/**
* 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);
}
/**
* Rasterize items.
* This method submits the drawing opeartions required to draw this item
* to the supplied DrawingContext, restricting drawing the specified area.
*
* This method does some common tasks and calls the item-specific rendering
* function, _renderItem(), to render e.g. paths or bitmaps.
*
* @param flags Rendering options. This deals mainly with cache control.
*/
unsigned
DrawingItem::render(DrawingContext &dc, Geom::IntRect const &area, unsigned flags, DrawingItem *stop_at)
{
bool outline = _drawing.outline();
bool render_filters = _drawing.renderFilters();
// stop_at is handled in DrawingGroup, but this check is required to handle the case
// where a filtered item with background-accessing filter has enable-background: new
if (this == stop_at) return RENDER_STOP;
// If we are invisible, return immediately
if (!_visible) return RENDER_OK;
if (_ctm.isSingular(1e-18)) return RENDER_OK;
// TODO convert outline rendering to a separate virtual function
if (outline) {
_renderOutline(dc, area, flags);
return RENDER_OK;
}
// carea is the area to paint
Geom::OptIntRect carea = Geom::intersect(area, _drawbox);
if (!carea) return RENDER_OK;
if (_antialias) {
cairo_set_antialias(dc.raw(), CAIRO_ANTIALIAS_DEFAULT);
} else {
cairo_set_antialias(dc.raw(), CAIRO_ANTIALIAS_NONE);
}
// render from cache if possible
if (_cached) {
if (_cache) {
_cache->prepare();
set_cairo_blend_operator( dc, _mix_blend_mode );
_cache->paintFromCache(dc, carea);
if (!carea) return RENDER_OK;
} else {
// There is no cache. This could be because caching of this item
// was just turned on after the last update phase, or because
// we were previously outside of the canvas.
Geom::OptIntRect cl = _drawing.cacheLimit();
cl.intersectWith(_drawbox);
if (cl) {
_cache = new DrawingCache(*cl);
}
}
} else {
// if our caching was turned off after the last update, it was already
// deleted in setCached()
}
// determine whether this shape needs intermediate rendering.
bool needs_intermediate_rendering = false;
bool &nir = needs_intermediate_rendering;
bool needs_opacity = (_opacity < 0.995);
// this item needs an intermediate rendering if:
nir |= (_clip != NULL); // 1. it has a clipping path
nir |= (_mask != NULL); // 2. it has a mask
nir |= (_filter != NULL && render_filters); // 3. it has a filter
nir |= needs_opacity; // 4. it is non-opaque
nir |= (_cache != NULL); // 5. it is cached
nir |= (_mix_blend_mode != SP_CSS_BLEND_NORMAL); // 6. Blend mode not normal
nir |= (_isolation == SP_CSS_ISOLATION_ISOLATE); // 7. Explicit isolatiom
/* How the rendering is done.
*
* Clipping, masking and opacity are done by rendering them to a surface
* and then compositing the object's rendering onto it with the IN operator.
* 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);
// 4. Apply filter.
if (_filter && render_filters) {
bool rendered = false;
if (_filter->uses_background() && _background_accumulate) {
DrawingItem *bg_root = this;
for (; bg_root; bg_root = bg_root->_parent) {
if (bg_root->_background_new) break;
}
if (bg_root) {
DrawingSurface bg(*iarea);
DrawingContext bgdc(bg);
bg_root->render(bgdc, *iarea, flags | RENDER_FILTER_BACKGROUND, this);
_filter->render(this, ict, &bgdc);
rendered = true;
}
}
if (!rendered) {
_filter->render(this, ict, NULL);
}
// Note that because the object was rendered to a group,
// the internals of the filter need to use cairo_get_group_target()
// instead of cairo_get_target().
}
// 5. Render object inside the composited mask + clip
ict.popGroupToSource();
ict.setOperator(CAIRO_OPERATOR_IN);
ict.paint();
// 6. Paint the completed rendering onto the base context (or into cache)
if (_cached && _cache) {
DrawingContext cachect(*_cache);
cachect.rectangle(*carea);
cachect.setOperator(CAIRO_OPERATOR_SOURCE);
cachect.setSource(&intermediate);
cachect.fill();
_cache->markClean(*carea);
}
dc.rectangle(*carea);
dc.setSource(&intermediate);
set_cairo_blend_operator( dc, _mix_blend_mode );
dc.fill();
dc.setSource(0,0,0,0);
// the call above is to clear a ref on the intermediate surface held by dc
return render_result;
}