来自图像的QPixmap导致分割错误

| 我在这里完全不知所措... 我正在尝试将QImage转换为QPixmap,但是我的程序始终由于以下堆栈跟踪而崩溃。奇怪的是,如果我指定的QRectF的左上角没有(0,0),那么它可以正常工作。我知道QImage也有一个复制方法,但是那也失败了(没有有用的stacktrace),所以我想我会尝试使用Pixmaps代替... Line 4/5的stacktrace是我的,但我基本上是在做以下事情
QImage _drawing = QImage(1024, 1024);
// fill _drawing with some data

QRect i_work = QRect(1, 1, 10, 10);
QRect i_break = QRect(0, 0, 10, 10);

QPixmap foo = QPixmap::fromImage(_drawing);
// QPixmap good = foo.copy(i_work); // I work
QPixmap broken = foo.copy(i_break); // Segmentation fault...
堆栈跟踪:
Program received signal SIGSEGV, Segmentation fault.
0x01f44024 in QBasicAtomicInt::ref (this=0xabababab)
    at ../../include/QtCore/../../src/corelib/arch/qatomic_i386.h:120
120     ../../include/QtCore/../../src/corelib/arch/qatomic_i386.h: No such file
 or directory.
        in ../../include/QtCore/../../src/corelib/arch/qatomic_i386.h
(gdb) bt
#0  0x01f44024 in QBasicAtomicInt::ref (this=0xabababab)
    at ../../include/QtCore/../../src/corelib/arch/qatomic_i386.h:120
#1  0x01964d3e in QImage::QImage (this=0x28cc70, image=...)
    at image\\qimage.cpp:1125
#2  0x01990682 in QRasterPixmapData::fromImage (this=0xc391a00,
    sourceImage=..., flags=...) at image\\qpixmap_raster.cpp:151
#3  0x019862ab in QPixmap::fromImage (image=..., flags=...)
    at image\\qpixmap.cpp:2031
#4  0x00423fdc in TxImage::getSelection (this=0xc3b6cb0, selection_area=...)
    at TxImage.cpp:207
#5  0x004421e2 in RomView::mouseReleaseEvent (this=0xc397978, event=0x28d5fc)
    at RomView.cpp:261
#6  0x019241a0 in QWidget::event (this=0xc397978, event=0x28d5fc)
    at kernel\\qwidget.cpp:8187
#7  0x01c9e6bc in QFrame::event (this=0xc397978, e=0x28d5fc)
    at widgets\\qframe.cpp:557
#8  0x01d2bf0f in QAbstractScrollArea::viewportEvent (this=0xc397978,
    e=0x28d5fc) at widgets\\qabstractscrollarea.cpp:1043
#9  0x01e9aae6 in QGraphicsView::viewportEvent (this=0xc397978,
    event=0x28d5fc) at graphicsview\\qgraphicsview.cpp:2862
#10 0x01f86a13 in QAbstractScrollAreaPrivate::viewportEvent (this=0xc3969f8,
    event=0x28d5fc) at widgets//qabstractscrollarea_p.h:100
#11 0x01f8506c in QAbstractScrollAreaFilter::eventFilter (this=0xbfa7388, o=
    0xbf43978, e=0x28d5fc) at widgets//qabstractscrollarea_p.h:116
#12 0x6a1ffc73 in QCoreApplicationPrivate::sendThroughObjectEventFilters (
    this=0xa7a46d8, receiver=0xbf43978, event=0x28d5fc)
    at kernel\\qcoreapplication.cpp:847
#13 0x018d96e5 in QApplicationPrivate::notify_helper (this=0xa7a46d8,
    receiver=0xbf43978, e=0x28d5fc) at kernel\\qapplication.cpp:4392
#14 0x018d7909 in QApplication::notify (this=0x28fe34, receiver=0xbf43978,
    e=0x28d5fc) at kernel\\qapplication.cpp:3959
#15 0x6a1ff9dc in QCoreApplication::notifyInternal (this=0x28fe34,
    receiver=0xbf43978, event=0x28d5fc) at kernel\\qcoreapplication.cpp:732
#16 0x01f4d53e in QCoreApplication::sendSpontaneousEvent (receiver=0xbf43978,
    event=0x28d5fc)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#17 0x018d6118 in QApplicationPrivate::sendMouseEvent (receiver=0xbf43978,
    event=0x28d5fc, alienWidget=0xc3adb70, nativeWidget=0x28fd60,
    buttonDown=0x237941c, lastMouseReceiver=..., spontaneous=true)
    at kernel\\qapplication.cpp:3056
#18 0x0193fc63 in QETWidget::translateMouseEvent (this=0x28fd60, msg=...)
    at kernel\\qapplication_win.cpp:3317
#19 0x0193aaa6 in QtWndProc (hwnd=0x130fb8, message=514, wParam=0,
    lParam=5373956) at kernel\\qapplication_win.cpp:1657
#20 0x762c62fa in USER32!OffsetRect () from C:\\Windows\\syswow64\\user32.dll
#21 0x900010c2 in ?? ()
#22 0x90909090 in ?? ()
#23 0x00df7d80 in operator+ ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)
(gdb)
我向您保证qatomic_i386.h存在,并查看第120行...
112: inline bool QBasicAtomicInt::ref()
113: {
114:     unsigned char ret;
115:    asm volatile(\"lock\\n\"
116:                 \"incl %0\\n\"
117:                 \"setne %1\"
118:                 : \"=m\" (_q_value), \"=qm\" (ret)
119:                 : \"m\" (_q_value)
120:                 : \"memory\");
121:    return ret != 0;
122: }
    
已邀请:
        很难说是怎么回事。但是QImage构造函数的QT Doc说   警告:这将创建一个QImage   与未初始化的数据。呼叫fill()   用适当的图像填充图像   绘制之前的像素值   与QPainter。 通过调用fill()方法确保QImage正确填充。也许这就是问题的原因。     
        我能够成功解决问题,但是我不确定潜在的问题,因为该解决方法对我而言并没有多大意义。 所以我在
QGraphicsScene
/
QGraphicsView
上渲染
QImage
。我在场景中的位置(0,0)有
QImage
,在位置(0,0)处也有
QGraphicsItem
。在调用
QImage
上的副本之前,从场景中删除另一个
QGraphicsItem
似乎可以解决此问题。我不知道ѭ10点有何特别之处。我唯一想到的是
QPoint(0,0)
上的
isNull
返回
true
。     

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