Rounded corner for new backends

src/backend/backend.c

@@ -339,6 +339,9 @@ void paint_all_new(session_t *ps, struct managed_win *t, bool ignore_damage) {
 			    &dim_opacity);
 			ps->backend_data->ops->set_image_property(
 			    ps->backend_data, IMAGE_PROPERTY_OPACITY, w->win_image, &w->opacity);
+			ps->backend_data->ops->set_image_property(
+			    ps->backend_data, IMAGE_PROPERTY_CORNER_RADIUS, w->win_image,
+			    (double[]){w->corner_radius});
 		}
 
 		if (w->opacity * MAX_ALPHA < 1) {

src/backend/backend.h

@@ -36,6 +36,7 @@ typedef void (*backend_ready_callback_t)(void *);
 // particular order:
 //
 // Color inversion -> Dimming -> Opacity multiply -> Limit maximum brightness
+// (Corner radius could be applied in any order)
 enum image_properties {
 	// Whether the color of the image is inverted
 	// 1 boolean, default: false
@@ -54,6 +55,9 @@ enum image_properties {
 	// brightness down to the max brightness value.
 	// 1 double, default: 1
 	IMAGE_PROPERTY_MAX_BRIGHTNESS,
+	// Gives the image a rounded corner.
+	// 1 double, default: 0
+	IMAGE_PROPERTY_CORNER_RADIUS,
 };
 
 enum image_operations {

src/backend/backend_common.c

@@ -449,6 +449,7 @@ bool default_set_image_property(backend_t *base attr_unused, enum image_properti
 		tex->ewidth = iargs[0];
 		tex->eheight = iargs[1];
 		break;
+	case IMAGE_PROPERTY_CORNER_RADIUS: tex->corner_radius = dargs[0]; break;
 	case IMAGE_PROPERTY_MAX_BRIGHTNESS: tex->max_brightness = dargs[0]; break;
 	}
 
@@ -468,6 +469,7 @@ struct backend_image *default_new_backend_image(int w, int h) {
 	ret->eheight = h;
 	ret->ewidth = w;
 	ret->color_inverted = false;
+	ret->corner_radius = 0;
 	return ret;
 }
 

src/backend/backend_common.h

@@ -37,6 +37,7 @@ struct backend_image {
 	double opacity;
 	double dim;
 	double max_brightness;
+	double corner_radius;
 	// Effective size of the image
 	int ewidth, eheight;
 	bool color_inverted;

src/backend/gl/gl_common.c

@@ -401,6 +401,9 @@ static void _gl_compose(backend_t *base, struct backend_image *img, GLuint targe
 	if (gd->win_shader.unifm_max_brightness >= 0) {
 		glUniform1f(gd->win_shader.unifm_max_brightness, (float)img->max_brightness);
 	}
+	if (gd->win_shader.unifm_corner_radius >= 0) {
+		glUniform1f(gd->win_shader.unifm_corner_radius, (float)img->corner_radius);
+	}
 
 	// log_trace("Draw: %d, %d, %d, %d -> %d, %d (%d, %d) z %d\n",
 	//          x, y, width, height, dx, dy, ptex->width, ptex->height, z);
@@ -900,6 +903,8 @@ static int gl_win_shader_from_string(const char *vshader_str, const char *fshade
 	ret->unifm_brightness = glGetUniformLocationChecked(ret->prog, "brightness");
 	ret->unifm_max_brightness =
 	    glGetUniformLocationChecked(ret->prog, "max_brightness");
+	ret->unifm_corner_radius =
+	    glGetUniformLocationChecked(ret->prog, "corner_radius");
 
 	gl_check_err();
 
