[librsvg/wip/aruiz/rust-pixbuf-loader: 1678/1678] gdk-pixbuf-loader: initial attempt to port to rust

[Alberto Ruiz <aruiz src gnome org>]

commit 891ef1fb5ee03d95fa091c8657caeb475b4a78dd
Author: Alberto Ruiz <crralb amazon com>
Date:   Sat Oct 24 05:09:07 2020 +0200

    gdk-pixbuf-loader: initial attempt to port to rust

 gdk-pixbuf-loader/Cargo.toml |  13 ++++
 gdk-pixbuf-loader/src/lib.rs | 155 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 168 insertions(+)
---
diff --git a/gdk-pixbuf-loader/Cargo.toml b/gdk-pixbuf-loader/Cargo.toml
new file mode 100644
index 000000000..07f0737df
--- /dev/null
+++ b/gdk-pixbuf-loader/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "gdk-pixbuf-loader"
+version = "0.0.1"
+authors = ["Alberto Ruiz <aruiz gnome org>"]
+workspace = "../"
+edition = "2018"
+
+
+[dependencies]
+librsvg = { path = "../librsvg_crate" }
+gdk-pixbuf-sys = "0.9.0"
+libc = "0.2"
+glib-sys = { version="0.9.1", features=["v2_50"] }
\ No newline at end of file
diff --git a/gdk-pixbuf-loader/src/lib.rs b/gdk-pixbuf-loader/src/lib.rs
new file mode 100644
index 000000000..7146abfde
--- /dev/null
+++ b/gdk-pixbuf-loader/src/lib.rs
@@ -0,0 +1,155 @@
+use gdk_pixbuf_sys::{GdkPixbuf, GdkPixbufAnimation, GdkPixbufSaveFunc};
+use glib_sys::GError;
+use libc::{c_char, c_int, c_uint, c_void, FILE};
+
+//const GDK_PIXBUF_FORMAT_WRITABLE: u32 = 0b1;
+const GDK_PIXBUF_FORMAT_SCALABLE: u32 = 0b10;
+const GDK_PIXBUF_FORMAT_THREADSAFE: u32 = 0b100;
+
+type GdkPixbufModuleSizeFunc = Option<extern "C" fn(*mut c_int, *mut c_int, *mut c_void)>;
+type GdkPixbufModulePreparedFunc =
+    Option<extern "C" fn(*mut GdkPixbuf, *mut GdkPixbufAnimation, *mut c_void)>;
+type GdkPixbufModuleUpdatedFunc =
+    Option<extern "C" fn(*mut GdkPixbuf, c_int, c_int, c_int, c_int, *mut c_void)>;
+
+#[repr(C)]
+struct GdkPixbufModulePattern {
+    prefix: *const u8,
+    mask: *const u8,
+    relevance: c_int,
+}
+
+#[repr(C)]
+struct GdkPixbufFormat {
+    name: *const u8,
+    signature: *const GdkPixbufModulePattern,
+    domain: *const u8,
+    description: *const u8,
+
+    mime_types: *const *const u8,
+    extensions: *const *const u8,
+
+    flags: u32,
+    disabled: c_int,
+    license: *const u8,
+}
+
+struct GdkPixbufModule {
+    module_name: *mut c_char,
+    module_path: *mut c_char,
+    module: *mut c_char,
+
+    info: Box<GdkPixbufFormat>,
+    load: extern "C" fn(*mut FILE, Option<*mut GError>) -> *mut GdkPixbuf,
+    load_xpm_data: extern "C" fn(*const [u8]) -> Box<GdkPixbuf>,
+    begin_load: extern "C" fn(
+        GdkPixbufModuleSizeFunc,
+        GdkPixbufModulePreparedFunc,
+        GdkPixbufModuleUpdatedFunc,
+        *mut c_void,
+        Option<*mut GError>,
+    ) -> *mut c_void,
+    stop_load: extern "C" fn(*mut c_void, Option<*mut GError>) -> c_int,
+    load_increment: extern "C" fn(*mut c_void, *const u8, c_uint, Option<*mut GError>) -> c_int,
