android - 加载/显示位图的最快方式；重用位图的最佳方式

Question

我需要以每秒不同的帧数显示图像，最大 FPS 为 30。图像来自 SD 卡，并且都具有相同的大小:480 x 640。我创建了 3 种可能的解决方案，但每个都有问题:

以下结果是 30 FPS。

我。不重复使用位图

• 很多 GC 调用:aprox。 每秒 30 次 GC

• CPU 负载:达到92%

  private Bitmap bitmap;
  
  private void startAnimation1() {
      TimerTask updateImage = new UpdateImage1();
      timer.scheduleAtFixedRate(updateImage, 0, 1000 / FPS);
  }
  
  class UpdateImage1 extends TimerTask {
      @Override
      public void run() {
          try {
              if (i == IMAGES_NR) {
                  i = 0;
              }
              bitmap = BitmapFactory.decodeStream(new FileInputStream(framesFiles[i]), null, null);
              i++;
          } catch (FileNotFoundException e) {
              System.out.println("Exception 1: " + e.getMessage());
          }
  
          runOnUiThread(new Runnable() {
              @Override
              public void run() {
                  imgView.setImageBitmap(bitmap);
              }
          });
      }
  }
  

二。通过 BitmapFactory.Options.inBitmap 重用位图

• GC 调用较低 - 每秒 1 或 2 次
• CPU 负载:达到84%

运行动画一段时间后，应用程序崩溃了:

06-20 15:08:58.158: WARN/System.err(7880): java.lang.ArrayIndexOutOfBoundsException: length=-5131855; regionStart=0; regionLength=1024
06-20 15:08:58.158: WARN/System.err(7880): at java.util.Arrays.checkOffsetAndCount(Arrays.java:1731)
06-20 15:08:58.158: WARN/System.err(7880): at java.io.BufferedInputStream.read(BufferedInputStream.java:273)
06-20 15:08:58.158: WARN/System.err(7880): at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
06-20 15:08:58.158: WARN/System.err(7880): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:587)
06-20 15:08:58.158: WARN/System.err(7880): at com.example.SendPreviewOptimization.MyActivity$UpdateImage2.run(MyActivity.java:148)
06-20 15:08:58.158: WARN/System.err(7880): at java.util.Timer$TimerImpl.run(Timer.java:284)
06-20 15:08:58.168: DEBUG/skia(7880): ---- read threw an exception
06-20 15:08:58.168: DEBUG/skia(7880): --- decoder->decode returned false
06-20 15:08:58.168: WARN/System.err(7880): java.lang.IllegalArgumentException: Problem decoding into existing bitmap
06-20 15:08:58.168: WARN/System.err(7880): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:590)
06-20 15:08:58.168: WARN/System.err(7880): at com.example.SendPreviewOptimization.MyActivity$UpdateImage2.run(MyActivity.java:148)
06-20 15:08:58.168: WARN/System.err(7880): at java.util.Timer$TimerImpl.run(Timer.java:284)
06-20 15:08:58.178: ERROR/msm8960.hwcomposer(330): prepareBypass: Unable to setup bypass due to non-pmem memory
06-20 15:08:58.198: ASSERT/libc(7880): Fatal signal 11 (SIGSEGV) at 0xffd1d447 (code=1)
06-20 15:08:58.238: ERROR/msm8960.hwcomposer(330): prepareBypass: Unable to setup bypass due to non-pmem memory
06-20 15:08:58.498: ERROR/MP-Decision(1448): DOWN Ld:25 Ns:1.100000 Ts:190 rq:0.000000 seq:194.000000
06-20 15:08:58.708: INFO/DEBUG(27660): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***



    private static BitmapFactory.Options bitmapOptions;
    private FileInputStream in;

    private void startAnimation2() {
        bitmapOptions = new BitmapFactory.Options();
        // setup bitmap reuse options:
        bitmapOptions.inPurgeable = true;
        bitmapOptions.inInputShareable = true;
        bitmapOptions.inBitmap = reusableBitmap;
        bitmapOptions.inMutable = true;
        bitmapOptions.inSampleSize = 1;

