backend: remove the read_pixel interface.

Sample the border color in the shader instead.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/backend/backend.c

@@ -343,14 +343,6 @@ void paint_all_new(session_t *ps, struct managed_win *t, bool ignore_damage) {
 			    ps->backend_data, IMAGE_PROPERTY_CORNER_RADIUS, w->win_image,
 			    (double[]){w->corner_radius});
 			if (w->corner_radius) {
-				struct color border_color;
-				ps->backend_data->ops->read_pixel(
-				    ps->backend_data, w->win_image, 0, w->heightb,
-				    &border_color);
-				ps->backend_data->ops->set_image_property(
-				    ps->backend_data, IMAGE_PROPERTY_BORDER_COLOR,
-				    w->win_image, &border_color);
-
 				int border_width = w->g.border_width;
 				if (border_width == 0) {
 					// Some WM has borders implemented as WM frames

src/backend/backend.h

@@ -58,9 +58,6 @@ enum image_properties {
 	// Gives the image a rounded corner.
 	// 1 double, default: 0
 	IMAGE_PROPERTY_CORNER_RADIUS,
-	// Border color
-	// 1 struct color, default: black
-	IMAGE_PROPERTY_BORDER_COLOR,
 	// Border width
 	// 1 int, default: 0
 	IMAGE_PROPERTY_BORDER_WIDTH,
@@ -251,20 +248,6 @@ struct backend_operations {
 	bool (*image_op)(backend_t *backend_data, enum image_operations op, void *image_data,
 	                 const region_t *reg_op, const region_t *reg_visible, void *args);
 
-	/**
-	 * Read the color of the pixel at given position of the given image. Image
-	 * properties have no effect.
-	 *
-	 * @param      backend_data backend_data
-	 * @param      image_data   an image data structure previously returned by the
-	 *                          backend. the image to read pixel from.
-	 * @param      x, y         coordinate of the pixel to read
-	 * @param[out] color        the color of the pixel
-	 * @return whether the operation is successful
-	 */
-	bool (*read_pixel)(backend_t *backend_data, void *image_data, int x, int y,
-	                   struct color *output);
-
 	/// Create another instance of the `image_data`. All `image_op` and
 	/// `set_image_property` calls on the returned image should not affect the
 	/// original image

src/backend/backend_common.c

@@ -451,7 +451,6 @@ bool default_set_image_property(backend_t *base attr_unused, enum image_properti
 		break;
 	case IMAGE_PROPERTY_CORNER_RADIUS: tex->corner_radius = dargs[0]; break;
 	case IMAGE_PROPERTY_MAX_BRIGHTNESS: tex->max_brightness = dargs[0]; break;
-	case IMAGE_PROPERTY_BORDER_COLOR: tex->border_color = *(struct color *)arg; break;
 	case IMAGE_PROPERTY_BORDER_WIDTH: tex->border_width = *(int *)arg; break;
 	}
 

src/backend/backend_common.h

@@ -41,7 +41,6 @@ struct backend_image {
 	// Effective size of the image
 	int ewidth, eheight;
 	bool color_inverted;
-	struct color border_color;
 	int border_width;
 };
 

src/backend/gl/gl_common.c

@@ -397,10 +397,6 @@ static void _gl_compose(backend_t *base, struct backend_image *img, GLuint targe
 	if (gd->win_shader.uniform_border_width >= 0) {
 		glUniform1f(gd->win_shader.uniform_border_width, (float)img->border_width);
 	}
-	if (gd->win_shader.uniform_border_color >= 0) {
-		glUniform3f(gd->win_shader.uniform_border_color, (float)img->border_color.red,
-		            (float)img->border_color.green, (float)img->border_color.blue);
-	}
 
 	// 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);
@@ -901,7 +897,6 @@ static int gl_win_shader_from_string(const char *vshader_str, const char *fshade
 	bind_uniform(ret, max_brightness);
 	bind_uniform(ret, corner_radius);
 	bind_uniform(ret, border_width);
-	bind_uniform(ret, border_color);
 
 	gl_check_err();
 
