[英]QT QImage - Copy Subsection of an Image as a Polygon
試圖將圖像的一部分復制為多邊形(特別是五邊形),但我對如何復制為矩形以外的任何內容更感興趣。
以下代碼只允許復制為矩形。
QImage copy(const QRect &rect = QRect()) const;
inline QImage copy(int x, int y, int w, int h) const
{ return copy(QRect(x, y, w, h)); }
void SelectionInstrument::copyImage(ImageArea &imageArea)
{
if (mIsSelectionExists)
{
imageArea.setImage(mImageCopy);
QClipboard *globalClipboard = QApplication::clipboard();
QImage copyImage;
if(mIsImageSelected)
{
copyImage = mSelectedImage;
}
else
{
copyImage = imageArea.getImage()->copy(mTopLeftPoint.x(), mTopLeftPoint.y(), mWidth, mHeight);
}
globalClipboard->setImage(copyImage, QClipboard::Clipboard);
}
}
如果要獲得非矩形區域,一般方法是使用 QPainter 的 setClipPath() 和 QPainterPath:
#include <QtWidgets>
static QImage copyImage(const QImage & input, const QPainterPath & path){
if(!input.isNull() && !path.isEmpty()){
QRect r = path.boundingRect().toRect().intersected(input.rect());
QImage tmp(input.size(), QImage::Format_ARGB32);
tmp.fill(Qt::transparent);
QPainter painter(&tmp);
painter.setClipPath(path);
painter.drawImage(QPoint{}, input, input.rect());
painter.end();
return tmp.copy(r);
}
return QImage();
}
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QImage image(QSize(256, 256), QImage::Format_ARGB32);
image.fill(QColor("salmon"));
QPainterPath path;
QPolygon poly;
poly << QPoint(128, 28)
<< QPoint(33, 97)
<< QPoint(69, 209)
<< QPoint(187, 209)
<< QPoint(223, 97);
path.addPolygon(poly);
QLabel *original_label = new QLabel;
original_label->setPixmap(QPixmap::fromImage(image));
QLabel *copy_label = new QLabel;
copy_label->setPixmap(QPixmap::fromImage(copyImage(image, path)));
QWidget w;
QHBoxLayout *lay = new QHBoxLayout(&w);
lay->addWidget(original_label);
lay->addWidget(copy_label);
w.show();
return a.exec();
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.