        TimerTask updateImage = new UpdateImage2();
        timer.scheduleAtFixedRate(updateImage, 0, 1000 / FPS);
    }

    class UpdateImage2 extends TimerTask {
        @Override
        public void run() {
            try {
                if (i == IMAGES_NR) {
                    i = 0;
                }

                //** version 1:
                in = new FileInputStream(framesFiles[i]);
                //decode into existing bitmap
                BitmapFactory.decodeStream(in, null, bitmapOptions);
                in.close();

                //** version 2:
                //BitmapFactory.decodeFile(framesFiles[i].getAbsolutePath(), bitmapOptions);

                i++;
            } catch (Exception e) {
                System.out.println("Exception 2: " + e.getMessage());
            }
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    imgView.setImageBitmap(reusableBitmap);
                }
            });
        }
    }

III.选项 III:使用缓冲区(使 Bytebuffer 更高效的一件事是使用直接内存。)

• 这个选项我无法让它工作:(

  private ByteBuffer buffer;
  private byte[] b;
  private IntBuffer mPixels;
  
  private void startAnimation3() {
      buffer = ByteBuffer.allocate(480 * 640 * 6);
      b = new byte[480 * 640 * 6];
      TimerTask updateImage = new UpdateImage3();
      timer.scheduleAtFixedRate(updateImage, 0, 1000 / FPS);
  }
  
  class UpdateImage3 extends TimerTask {
      public void run() {
          try {
              if (i == IMAGES_NR) {
                  i = 0;
              }
              FileInputStream frameInputStream = new FileInputStream(framesFiles[i]);
              frameInputStream.read(b);
              buffer.wrap(b);
              buffer.position(0);
              reusableBitmap.copyPixelsFromBuffer(buffer);
              frameInputStream.close();
              i++;
          } catch (Exception e) {
              System.out.println("Exception 3: " + e.getMessage());
          }
          runOnUiThread(new Runnable() {
              @Override
              public void run() {
                  imgView.setImageBitmap(reusableBitmap);
              }
          });
      }
  }
  
  private ByteBuffer copyToBuffer(Bitmap bitmap) {
      int size = bitmap.getHeight() * bitmap.getRowBytes();
      ByteBuffer buffer = ByteBuffer.allocateDirect(size);
      bitmap.copyPixelsToBuffer(buffer);
      return buffer;
  }
  

---

在上述每个解决方案中，我在 logcat 中收到很多

ERROR/msm8960.hwcomposer(330): prepareBypass: Unable to setup bypass due to non-pmem memory

我不知 Prop 体是什么意思。

我以前没有使用过位图重用，不知道哪个是最好的解决方案。

我在这里添加了我创建的项目:https://www.dropbox.com/sh/3xov369u1bmjpd1/qBQax4t48D还有 2 帧/图像。

对 Neron T 的回答

我试过那个库:

    //Option IV:
    private AQuery aquery;

    private void startAnimation4() {
        aquery = new AQuery(this);
        aquery.id(R.id.imgView);

        TimerTask updateImage = new UpdateImage4();
        timer.scheduleAtFixedRate(updateImage, 0, 1000 / FPS);
    }

    class UpdateImage4 extends TimerTask {
        public void run() {
            try {
                if (i == 29) {
                    i = 0;
                }
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        //load image from file, down sample to target width of 300 pixels
                        aquery.image(framesFiles[i],300);
                    }
                });
                i++;
            } catch (Exception e) {
                System.out.println("Exception 4: " + e.getMessage());
            }
        }
    }

它没有像我预期的那样工作 - 我在每张照片前都有一个闪烁的效果。我想首先它会清除图片，然后再添加一张新图片:(

Answer 1

请注意，您不能从不是 UIThread(主线程)的线程内部修改 View ，请尝试使用 AsyncTasks。使用图像而无需考虑太多的简单方法是使用像 Android Query 这样的框架，看看 here .

如果您想手动检查 this和 this .