_a_l structure.
_w_i_d_t_h Specifies the width of the image, in pixels.
_x_i_m_a_g_e Specifies the image.
_x
_y Specify the x and y coordinates.

DESCRIPTION

The _X_I_n_i_t_I_m_a_g_e function initializes the internal image manipulation routines of an image structure, based on the values of the various structure members. All fields other than the manipulation routines must already be initialized. If the bytes_per_line member is zero, _X_I_n_i_t_I_m_a_g_e will assume the image data is contiguous in memory and set the bytes_per_line member to an appropriate value based on the other members; otherwise, the value of bytes_per_line is not changed. All of the manipulation routines are initialized to functions that other Xlib image manipulation functions need to operate on the type of image specified by the rest of the structure.

This function must be called for any image constructed by the client before passing it to any other Xlib function. Image structures created or returned by Xlib do not need to be initialized in this fashion.

This function returns a nonzero status if initialization of the structure is successful. It returns zero if it detected some error or inconsistency in the structure, in which case the image is not changed.

The _X_C_r_e_a_t_e_I_m_a_g_e function allocates the memory needed for an _X_I_m_a_g_e structure for the specified display but does not allocate space for the image itself. Rather, it initializes the structure byte-order, bit-order, and bitmap-unit values from the display and returns a pointer to the _X_I_m_a_g_e structure. The red, green, and blue mask values are defined for Z format images only and are derived from the _V_i_s_u_a_l structure passed in. Other values also are passed in. The offset permits the rapid displaying of the image without requiring each scanline to be shifted into position. If you pass a zero value in bytes_per_line, Xlib assumes that the scanlines are contiguous in memory and calculates the value of bytes_per_line itself.

Note that when the image is created using _X_C_r_e_a_t_e_I_m_a_g_e, _X_G_e_t_I_m_a_g_e, or _X_S_u_b_I_m_a_g_e, the destroy procedure that the _X_D_e_s_t_r_o_y_I_m_a_g_e function calls frees both the image structure and the data pointed to by the image structure.

The basic functions used to get a pixel, set a pixel, create a subimage, and add a constant value to an image are defined in the image object. The functions in this section are really macro invocations of the functions in the image object and are defined in <_X_1_1_/_X_u_t_i_l_._h>.

The _X_G_e_t_P_i_x_e_l function returns the specified pixel from the named image. The pixel value is returned in normalized format (that is, the least significant byte of the long is the least significant byte of the pixel). The image must contain the x and y coordinates.

The _X_P_u_t_P_i_x_e_l function overwrites the pixel in the named image with the specified pixel value. The input pixel value must be in normalized format (that is, the least significant byte of the long is the least significant byte of the pixel). The image must contain the x and y coordinates.

The _X_S_u_b_I_m_a_g_e function creates a new image that is a subsection of an existing one. It allocates the memory necessary for the new _X_I_m_a_g_e structure and returns a pointer to the new image. The data is copied from the source image, and the image must contain the rectangle defined by x, y, subimage_width, and subimage_height.

The _X_A_d_d_P_i_x_e_l function adds a constant value to every pixel in an image. It is useful when you have a base pixel value from allocating color resources and need to manipulate the image to that form.

The _X_D_e_s_t_r_o_y_I_m_a_g_e function deallocates the memory associated with the _X_I_m_a_g_e structure.

SEE ALSO

XPutImage(3X11)
_X_l_i_b _- _C _L_a_n_g_u_a_g_e _X _I_n_t_e_r_f_a_c_e