C++ DrawingContext::setSource方法代码示例

unsigned DrawingText::_renderItem(DrawingContext &ct, Geom::IntRect const &/*area*/, unsigned /*flags*/, DrawingItem * /*stop_at*/)
{
    if (_drawing.outline()) {
        guint32 rgba = _drawing.outlinecolor;
        Inkscape::DrawingContext::Save save(ct);
        ct.setSource(rgba);
        ct.setTolerance(0.5); // low quality, but good enough for outline mode

        for (ChildrenList::iterator i = _children.begin(); i != _children.end(); ++i) {
            DrawingGlyphs *g = dynamic_cast<DrawingGlyphs *>(&*i);
            if (!g) throw InvalidItemException();

            Inkscape::DrawingContext::Save save(ct);
            // skip glpyhs with singular transforms
            if (g->_ctm.isSingular()) continue;
            ct.transform(g->_ctm);
            ct.path(*g->_font->PathVector(g->_glyph));
            ct.fill();
        }
        return RENDER_OK;
    }

    // NOTE: this is very similar to drawing-shape.cpp; the only difference is in path feeding
    bool has_stroke, has_fill;

    has_fill   = _nrstyle.prepareFill(ct, _item_bbox);
    has_stroke = _nrstyle.prepareStroke(ct, _item_bbox);

    if (has_fill || has_stroke) {
        for (ChildrenList::iterator i = _children.begin(); i != _children.end(); ++i) {
            DrawingGlyphs *g = dynamic_cast<DrawingGlyphs *>(&*i);
            if (!g) throw InvalidItemException();

            Inkscape::DrawingContext::Save save(ct);
            if (g->_ctm.isSingular()) continue;
            ct.transform(g->_ctm);
            ct.path(*g->_font->PathVector(g->_glyph));
        }

        Inkscape::DrawingContext::Save save(ct);
        ct.transform(_ctm);
        if (has_fill) {
            _nrstyle.applyFill(ct);
            ct.fillPreserve();
        }
        if (has_stroke) {
            _nrstyle.applyStroke(ct);
            ct.strokePreserve();
        }
        ct.newPath(); // clear path
    }
    return RENDER_OK;
}

void
Drawing::render(DrawingContext &ct, Geom::IntRect const &area, unsigned flags)
{
    if (_root) {
        _root->render(ct, area, flags);
    }

    if (colorMode() == COLORMODE_GRAYSCALE) {
        // apply grayscale filter on top of everything
        cairo_surface_t *input = ct.rawTarget();
        cairo_surface_t *out = ink_cairo_surface_create_identical(input);
        ink_cairo_surface_filter(input, out, _grayscale_colormatrix);
        Geom::Point origin = ct.targetLogicalBounds().min();
        ct.setSource(out, origin[Geom::X], origin[Geom::Y]);
        ct.setOperator(CAIRO_OPERATOR_SOURCE);
        ct.paint();
        ct.setOperator(CAIRO_OPERATOR_OVER);
    
        cairo_surface_destroy(out);
    }
}

/**
 * Paints the clean area from cache and modifies the @a area
 * parameter to the bounds of the region that must be repainted.
 */
void
DrawingCache::paintFromCache(DrawingContext &dc, Geom::OptIntRect &area)
{
    if (!area) return;

    // We subtract the clean region from the area, then get the bounds
    // of the resulting region. This is the area that needs to be repainted
    // by the item.
    // Then we subtract the area that needs to be repainted from the
    // original area and paint the resulting region from cache.
    cairo_rectangle_int_t area_c = _convertRect(*area);
    cairo_region_t *dirty_region = cairo_region_create_rectangle(&area_c);
    cairo_region_t *cache_region = cairo_region_copy(dirty_region);
    cairo_region_subtract(dirty_region, _clean_region);

    if (cairo_region_is_empty(dirty_region)) {
        area = Geom::OptIntRect();
    } else {
        cairo_rectangle_int_t to_repaint;
        cairo_region_get_extents(dirty_region, &to_repaint);
        area = _convertRect(to_repaint);
        cairo_region_subtract_rectangle(cache_region, &to_repaint);
    }
    cairo_region_destroy(dirty_region);

    if (!cairo_region_is_empty(cache_region)) {
        int nr = cairo_region_num_rectangles(cache_region);
        cairo_rectangle_int_t tmp;
        for (int i = 0; i < nr; ++i) {
            cairo_region_get_rectangle(cache_region, i, &tmp);
            dc.rectangle(_convertRect(tmp));
        }
        dc.setSource(this);
        dc.fill();
    }
    cairo_region_destroy(cache_region);
}

//.........这里部分代码省略.........
     * The object itself is rendered to a group.
     *
     * Opacity is done by rendering the clipping path with an alpha
     * value corresponding to the opacity. If there is no clipping path,
     * the entire intermediate surface is painted with alpha corresponding
     * to the opacity value.
     */

    // Short-circuit the simple case.
    // We also use this path for filter background rendering, because masking, clipping,
    // filters and opacity do not apply when rendering the ancestors of the filtered
    // element
    if ((flags & RENDER_FILTER_BACKGROUND) || !needs_intermediate_rendering) {
        return _renderItem(dc, *carea, flags & ~RENDER_FILTER_BACKGROUND, stop_at);
    }

    // iarea is the bounding box for intermediate rendering
    // Note 1: Pixels inside iarea but outside carea are invalid
    //         (incomplete filter dependence region).
    // Note 2: We only need to render carea of clip and mask, but
    //         iarea of the object.
    Geom::OptIntRect iarea = carea;
    // expand carea to contain the dependent area of filters.
    if (_filter && render_filters) {
        _filter->area_enlarge(*iarea, this);
        iarea.intersectWith(_drawbox);
    }

    DrawingSurface intermediate(*iarea);
    DrawingContext ict(intermediate);
    unsigned render_result = RENDER_OK;

    // 1. Render clipping path with alpha = opacity.
    ict.setSource(0,0,0,_opacity);
    // Since clip can be combined with opacity, the result could be incorrect
    // for overlapping clip children. To fix this we use the SOURCE operator
    // instead of the default OVER.
    ict.setOperator(CAIRO_OPERATOR_SOURCE);
    ict.paint();
    if (_clip) {
        ict.pushGroup();
        _clip->clip(ict, *carea); // fixme: carea or area?
        ict.popGroupToSource();
        ict.setOperator(CAIRO_OPERATOR_IN);
        ict.paint();
    }
    ict.setOperator(CAIRO_OPERATOR_OVER); // reset back to default

    // 2. Render the mask if present and compose it with the clipping path + opacity.
    if (_mask) {
        ict.pushGroup();
        _mask->render(ict, *carea, flags);

        cairo_surface_t *mask_s = ict.rawTarget();
        // Convert mask's luminance to alpha
        ink_cairo_surface_filter(mask_s, mask_s, MaskLuminanceToAlpha());
        ict.popGroupToSource();
        ict.setOperator(CAIRO_OPERATOR_IN);
        ict.paint();
        ict.setOperator(CAIRO_OPERATOR_OVER);
    }

    // 3. Render object itself
    ict.pushGroup();
    render_result = _renderItem(ict, *iarea, flags, stop_at);