pixman: fix vnc tight png/jpeg support

This patch adds an x argument to qemu_pixman_linebuf_fill so it can
also be used to convert a partial scanline.  Then fix tight + png/jpeg
encoding by passing in the x+y offset, so the data is read from the
correct screen location instead of the upper left corner.

Cc: 1087974@bugs.launchpad.net
Cc: qemu-stable@nongnu.org
Reported-by: Tim Hardeneck <thardeck@suse.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

hw/vga.c

@@ -2413,7 +2413,7 @@ void ppm_save(const char *filename, struct DisplaySurface *ds, Error **errp)
     }
     linebuf = qemu_pixman_linebuf_create(PIXMAN_BE_r8g8b8, width);
     for (y = 0; y < height; y++) {
-        qemu_pixman_linebuf_fill(linebuf, ds->image, width, y);
+        qemu_pixman_linebuf_fill(linebuf, ds->image, width, 0, y);
         clearerr(f);
         ret = fwrite(pixman_image_get_data(linebuf), 1,
                      pixman_image_get_stride(linebuf), f);

qemu-pixman.c

@@ -52,10 +52,10 @@ pixman_image_t *qemu_pixman_linebuf_create(pixman_format_code_t format,
 }
 
 void qemu_pixman_linebuf_fill(pixman_image_t *linebuf, pixman_image_t *fb,
-                              int width, int y)
+                              int width, int x, int y)
 {
     pixman_image_composite(PIXMAN_OP_SRC, fb, NULL, linebuf,
-                           0, y, 0, 0, 0, 0, width, 1);
+                           x, y, 0, 0, 0, 0, width, 1);
 }
 
 pixman_image_t *qemu_pixman_mirror_create(pixman_format_code_t format,

qemu-pixman.h

@@ -31,7 +31,7 @@ pixman_format_code_t qemu_pixman_get_format(PixelFormat *pf);
 pixman_image_t *qemu_pixman_linebuf_create(pixman_format_code_t format,
                                            int width);
 void qemu_pixman_linebuf_fill(pixman_image_t *linebuf, pixman_image_t *fb,
-                              int width, int y);
+                              int width, int x, int y);
 pixman_image_t *qemu_pixman_mirror_create(pixman_format_code_t format,
                                           pixman_image_t *image);
 void qemu_pixman_image_unref(pixman_image_t *image);

ui/vnc-enc-tight.c

@@ -1212,7 +1212,7 @@ static int send_jpeg_rect(VncState *vs, int x, int y, int w, int h, int quality)
     buf = (uint8_t *)pixman_image_get_data(linebuf);
     row[0] = buf;
     for (dy = 0; dy < h; dy++) {
-        qemu_pixman_linebuf_fill(linebuf, vs->vd->server, w, dy);
+        qemu_pixman_linebuf_fill(linebuf, vs->vd->server, w, x, y + dy);
         jpeg_write_scanlines(&cinfo, row, 1);
     }
     qemu_pixman_image_unref(linebuf);
@@ -1356,7 +1356,7 @@ static int send_png_rect(VncState *vs, int x, int y, int w, int h,
         if (color_type == PNG_COLOR_TYPE_PALETTE) {
             memcpy(buf, vs->tight.tight.buffer + (dy * w), w);
         } else {
-            qemu_pixman_linebuf_fill(linebuf, vs->vd->server, w, dy);
+            qemu_pixman_linebuf_fill(linebuf, vs->vd->server, w, x, y + dy);
         }
         png_write_row(png_ptr, buf);
     }

ui/vnc.c

@@ -2569,7 +2569,7 @@ static int vnc_refresh_server_surface(VncDisplay *vd)
             uint8_t *server_ptr;
 
             if (vd->guest.format != VNC_SERVER_FB_FORMAT) {
-                qemu_pixman_linebuf_fill(tmpbuf, vd->guest.fb, width, y);
+                qemu_pixman_linebuf_fill(tmpbuf, vd->guest.fb, width, 0, y);
                 guest_ptr = (uint8_t *)pixman_image_get_data(tmpbuf);
             } else {
                 guest_ptr = guest_row;