qt 拖拽 修改大小(二)

最近项目需要实现windows下橡皮筋的效果，所以对此做了一些了解，特此记录。

首先windows系统是支持橡皮筋效果的，需要使用win32方 法：SystemParametersInfo(SPI_SETDRAGFULLWINDOWS, showFullWindow, NULL, 0);showFullWindow是一个变量，如果需要windows默认支持橡皮筋则需要传递参数false，否则传递参数true，如果使用 windows默认的橡皮筋缩放，效果如图1所示，会产生一个矩形框，不管是窗口移动还是放大缩小，都会对该矩形框作用，然后当鼠标弹起时，真实窗口才会 移动或者放大缩小。如果不使用橡皮筋拖拽的方式，那么窗口就是实时的拖拽。

void WidgetData::resizeWidget(const QPoint& globalMousePos)

{

QRect origRect;

if (d_ptr->mUseRubberBandOnResize)

{

origRect = mRubberBand->frameGeometry();

}

else

{

origRect = mWidget->frameGeometry();

}

int left = origRect.left();

int top = origRect.top();

int right = origRect.right();

int bottom = origRect.bottom();

origRect.getCoords(&left, &top, &right, &bottom);

int minWidth = mWidget->minimumWidth();

int minHeight = mWidget->minimumHeight();

if (mPressedMousePos.onTopLeftEdge)

{

left = globalMousePos.x();

top = globalMousePos.y();

}

else if (mPressedMousePos.onBottomLeftEdge)

{

left = globalMousePos.x();

bottom = globalMousePos.y();

}

else if (mPressedMousePos.onTopRightEdge)

{

right = globalMousePos.x();

top = globalMousePos.y();

}

else if (mPressedMousePos.onBottomRightEdge)

{

right = globalMousePos.x();

bottom = globalMousePos.y();

}

else if (mPressedMousePos.onLeftEdge)

{

left = globalMousePos.x();

int max_width = mWidget->maximumWidth();

if (right - left > max_width)

{

return;

}

}

else if (mPressedMousePos.onRightEdge)

{

right = globalMousePos.x();

}

else if (mPressedMousePos.onTopEdge)

{

top = globalMousePos.y();

}

else if (mPressedMousePos.onBottomEdge)

{

bottom = globalMousePos.y();

}

QRect newRect(QPoint(left, top), QPoint(right, bottom));

if (newRect.isValid())

{

if (minWidth > newRect.width())

{

//determine what has caused the width change.

if (left != origRect.left())

newRect.setLeft(origRect.left());

else

newRect.setRight(origRect.right());

}

if (minHeight > newRect.height())

{

//determine what has caused the height change.

if (top != origRect.top())

newRect.setTop(origRect.top());

else

newRect.setBottom(origRect.bottom());

}

if (d_ptr->mUseRubberBandOnResize)

{

if (mRubberBand->isVisible() == false)

{

mRubberBand->show();

}

mRubberBand->setGeometry(newRect);

}

else

{

//mWidget->setGeometry(newRect);

mWidget->move(newRect.topLeft());

mWidget->resize(newRect.size());

}

}

else

{

//qDebug() << "Calculated Rect is not valid" << newRect;

}

}

void WidgetData::moveWidget(const QPoint & globalMousePos)

{

bool canMove = false;

if (d_ptr->mLocalOnMove == true && d_ptr->mCanMoveFlag != true)

{

for (int i = 0; i < d_ptr->mLocalWidget.size(); ++i)

{

if (d_ptr->mLocalWidget[i]->rect().contains(d_ptr->mLocalWidget[i]->mapFromGlobal(globalMousePos)))

{

canMove = true;

d_ptr->mCanMoveFlag = true;

break;

}

}

}

else

{

canMove = true;

}

if (canMove)

{

if (d_ptr->mUseRubberBandOnMove)

{

if (mRubberBand->isVisible() == false)

{

mRubberBand->show();

}

mRubberBand->move(globalMousePos - mDragPos);

}

else

{

mWidget->move(globalMousePos - mDragPos);

}

}

}

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