Some small rendering fixes.

* halo background draw fixed
* tiled images clip correctly
* new interface/setter for reducing clipping area.

src/draw.cpp

@@ -281,8 +281,10 @@ void draw::flipped(const texture& tex, bool flip_h, bool flip_v)
 void draw::tiled(const texture& tex, const SDL_Rect& dst, bool centered,
 	bool mirrored)
 {
-	// TODO: highdpi - should this draw at full res? Or game res? For now it's using game res to ensure consistency of the result.
-	// TODO: highdpi - does this ever need to clip the source texture? It doesn't seem so
+	// TODO: highdpi - should this draw at full res? Or game res? For now it's using game res. To draw in higher res, width and height would have to be specified.
+
+	// Reduce clip to dst.
+	auto clipper = CVideo::get_singleton().reduce_clip(dst);
 
 	const int xoff = centered ? (dst.w - tex.w()) / 2 : 0;
 	const int yoff = centered ? (dst.h - tex.h()) / 2 : 0;

src/gui/core/canvas.cpp

@@ -157,17 +157,24 @@ void rectangle_shape::draw(
 {
 	const auto rects = calculate_rects(portion_to_draw, variables);
 	if(rects.empty) {
+		DBG_GUI_D << "Rectangle: nothing to draw" << std::endl;
 		return;
 	}
 
 	const color_t fill_color = fill_color_(variables);
+	const color_t border_color = border_color_(variables);
+	SDL_Rect r = rects.unclipped_around_viewport;
+	r.x += draw_location.x;
+	r.y += draw_location.y;
+
+	DBG_GUI_D << "Rectangle: draw at " << r
+		<< " with bounds " << portion_to_draw << std::endl;
 
 	// Fill the background, if applicable
 	if(!fill_color.null()) {
+		DBG_GUI_D << "fill " << fill_color << std::endl;
 		draw::set_color(fill_color);
-		auto area = rects.unclipped_around_viewport;
-		area.x += draw_location.x;
-		area.y += draw_location.y;
+		SDL_Rect area = r;
 		area.x += border_thickness_;
 		area.y += border_thickness_;
 		area.w -= 2 * border_thickness_;
@@ -177,11 +184,11 @@ void rectangle_shape::draw(
 	}
 
 	// Draw the border
-	draw::set_color(border_color_(variables));
+	draw::set_color(border_color);
+	DBG_GUI_D << "border thickness " << border_thickness_
+		<< ", colour " << border_color << std::endl;
 	for(int i = 0; i < border_thickness_; ++i) {
-		auto dimensions = rects.unclipped_around_viewport;
-		dimensions.x += draw_location.x;
-		dimensions.y += draw_location.y;
+		SDL_Rect dimensions = r;
 		dimensions.x += i;
 		dimensions.y += i;
 		dimensions.w -= 2 * i;

src/halo.cpp

@@ -248,7 +248,7 @@ bool halo_impl::effect::render()
 
 void halo_impl::effect::unrender()
 {
-	if (tex_ || buffer_) {
+	if (!tex_ || !buffer_) {
 		return;
 	}
 

src/video.cpp

@@ -534,6 +534,16 @@ CVideo::clip_setter CVideo::set_clip(const SDL_Rect& clip)
 	return CVideo::clip_setter(*this, clip);
 }
 
+CVideo::clip_setter CVideo::reduce_clip(const SDL_Rect& clip)
+{
+	SDL_Rect c = get_clip();
+	if (c == sdl::empty_rect) {
+		return CVideo::clip_setter(*this, clip);
+	} else {
+		return CVideo::clip_setter(*this, sdl::intersect_rects(clip, c));
+	}
+}
+
 void CVideo::force_clip(const SDL_Rect& clip)
 {
 	// Set the clipping area both on the drawing surface,

src/video.hpp

@@ -415,6 +415,14 @@ public:
 	 */
 	clip_setter set_clip(const SDL_Rect& clip);
 
+	/**
+	 * Set the clipping area to the intersection of the current clipping
+	 * area and the given rectangle.
+	 *
+	 * Otherwise acts as set_clip().
+	 */
+	clip_setter reduce_clip(const SDL_Rect& clip);
+
 	/**
 	 * Set the clipping area, without any provided way of setting it back.
 	 *