renderer: Bring button drawing closer to Rust

eek/eek-renderer.c

@@ -18,8 +18,6 @@
  * 02110-1301 USA
  */
 
-#include "config.h"
-
 #include <math.h>
 #include <string.h>
 #include <gdk-pixbuf/gdk-pixbuf.h>
@@ -60,21 +58,21 @@ render_outline (cairo_t     *cr,
         position.x, position.y, position.width, position.height);
 }
 
-static void render_button_in_context(gint scale_factor,
+/// Rust interface
+void eek_render_button_in_context(uint32_t scale_factor,
                                      cairo_t     *cr,
                                      GtkStyleContext *ctx,
-                                     const struct squeek_button *button) {
+                                     EekBounds bounds,
+                                     const char *icon_name,
+                                     const gchar *label) {
     /* blank background */
     cairo_set_source_rgba (cr, 0.0, 0.0, 0.0, 0.0);
     cairo_paint (cr);
 
-    EekBounds bounds = squeek_button_get_bounds(button);
     render_outline (cr, ctx, bounds);
     cairo_paint (cr);
 
     /* render icon (if any) */
-    const char *icon_name = squeek_button_get_icon_name(button);
-
     if (icon_name) {
         cairo_surface_t *icon_surface =
             eek_renderer_get_icon_surface (icon_name, 16, scale_factor);
@@ -104,25 +102,27 @@ static void render_button_in_context(gint scale_factor,
         }
     }
 
-    const gchar *label = squeek_button_get_label(button);
     if (label) {
-        render_button_label (cr, ctx, label, squeek_button_get_bounds(button));
+        render_button_label (cr, ctx, label, bounds);
     }
 }
 
-void
+/// Prepare context for drawing the button.
-eek_render_button (EekRenderer *self,
+/// The context MUST be released using the corresponing "put" procedure
-            cairo_t     *cr,
+/// before drawing the next button.
-            const struct squeek_button *button,
+/// Interface for Rust.
-               gboolean     pressed,
+GtkStyleContext *
-               gboolean     locked)
+eek_get_style_context_for_button (EekRenderer *self,
+                                  const char *name,
+                                  const char *outline_name,
+               uint64_t     pressed,
+               uint64_t     locked)
 {
     GtkStyleContext *ctx = self->button_context;
     /* Set the name of the button on the widget path, using the name obtained
        from the button's symbol. */
     g_autoptr (GtkWidgetPath) path = NULL;
     path = gtk_widget_path_copy (gtk_style_context_get_path (ctx));
-    const char *name = squeek_button_get_name(button);
     gtk_widget_path_iter_set_name (path, -1, name);
 
     /* Update the style context with the updated widget path. */
@@ -131,14 +131,17 @@ eek_render_button (EekRenderer *self,
        (pressed) or normal. */
     gtk_style_context_set_state(ctx,
         pressed ? GTK_STATE_FLAG_ACTIVE : GTK_STATE_FLAG_NORMAL);
-    const char *outline_name = squeek_button_get_outline_name(button);
     if (locked) {
         gtk_style_context_add_class(ctx, "locked");
     }
     gtk_style_context_add_class(ctx, outline_name);
+    return ctx;
+}
 
-    render_button_in_context(self->scale_factor, cr, ctx, button);
+/// Interface for Rust.
-
+void eek_put_style_context_for_button(GtkStyleContext *ctx,
+                                      const char *outline_name,
+                                      uint64_t locked) {
     // Save and restore functions don't work if gtk_render_* was used in between
     gtk_style_context_set_state(ctx, GTK_STATE_FLAG_NORMAL);
     gtk_style_context_remove_class(ctx, outline_name);
@@ -333,6 +336,11 @@ eek_renderer_set_scale_factor (EekRenderer *renderer, gint scale)
     renderer->scale_factor = scale;
 }
 
