The process of the hierarchy dump in android
The simple overview of ui dump process in android is like the following figure:
(2 years ago, I was involved in the project that developed the android test automation tool.)
The related source code is as below:
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ViewServer.java
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class ViewServer implements Runnable {
private final WindowManagerService mWindowManager;
class ViewServerWorker implements Runnable, WindowManagerService.WindowChangeListener {
private Socket mClient;
private boolean mNeedWindowListUpdate;
private boolean mNeedFocusedWindowUpdate;
public ViewServerWorker(Socket client) {
mClient = client;
mNeedWindowListUpdate = false;
mNeedFocusedWindowUpdate = false;
}
public void run() {
BufferedReader in = null;
try {
in = new BufferedReader(new InputStreamReader(mClient.getInputStream()), 1024);
final String request = in.readLine();
String command;
String parameters;
int index = request.indexOf(' ');
if (index == -1) {
command = request;
parameters = "";
} else {
command = request.substring(0, index);
parameters = request.substring(index + 1);
}
boolean result;
if (COMMAND_PROTOCOL_VERSION.equalsIgnoreCase(command)) {
result = writeValue(mClient, VALUE_PROTOCOL_VERSION);
} else if (COMMAND_SERVER_VERSION.equalsIgnoreCase(command)) {
result = writeValue(mClient, VALUE_SERVER_VERSION);
} else if (COMMAND_WINDOW_MANAGER_LIST.equalsIgnoreCase(command)) {
result = mWindowManager.viewServerListWindows(mClient);
} else if (COMMAND_WINDOW_MANAGER_GET_FOCUS.equalsIgnoreCase(command)) {
result = mWindowManager.viewServerGetFocusedWindow(mClient);
} else if (COMMAND_WINDOW_MANAGER_AUTOLIST.equalsIgnoreCase(command)) {
result = windowManagerAutolistLoop();
} else {
result = mWindowManager.viewServerWindowCommand(mClient,command, parameters);
}
// ...
}
}
}
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WindowManagerService.java
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https://android.googlesource.com/platform/frameworks/base/+/master/services/java/com/android/server/wm/WindowManagerService.java
public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor, WindowManagerPolicy.WindowManagerFuncs,
DisplayManagerService.WindowManagerFuncs, DisplayManager.DisplayListener {
boolean viewServerWindowCommand(Socket client, String command, String parameters) {
// Any uncaught exception will crash the system process
try {
// Find the hashcode of the window
int index = parameters.indexOf(' ');
if (index == -1) {
index = parameters.length();
}
final String code = parameters.substring(0, index);
int hashCode = (int) Long.parseLong(code, 16);
// Extract the command's parameter after the window description
if (index < parameters.length()) {
parameters = parameters.substring(index + 1);
} else {
parameters = "";
}
final WindowState window = findWindow(hashCode);
if (window == null) {
return false;
}
data = Parcel.obtain();
data.writeInterfaceToken("android.view.IWindow");
data.writeString(command);
data.writeString(parameters);
data.writeInt(1);
ParcelFileDescriptor.fromSocket(client).writeToParcel(data, 0);
reply = Parcel.obtain();
final IBinder binder = window.mClient.asBinder();
// TODO: GET THE TRANSACTION CODE IN A SAFER MANNER
binder.transact(IBinder.FIRST_CALL_TRANSACTION, data, reply, 0);
}
}
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WindowState.java
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https://android.googlesource.com/platform/frameworks/base/+/master/services/java/com/android/server/wm/WindowState.java
import android.view.IWindow;
final class WindowState implements WindowManagerPolicy.WindowState {
final IWindow mClient;
}
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IWindow.aidl
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https://android.googlesource.com/platform/frameworks/base/+/master/core/java/com/android/internal/view/BaseIWindow.java
oneway interface IWindow {
void executeCommand(String command, String parameters, in ParcelFileDescriptor descriptor);
}
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ViewRootImpl.java
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https://android.googlesource.com/platform/frameworks/base/+/17d28ca/core/java/android/view/ViewRootImpl.java
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, HardwareRenderer.HardwareDrawCallbacks {
static class W extends IWindow.Stub {
@Override
public void executeCommand(String command, String parameters, ParcelFileDescriptor out) {
final ViewRootImpl viewAncestor = mViewAncestor.get();
if (viewAncestor != null) {
final View view = viewAncestor.mView;
if (view != null) {
if (checkCallingPermission(Manifest.permission.DUMP) !=
PackageManager.PERMISSION_GRANTED) {
throw new SecurityException("Insufficient permissions to invoke"
+ " executeCommand() from pid=" + Binder.getCallingPid()
+ ", uid=" + Binder.getCallingUid());
}
OutputStream clientStream = null;
try {
clientStream = new ParcelFileDescriptor.AutoCloseOutputStream(out);
ViewDebug.dispatchCommand(view, command, parameters, clientStream);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (clientStream != null) {
try {
clientStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
}
}
}
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ViewDebug.java
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https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/view/ViewDebug.java
/**
* Various debugging/tracing tools related to {@link View} and the view hierarchy.
*/
class ViewDebug
{
void dispatchCommand(View view, String command, String parameters,
OutputStream clientStream) throws IOException {
if (REMOTE_COMMAND_DUMP.equalsIgnoreCase(command)) {
dump(view, false, true, clientStream);
}
/**
* Dumps the view hierarchy starting from the given view.
* @hide
*/
public static void dump(View root, boolean skipChildren, boolean includeProperties,
OutputStream clientStream) throws IOException {
BufferedWriter out = null;
try {
out = new BufferedWriter(new OutputStreamWriter(clientStream, "utf-8"), 32 * 1024);
View view = root.getRootView();
if (view instanceof ViewGroup) {
ViewGroup group = (ViewGroup) view;
dumpViewHierarchy(group.getContext(), group, out, 0,
skipChildren, includeProperties);
}
out.write("DONE.");
out.newLine();
} catch (Exception e) {
android.util.Log.w("View", "Problem dumping the view:", e);
} finally {
if (out != null) {
out.close();
}
}
}
private static void dumpViewHierarchy(Context context, ViewGroup group,
BufferedWriter out, int level, boolean skipChildren, boolean includeProperties) {
if (!dumpView(context, group, out, level, includeProperties)) {
return;
}
if (skipChildren) {
return;
}
final int count = group.getChildCount();
for (int i = 0; i < count; i++) {
final View view = group.getChildAt(i);
if (view instanceof ViewGroup) {
dumpViewHierarchy(context, (ViewGroup) view, out, level + 1, skipChildren,
includeProperties);
} else {
dumpView(context, view, out, level + 1, includeProperties);
}
if (view.mOverlay != null) {
ViewOverlay overlay = view.getOverlay();
ViewGroup overlayContainer = overlay.mOverlayViewGroup;
dumpViewHierarchy(context, overlayContainer, out, level + 2, skipChildren,
includeProperties);
}
}
if (group instanceof HierarchyHandler) {
((HierarchyHandler)group).dumpViewHierarchyWithProperties(out, level + 1);
}
}
}
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