+    load_animation: extern "C" fn(*mut FILE, Option<*mut GError>) -> *mut GdkPixbufAnimation,
+    save: extern "C" fn(
+        *mut FILE,
+        *mut GdkPixbuf,
+        *mut *mut c_char,
+        *mut *mut c_char,
+        Option<*mut GError>,
+    ) -> c_int,
+    save_to_callback: extern "C" fn(
+        GdkPixbufSaveFunc,
+        *mut c_void,
+        *mut GdkPixbuf,
+        *mut *mut c_char,
+        *mut *mut c_char,
+        Option<*mut GError>,
+    ) -> c_int,
+    is_save_option_supported: extern "C" fn(*const c_char) -> c_int,
+
+    _reserved1: *mut c_void,
+    _reserved2: *mut c_void,
+    _reserved3: *mut c_void,
+    _reserved4: *mut c_void,
+}
+
+#[no_mangle]
+extern "C" fn begin_load(
+    size_func: GdkPixbufModuleSizeFunc,
+    prep_func: GdkPixbufModulePreparedFunc,
+    update_func: GdkPixbufModuleUpdatedFunc,
+    user_data: *mut c_void,
+    error: Option<*mut GError>,
+) -> *mut c_void {
+    std::ptr::null_mut()
+}
+
+#[no_mangle]
+extern "C" fn stop_load(user_data: *mut c_void, error: Option<*mut GError>) -> c_int {
+    1
+}
+
+#[no_mangle]
+extern "C" fn load_increment(
+    user_data: *mut c_void,
+    buffer: *const u8,
+    size: c_uint,
+    error: Option<*mut GError>,
+) -> c_int {
+    1
+}
+
+#[no_mangle]
+extern "C" fn fill_vtable(module: &mut GdkPixbufModule) {
+    module.begin_load = begin_load;
+    module.stop_load = stop_load;
+    module.load_increment = load_increment;
+}
+
+#[no_mangle]
+extern "C" fn fill_info(info: &mut GdkPixbufFormat) {
+    let signature = vec![
+        GdkPixbufModulePattern {
+            mask: " <svg".as_ptr(),
+            prefix: "*    ".as_ptr(),
+            relevance: 100,
+        },
+        GdkPixbufModulePattern {
+            mask: " <!DOCTYPE svg".as_ptr(),
+            prefix: "*             ".as_ptr(),
+            relevance: 100,
+        },
+        GdkPixbufModulePattern {
+            mask: std::ptr::null(),
+            prefix: std::ptr::null(),
+            relevance: 0,
+        },
+    ];
+
+    let mime_types = [
+        "image/svg+xml\0".as_ptr(),
+        "image/svg\0".as_ptr(),
+        "image/svg-xml\0".as_ptr(),
+        "image/vnd.adobe.svg+xml\0".as_ptr(),
+        "text/xml-svg\0".as_ptr(),
+        "image/svg+xml-compressed\0".as_ptr(),
+        std::ptr::null(),
+    ];
+
+    let extensions = [
+        "svg\0".as_ptr(),
+        "svgz\0".as_ptr(),
+        "svg.gz\0".as_ptr(),
+        std::ptr::null(),
+    ];
+
+    info.name = "svg\0".as_ptr();
+    info.signature = signature.as_ptr();
+    info.description = "Scalable Vector Graphics".as_ptr(); //TODO: Gettext this
+    info.mime_types = mime_types.as_ptr();
+    info.extensions = extensions.as_ptr();
+    info.flags = GDK_PIXBUF_FORMAT_SCALABLE | GDK_PIXBUF_FORMAT_THREADSAFE;
+    info.license = "LGPLv2".as_ptr();
+}