Replace direct use of Cairo contexts and surfaces in the rendering tree

with wrappers which keep some extra information about the surface,
amd NRRect and NRRectL use with Geom::Rect and Geom::IntRect.
Should simplify implementing filter primitive subregions.

(bzr r10347.1.17)

1 files changed, 149 insertions, 0 deletions

diff --git a/src/display/drawing-surface.cpp b/src/display/drawing-surface.cpp
new file mode 100644
index 000000000..e50a732c6
--- /dev/null
+++ b/src/display/drawing-surface.cpp
@@ -0,0 +1,149 @@
+/**
+ * @file
+ * @brief Cairo surface that remembers its origin
+ *//*
+ * Authors:
+ *   Krzysztof Kosiński <tweenk.pl@gmail.com>
+ *
+ * Copyright (C) 2011 Authors
+ * Released under GNU GPL, read the file 'COPYING' for more information
+ */
+
+#include "display/drawing-surface.h"
+#include "display/cairo-utils.h"
+
+namespace Inkscape {
+
+using Geom::X;
+using Geom::Y;
+
+
+/** @class DrawingSurface
+ * @brief Drawing surface that remembers its origin.
+ *
+ * This is a very minimalistic wrapper over cairo_surface_t. The main
+ * extra functionality provided by this class is that it automates
+ * the mapping from "logical space" (coordinates in the rendering)
+ * and the "physical space" (surface pixels). For example, patterns
+ * have to be rendered on surfaces which have possibly non-integer
+ * widths and heights.
+ */
+
+/** @brief Creates a surface with the given physical extents.
+ * When a drawing context is created for this surface, its pixels
+ * will cover the area under the given rectangle. */
+DrawingSurface::DrawingSurface(Geom::IntRect const &area)
+    : _surface(cairo_image_surface_create(CAIRO_FORMAT_ARGB32, area.width(), area.height()))
+    , _origin(area.min())
+    , _scale(1, 1)
+{}
+
+/** @brief Creates a surface with the given logical extents.
+ * When a drawing context is created for this surface, its pixels
+ * will cover the area under the given rectangle. If the rectangle
+ * has non-integer width, there will be slightly more than 1 pixel
+ * per logical unit. */
+DrawingSurface::DrawingSurface(Geom::Rect const &area)
+    : _surface(cairo_image_surface_create(CAIRO_FORMAT_ARGB32, ceil(area.width()), ceil(area.height())))
+    , _origin(area.min())
+    , _scale(ceil(area.width()) / area.width(), ceil(area.height()) / area.height())
+{}
+
+/** @brief Creates a surface with the given logical and physical extents.
+ * When a drawing context is created for this surface, its pixels
+ * will cover the area under the given rectangle. IT will contain
+ * the number of pixels specified by the second argument.
+ * @param logbox Logical extents of the surface
+ * @param pixdims Pixel dimensions of the surface. */
+DrawingSurface::DrawingSurface(Geom::Rect const &logbox, Geom::IntPoint const &pixdims)
+    : _surface(cairo_image_surface_create(CAIRO_FORMAT_ARGB32, pixdims[X], pixdims[Y]))
+    , _origin(logbox.min())
+    , _scale(pixdims[X] / logbox.width(), pixdims[Y] / logbox.height())
+{}
+
+/** @brief Wrap a cairo_surface_t.
+ * This constructor will take an extra reference on @a surface, which will
+ * be released on destruction. */
+DrawingSurface::DrawingSurface(cairo_surface_t *surface, Geom::Point const &origin)
+    : _surface(surface)
+    , _origin(origin)
+    , _scale(1, 1)
+{
+    cairo_surface_reference(surface);
+}
+
+DrawingSurface::~DrawingSurface()
+{
+    cairo_surface_destroy(_surface);
+}
+
+/// Get the logical extents of the surface.
+Geom::Rect
+DrawingSurface::area() const
+{
+    Geom::Rect r = Geom::Rect::from_xywh(_origin, dimensions());
+    return r;
+}
+
+/// Get the logical width and weight of the surface as a point.
+Geom::Point
+DrawingSurface::dimensions() const
+{
+    double w = cairo_image_surface_get_width(_surface);
+    double h = cairo_image_surface_get_height(_surface);
+    Geom::Point logical_dims(w / _scale[X], h / _scale[Y]);
+    return logical_dims;
+}
+
+Geom::Point
+DrawingSurface::origin() const
+{
+    return _origin;
+}
+
+Geom::Scale
+DrawingSurface::scale() const
+{
+    return _scale;
+}
+
+/// Get the transformation applied to the drawing context on construction.
+Geom::Affine
+DrawingSurface::drawingTransform() const
+{
+    Geom::Affine ret = _scale * Geom::Translate(-_origin);
+    return ret;
+}
+
+cairo_surface_type_t
+DrawingSurface::type() const
+{
+    // currently hardcoded
+    return CAIRO_SURFACE_TYPE_IMAGE;
+}
+
+/** @brief Create a drawing context for this surface.
+ * It's better to use the surface constructor of DrawingContext. */
+cairo_t *
+DrawingSurface::createRawContext()
+{
+    cairo_t *ct = cairo_create(_surface);
+    if (_scale != Geom::Scale::identity()) {
+        cairo_scale(ct, _scale[X], _scale[Y]);
+    }
+    cairo_translate(ct, -_origin[X], -_origin[Y]);
+    return ct;
+}
+
+} // end namespace Inkscape
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :