Introduce libwayland-cursor, a cursor helper library

The purpose of this library is to be the equivalent of libXcursor in
the X world. This library is compatible with X cursor themes and loads
them directly into an shm pool making it easy for the clients to get
buffer for each cursor image.

The code for handling the X cursor theme was taken from libXcursor. The
files cursor/xcursor.[ch] are a stripped down version of that library
containing only the interfaces necessary for implementing the wayland
counterpart.

cursor/wayland-cursor.c

@@ -0,0 +1,356 @@
+/*
+ * Copyright © 2012 Intel Corporation
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#include "xcursor.h"
+#include "wayland-cursor.h"
+#include "wayland-client.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+struct shm_pool {
+	struct wl_shm_pool *pool;
+	int fd;
+	unsigned int size;
+	unsigned int used;
+	char *data;
+};
+
+static struct shm_pool *
+shm_pool_create(struct wl_shm *shm, int size)
+{
+	struct shm_pool *pool;
+	char filename[] = "/tmp/wayland-shm-XXXXXX";
+
+	pool = malloc(sizeof *pool);
+	if (!pool)
+		return NULL;
+
+	pool->fd = mkstemp(filename);
+	if (pool->fd < 0)
+		return NULL;
+
+	if (ftruncate(pool->fd, size) < 0) {
+		close(pool->fd);
+		return NULL;
+	}
+
+	pool->data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED,
+			  pool->fd, 0);
+	unlink(filename);
+
+	if (pool->data == MAP_FAILED) {
+		close(pool->fd);
+		return NULL;
+	}
+
+	pool->pool = wl_shm_create_pool(shm, pool->fd, size);
+	pool->size = size;
+	pool->used = 0;
+
+	return pool;
+}
+
+static int
+shm_pool_resize(struct shm_pool *pool, int size)
+{
+	if (ftruncate(pool->fd, size) < 0)
+		return 0;
+
+	wl_shm_pool_resize(pool->pool, size);
+
+	munmap(pool->data, pool->size);
+
+	pool->data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED,
+			  pool->fd, 0);
+	pool->size = size;
+
+	return 1;
+}
+
+static int
+shm_pool_allocate(struct shm_pool *pool, int size)
+{
+	int offset;
+
+	if (pool->used + size > pool->size)
+		if (!shm_pool_resize(pool, 2 * pool->size + size))
+			return -1;
+
+	offset = pool->used;
+	pool->used += size;
+
+	return offset;
+}
+
+static void
+shm_pool_destroy(struct shm_pool *pool)
+{
+	munmap(pool->data, pool->size);
+	wl_shm_pool_destroy(pool->pool);
+	free(pool);
+}
+
+
+static const char *cursor_names[] = {
+	"bottom_left_corner",
+	"bottom_right_corner",
+	"bottom_side",
+	"grabbing",
+	"left_ptr",
+	"left_side",
+	"right_side",
+	"top_left_corner",
+	"top_right_corner",
+	"top_side",
+	"xterm",
+	"hand1",
+};
+
+struct wl_cursor_theme {
+	unsigned int cursor_count;
+	struct wl_cursor **cursors;
+	struct wl_shm *shm;
+	struct shm_pool *pool;
+	char *name;
+	int size;
+};
+
+struct cursor_image {
+	struct wl_cursor_image image;
+	struct wl_cursor_theme *theme;
+	struct wl_buffer *buffer;
+	int offset; /* data offset of this image in the shm pool */
+};
+
+/** Get an shm buffer for a cursor image
+ *
+ * \param image The cursor image
+ * \return An shm buffer for the cursor image. The user should not destroy
+ * the returned buffer.
+ */
+WL_EXPORT struct wl_buffer *
+wl_cursor_image_get_buffer(struct wl_cursor_image *_img)
+{
+	struct cursor_image *image = (struct cursor_image *) _img;
+	struct wl_cursor_theme *theme = image->theme;
+
+	if (!image->buffer) {
+		image->buffer =
+			wl_shm_pool_create_buffer(theme->pool->pool,
+						  image->offset,
+						  _img->width, _img->height,
+						  _img->width * 4,
+						  WL_SHM_FORMAT_ARGB8888);
+	};
+
+	return image->buffer;
+}
+
+static void
+wl_cursor_image_destroy(struct wl_cursor_image *_img)
+{
+	struct cursor_image *image = (struct cursor_image *) _img;
+
+	if (image->buffer)
+		wl_buffer_destroy(image->buffer);
+
+	free(image);
+}
+
+static void
+wl_cursor_destroy(struct wl_cursor *cursor)
+{
+	unsigned int i;
+
+	for (i = 0; i < cursor->image_count; i++)
+		wl_cursor_image_destroy(cursor->images[i]);
+
+	free(cursor->name);
+	free(cursor);
+}
+
+static struct wl_cursor *
+load_cursor(struct wl_cursor_theme *theme, const char *name)
