我又来问问题了，图片太大，开发板out of memory，如何处理！ [复制链接]

各位好，现在要用qt做图片播放器，但是现在的图片一般尺寸很大，所以自己从网上下载了一些尺寸很大的图片，几千到一万像素都有，尺寸太大的时候，image load，开发板会out of memory，如何才能处理大图片使之可以被播放，或者什么情况下会预测到out of memory，谢谢了

用指针呢？

开发板上的信息如下，我想能不能预测到load image会造成out of memory那我就不load，提示无法播放
后来我看源码，QImage.load(image)是使用QImageReader.read(image)，然后是使用QImageIOHandler.read(image)
QImageIOHandler里的read函数是纯虚函数，可是查看qimageiohandler.cpp里面，找不到read函数

tango3[pdt]# free
                       total         used         free       shared      buffers
  Mem:       191728        92112        99616            0         2608
Swap:            0            0            0
Total:       191728        92112        99616
tango3[pdt]# get key: 000000100a 00 ENTER PDT


get key = 000000100a 00 ENTER PDT:KEYPAD_KEY5:0x01000005:Qt::NoModifier:0x00000000:0

[ItemClicked:3387]:

-----FilelistForm::ItemClicked, 2------

##### DEBUG #### [checkUsbCardReader:451]:[DeviceAutoDetection:] Check usb carder Reader
Set Display Background to 0
[PlayItem:4943]:

-----FilelistForm::PlayItem, 2------

"/media/USB/USB1_Disk1/IMAGES/Pics/pictures/Schmitt_Fingers_HiRes.jpg"


CCCCCCCCCCCCCCCCCCCCCCCCCCCC  playphoto


free
                        total         used         free       shared      buffers
  Mem:       191728       125712        66016            0         4496
Swap:            0            0            0
Total:       191728       125712        66016
tango3[pdt]# free
                       total         used         free       shared      buffers
  Mem:       191728       166688        25040            0         7056
Swap:            0            0            0
Total:       191728       166688        25040
tango3[pdt]# free
                        total         used         free       shared      buffers
  Mem:       191728       188304         3424            0          384
Swap:            0            0            0
Total:       191728       188304         3424
tango3[pdt]# printk: 6 messages suppressed.
desktop invoked oom-killer: gfp_mask=0xd0, order=0, oomkilladj=0
Call Trace:
[<8400fdfc>] dump_stack+0x8/0x34
[<84062568>] out_of_memory+0x2e0/0x358
[<84064b14>] __alloc_pages+0x3c8/0x3dc
[<840876e4>] cache_alloc_refill+0x37c/0x7d4
[<8408733c>] kmem_cache_alloc+0x74/0xa0
[<8412c650>] nfs_create_request+0x4c/0x1fc
[<8412e6c0>] readpage_async_filler+0xb4/0x238
[<8406790c>] read_cache_pages+0x114/0x168
[<8412e280>] nfs_readpages+0x118/0x1f0
[<84067130>] __do_page_cache_readahead+0x280/0x3a0
[<8405e884>] filemap_nopage+0x2a4/0x4d4
[<84070cdc>] __handle_mm_fault+0x178/0xe24
[<84013f94>] do_page_fault+0x144/0x3c0
[<840097a4>] ret_from_exception+0x0/0x10

Mem-info:
DMA per-cpu:
CPU    0: Hot: hi:   18, btch:   3 usd:   3   Cold: hi:    6, btch:   1 usd:   0
Active:10587 inactive:445 dirty:0 writeback:0 unstable:0
free:96 slab:649 mapped:21 pagetables:90 bounce:0
DMA free:1536kB min:2032kB low:2528kB high:3040kB active:169392kB inactive:7120kB present:261632kB pages_scanned:67179 all_unreclaimable? yes
lowmem_reserve[]: 0 0
DMA: 0*16kB 2*32kB 1*64kB 1*128kB 1*256kB 0*512kB 1*1024kB 0*2048kB 0*4096kB 0*8192kB 0*16384kB = 1536kB
Swap cache: add 0, delete 0, find 0/0, race 0+0
Free swap  = 0kB
Total swap = 0kB
Free swap:            0kB
16384 pages of RAM
0 pages of HIGHMEM
4401 reserved pages
77 pages shared
0 pages swap cached
Out of memory: kill process 885 (sh) score 1711 or a child
Killed process 1306 (desktop)


在开发板上是这些信息，播放图片前后free可以看出内存的使用情况，然后就out了...

调试的时候out of mem是在哪里？

看不出什么特别的东东。。。坐等。。。

void MediaPreviewForm::playPhoto(QString filename)
{
    QFile file(filename);
    QImageReader imageReader(filename);

    float scale = 1;
    //加个判断，如果图像尺寸大于4096，就缩放到4096，可是图像的大小好像没有变（不是指尺寸），这里应该怎么做吗？
    if (imageReader.size().width() > MAX_PHOTO_SIZE || imageReader.size().height() > MAX_PHOTO_SIZE)
    {
        scale = imageReader.size().width() > imageReader.size().height() ?
                MAX_PHOTO_SIZE/imageReader.size().width() :
                MAX_PHOTO_SIZE/imageReader.size().height();
        //QMatrix matrix;
        //matrix.scale(scale, scale);
        QSize imageSize = imageReader.size();
        qDebug()<<"imageSize"<<imageSize;
        imageSize.scale(imageSize.width()*scale, imageSize.height()*scale, Qt::KeepAspectRatio);
        //imageReader.setFormat("png");
        imageSize.scale(MAX_PHOTO_SIZE, MAX_PHOTO_SIZE, Qt::KeepAspectRatio);
        imageReader.setScaledSize(imageSize);
    }

    //qDebug()<<Q_ASSERT(image.load(filename));
    image = imageReader.read();

    int screenW = qApp->desktop()->size().width();
    int screenH = qApp->desktop()->size().height();

    float imageW = image.size().width();
    float imageH = image.size().height();

    scale = scalePhoto(screenW, screenH, imageW, imageH, PLAY_PHOTO);

    int scaleW = imageW*scale;
    int scaleH = imageH*scale;

/*
    QMatrix matrix;
    matrix.scale(scale, scale);
    image = image.transformed(matrix);
*/
    imageLabel->setPixmap(QPixmap::fromImage(image));

    imageLabel->setGeometry((screenW - scaleW)/2, (screenH - scaleH)/2, scaleW, scaleH);
    imageLabel->show();

    update();
}

代码在这里，老大帮我看看，谢谢了

How do you load an Image?

另外load之前，free看了一下，开发板上还有100M free的，图片大概是10M多，怎么就out of memory了...是不是和image尺寸大小有关系