@@ -1534,11 +1539,18 @@ void gl_get_blur_size(void *blur_context, int *width, int *height) {
 const char *win_shader_glsl = GLSL(330,
 	uniform float opacity;
 	uniform float dim;
+	uniform float corner_radius;
 	uniform bool invert_color;
 	in vec2 texcoord;
 	uniform sampler2D tex;
 	uniform sampler2D brightness;
 	uniform float max_brightness;
+	// Signed distance field for rectangle center at (0, 0), with size of
+	// half_size * 2
+	float rectangle_sdf(vec2 point, vec2 half_size) {
+		vec2 d = abs(point) - half_size;
+		return length(max(d, 0.0));
+	}
 
 	void main() {
 		vec4 c = texelFetch(tex, ivec2(texcoord), 0);
@@ -1555,6 +1567,12 @@ const char *win_shader_glsl = GLSL(330,
 		if (brightness > max_brightness)
 			c.rgb = c.rgb * (max_brightness / brightness);
 
+		vec2 outer_size = vec2(textureSize(tex, 0));
+		vec2 inner_size = outer_size - vec2(corner_radius) * 2.0f;
+		float rect_distance = rectangle_sdf(texcoord - outer_size / 2.0f,
+		    inner_size / 2.0f) - corner_radius;
+		c *= 1.0f - clamp(rect_distance, 0.0f, 1.0f);
+
 		gl_FragColor = c;
 	}
 );

src/backend/gl/gl_common.h

@@ -22,6 +22,7 @@ typedef struct {
 	GLint unifm_dim;
 	GLint unifm_brightness;
 	GLint unifm_max_brightness;
+	GLint unifm_corner_radius;
 } gl_win_shader_t;
 
 // Program and uniforms for brightness shader

src/backend/xrender/xrender.c

@@ -88,9 +88,84 @@ struct _xrender_image_data_inner {
 	bool owned;
 };
 
-static void compose_impl(struct _xrender_data *xd, const struct backend_image *img,
-                         int dst_x, int dst_y, const region_t *reg_paint,
+struct xrender_image {
+	struct backend_image base;
+
+	// A cached picture of a rounded rectangle. Xorg rasterizes shapes on CPU so it's
+	// exceedingly slow.
+	xcb_render_picture_t rounded_rectangle;
+};
+
+/// Make a picture of size width x height, which has a rounded rectangle of corner_radius
+/// rendered in it.
+xcb_render_picture_t
+make_rounded_corner_picture(xcb_connection_t *c, xcb_render_picture_t src,
+                            xcb_drawable_t root, int width, int height, int corner_radius) {
+	auto picture = x_create_picture_with_standard(c, root, width, height,
+	                                              XCB_PICT_STANDARD_ARGB_32, 0, NULL);
+	if (picture == XCB_NONE) {
+		return picture;
+	}
+
+	int inner_height = height - 2 * corner_radius;
+	int cap_height = corner_radius;
+	if (inner_height < 0) {
+		cap_height = height / 2;
+		inner_height = 0;
+	}
+	auto points = ccalloc(cap_height * 4 + 4, xcb_render_pointfix_t);
+	int point_count = 0;
+
+#define ADD_POINT(px, py)                                                                \
+	assert(point_count < cap_height * 4 + 4);                                        \
+	points[point_count].x = DOUBLE_TO_XFIXED(px);                                    \
+	points[point_count].y = DOUBLE_TO_XFIXED(py);                                    \
+	point_count += 1;
+
+	// The top cap
+	for (int i = 0; i <= cap_height; i++) {
+		double y = corner_radius - i;
+		double delta = sqrt(corner_radius * corner_radius - y * y);
+		double left = corner_radius - delta;
+		double right = width - corner_radius + delta;
+		if (left >= right) {
+			continue;
+		}
+		ADD_POINT(left, i);
+		ADD_POINT(right, i);
+	}
+
+	// The middle rectangle
+	if (inner_height > 0) {
+		ADD_POINT(0, cap_height + inner_height);
+		ADD_POINT(width, cap_height + inner_height);
+	}
+
+	// The bottom cap
+	for (int i = cap_height + inner_height + 1; i <= height; i++) {
+		double y = corner_radius - (height - i);
+		double delta = sqrt(corner_radius * corner_radius - y * y);
+		double left = corner_radius - delta;
+		double right = width - corner_radius + delta;
+		if (left >= right) {
+			break;
+		}
+		ADD_POINT(left, i);
+		ADD_POINT(right, i);
+	}
+#undef ADD_POINT
+
+	XCB_AWAIT_VOID(xcb_render_tri_strip, c, XCB_RENDER_PICT_OP_SRC, src, picture,
+	               x_get_pictfmt_for_standard(c, XCB_PICT_STANDARD_A_8), 0, 0,
+	               (uint32_t)point_count, points);
+	free(points);
+	return picture;
+}
+
+static void compose_impl(struct _xrender_data *xd, struct xrender_image *xrimg, int dst_x,
+                         int dst_y, const region_t *reg_paint,
                          const region_t *reg_visible, xcb_render_picture_t result) {
+	const struct backend_image *img = &xrimg->base;
 	auto alpha_pict = xd->alpha_pict[(int)(img->opacity * MAX_ALPHA)];
 	auto inner = (struct _xrender_image_data_inner *)img->inner;
 	region_t reg;
@@ -110,7 +185,12 @@ static void compose_impl(struct _xrender_data *xd, const struct backend_image *i
 	pixman_region32_init(&reg);
 	pixman_region32_intersect(&reg, (region_t *)reg_paint, (region_t *)reg_visible);
 	x_set_picture_clip_region(xd->base.c, result, 0, 0, &reg);
-	if ((img->color_inverted || img->dim != 0) && has_alpha) {
+	if (img->corner_radius != 0 && xrimg->rounded_rectangle == XCB_NONE) {
+		xrimg->rounded_rectangle = make_rounded_corner_picture(
+		    xd->base.c, xd->white_pixel, xd->base.root, inner->width,
+		    inner->height, (int)img->corner_radius);
+	}
+	if (((img->color_inverted || img->dim != 0) && has_alpha) || img->corner_radius != 0) {
 		// Apply image properties using a temporary image, because the source
 		// image is transparent. Otherwise the properties can be applied directly
 		// on the target image.
@@ -159,6 +239,13 @@ static void compose_impl(struct _xrender_data *xd, const struct backend_image *i
 			                           tmp_pict, dim_color, 1, &rect);
 		}
 
