X11: 画像 (XImage)

$ cc -o run 19-image.c util.c -lX11

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include "util.h"

#define WIDTH  200
#define HEIGHT 200

int g_cur_type = 0;

/* バッファにピクセル値をセット */

static void _setpixel(XImage *img,uint8_t *buf,uint32_t pixcol)
{
    //マシンとイメージのバイトオーダーが同じであると想定

    switch(img->bits_per_pixel)
    {
        case 32:
            *((uint32_t *)buf) = pixcol;
            break;
        case 24:
            if(img->byte_order == LSBFirst)
            {
                buf[0] = (uint8_t)pixcol;
                buf[1] = (uint8_t)(pixcol >> 8);
                buf[2] = (uint8_t)(pixcol >> 16);
            }
            else
            {
                buf[0] = (uint8_t)(pixcol >> 16);
                buf[1] = (uint8_t)(pixcol >> 8);
                buf[2] = (uint8_t)pixcol;
            }
            break;
        case 16:
            *((uint16_t *)buf) = pixcol;
            break;
    }
}

/* グラデーションを描画 */

static void _draw_image(XImage *img,int type)
{
    uint8_t *pd,*pdY;
    int ix,iy,bytes,n;
    uint32_t pixcol;

    pdY = (uint8_t *)img->data;
    bytes = img->bits_per_pixel / 8;

    for(iy = 0; iy < img->height; iy++)
    {
        pd = pdY;

        n = iy * 255 / (img->height - 1);
        
        pixcol = rgb_to_pixel_sep(
            (type == 0)? n: 0,
            (type == 1)? n: 0,
            (type == 2)? n: 0);
        
        for(ix = 0; ix < img->width; ix++)
        {
            _setpixel(img, pd, pixcol);
            
            pd += bytes;
        }

        pdY += img->bytes_per_line;
    }
}

int main(int argc,char **argv)
{
    Display *disp;
    XSetWindowAttributes attr;
    Window win;
    XEvent ev;
    XImage *ximg = NULL;
    
    disp = XOpenDisplay(NULL);
    if(!disp) return 1;

    set_display(disp);

    //ウィンドウ作成

    attr.event_mask = ButtonPressMask | ExposureMask;

    win = XCreateWindow(disp, DefaultRootWindow(disp),
        0, 0, WIDTH, HEIGHT, 0,
        CopyFromParent, CopyFromParent, CopyFromParent,
        CWEventMask, &attr);

    //XImage

    ximg = XCreateImage(disp, DefaultVisualOfScreen(g_disp.screen), g_disp.depth,
        ZPixmap, 0, NULL, WIDTH, HEIGHT, BitmapPad(disp), 0);

    if(!ximg)
    {
        printf("failed XCreateImage\n");
        goto END;
    }

    printf("depth: %d\nbits_per_pixel: %d\nbytes_per_line: %d\n",
        ximg->depth, ximg->bits_per_pixel, ximg->bytes_per_line);

    ximg->data = (char *)malloc(ximg->bytes_per_line * HEIGHT);
    if(!ximg->data) goto END;

    _draw_image(ximg, g_cur_type);

    //イベント

    XMapWindow(disp, win);

    while(1)
    {
        XNextEvent(disp, &ev);

        switch(ev.type)
        {
            case Expose:
                XPutImage(disp, win, g_disp.gc, ximg,
                    ev.xexpose.x, ev.xexpose.y,
                    ev.xexpose.x, ev.xexpose.y,
                    ev.xexpose.width, ev.xexpose.height);

                printf("[Expose] (%d,%d)-(%dx%d)\n",
                    ev.xexpose.x, ev.xexpose.y, ev.xexpose.width, ev.xexpose.height);
                fflush(stdout);
                break;
            case ButtonPress:
                if(ev.xbutton.button == Button1)
                {
                    g_cur_type++;
                    if(g_cur_type == 3) g_cur_type = 0;
                
                    _draw_image(ximg, g_cur_type);

                    XPutImage(disp, win, g_disp.gc, ximg,
                        0, 0, 0, 0, WIDTH, HEIGHT);
                }
                else
                    goto END;
        }
    }

END:
    if(ximg) XDestroyImage(ximg);

    XCloseDisplay(disp);

    return 0;
}