Import of the watch repository from Pebble

src/fw/applib/ui/content_indicator_private.h

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+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "applib/app_timer.h"
+#include "applib/ui/scroll_layer.h"
+#include "applib/ui/layer.h"
+#include "util/buffer.h"
+
+typedef struct {
+  ContentIndicatorDirection direction:2;
+  bool content_available:1;
+  AppTimer *timeout_timer;
+  ContentIndicatorConfig config;
+  LayerUpdateProc original_update_proc;
+} ContentIndicatorDirectionData;
+
+struct ContentIndicator {
+  ContentIndicatorDirectionData direction_data[NumContentIndicatorDirections];
+  //! Needed to find the ContentIndicator belonging to a ScrollLayer
+  //! @see \ref content_indicator_get_or_create_for_scroll_layer()
+  ScrollLayer *scroll_layer;
+};
+
+//! TODO: There are no videos from design yet for this timeout, so it was arbitrarily chosen.
+#define CONTENT_INDICATOR_TIMEOUT_MS 1200
+
+//! The maximum number of ContentIndicator pointers that a ContentIndicatorsBuffer should hold.
+//! This affects two separate buffers: one for kernel (i.e. all modals together) and one for the
+//! currently running app. If an attempt is made to exceed this size by initializing an additional
+//! ContentIndicator, then \ref content_indicator_init() will trigger an assertion. If an attempt
+//! is made to exceed this size by creating an additional ContentIndicator, then
+//! \ref content_indicator_create() will return `NULL`.
+#define CONTENT_INDICATOR_BUFFER_SIZE 4
+
+//! The maximum size (in Bytes) of the buffer of ContentIndicators.
+#define CONTENT_INDICATOR_BUFFER_SIZE_BYTES (CONTENT_INDICATOR_BUFFER_SIZE * \
+                                             sizeof(ContentIndicator *))
+
+//! This union allows us to statically allocate the storage for a buffer of content indicators.
+typedef union {
+  Buffer buffer;
+  uint8_t buffer_storage[sizeof(Buffer) + CONTENT_INDICATOR_BUFFER_SIZE_BYTES];
+} ContentIndicatorsBuffer;
+
+//! @internal
+//! Retrieves the ContentIndicator for the given ScrollLayer.
+//! @param scroll_layer The ScrollLayer for which to retrieve the ContentIndicator.
+//! @return A pointer to the ContentIndicator.
+//! `NULL` if the ContentIndicator could not be found.
+ContentIndicator *content_indicator_get_for_scroll_layer(ScrollLayer *scroll_layer);
+
+//! @internal
+//! Retrieves the ContentIndicator for the given ScrollLayer, or creates one if none exists.
+//! @param scroll_layer The ScrollLayer for which to retrieve the ContentIndicator.
+//! @return A pointer to the ContentIndicator.
+//! `NULL` if the ContentIndicator could not be found and could not be created.
+ContentIndicator *content_indicator_get_or_create_for_scroll_layer(ScrollLayer *scroll_layer);
+
+//! @internal
+//! Destroys a ContentIndicator for the given ScrollLayer.
+//! @param scroll_layer The ScrollLayer for which to destroy a ContentIndicator.
+void content_indicator_destroy_for_scroll_layer(ScrollLayer *scroll_layer);
+
+//! @internal
+//! Initializes the given ContentIndicatorsBuffer.
+//! @param content_indicators_buffer A pointer to the ContentIndicatorsBuffer to initialize.
+void content_indicator_init_buffer(ContentIndicatorsBuffer *content_indicators_buffer);