Add a C-api for retrieving display info.
As HWUI will need to depend on ABI-stable interfaces moving forward, we
need such an interface against SurfaceComposer for retrieving display
metadata.
This CL won't contain a map file to stabilize the ABI yet, as I expect
that there will be some flux due to refresh rate apis.
Bug: 136263392
Test: builds
Change-Id: I7227e2e72789d36a21534840eac88817135251c3
diff --git a/libs/nativedisplay/include/apex/display.h b/libs/nativedisplay/include/apex/display.h
new file mode 100644
index 0000000..7af452a
--- /dev/null
+++ b/libs/nativedisplay/include/apex/display.h
@@ -0,0 +1,125 @@
+/*
+ * Copyright 2019 The Android Open Source Project
+ *
+ * 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 <inttypes.h>
+
+__BEGIN_DECLS
+
+/**
+ * Opaque handle for a native display
+ */
+typedef struct ADisplay ADisplay;
+
+/**
+ * Enum describing the possible types of a display
+ */
+enum ADisplayType {
+ /**
+ * A display that is the internal, or "primary" display for a device.
+ */
+ DISPLAY_TYPE_INTERNAL = 0,
+
+ /**
+ * A display that is externally connected for a device.
+ */
+ DISPLAY_TYPE_EXTERNAL = 1,
+};
+
+/**
+ * Opaque handle for display metadata
+ */
+typedef struct ADisplayConfig ADisplayConfig;
+
+/**
+ * Acquires a list of display handles. Memory is allocated for the list and is
+ * owned by the caller. The caller is responsible for freeing this memory by
+ * calling ADisplayList_release.
+ *
+ * Returns the size of the returned list on success.
+ * Returns -errno on error.
+ */
+int ADisplay_acquirePhysicalDisplays(ADisplay*** outDisplays);
+
+/**
+ * Releases a list of display handles created by
+ * ADisplayList_acquirePhysicalDisplays.
+ */
+void ADisplay_release(ADisplay** displays);
+
+/**
+ * Queries the maximum supported fps for the given display.
+ */
+float ADisplay_getMaxSupportedFps(ADisplay* display);
+
+/**
+ * Queries the display's type.
+ */
+ADisplayType ADisplay_getDisplayType(ADisplay* display);
+
+/**
+ * Gets the current display configuration for the given display.
+ *
+ * Memory is *not* allocated for the caller. As such, the returned output
+ * configuration's lifetime will not be longer than the ADisplay* passed to this
+ * function - if ADisplay_release is called destroying the ADisplay object then
+ * it is invalid to access the ADisplayConfig returned here.
+ *
+ * Note that the current display configuration can change. Listening to updates
+ * to the current display configuration should be done via Choreographer. If
+ * such an update is observed, then this method should be recalled to get the
+ * new current configuration.
+ *
+ * Returns OK on success, -errno on failure.
+ */
+int ADisplay_getCurrentConfig(ADisplay* display, ADisplayConfig** outConfig);
+
+/**
+ * Queries the density for a given display configuration.
+ */
+float ADisplayConfig_getDensity(ADisplayConfig* config);
+
+/**
+ * Queries the width in pixels for a given display configuration.
+ */
+int32_t ADisplayConfig_getWidth(ADisplayConfig* config);
+
+/**
+ * Queries the height in pixels for a given display configuration.
+ */
+int32_t ADisplayConfig_getHeight(ADisplayConfig* config);
+
+/**
+ * Queries the display refresh rate for a given display configuration.
+ */
+float ADisplayConfig_getFps(ADisplayConfig* config);
+
+/**
+ * Queries the vsync offset from which the system compositor is scheduled to
+ * run. If a vsync occurs at time T, and the compositor runs at time T + S, then
+ * this returns S in nanoseconds.
+ */
+int64_t ADisplayConfig_getCompositorOffsetNanos(ADisplayConfig* config);
+
+/**
+ * Queries the vsync offset from which applications are scheduled to run. If a
+ * vsync occurs at time T, and applications run at time T + S, then this returns
+ * S in nanoseconds.
+ */
+int64_t ADisplayConfig_getAppVsyncOffsetNanos(ADisplayConfig* config);
+
+__END_DECLS