@@ -1534,7 +1529,6 @@ const char *win_shader_glsl = GLSL(330,
 	uniform float dim;
 	uniform float corner_radius;
 	uniform float border_width;
-	uniform vec3 border_color;
 	uniform bool invert_color;
 	in vec2 texcoord;
 	uniform sampler2D tex;
@@ -1549,6 +1543,7 @@ const char *win_shader_glsl = GLSL(330,
 
 	void main() {
 		vec4 c = texelFetch(tex, ivec2(texcoord), 0);
+		vec4 border_color = texture(tex, vec2(0.0, 0.5));
 		if (invert_color) {
 			c = vec4(c.aaa - c.rgb, c.a);
 		}
@@ -1567,10 +1562,10 @@ const char *win_shader_glsl = GLSL(330,
 		float rect_distance = rectangle_sdf(texcoord - outer_size / 2.0f,
 		    inner_size / 2.0f) - corner_radius;
 		if (rect_distance > 0.0f) {
-			c = (1.0f - clamp(rect_distance, 0.0f, 1.0f)) * vec4(border_color, 1.0);
+			c = (1.0f - clamp(rect_distance, 0.0f, 1.0f)) * border_color;
 		} else {
 			float factor = clamp(rect_distance + border_width, 0.0f, 1.0f);
-			c = (1.0f - factor) * c + factor * vec4(border_color, 1.0);
+			c = (1.0f - factor) * c + factor * border_color;
 		}
 
 		gl_FragColor = c;
@@ -1913,29 +1908,3 @@ bool gl_image_op(backend_t *base, enum image_operations op, void *image_data,
 
 	return true;
 }
-
-bool gl_read_pixel(backend_t *base attr_unused, void *image_data, int x, int y,
-                   struct color *output) {
-	struct backend_image *tex = image_data;
-	auto inner = (struct gl_texture *)tex->inner;
-	GLuint fbo;
-	glGenFramebuffers(1, &fbo);
-	glBindFramebuffer(GL_READ_FRAMEBUFFER, fbo);
-	glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
-	                       inner->texture, 0);
-	glReadBuffer(GL_COLOR_ATTACHMENT0);
-	GLfloat color[4];
-	glReadPixels(x, inner->y_inverted ? inner->height - y : y, 1, 1, GL_RGBA,
-	             GL_FLOAT, color);
-	output->alpha = color[3];
-	output->red = color[0];
-	output->green = color[1];
-	output->blue = color[2];
-
-	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
-	glDeleteFramebuffers(1, &fbo);
-
-	bool ret = glGetError() == GL_NO_ERROR;
-	gl_clear_err();
-	return ret;
-}

src/backend/gl/gl_common.h

@@ -37,7 +37,6 @@ typedef struct {
 	GLint uniform_max_brightness;
 	GLint uniform_corner_radius;
 	GLint uniform_border_width;
-	GLint uniform_border_color;
 } gl_win_shader_t;
 
 // Program and uniforms for brightness shader

src/backend/gl/glx.c

@@ -530,7 +530,6 @@ struct backend_operations glx_ops = {
     .compose = gl_compose,
     .image_op = gl_image_op,
     .set_image_property = default_set_image_property,
-    .read_pixel = gl_read_pixel,
     .clone_image = default_clone_image,
     .blur = gl_blur,
     .is_image_transparent = default_is_image_transparent,

src/backend/xrender/xrender.c

@@ -745,30 +745,6 @@ static void get_blur_size(void *blur_context, int *width, int *height) {
 	*height = ctx->resize_height;
 }
 
-static bool
-read_pixel(backend_t *backend_data, void *image_data, int x, int y, struct color *output) {
-	auto xd = (struct _xrender_data *)backend_data;
-	auto img = (struct backend_image *)image_data;
-	auto inner = (struct _xrender_image_data_inner *)img->inner;
-
-	auto r = XCB_AWAIT(xcb_get_image, xd->base.c, XCB_IMAGE_FORMAT_XY_PIXMAP, inner->pixmap,
-	                   to_i16_checked(x), to_i16_checked(y), 1, 1, (uint32_t)-1L);
-
-	if (!r) {
-		return false;
-	}
-
-	// Color format seems to be BGRA8888, see glamor_format_for_pixmap from the
-	// Xserver codebase.
-	uint8_t *pixels = xcb_get_image_data(r);
-	output->blue = pixels[0] / 255.0;
-	output->green = pixels[1] / 255.0;
-	output->red = pixels[2] / 255.0;
-	output->alpha = pixels[3] / 255.0;
-
-	return true;
-}
-
 static backend_t *backend_xrender_init(session_t *ps) {
 	auto xd = ccalloc(1, struct _xrender_data);
 	init_backend_base(&xd->base, ps);
@@ -888,7 +864,6 @@ struct backend_operations xrender_ops = {
     .max_buffer_age = 2,
 
     .image_op = image_op,
-    .read_pixel = read_pixel,
     .clone_image = clone_image,
     .set_image_property = set_image_property,
     .create_blur_context = create_blur_context,