Remember last selection

src/persistent.c

@@ -0,0 +1,95 @@
+#include <errno.h>
+#include <sfdo-basedir.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "dulcepan.h"
+
+#define STATE_SUBPATH "dulcepan"
+
+// State format:
+//
+// <output name>
+// <x> <y> <width> <height>
+
+void dp_persistent_load(struct dp_state *state) {
+	size_t dir_len;
+	const char *dir = sfdo_basedir_get_cache_home(state->basedir_ctx, &dir_len);
+	state->persistent_path = dp_zalloc(dir_len + sizeof(STATE_SUBPATH));
+	memcpy(state->persistent_path, dir, dir_len);
+	memcpy(state->persistent_path + dir_len, STATE_SUBPATH, sizeof(STATE_SUBPATH));
+
+	FILE *fp = fopen(state->persistent_path, "r");
+	if (fp == NULL) {
+		if (errno != ENOENT) {
+			dp_log_error("Failed to open %s: %s", state->persistent_path, strerror(errno));
+		}
+		return;
+	}
+
+	char name[32];
+	int x, y, width, height;
+	int n_read = 0;
+
+	fgets(name, sizeof(name), fp);
+	size_t name_len = strlen(name);
+	if (name[name_len - 1] == '\n') {
+		name[--name_len] = '\0';
+	}
+	n_read += fscanf(fp, "%d %d %d %d", &x, &y, &width, &height);
+
+	bool ok = ferror(fp) == 0 && n_read == 4;
+	fclose(fp);
+
+	if (!ok) {
+		dp_log_error("Persistent state: bad format");
+		return;
+	}
+
+	struct dp_output *selection_output = NULL;
+
+	struct dp_output *output;
+	wl_list_for_each (output, &state->outputs, link) {
+		if (strcmp(output->name, name) == 0) {
+			selection_output = output;
+			break;
+		}
+	}
+
+	if (selection_output == NULL) {
+		dp_log_error("Persistent state: failed to find cached output %s", name);
+		return;
+	}
+
+	if (x < 0 || y < 0 || x + width > selection_output->transformed_width ||
+			y + height >= selection_output->transformed_height) {
+		dp_log_error("Persistent state: invalid selection geometry", name);
+		return;
+	}
+
+	struct dp_selection *selection = &state->selection;
+	selection->output = selection_output;
+	selection->x = x;
+	selection->y = y;
+	selection->width = width;
+	selection->height = height;
+}
+
+void dp_persistent_save(struct dp_state *state) {
+	struct dp_selection *selection = &state->selection;
+	if (selection->output != NULL) {
+		FILE *fp = fopen(state->persistent_path, "w");
+		if (fp == NULL) {
+			dp_log_error("Failed to open %s: %s", state->persistent_path, strerror(errno));
+		} else {
+			fprintf(fp,
+					"%s\n"
+					"%d %d %d %d\n",
+					selection->output->name, selection->x, selection->y, selection->width,
+					selection->height);
+			fclose(fp);
+		}
+	}
+
+	free(state->persistent_path);
+}