+/// Rust interface.
+uint32_t eek_renderer_get_scale_factor(EekRenderer *renderer) {
+    return renderer->scale_factor;
+}
+
 cairo_surface_t *
 eek_renderer_get_icon_surface (const gchar *icon_name,
                                gint size,

src/drawing.rs

@@ -5,18 +5,21 @@ use std::cell::RefCell;
 
 use ::action::Action;
 use ::keyboard;
-use ::layout::{ Button, Layout };
+use ::layout::{ Button, Label, Layout };
-use ::layout::c::{ EekGtkKeyboard, Point };
+use ::layout::c::{ Bounds, EekGtkKeyboard, Point };
 use ::submission::Submission;
 
 use glib::translate::FromGlibPtrNone;
 use gtk::WidgetExt;
 
+use std::ffi::CStr;
+use std::ptr;
+
 mod c {
     use super::*;
 
     use cairo_sys;
-    use std::os::raw::c_void;
+    use std::os::raw::{ c_char, c_void };
     
     // This is constructed only in C, no need for warnings
     #[allow(dead_code)]
@@ -24,18 +27,45 @@ mod c {
     #[derive(Clone, Copy)]
     pub struct EekRenderer(*const c_void);
 
+    // This is constructed only in C, no need for warnings
+    /// Just don't clone this for no reason.
+    #[allow(dead_code)]
+    #[repr(transparent)]
+    #[derive(Clone, Copy)]
+    pub struct GtkStyleContext(*const c_void);
+
+
     #[no_mangle]
     extern "C" {
-        // Button and View inside CButtonPlace are safe to pass to C
-        // as long as they don't outlive the call
-        // and nothing dereferences them
         #[allow(improper_ctypes)]
-        pub fn eek_render_button(
+        pub fn eek_renderer_get_scale_factor(
             renderer: EekRenderer,
+        ) -> u32;
+
+        #[allow(improper_ctypes)]
+        pub fn eek_render_button_in_context(
+            scale_factor: u32,
             cr: *mut cairo_sys::cairo_t,
-            button: *const Button,
+            ctx: GtkStyleContext,
+            bounds: Bounds,
+            icon_name: *const c_char,
+            label: *const c_char,
+        );
+
+        #[allow(improper_ctypes)]
+        pub fn eek_get_style_context_for_button(
+            renderer: EekRenderer,
+            name: *const c_char,
+            outline_name: *const c_char,
             pressed: u64,
             locked: u64,
+        ) -> GtkStyleContext;
+
+        #[allow(improper_ctypes)]
+        pub fn eek_put_style_context_for_button(
+            ctx: GtkStyleContext,
+            outline_name: *const c_char,
+            locked: u64,
         );
     }
 
@@ -109,16 +139,75 @@ pub fn render_button_at_position(
         button.size.width, button.size.height
     );
     cr.clip();
-    unsafe {
+
-        c::eek_render_button(
+    let scale_factor = unsafe {
+        c::eek_renderer_get_scale_factor(renderer)
+    };
+    let bounds = button.get_bounds();
+    let (label_c, icon_name_c) = match &button.label {
+        Label::Text(text) => (text.as_ptr(), ptr::null()),
+        Label::IconName(name) => {
+            let l = unsafe {
+                // CStr doesn't allocate anything, so it only points to
+                // the 'static str, avoiding a memory leak
+                CStr::from_bytes_with_nul_unchecked(b"icon\0")
+            };
+            (l.as_ptr(), name.as_ptr())
+        },
+    };
+
+    with_button_context(
         renderer,
+        button,
+        pressed,
+        locked,
+        |ctx| unsafe {
+            // TODO: split into separate procedures:
+            // draw outline, draw label, draw icon.
+            c::eek_render_button_in_context(
+                scale_factor,
                 cairo::Context::to_raw_none(&cr),
-            button as *const Button,
+                *ctx,
+                bounds,
+                icon_name_c,
+                label_c,
+            )
+        }
+    );
+
+    cr.restore();
+}
+
+fn with_button_context<R, F: FnOnce(&c::GtkStyleContext) -> R>(
+    renderer: c::EekRenderer,
+    button: &Button,
+    pressed: keyboard::PressType,
+    locked: bool,
+    operation: F,
+) -> R {
+    let outline_name_c = button.outline_name.as_ptr();
+    
+    let ctx = unsafe {
+        c::eek_get_style_context_for_button(
+            renderer,
+            button.name.as_ptr(),
+            outline_name_c,
             pressed as u64,
             locked as u64,
         )
     };
-    cr.restore();
+    
+    let r = operation(&ctx);
+
+    unsafe {
+        c::eek_put_style_context_for_button(
+            ctx,
+            outline_name_c,
+            locked as u64,
+        )
+    };
+
+    r
 }
 
