Add awesome.load_image()

This uses imlib2 for loading the image and thus supports more image formats than
just PNG.

Almost fixes: FS#958

Signed-off-by: Uli Schlachter <psychon@znc.in>

awesomeConfig.cmake

@@ -144,6 +144,7 @@ pkg_check_modules(AWESOME_REQUIRED REQUIRED
     cairo-xcb
     libstartup-notification-1.0>=0.10
     xproto>=7.0.15
+    imlib2
     libxdg-basedir>=1.0.0)
 
 if(NOT AWESOME_REQUIRED_FOUND OR NOT AWESOME_COMMON_REQUIRED_FOUND)

draw.c

@@ -29,6 +29,8 @@
 #include <ctype.h>
 #include <math.h>
 
+#include <Imlib2.h>
+
 #include "globalconf.h"
 #include "screen.h"
 
@@ -160,4 +162,69 @@ draw_dup_image_surface(cairo_surface_t *surface)
     return res;
 }
 
+static const char *
+image_imlib_load_strerror(Imlib_Load_Error e)
+{
+    switch(e)
+    {
+      case IMLIB_LOAD_ERROR_FILE_DOES_NOT_EXIST:
+        return "no such file or directory";
+      case IMLIB_LOAD_ERROR_FILE_IS_DIRECTORY:
+        return "file is a directory";
+      case IMLIB_LOAD_ERROR_PERMISSION_DENIED_TO_READ:
+        return "read permission denied";
+      case IMLIB_LOAD_ERROR_NO_LOADER_FOR_FILE_FORMAT:
+        return "no loader for file format";
+      case IMLIB_LOAD_ERROR_PATH_TOO_LONG:
+        return "path too long";
+      case IMLIB_LOAD_ERROR_PATH_COMPONENT_NON_EXISTANT:
+        return "path component non existent";
+      case IMLIB_LOAD_ERROR_PATH_COMPONENT_NOT_DIRECTORY:
+        return "path component not a directory";
+      case IMLIB_LOAD_ERROR_PATH_POINTS_OUTSIDE_ADDRESS_SPACE:
+        return "path points outside address space";
+      case IMLIB_LOAD_ERROR_TOO_MANY_SYMBOLIC_LINKS:
+        return "too many symbolic links";
+      case IMLIB_LOAD_ERROR_OUT_OF_MEMORY:
+        return "out of memory";
+      case IMLIB_LOAD_ERROR_OUT_OF_FILE_DESCRIPTORS:
+        return "out of file descriptors";
+      case IMLIB_LOAD_ERROR_PERMISSION_DENIED_TO_WRITE:
+        return "write permission denied";
+      case IMLIB_LOAD_ERROR_OUT_OF_DISK_SPACE:
+        return "out of disk space";
+      case IMLIB_LOAD_ERROR_UNKNOWN:
+        return "unknown error, that's really bad";
+      case IMLIB_LOAD_ERROR_NONE:
+        return "no error, oops";
+    }
+
+    return "unknown error";
+}
+
+/** Load the specified path into a cairo surface
+ * \param L Lua state
+ * \param path file to load
+ * \return A cairo image surface or NULL on error.
+ */
+int
+draw_load_image(lua_State *L, const char *path)
+{
+    Imlib_Image imimage;
+    Imlib_Load_Error e = IMLIB_LOAD_ERROR_NONE;
+    int ret;
+
+    imimage = imlib_load_image_with_error_return(path, &e);
+    if (!imimage) {
+        luaL_error(L, "Cannot load image '%s': %s", path, image_imlib_load_strerror(e));
+        return 0;
+    }
+
+    imlib_context_set_image(imimage);
+    ret = luaA_surface_from_data(L, imlib_image_get_width(),
+            imlib_image_get_height(), imlib_image_get_data_for_reading_only());
+    imlib_free_image_and_decache();
+    return ret;
+}
+
 // vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

draw.h

@@ -67,6 +67,7 @@ a_iso2utf8(const char *str, ssize_t len, char **dest, ssize_t *dlen)
 
 int luaA_surface_from_data(lua_State *L, int width, int height, uint32_t *data);
 cairo_surface_t *draw_dup_image_surface(cairo_surface_t *surface);
+int draw_load_image(lua_State *L, const char *path);
 
 #endif
 // vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

luaa.c

@@ -102,6 +102,19 @@ luaA_restart(lua_State *L)
     return 0;
 }
 
+/** Load an image from a given path.
+ * \param L The Lua VM state.
+ * \return The number of elements pushed on stack.
+ * \luastack
+ * \lparam The command line to execute.
+ */
+static int
+luaA_load_image(lua_State *L)
+{
+    const char *filename = luaL_checkstring(L, 1);
+    return draw_load_image(L, filename);
+}
+
 /** UTF-8 aware string length computing.
  * \param L The Lua VM state.
  * \return The number of elements pushed on stack.
@@ -516,6 +529,7 @@ luaA_init(xdgHandle* xdg)
         { "disconnect_signal", luaA_awesome_disconnect_signal },
         { "emit_signal", luaA_awesome_emit_signal },
         { "systray", luaA_systray },
+        { "load_image", luaA_load_image },
         { "__index", luaA_awesome_index },
         { NULL, NULL }
     };

luadoc/awesome.lua

@@ -35,6 +35,12 @@ module("awesome")
 -- @param use_sn Use startup-notification, true or false, default to true.
 -- @return Process ID if everything is OK, or an error string if an error occured.
 
+--- Load an image
+-- @param name The file name
+-- @return An oocairo image surface
+-- @name load_image
+-- @class function
+
 --- Add a global signal.
 -- @param name A string with the event name.
 -- @param func The function to call.