+{
+	XcursorImages *images;
+	struct wl_cursor *cursor;
+	struct cursor_image *image;
+	int i, size;
+
+	images = XcursorLibraryLoadImages(name, theme->name, theme->size);
+	if (!images)
+		return NULL;
+
+	cursor = malloc(sizeof *cursor);
+	if (!cursor) {
+		XcursorImagesDestroy(images);
+		return NULL;
+	}
+
+	cursor->image_count = images->nimage;
+	cursor->images = malloc(images->nimage * sizeof cursor->images[0]);
+	if (!cursor->images) {
+		XcursorImagesDestroy(images);
+		free(cursor);
+		return NULL;
+	}
+
+	cursor->name = strdup(name);
+
+	for (i = 0; i < images->nimage; i++) {
+		image = malloc(sizeof *image);
+		cursor->images[i] = (struct wl_cursor_image *) image;
+
+		image->theme = theme;
+		image->buffer = NULL;
+
+		image->image.width = images->images[i]->width;
+		image->image.height = images->images[i]->height;
+		image->image.hotspot_x = images->images[i]->xhot;
+		image->image.hotspot_y = images->images[i]->yhot;
+		image->image.delay = images->images[i]->delay;
+
+		/* copy pixels to shm pool */
+		size = image->image.width * image->image.height * 4;
+		image->offset = shm_pool_allocate(theme->pool, size);
+		memcpy(theme->pool->data + image->offset,
+		       images->images[i]->pixels, size);
+	}
+
+	XcursorImagesDestroy(images);
+
+	return cursor;
+}
+
+/** Load a cursor theme to memory shared with the compositor
+ *
+ * \param name The name of the cursor theme to load. If %NULL, the default
+ * theme will be loaded.
+ * \param size Desired size of the cursor images.
+ * \param shm The compositor's shm interface.
+ *
+ * \return An object representing the theme that should be destroyed with
+ * wl_cursor_theme_destroy() or %NULL on error.
+ */
+WL_EXPORT struct wl_cursor_theme *
+wl_cursor_theme_load(const char *name, int size, struct wl_shm *shm)
+{
+	struct wl_cursor_theme *theme;
+	unsigned int i;
+
+	theme = malloc(sizeof *theme);
+	if (!theme)
+		return NULL;
+
+	if (!name)
+		name = "default";
+
+	theme->name = strdup(name);
+	theme->size = size;
+	theme->cursor_count = ARRAY_LENGTH(cursor_names);
+
+	theme->cursors =
+		malloc(theme->cursor_count * sizeof theme->cursors[0]);
+	if (!theme->cursors) {
+		free(theme);
+		return NULL;
+	}
+
+	theme->pool =
+		shm_pool_create(shm, theme->cursor_count * size * size * 4);
+
+	for (i = 0; i < theme->cursor_count; i++)
+		theme->cursors[i] = load_cursor(theme, cursor_names[i]);
+
+	return theme;
+}
+
+/** Destroys a cursor theme object
+ *
+ * \param theme The cursor theme to be destroyed
+ */
+WL_EXPORT void
+wl_cursor_theme_destroy(struct wl_cursor_theme *theme)
+{
+	unsigned int i;
+
+	for (i = 0; i < theme->cursor_count; i++)
+		wl_cursor_destroy(theme->cursors[i]);
+
+	shm_pool_destroy(theme->pool);
+
+	free(theme->cursors);
+	free(theme);
+}
+
+/** Get the cursor for a given type from a cursor theme
+ *
+ * \param theme The cursor theme
+ * \patam type The desired cursor type
+ * \return The theme's cursor of the given type or %NULL if there is no
+ * such cursor
+ */
+WL_EXPORT struct wl_cursor *
+wl_cursor_theme_get_cursor(struct wl_cursor_theme *theme,
+			   enum wl_cursor_type type)
+{
+	if (type < theme->cursor_count)
+		return theme->cursors[type];
+
+	return NULL;
+}
+
+/** Get the cursor for a given name from a cursor theme
+ *
+ * \param theme The cursor theme
+ * \param name Name of the desired cursor
+ * \return The theme's cursor of the given name or %NULL if there is no
+ * such cursor
+ */
+WL_EXPORT struct wl_cursor *
+wl_cursor_theme_get_cursor_by_name(struct wl_cursor_theme *theme,
+				   const char *name)
+{
+	unsigned int i;
+	struct wl_cursor *cursor;
+
+	for (i = 0; i < theme->cursor_count; i++) {
+		if (strcmp(name, theme->cursors[i]->name) == 0)
+			return theme->cursors[i];
+	}
+
+	cursor = load_cursor(theme, name);
+	if (!cursor)
+		return NULL;
+
+	theme->cursor_count++;
+	theme->cursors =
+		realloc(theme->cursors,
+			theme->cursor_count * sizeof theme->cursors[0]);
+
+	theme->cursors[theme->cursor_count - 1] = cursor;
+
+	return cursor;
+}