SystemUI之ScreenShot

ScreenShot流程

base/services/core/java/com/android/server/policy/PhoneWindowManager.java

物理截屏：按下power键和音量下键

private void initKeyCombinationRules() {
        mKeyCombinationManager = new KeyCombinationManager();
        final boolean screenshotChordEnabled = mContext.getResources().getBoolean(
                com.android.internal.R.bool.config_enableScreenshotChord);

        if (screenshotChordEnabled) {
            mKeyCombinationManager.addRule(
                    //按下电源键和音量下键
                    new TwoKeysCombinationRule(KEYCODE_VOLUME_DOWN, KEYCODE_POWER) {
                        @Override
                        void execute() {
                            mPowerKeyHandled = true;
                            interceptScreenshotChord();
                        }
                        @Override
                        void cancel() {
                            cancelPendingScreenshotChordAction();
                        }
                    });
        }
}

收到截屏指令后，执行interceptScreenshotChord方法，

设置截屏类型

全屏：TAKE_SCREENSHOT_FULLSCREEN

用户选择区域：TAKE_SCREENSHOT_SELECTED_REGION

调用者提供的图像：TAKE_SCREENSHOT_PROVIDED_IMAGE

设置截屏来源

SCREENSHOT_KEY_CHORD

SCREENSHOT_KEY_OTHER

SCREENSHOT_OVERVIEW

SCREENSHOT_ACCESSIBILITY_ACTIONS

SCREENSHOT_OTHER

SCREENSHOT_VENDOR_GESTURE

private void interceptScreenshotChord() {
        mHandler.removeCallbacks(mScreenshotRunnable);
        mScreenshotRunnable.setScreenshotType(TAKE_SCREENSHOT_FULLSCREEN);
        mScreenshotRunnable.setScreenshotSource(SCREENSHOT_KEY_CHORD);
        mHandler.postDelayed(mScreenshotRunnable, getScreenshotChordLongPressDelay());
    }

执行ScreenRunnale.run()方法

private class ScreenshotRunnable implements Runnable {
        private int mScreenshotType = TAKE_SCREENSHOT_FULLSCREEN;
        private int mScreenshotSource = SCREENSHOT_KEY_OTHER;

        public void setScreenshotType(int screenshotType) {
            mScreenshotType = screenshotType;
        }

        public void setScreenshotSource(int screenshotSource) {
            mScreenshotSource = screenshotSource;
        }

        @Override
        public void run() {
            mDefaultDisplayPolicy.takeScreenshot(mScreenshotType, mScreenshotSource);
        }
    }

截屏takeScreenshot()

base/services/core/java/com/android/server/wm/DisplayPolicy.java

public void takeScreenshot(int screenshotType, int source) {
        if (mScreenshotHelper != null) {
            mScreenshotHelper.takeScreenshot(screenshotType,
                    getStatusBar() != null && getStatusBar().isVisible(),
                    getNavigationBar() != null && getNavigationBar().isVisible(),
                    source, mHandler, null /* completionConsumer */);
        }
    }

base/packages/SystemUI/src/com/android/systemui/screenshot/TakeScreenshotService.java

创建一个 GlobalScreenshot 对象，通过GlobalScreenshot对象实现截屏
private final GlobalScreenshot mScreenshot;

在Handler中对三种截屏方式做处理

private Handler mHandler = new Handler(Looper.myLooper()) {
        @Override
        public void handleMessage(Message msg) {
            final Messenger callback = msg.replyTo;
            Consumer<Uri> uriConsumer = uri -> {
                Message reply = Message.obtain(null, SCREENSHOT_MSG_URI, uri);
                try {
                    callback.send(reply);
                } catch (RemoteException e) {
                }
            };
            Runnable onComplete = () -> {
                Message reply = Message.obtain(null, SCREENSHOT_MSG_PROCESS_COMPLETE);
                try {
                    callback.send(reply);
                } catch (RemoteException e) {
                }
            };

            // If the storage for this user is locked, we have no place to store
            // the screenshot, so skip taking it instead of showing a misleading
            // animation and error notification.
            if (!mUserManager.isUserUnlocked()) {
                Log.w(TAG, "Skipping screenshot because storage is locked!");
                post(() -> uriConsumer.accept(null));
                post(onComplete);
                return;
            }

