Center the keyboard horizontally

Also simplify individual key rendering to make the rendering model more
coherent.

eek/eek-gtk-keyboard.c

@@ -159,7 +159,8 @@ eek_gtk_keyboard_real_size_allocate (GtkWidget     *self,
 }
 
 static void depress(EekGtkKeyboard *self,
-                    gdouble x, gdouble y, guint32 time) {
+                    gdouble x, gdouble y, guint32 time)
+{
     EekGtkKeyboardPrivate *priv = eek_gtk_keyboard_get_instance_private (self);
     EekKey *key = eek_renderer_find_key_by_position (priv->renderer, x, y);
 
@@ -482,27 +483,15 @@ render_pressed_key (GtkWidget *widget,
 {
     EekGtkKeyboard        *self = EEK_GTK_KEYBOARD (widget);
     EekGtkKeyboardPrivate *priv = eek_gtk_keyboard_get_instance_private (self);
-    EekBounds bounds, large_bounds;
 
     GdkWindow         *window  = gtk_widget_get_window (widget);
     cairo_region_t    *region  = gdk_window_get_clip_region (window);
     GdkDrawingContext *context = gdk_window_begin_draw_frame (window, region);
     cairo_t           *cr      = gdk_drawing_context_get_cairo_context (context);
-    gdouble            scale   = eek_renderer_get_scale (priv->renderer);
 
-    eek_renderer_get_key_bounds (priv->renderer, key, &bounds, TRUE);
-    magnify_bounds (widget, &bounds, &large_bounds, 1.5);
-
-    cairo_save (cr);
-    cairo_scale (cr, scale, scale);
-    cairo_translate (cr, bounds.x, bounds.y);
     eek_renderer_render_key (priv->renderer, cr, key, 1.0, TRUE);
-    cairo_restore (cr);
 /*
-    cairo_save (cr);
-    cairo_translate (cr, large_bounds.x, large_bounds.y);
     eek_renderer_render_key (priv->renderer, cr, key, 1.5, TRUE);
-    cairo_restore (cr);
 */
     gdk_window_end_draw_frame (window, context);
 
@@ -515,21 +504,13 @@ render_locked_key (GtkWidget *widget,
 {
     EekGtkKeyboard        *self = EEK_GTK_KEYBOARD (widget);
     EekGtkKeyboardPrivate *priv = eek_gtk_keyboard_get_instance_private (self);
-    EekBounds bounds;
 
     GdkWindow         *window  = gtk_widget_get_window (widget);
     cairo_region_t    *region  = gdk_window_get_clip_region (window);
     GdkDrawingContext *context = gdk_window_begin_draw_frame (window, region);
     cairo_t           *cr      = gdk_drawing_context_get_cairo_context (context);
-    gdouble            scale   = eek_renderer_get_scale (priv->renderer);
 
-    eek_renderer_get_key_bounds (priv->renderer, key, &bounds, TRUE);
-
-    cairo_save (cr);
-    cairo_scale (cr, scale, scale);
-    cairo_translate (cr, bounds.x, bounds.y);
     eek_renderer_render_key (priv->renderer, cr, key, 1.0, TRUE);
-    cairo_restore (cr);
 
     gdk_window_end_draw_frame (window, context);
 
@@ -542,7 +523,6 @@ render_released_key (GtkWidget *widget,
 {
     EekGtkKeyboard        *self = EEK_GTK_KEYBOARD (widget);
     EekGtkKeyboardPrivate *priv = eek_gtk_keyboard_get_instance_private (self);
-    EekBounds bounds, large_bounds;
 
     GdkWindow         *window  = gtk_widget_get_window (widget);
     cairo_region_t    *region  = gdk_window_get_clip_region (window);

eek/eek-renderer.c

@@ -452,6 +452,11 @@ render_key (EekRenderer *self,
     g_object_unref (layout);
 }
 
+/*
+    Applies a transformation to the bounds for a given key, consisting of
+    scaling and rotation. The scale factor is separate to the normal scale
+    factor for the keyboard as a whole and is applied cumulatively.
+*/
 void
 eek_renderer_apply_transformation_for_key (EekRenderer *self,
                                            cairo_t     *cr,
@@ -581,6 +586,10 @@ eek_renderer_real_render_key_outline (EekRenderer *self,
     cairo_restore (cr);
 }
 
+/*
+    Renders a key separately from the normal keyboard rendering. As a result,
+    the transformation for the context needs to be set up.
+*/
 static void
 eek_renderer_real_render_key (EekRenderer *self,
                               cairo_t     *cr,
@@ -589,9 +598,14 @@ eek_renderer_real_render_key (EekRenderer *self,
                               gboolean     rotate)
 {
     EekRendererPrivate *priv = eek_renderer_get_instance_private (self);
+    EekBounds bounds;
+
+    eek_renderer_get_key_bounds (self, key, &bounds, rotate);
 
     cairo_save (cr);
     cairo_translate (cr, priv->origin_x, priv->origin_y);
+    cairo_scale (cr, priv->scale, priv->scale);
+    cairo_translate (cr, bounds.x, bounds.y);
     eek_renderer_apply_transformation_for_key (self, cr, key, scale, rotate);
     render_key (self, cr, key, eek_key_is_pressed (key) || eek_key_is_locked (key));
     cairo_restore (cr);
@@ -851,12 +865,11 @@ eek_renderer_set_allocation_size (EekRenderer *renderer,
 
     scale = MIN(width / w, height / h);
 
-    if (scale != priv->scale) {
     priv->scale = scale;
-        priv->origin_x = 0;
-        priv->origin_y = 0;
+    /* Set the rendering offset in widget coordinates to center the keyboard */
+    priv->origin_x = (width - (scale * w)) / 2;
+    priv->origin_y = (height - (scale * h)) / 2;
     invalidate (renderer);
-    }
 }
 
 void
@@ -1223,6 +1236,10 @@ find_key_by_position_section_callback (EekElement *element,
     return data->key ? 0 : -1;
 }
 
+/*
+    Returns the key located at the position x, y in widget coordinates, or
+    NULL if no key can be found at that location.
+*/
 EekKey *
 eek_renderer_find_key_by_position (EekRenderer *renderer,
                                    gdouble      x,
@@ -1234,13 +1251,12 @@ eek_renderer_find_key_by_position (EekRenderer *renderer,
     g_return_val_if_fail (EEK_IS_RENDERER(renderer), NULL);
 
     EekRendererPrivate *priv = eek_renderer_get_instance_private (renderer);
-    x /= priv->scale;
-    y /= priv->scale;
-    x -= priv->origin_x;
-    y -= priv->origin_y;
-
     eek_element_get_bounds (EEK_ELEMENT(priv->keyboard), &bounds);
 
+    /* Transform from widget coordinates to keyboard coordinates */
+    x = (x - priv->origin_x)/priv->scale - bounds.x;
+    y = (y - priv->origin_y)/priv->scale - bounds.y;
+
     if (x < bounds.x ||
         y < bounds.y ||
         x > bounds.width ||