From e797e5a324f1b4e30447a70c2700c10604ec6c6c Mon Sep 17 00:00:00 2001
From: Kirill Primak <vyivel@eclair.cafe>
Date: Fri, 9 Aug 2024 15:57:45 +0300
Subject: [PATCH] output: make swapchain lazy

---
 src/dulcepan.h |  1 +
 src/output.c   | 38 +++++++++++++++++++++-----------------
 2 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/src/dulcepan.h b/src/dulcepan.h
index 073d860..007dd9a 100644
--- a/src/dulcepan.h
+++ b/src/dulcepan.h
@@ -71,6 +71,7 @@ struct dp_output {
 	void *frame_data;
 	size_t frame_size;
 
+	// wl_buffer is NULL if uninitialized
 	struct dp_buffer swapchain[DP_SWAPCHAIN_LEN];
 
 	struct wl_list link;
diff --git a/src/output.c b/src/output.c
index 224f801..c286468 100644
--- a/src/output.c
+++ b/src/output.c
@@ -126,6 +126,19 @@ static const struct wl_buffer_listener buffer_listener = {
 	.release = buffer_handle_release,
 };
 
+static void init_buffer(struct dp_output *output, struct dp_buffer *buffer) {
+	int stride = output->transformed_width * 4;
+
+	buffer->wl_buffer =
+			dp_buffer_create(output->state, output->transformed_width, output->transformed_height,
+					stride, WL_SHM_FORMAT_ARGB8888, &buffer->data, &buffer->size);
+	buffer->cairo_surface = cairo_image_surface_create_for_data(buffer->data, CAIRO_FORMAT_ARGB32,
+			output->transformed_width, output->transformed_height, stride);
+	buffer->cairo = cairo_create(buffer->cairo_surface);
+
+	wl_buffer_add_listener(buffer->wl_buffer, &buffer_listener, buffer);
+}
+
 static void output_handle_geometry(void *data, struct wl_output *wl_output, int32_t x, int32_t y,
 		int32_t phys_width, int32_t phys_height, int32_t subpixel, const char *make,
 		const char *model, int32_t transform) {
@@ -208,19 +221,6 @@ static void output_handle_done(void *data, struct wl_output *wl_output) {
 	wl_subsurface_set_desync(output->select_subsurface);
 
 	wl_surface_set_user_data(output->select_surface, output);
-
-	for (size_t i = 0; i < DP_SWAPCHAIN_LEN; i++) {
-		struct dp_buffer *buffer = &output->swapchain[i];
-		int stride = output->transformed_width * 4;
-		buffer->wl_buffer =
-				dp_buffer_create(state, output->transformed_width, output->transformed_height,
-						stride, WL_SHM_FORMAT_ARGB8888, &buffer->data, &buffer->size);
-		buffer->cairo_surface = cairo_image_surface_create_for_data(buffer->data,
-				CAIRO_FORMAT_ARGB32, output->transformed_width, output->transformed_height, stride);
-		buffer->cairo = cairo_create(buffer->cairo_surface);
-
-		wl_buffer_add_listener(buffer->wl_buffer, &buffer_listener, buffer);
-	}
 }
 
 static void output_handle_scale(void *data, struct wl_output *wl_output, int32_t scale) {
@@ -330,6 +330,8 @@ static void redraw(struct dp_output *output) {
 	if (buffer == NULL) {
 		dp_log_error("Output %s: no free buffers in a swapchain\n", output->name);
 		return;
+	} else if (buffer->wl_buffer == NULL) {
+		init_buffer(output, buffer);
 	}
 	buffer->used = true;
 
@@ -438,10 +440,12 @@ void dp_output_destroy(struct dp_output *output) {
 
 	for (size_t i = 0; i < DP_SWAPCHAIN_LEN; i++) {
 		struct dp_buffer *buffer = &output->swapchain[i];
-		wl_buffer_destroy(buffer->wl_buffer);
-		cairo_destroy(buffer->cairo);
-		cairo_surface_destroy(buffer->cairo_surface);
-		munmap(buffer->data, buffer->size);
+		if (buffer->wl_buffer != NULL) {
+			wl_buffer_destroy(buffer->wl_buffer);
+			cairo_destroy(buffer->cairo);
+			cairo_surface_destroy(buffer->cairo_surface);
+			munmap(buffer->data, buffer->size);
+		}
 	}
 
 	wl_subsurface_destroy(output->select_subsurface);