+		if (img->corner_radius != 0) {
+			// Clip tmp_pict with a rounded rectangle
+			xcb_render_composite(xd->base.c, XCB_RENDER_PICT_OP_IN_REVERSE,
+			                     xrimg->rounded_rectangle, XCB_NONE, tmp_pict,
+			                     0, 0, 0, 0, 0, 0, tmpw, tmph);
+		}
+
 		xcb_render_composite(xd->base.c, XCB_RENDER_PICT_OP_OVER, tmp_pict,
 		                     alpha_pict, result, 0, 0, 0, 0, to_i16_checked(dst_x),
 		                     to_i16_checked(dst_y), tmpew, tmpeh);
@@ -350,11 +437,11 @@ bind_pixmap(backend_t *base, xcb_pixmap_t pixmap, struct xvisual_info fmt, bool
 		return NULL;
 	}
 
-	auto img = ccalloc(1, struct backend_image);
+	auto img = ccalloc(1, struct xrender_image);
 	auto inner = ccalloc(1, struct _xrender_image_data_inner);
 	inner->depth = (uint8_t)fmt.visual_depth;
-	inner->width = img->ewidth = r->width;
-	inner->height = img->eheight = r->height;
+	inner->width = img->base.ewidth = r->width;
+	inner->height = img->base.eheight = r->height;
 	inner->pixmap = pixmap;
 	inner->has_alpha = fmt.alpha_size != 0;
 	inner->pict =
@@ -363,8 +450,9 @@ bind_pixmap(backend_t *base, xcb_pixmap_t pixmap, struct xvisual_info fmt, bool
 	inner->visual = fmt.visual;
 	inner->refcount = 1;
 
