如何在 xlib 的 window 中显示 xmp 图像文件？ （我正在用 C 编码）

Question

I am creating Chess in C, and I need to print the board after every move. I have managed to print the board using strings as pieces but I would like to replace the strings with images of actual pieces.

I haven't been able to find a solution for displaying an image in an X11 window.

for(i=0;i<8;i++){
for(j=0;j<8;j++){
    if(board[i][j]>0){
        if(board[i][j]==100)
            strcpy(text,"Pawn");
        else if(board[i][j]==300)
            strcpy(text,"Knight");
        else if(board[i][j]==400)
            strcpy(text,"Bishop");
        else if(board[i][j]==500)
            strcpy(text,"Rook");
        else if(board[i][j]==900)
            strcpy(text,"Queen");
        else if(board[i][j]==10000)
            strcpy(text,"King");
XSetForeground(dpy,gc,whiteColor);
XDrawString(dpy,w,gc,j*100+20,i*100+50, text, strlen(text));

This snippet displays the white pieces using text in white color.

Answer 1

Drawing XMP file is not supported directly with X11. There is built-in support for png , jpeg and the older format (pixmap, bitmap, etc). First step will be to convert the XMP into fixed size image (from the code, looks like 20*50).

In general, you want to preload the images (from files):

#include <Xm/Xm.h>

 static unsigned char data[] = {
                0x13, 0x00, 0x15, 0x00, 0x93, 0xcd, 0x55, 0xa5, 0x93, 0xc5, 0x00, 0x80,
0x00, 0x60

        } ;
Screen s = DefaultScreenOfDisplay(d) ;
Pixel fg = XWhitePixelOfScreen(s) ;
Pixel bg = XBlackPixelOfScreen(s) ;
// Pixmap king_pm = XmGetPixmap(s, "king.png", fg, bg) ;
// Pixmap queen_pm = XmGetPixmap(s, "queen.png", fg, bg) ;

Pixmap king_pm = XCreatePixmapFromBitmapData(d, RootWindowOfScreen(s), data, 8, 8, fg, bg, 8) ;

Then drawing is based on COPYING the pixmap into the display (using the indices as above). For example, to draw the king.

   XCopyArea(dpy, king_pm, gc, 0, 0, 20, 50, j*100+20,i*100+50) ;

Disclaimer: I do not have a way to test this code. You might need to troubleshoot/fix as needed.