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Commit c875ba73 authored by Winson Chung's avatar Winson Chung
Browse files

Minor optimization to skip bitmap copy during luma sampling 

- Attach the hw buffer to an image reader surface and sample
  the bytes directly

Bug: 149318305
Test: Rotate the device and measure the time to get the luma
Change-Id: I50512d6741109ee07a309f840c2936afd19af96e
parent 10e5f365

services/core/java/com/android/server/wm/ScreenRotationAnimation.java

+6 −0
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ 


package com.android.server.wm;



import static android.os.Trace.TRACE_TAG_WINDOW_MANAGER;



import static com.android.server.wm.AnimationSpecProto.ROTATE;

import static com.android.server.wm.ProtoLogGroup.WM_DEBUG_ORIENTATION;

import static com.android.server.wm.ProtoLogGroup.WM_SHOW_SURFACE_ALLOC;
@@ -36,6 +38,7 @@ import android.graphics.Color; 
import android.graphics.Matrix;

import android.graphics.Point;

import android.graphics.Rect;

import android.os.Trace;

import android.util.Slog;

import android.util.proto.ProtoOutputStream;

import android.view.Display;
@@ -205,8 +208,11 @@ class ScreenRotationAnimation { 
            SurfaceControl.ScreenshotGraphicBuffer gb =

                    mService.mDisplayManagerInternal.screenshot(displayId);

            if (gb != null) {

                Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER,

                        "ScreenRotationAnimation#getMedianBorderLuma");

                mStartLuma = RotationAnimationUtils.getMedianBorderLuma(gb.getGraphicBuffer(),

                        gb.getColorSpace());

                Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);

                try {

                    surface.attachAndQueueBufferWithColorSpace(gb.getGraphicBuffer(),

                            gb.getColorSpace());

services/core/java/com/android/server/wm/utils/RotationAnimationUtils.java

+47 −14
Original line number Diff line number Diff line
@@ -16,16 +16,21 @@ 


package com.android.server.wm.utils;



import android.graphics.Bitmap;

import static android.graphics.PixelFormat.RGBA_8888;



import android.graphics.Color;

import android.graphics.ColorSpace;

import android.graphics.GraphicBuffer;

import android.graphics.Matrix;

import android.graphics.Point;

import android.graphics.Rect;

import android.media.Image;

import android.media.ImageReader;

import android.view.Display;

import android.view.Surface;

import android.view.SurfaceControl;



import java.nio.ByteBuffer;

import java.util.Arrays;
@@ -38,31 +43,59 @@ public class RotationAnimationUtils { 
     * @return the average luminance of all the pixels at the borders of the bitmap

     */

    public static float getMedianBorderLuma(GraphicBuffer graphicBuffer, ColorSpace colorSpace) {

        Bitmap hwBitmap = Bitmap.wrapHardwareBuffer(graphicBuffer, colorSpace);

        if (hwBitmap == null) {

        if (graphicBuffer == null || graphicBuffer.getFormat() != RGBA_8888) {

            return 0;

        }



        Bitmap swaBitmap = hwBitmap.copy(Bitmap.Config.ARGB_8888, false);

        int height = swaBitmap.getHeight();

        int width = swaBitmap.getWidth();

        ImageReader ir = ImageReader.newInstance(graphicBuffer.getWidth(),

                graphicBuffer.getHeight(), graphicBuffer.getFormat(), 1);

        ir.getSurface().attachAndQueueBufferWithColorSpace(graphicBuffer, colorSpace);

        Image image = ir.acquireLatestImage();

        if (image == null || image.getPlanes().length == 0) {

            return 0;

        }



        Image.Plane plane = image.getPlanes()[0];

        ByteBuffer buffer = plane.getBuffer();

        int width = image.getWidth();

        int height = image.getHeight();

        int pixelStride = plane.getPixelStride();

        int rowStride = plane.getRowStride();

        float[] borderLumas = new float[2 * width + 2 * height];

        int i;

        int index = 0;

        for (i = 0; i < width; i++, index += 2) {

            borderLumas[index] = swaBitmap.getColor(i, 0).luminance();

            borderLumas[index + 1] = swaBitmap.getColor(i, height - 1).luminance();



        // Grab the top and bottom borders

        int l = 0;

        for (int x = 0; x < width; x++) {

            borderLumas[l++] = getPixelLuminance(buffer, x, 0, pixelStride, rowStride);

            borderLumas[l++] = getPixelLuminance(buffer, x, height - 1, pixelStride, rowStride);

        }

        for (i = 0; i < height; i++, index += 2) {

            borderLumas[index] = swaBitmap.getColor(0, i).luminance();

            borderLumas[index + 1] = swaBitmap.getColor(width - 1, i).luminance();



        // Grab the left and right borders

        for (int y = 0; y < height; y++) {

            borderLumas[l++] = getPixelLuminance(buffer, 0, y, pixelStride, rowStride);

            borderLumas[l++] = getPixelLuminance(buffer, width - 1, y, pixelStride, rowStride);

        }



        // Cleanup

        ir.close();



        // Oh, is this too simple and inefficient for you?

        // How about implementing a O(n) solution? https://en.wikipedia.org/wiki/Median_of_medians

        Arrays.sort(borderLumas);

        return borderLumas[borderLumas.length / 2];

    }



    private static float getPixelLuminance(ByteBuffer buffer, int x, int y,

            int pixelStride, int rowStride) {

        int offset = y * rowStride + x * pixelStride;

        int pixel = 0;

        pixel |= (buffer.get(offset) & 0xff) << 16;     // R

        pixel |= (buffer.get(offset + 1) & 0xff) << 8;  // G

        pixel |= (buffer.get(offset + 2) & 0xff);       // B

        pixel |= (buffer.get(offset + 3) & 0xff) << 24; // A

        return Color.valueOf(pixel).luminance();

    }



    /**

     * Gets the average border luma by taking a screenshot of the {@param surfaceControl}.

     * @see #getMedianBorderLuma(GraphicBuffer, ColorSpace)