-	img->inner = (struct backend_image_inner_base *)inner;
-	img->opacity = 1;
+	img->base.inner = (struct backend_image_inner_base *)inner;
+	img->base.opacity = 1;
+	img->rounded_rectangle = XCB_NONE;
 	free(r);
 
 	if (inner->pict == XCB_NONE) {
@@ -382,10 +470,12 @@ static void release_image_inner(backend_t *base, struct _xrender_image_data_inne
 	free(inner);
 }
 static void release_image(backend_t *base, void *image) {
-	struct backend_image *img = image;
-	img->inner->refcount--;
-	if (img->inner->refcount == 0) {
-		release_image_inner(base, (void *)img->inner);
+	struct xrender_image *img = image;
+	xcb_free_pixmap(base->c, img->rounded_rectangle);
+	img->rounded_rectangle = XCB_NONE;
+	img->base.inner->refcount -= 1;
+	if (img->base.inner->refcount == 0) {
+		release_image_inner(base, (void *)img->base.inner);
 	}
 	free(img);
 }
@@ -735,6 +825,19 @@ static backend_t *backend_xrender_init(session_t *ps) {
 	return NULL;
 }
 
+static bool
+set_image_property(backend_t *base, enum image_properties op, void *image, void *args) {
+	auto xrimg = (struct xrender_image *)image;
+	if (op == IMAGE_PROPERTY_CORNER_RADIUS &&
+	    ((double *)args)[0] != xrimg->base.corner_radius &&
+	    xrimg->rounded_rectangle != XCB_NONE) {
+		// Free cached rounded rectangle if corner radius changed
+		xcb_free_pixmap(base->c, xrimg->rounded_rectangle);
+		xrimg->rounded_rectangle = XCB_NONE;
+	}
+	return default_set_image_property(base, op, image, args);
+}
+
 struct backend_operations xrender_ops = {
     .init = backend_xrender_init,
     .deinit = deinit,
@@ -754,7 +857,7 @@ struct backend_operations xrender_ops = {
     .image_op = image_op,
     .read_pixel = read_pixel,
     .clone_image = default_clone_image,
-    .set_image_property = default_set_image_property,
+    .set_image_property = set_image_property,
     .create_blur_context = create_blur_context,
     .destroy_blur_context = destroy_blur_context,
     .get_blur_size = get_blur_size,

src/options.c

@@ -1013,12 +1013,6 @@ bool get_cfg(options_t *opt, int argc, char *const *argv, bool shadow_enable,
 		         "properly under X Render backend.");
 	}
 
-	if (opt->corner_radius > 0 && opt->experimental_backends) {
-		log_warn("Rounded corner is only supported on legacy backends, it "
-		         "will be disabled");
-		opt->corner_radius = 0;
-	}
-
 	return true;
 }
 

src/x.c

@@ -652,10 +652,6 @@ bool x_fence_sync(xcb_connection_t *c, xcb_sync_fence_t f) {
 	return false;
 }
 
-// xcb-render specific macros
-#define XFIXED_TO_DOUBLE(value) (((double)(value)) / 65536)
-#define DOUBLE_TO_XFIXED(value) ((xcb_render_fixed_t)(((double)(value)) * 65536))
-
 /**
  * Convert a struct conv to a X picture convolution filter, normalizing the kernel
  * in the process. Allow the caller to specify the element at the center of the kernel,

src/x.h

@@ -87,6 +87,10 @@ struct xvisual_info {
 #define log_fatal_x_error(e, fmt, ...)                                                   \
 	LOG(FATAL, fmt " (%s)", ##__VA_ARGS__, x_strerror(e))
 
+// xcb-render specific macros
+#define XFIXED_TO_DOUBLE(value) (((double)(value)) / 65536)
+#define DOUBLE_TO_XFIXED(value) ((xcb_render_fixed_t)(((double)(value)) * 65536))
+
 /// Wraps x_new_id. abort the program if x_new_id returns error
 static inline uint32_t x_new_id(xcb_connection_t *c) {
 	auto ret = xcb_generate_id(c);