Estimate output size with wp-fractional-scale-v1

And if available, use wp-viewporter to submit buffers whose size
exactly matches the "physical" pixel dimensions of the output.

1 files changed, 38 insertions, 1 deletions

diff --git a/main.c b/main.c
index af314f1..f15669e 100644
--- a/main.c
+++ b/main.c
@@ -14,6 +14,7 @@
 #include "wlr-layer-shell-unstable-v1-client-protocol.h"
 #include "viewporter-client-protocol.h"
 #include "single-pixel-buffer-v1-client-protocol.h"
+#include "fractional-scale-v1-client-protocol.h"
 
 /*
  * If `color` is a hexadecimal string of the form 'rrggbb' or '#rrggbb',
@@ -47,6 +48,7 @@ struct swaybg_state {
 	struct zwlr_layer_shell_v1 *layer_shell;
 	struct wp_viewporter *viewporter;
 	struct wp_single_pixel_buffer_manager_v1 *single_pixel_buffer_manager;
+	struct wp_fractional_scale_manager_v1 *fract_scale_manager;
 	struct wl_list configs;  // struct swaybg_output_config::link
 	struct wl_list outputs;  // struct swaybg_output::link
 	struct wl_list images;   // struct swaybg_image::link
@@ -80,9 +82,11 @@ struct swaybg_output {
 	struct wl_surface *surface;
 	struct zwlr_layer_surface_v1 *layer_surface;
 	struct wp_viewport *viewport;
+	struct wp_fractional_scale_v1 *fract_scale;
 
 	uint32_t width, height;
 	int32_t scale;
+	uint32_t pref_fract_scale;
 
 	uint32_t configure_serial;
 	bool dirty, needs_ack;
@@ -146,6 +150,8 @@ static struct wl_buffer *draw_buffer(const struct swaybg_output *output,
 	return wl_buf;
 }
 
+#define FRACT_DENOM 120
+
 // Return the size of the buffer that should be attached to this output
 static void get_buffer_size(const struct swaybg_output *output,
 		uint32_t *buffer_width, uint32_t *buffer_height) {
@@ -153,6 +159,12 @@ static void get_buffer_size(const struct swaybg_output *output,
 			output->state->viewporter) {
 		*buffer_width = 1;
 		*buffer_height = 1;
+	} else if (output->fract_scale && output->state->viewporter) {
+		// rounding mode is 'round half up'
+		*buffer_width = (output->width * output->pref_fract_scale +
+			FRACT_DENOM / 2) / FRACT_DENOM;
+		*buffer_height = (output->height * output->pref_fract_scale +
+			FRACT_DENOM / 2) / FRACT_DENOM;
 	} else {
 		*buffer_width = output->width * output->scale;
 		*buffer_height = output->height * output->scale;
@@ -223,6 +235,9 @@ static void destroy_swaybg_output(struct swaybg_output *output) {
 	if (output->viewport != NULL) {
 		wp_viewport_destroy(output->viewport);
 	}
+	if (output->fract_scale != NULL) {
+		wp_fractional_scale_v1_destroy(output->fract_scale);
+	}
 	wl_output_destroy(output->wl_output);
 	free(output->name);
 	free(output->identifier);
@@ -253,6 +268,16 @@ static const struct zwlr_layer_surface_v1_listener layer_surface_listener = {
 	.closed = layer_surface_closed,
 };
 
+static void fract_preferred_scale(void *data, struct wp_fractional_scale_v1 *f,
+		uint32_t scale) {
+	struct swaybg_output *output = data;
+	output->pref_fract_scale = scale;
+}
+
+static const struct wp_fractional_scale_v1_listener fract_scale_listener = {
+	.preferred_scale = fract_preferred_scale
+};
+
 static void output_geometry(void *data, struct wl_output *output, int32_t x,
 		int32_t y, int32_t width_mm, int32_t height_mm, int32_t subpixel,
 		const char *make, const char *model, int32_t transform) {
@@ -275,8 +300,17 @@ static void create_layer_surface(struct swaybg_output *output) {
 	wl_surface_set_input_region(output->surface, input_region);
 	wl_region_destroy(input_region);
 
+	if (output->state->fract_scale_manager) {
+		output->fract_scale = wp_fractional_scale_manager_v1_get_fractional_scale(
+			output->state->fract_scale_manager, output->surface);
+		assert(output->fract_scale);
+		wp_fractional_scale_v1_add_listener(output->fract_scale,
+			&fract_scale_listener, output);
+	}
+
 	if (output->state->viewporter &&
-			output->config->mode == BACKGROUND_MODE_SOLID_COLOR) {
+			(output->config->mode == BACKGROUND_MODE_SOLID_COLOR ||
+				output->state->fract_scale_manager)) {
 		output->viewport =  wp_viewporter_get_viewport(
 			output->state->viewporter, output->surface);
 	}
@@ -400,6 +434,9 @@ static void handle_global(void *data, struct wl_registry *registry,
 			wp_single_pixel_buffer_manager_v1_interface.name) == 0) {
 		state->single_pixel_buffer_manager = wl_registry_bind(registry, name,
 			&wp_single_pixel_buffer_manager_v1_interface, 1);
+	} else if (strcmp(interface, wp_fractional_scale_manager_v1_interface.name) == 0) {
+		state->fract_scale_manager = wl_registry_bind(registry, name,
+			&wp_fractional_scale_manager_v1_interface, 1);
 	}
 }