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

1 files changed, 40 insertions, 11 deletions

diff --git a/src/cairo-gstate.c b/src/cairo-gstate.c
index 35386e43..39832339 100644
--- a/src/cairo-gstate.c
+++ b/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);
 }