            ScreenshotHelper.ScreenshotRequest screenshotRequest =
                    (ScreenshotHelper.ScreenshotRequest) msg.obj;

            mUiEventLogger.log(ScreenshotEvent.getScreenshotSource(screenshotRequest.getSource()));

            switch (msg.what) {
                case WindowManager.TAKE_SCREENSHOT_FULLSCREEN:
                    mScreenshot.takeScreenshot(uriConsumer, onComplete);
                    break;
                case WindowManager.TAKE_SCREENSHOT_SELECTED_REGION:
                    mScreenshot.takeScreenshotPartial(uriConsumer, onComplete);
                    break;
                case WindowManager.TAKE_SCREENSHOT_PROVIDED_IMAGE:
                    Bitmap screenshot = BitmapUtil.bundleToHardwareBitmap(
                            screenshotRequest.getBitmapBundle());
                    Rect screenBounds = screenshotRequest.getBoundsInScreen();
                    Insets insets = screenshotRequest.getInsets();
                    int taskId = screenshotRequest.getTaskId();
                    int userId = screenshotRequest.getUserId();
                    ComponentName topComponent = screenshotRequest.getTopComponent();
                    mScreenshot.handleImageAsScreenshot(screenshot, screenBounds, insets,
                            taskId, userId, topComponent, uriConsumer, onComplete);
                    break;
                default:
                    Log.d(TAG, "Invalid screenshot option: " + msg.what);
            }
        }
    };

当截取全屏时

base/packages/SystemUI/src/com/android/systemui/screenshot/GlobalScreenshot.java

private void takeScreenshot(Consumer<Uri> finisher, Rect crop) {
        // copy the input Rect, since SurfaceControl.screenshot can mutate it
        Rect screenRect = new Rect(crop);
        int rot = mDisplay.getRotation();
        int width = crop.width();
        int height = crop.height();
        takeScreenshot(SurfaceControl.screenshot(crop, width, height, rot), finisher, screenRect,
                Insets.NONE, true);
    }

private void takeScreenshot(Bitmap screenshot, Consumer<Uri> finisher, Rect screenRect,
            Insets screenInsets, boolean showFlash) {
        dismissScreenshot("new screenshot requested", true);

        mScreenBitmap = screenshot;

        if (mScreenBitmap == null) {
            mNotificationsController.notifyScreenshotError(
                    R.string.screenshot_failed_to_capture_text);
            finisher.accept(null);
            mOnCompleteRunnable.run();
            return;
        }

        if (!isUserSetupComplete()) {
            // User setup isn't complete, so we don't want to show any UI beyond a toast, as editing
            // and sharing shouldn't be exposed to the user.
            saveScreenshotAndToast(finisher);
            return;
        }

        // Optimizations
        mScreenBitmap.setHasAlpha(false);
        mScreenBitmap.prepareToDraw();

        onConfigChanged(mContext.getResources().getConfiguration());

        if (mDismissAnimation != null && mDismissAnimation.isRunning()) {
            mDismissAnimation.cancel();
        }

        // The window is focusable by default
        setWindowFocusable(true);

        // Start the post-screenshot animation
        startAnimation(finisher, screenRect, screenInsets, showFlash);
    }

截屏之后开始截屏动画

private void startAnimation(final Consumer<Uri> finisher, Rect screenRect, Insets screenInsets,
            boolean showFlash) {

        // If power save is on, show a toast so there is some visual indication that a
        // screenshot has been taken.
        PowerManager powerManager = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
        if (powerManager.isPowerSaveMode()) {
            Toast.makeText(mContext, R.string.screenshot_saved_title, Toast.LENGTH_SHORT).show();
        }

        mScreenshotHandler.post(() -> {
            if (!mScreenshotLayout.isAttachedToWindow()) {
                mWindowManager.addView(mScreenshotLayout, mWindowLayoutParams);
            }
            mScreenshotAnimatedView.setImageDrawable(
                    createScreenDrawable(mScreenBitmap, screenInsets));
            setAnimatedViewSize(screenRect.width(), screenRect.height());
            // Show when the animation starts
            mScreenshotAnimatedView.setVisibility(View.GONE);

            mScreenshotPreview.setImageDrawable(createScreenDrawable(mScreenBitmap, screenInsets));
            // make static preview invisible (from gone) so we can query its location on screen
            mScreenshotPreview.setVisibility(View.INVISIBLE);

            mScreenshotHandler.post(() -> {
                mScreenshotLayout.getViewTreeObserver().addOnComputeInternalInsetsListener(this);

                mScreenshotAnimation =
                        createScreenshotDropInAnimation(screenRect, showFlash);

                saveScreenshotInWorkerThread(finisher, new ActionsReadyListener() {
                    @Override
                    void onActionsReady(SavedImageData imageData) {
                        showUiOnActionsReady(imageData);
                    }
                });

                // Play the shutter sound to notify that we've taken a screenshot
                mCameraSound.play(MediaActionSound.SHUTTER_CLICK);

                mScreenshotPreview.setLayerType(View.LAYER_TYPE_HARDWARE, null);
                mScreenshotPreview.buildLayer();
                mScreenshotAnimation.start();
            });
        });
    }