Add device_x_scale and device_y_scale to surface so that the coordinate system seen by the backend can differ from the nominal device coordinate space used by the application.

Useful for printer backends where the device coordinate space should be in pixels while the user visible device space is in points.
There is no API to set these values; the backends using this functionality should do that themselves before the first cairo_t is created.
reviewed by: cworth

ChangeLog

@@ -1,3 +1,30 @@
+2005-08-24  Keith Packard  <keithp@keithp.com>
+
+	reviewed by: cworth
+
+	* src/cairo-gstate-private.h:
+	* src/cairo-gstate.c: (_cairo_gstate_init),
+	(_cairo_gstate_apply_device_transform),
+	(_cairo_gstate_apply_device_inverse_transform),
+	(_cairo_gstate_get_matrix), (_cairo_gstate_set_matrix),
+	(_cairo_gstate_identity_matrix), (_cairo_gstate_user_to_backend),
+	(_cairo_gstate_backend_to_user):
+	* src/cairo-surface.c: (_cairo_surface_init),
+	(cairo_surface_set_device_offset):
+	* src/cairoint.h:
+	Add device_x_scale and device_y_scale to
+	surface so that the coordinate system seen
+	by the backend can differ from the nominal
+	device coordinate space used by the application.
+	
+	Useful for printer backends where the device
+	coordinate space should be in pixels while the
+	user visible device space is in points.
+
+	There is no API to set these values; the backends
+	using this functionality should do that themselves
+	before the first cairo_t is created.
+
 2005-08-24  Carl Worth  <cworth@cworth.org>
 
 	* src/cairo.c: (cairo_show_text): Fix cairo_show_text to advance

src/cairo-gstate-private.h

@@ -63,14 +63,14 @@ struct _cairo_gstate {
 
     cairo_clip_t clip;
 
+    cairo_surface_t *target;
+
     cairo_matrix_t ctm;
     cairo_matrix_t ctm_inverse;
     cairo_matrix_t source_ctm_inverse; /* At the time ->source was set */
 
     cairo_pen_t pen_regular;
 
-    cairo_surface_t *target;
-
     cairo_pattern_t *source;
 
     struct _cairo_gstate *next;

src/cairo-gstate.c

@@ -116,13 +116,13 @@ _cairo_gstate_init (cairo_gstate_t  *gstate,
     
     _cairo_clip_init (&gstate->clip, target);
 
+    gstate->target = cairo_surface_reference (target);
+
     _cairo_gstate_identity_matrix (gstate);
-    cairo_matrix_init_identity (&gstate->source_ctm_inverse);
+    gstate->source_ctm_inverse = gstate->ctm_inverse;
 
     _cairo_pen_init_empty (&gstate->pen_regular);
 
-    gstate->target = cairo_surface_reference (target);
-
     gstate->source = _cairo_pattern_create_solid (CAIRO_COLOR_BLACK);
     if (gstate->source->status)
 	return CAIRO_STATUS_NO_MEMORY;
@@ -491,10 +491,37 @@ _cairo_gstate_get_miter_limit (cairo_gstate_t *gstate)
     return gstate->miter_limit;
 }
 
+static void
+_cairo_gstate_apply_device_transform (cairo_gstate_t    *gstate,
+				      cairo_matrix_t	*matrix)
+{
+    if (gstate->target->device_x_scale != 1.0 ||
+	gstate->target->device_y_scale != 1.0)
+    {
+	cairo_matrix_scale (matrix,
+			    gstate->target->device_x_scale,
+			    gstate->target->device_y_scale);
+    }
+}
+
+static void
+_cairo_gstate_apply_device_inverse_transform (cairo_gstate_t    *gstate,
+					      cairo_matrix_t	*matrix)
+{
+    if (gstate->target->device_x_scale != 1.0 ||
+	gstate->target->device_y_scale != 1.0)
+    {
+	cairo_matrix_scale (matrix,
+			    1/gstate->target->device_x_scale,
+			    1/gstate->target->device_y_scale);
+    }
+}
+
 void
 _cairo_gstate_get_matrix (cairo_gstate_t *gstate, cairo_matrix_t *matrix)
 {
     *matrix = gstate->ctm;
+    _cairo_gstate_apply_device_inverse_transform (gstate, matrix);
 }
 
 cairo_status_t
@@ -580,6 +607,9 @@ _cairo_gstate_set_matrix (cairo_gstate_t       *gstate,
     if (status)
 	return status;
 
+    _cairo_gstate_apply_device_transform (gstate, &gstate->ctm);
+    _cairo_gstate_apply_device_inverse_transform (gstate, &gstate->ctm_inverse);
+
     return CAIRO_STATUS_SUCCESS;
 }
 
@@ -591,6 +621,9 @@ _cairo_gstate_identity_matrix (cairo_gstate_t *gstate)
     cairo_matrix_init_identity (&gstate->ctm);
     cairo_matrix_init_identity (&gstate->ctm_inverse);
 
+    _cairo_gstate_apply_device_transform (gstate, &gstate->ctm);
+    _cairo_gstate_apply_device_inverse_transform (gstate, &gstate->ctm_inverse);
+
     return CAIRO_STATUS_SUCCESS;
 }
 
@@ -632,19 +665,15 @@ void
 _cairo_gstate_user_to_backend (cairo_gstate_t *gstate, double *x, double *y)
 {
     cairo_matrix_transform_point (&gstate->ctm, x, y);
-    if (gstate->target) {
-	*x += gstate->target->device_x_offset;
-	*y += gstate->target->device_y_offset;
-    }
+    *x += gstate->target->device_x_offset;
+    *y += gstate->target->device_y_offset;
 }
 
 void
 _cairo_gstate_backend_to_user (cairo_gstate_t *gstate, double *x, double *y)
 {
-    if (gstate->target) {
-	*x -= gstate->target->device_x_offset;
-	*y -= gstate->target->device_y_offset;
-    }
+    *x -= gstate->target->device_x_offset;
+    *y -= gstate->target->device_y_offset;
     cairo_matrix_transform_point (&gstate->ctm_inverse, x, y);
 }
 

src/cairo-surface.c

@@ -147,8 +147,10 @@ _cairo_surface_init (cairo_surface_t			*surface,
 
     _cairo_user_data_array_init (&surface->user_data);
 
-    surface->device_x_offset = 0;
-    surface->device_y_offset = 0;
+    surface->device_x_offset = 0.0;
+    surface->device_y_offset = 0.0;
+    surface->device_x_scale = 1.0;
+    surface->device_y_scale = 1.0;
 
     surface->next_clip_serial = 0;
     surface->current_clip_serial = 0;
@@ -542,8 +544,8 @@ cairo_surface_set_device_offset (cairo_surface_t *surface,
 	return;
     }
 
-    surface->device_x_offset = x_offset;
-    surface->device_y_offset = y_offset;
+    surface->device_x_offset = x_offset * surface->device_x_scale;
+    surface->device_y_offset = y_offset * surface->device_y_scale;
 }
 
 /**

src/cairoint.h

@@ -852,6 +852,8 @@ struct _cairo_surface {
 
     double device_x_offset;
     double device_y_offset;
+    double device_x_scale;
+    double device_y_scale;
 
     /*
      * Each time a clip region is modified, it gets the next value in this