 pub fn queue_redraw(keyboard: EekGtkKeyboard) {

src/layout.h

@@ -26,12 +26,6 @@ struct squeek_layout_state {
 
 struct squeek_layout;
 
-EekBounds squeek_button_get_bounds(const struct squeek_button*);
-const char *squeek_button_get_label(const struct squeek_button*);
-const char *squeek_button_get_icon_name(const struct squeek_button*);
-const char *squeek_button_get_name(const struct squeek_button*);
-const char *squeek_button_get_outline_name(const struct squeek_button*);
-
 void squeek_button_print(const struct squeek_button* button);
 
 struct transformation squeek_layout_calculate_transformation(

src/layout.rs

@@ -41,9 +41,7 @@ pub mod c {
     use super::*;
 
     use gtk_sys;
-    use std::ffi::CStr;
     use std::os::raw::{ c_char, c_void };
-    use std::ptr;
 
     use std::ops::{ Add, Sub };
 
@@ -163,57 +161,6 @@ pub mod c {
 
     // The following defined in Rust. TODO: wrap naked pointers to Rust data inside RefCells to prevent multiple writers
     
-    #[no_mangle]
-    pub extern "C"
-    fn squeek_button_get_bounds(button: *const ::layout::Button) -> Bounds {
-        let button = unsafe { &*button };
-        Bounds {
-            x: 0.0, y: 0.0,
-            width: button.size.width, height: button.size.height
-        }
-    }
-
-    #[no_mangle]
-    pub extern "C"
-    fn squeek_button_get_label(
-        button: *const ::layout::Button
-    ) -> *const c_char {
-        let button = unsafe { &*button };
-        match &button.label {
-            Label::Text(text) => text.as_ptr(),
-            // returning static strings to C is a bit cumbersome
-            Label::IconName(_) => unsafe {
-                // CStr doesn't allocate anything, so it only points to
-                // the 'static str, avoiding a memory leak
-                CStr::from_bytes_with_nul_unchecked(b"icon\0")
-            }.as_ptr(),
-        }
-    }
-    
-    #[no_mangle]
-    pub extern "C"
-    fn squeek_button_get_icon_name(button: *const Button) -> *const c_char {
-        let button = unsafe { &*button };
-        match &button.label {
-            Label::Text(_) => ptr::null(),
-            Label::IconName(name) => name.as_ptr(),
-        }
-    }
-    
-    #[no_mangle]
-    pub extern "C"
-    fn squeek_button_get_name(button: *const Button) -> *const c_char {
-        let button = unsafe { &*button };
-        button.name.as_ptr()
-    }
-    
-    #[no_mangle]
-    pub extern "C"
-    fn squeek_button_get_outline_name(button: *const Button) -> *const c_char {
-        let button = unsafe { &*button };
-        button.outline_name.as_ptr()
-    }
-    
     #[no_mangle]
     pub extern "C"
     fn squeek_button_print(button: *const ::layout::Button) {
@@ -485,6 +432,15 @@ pub struct Button {
     pub state: Rc<RefCell<KeyState>>,
 }
 
+impl Button {
+    pub fn get_bounds(&self) -> c::Bounds {
+        c::Bounds {
+            x: 0.0, y: 0.0,
+            width: self.size.width, height: self.size.height,
+        }
+    }
+}
+
 /// The graphical representation of a row of buttons
 #[derive(Clone, Debug)]
 pub struct Row {