+/*
+ * _NET_WM_ICON helpers for slide puzzle game
+ * Copyright © 2022 Nick Bowler
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef EWMHICON_H_
+#define EWMHICON_H_
+
+/*
+ * Define X_DISPLAY_MISSING to allow building without X11 (for test purposes)
+ */
+#if !X_DISPLAY_MISSING
+# include <X11/Intrinsic.h>
+#else
+
+/* Stub types to allow compilation */
+typedef struct {
+ unsigned short red, green, blue;
+} XColor;
+
+typedef struct stub_widget *Widget;
+
+#endif
+
+enum { COLOUR_PRIMARY, COLOUR_DARK, COLOUR_LIGHT, COLOUR_MAX };
+
+/*
+ * Helpers for drawing window icons in various sizes. The tileXX functions
+ * draw one (out of 9) tiles at a particular size using a particular colour
+ * set. Call for each tile position to draw a complete icon.
+ */
+enum { ICON_16x16, ICON_24x24, ICON_32x32, ICON_48x48, ICON_MAX };
+#define EWMH_ICON_NELEM (2+16*16 + 2+24*24 + 2+32*32 + 2+48*48)
+
+void ewmh_tile16(unsigned long *icon, const XColor *c, int tile_x, int tile_y);
+void ewmh_tile24(unsigned long *icon, const XColor *c, int tile_x, int tile_y);
+void ewmh_tile32(unsigned long *icon, const XColor *c, int tile_x, int tile_y);
+void ewmh_tile48(unsigned long *icon, const XColor *c, int tile_x, int tile_y);
+
+/*
+ * Allocate storage for the EWMH _NET_WM_ICON array. The sizes array is
+ * populated with pointers to the beginning of each icon's pixel data. For
+ * example, sizes[ICON_24x24] points to the first pixel of the 24x24 image.
+ *
+ * The returned value can then be passed to XChangeProperty to set the icon,
+ * (use EWMH_ICON_NELEM for the number of elements) and must be freed by the
+ * caller.
+ */
+void *ewmh_icon_alloc(unsigned long **sizes);
+
+/*
+ * Check if the root window indicates support for EWMH icons. Returns 1 if
+ * supported, or 0 otherwise.
+ */
+int ewmh_probe_wm_icon(Widget shell);
+
+#endif