QT4如何模糊QPixmap图像?
我正在寻找以下其中一项:
Blur(pixmap);
painter.Blur();
painter.Blur(rect);
这样做的最佳方式是什么?
答案 0 :(得分:9)
1st)宣布外部QT例程:
QT_BEGIN_NAMESPACE
extern Q_WIDGETS_EXPORT void qt_blurImage( QPainter *p, QImage &blurImage, qreal radius, bool quality, bool alphaOnly, int transposed = 0 );
QT_END_NAMESPACE
2)使用:
extern QImage srcImg;//source image
QPixmap pxDst( srcImg.size() );//blurred destination
pxDst.fill( Qt::transparent );
{
QPainter painter( &pxDst );
qt_blurImage( &painter, srcImg, 2, true, false );//blur radius: 2px
}
答案 1 :(得分:6)
方法1a:抓住原始位并自己动手。您需要充分熟悉位图和模糊算法以自己实现模糊。如果您想要那种精确度,那么就可以了。
QImage image = pixmap.toImage();
if (image.format() != QImage::Format_RGB32)
image = image.convertToFormat(QImage::Format_RGB32);
uchar* bits = image.bits();
int rowBytes = image.bytesPerLine();
DoMyOwnBlurAlgorithm(bits, image.width(), image.height(), rowBytes);
return QPixmap::fromImage(image);
方法1b:谁需要原始位?您可以使用image.pixel(x,y)和image.setPixel(x,y,color)代替。这不会像1a那么快,但它应该更容易理解和编码。
QImage image = pixmap.toImage();
QImage output(image.width(), image.height(), image.format());
for (int y=0; y<image.height(); ++y)
for (int x=0; x<image.width(); ++x)
output.setPixel(getBlurredColor(image, x, y));
return output;
方法2:通过小部件或场景使用QGraphicsBlurEffect。这里的代码使用标签小部件:
QPixmap BlurAPixmap(const QPixmap& inPixmap)
{
QLabel* label = new QLabel();
label->setPixmap(inPixmap);
label->setGraphicsEffect(new QGraphicsBlurEffect());
QPixmap output(inPixmap.width(), inPixmap.height());
QPainter painter(&output);
label->render(&painter);
return output;
}
根据需要调整。例如,我假设默认的图形模糊效果是可以接受的。我在我的项目中使用方法2。
答案 2 :(得分:5)
看看这个:
#include <QtGui/QApplication>
#include <QImage>
#include <QPixmap>
#include <QLabel>
QImage blurred(const QImage& image, const QRect& rect, int radius, bool alphaOnly = false)
{
int tab[] = { 14, 10, 8, 6, 5, 5, 4, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2 };
int alpha = (radius < 1) ? 16 : (radius > 17) ? 1 : tab[radius-1];
QImage result = image.convertToFormat(QImage::Format_ARGB32_Premultiplied);
int r1 = rect.top();
int r2 = rect.bottom();
int c1 = rect.left();
int c2 = rect.right();
int bpl = result.bytesPerLine();
int rgba[4];
unsigned char* p;
int i1 = 0;
int i2 = 3;
if (alphaOnly)
i1 = i2 = (QSysInfo::ByteOrder == QSysInfo::BigEndian ? 0 : 3);
for (int col = c1; col <= c2; col++) {
p = result.scanLine(r1) + col * 4;
for (int i = i1; i <= i2; i++)
rgba[i] = p[i] << 4;
p += bpl;
for (int j = r1; j < r2; j++, p += bpl)
for (int i = i1; i <= i2; i++)
p[i] = (rgba[i] += ((p[i] << 4) - rgba[i]) * alpha / 16) >> 4;
}
for (int row = r1; row <= r2; row++) {
p = result.scanLine(row) + c1 * 4;
for (int i = i1; i <= i2; i++)
rgba[i] = p[i] << 4;
p += 4;
for (int j = c1; j < c2; j++, p += 4)
for (int i = i1; i <= i2; i++)
p[i] = (rgba[i] += ((p[i] << 4) - rgba[i]) * alpha / 16) >> 4;
}
for (int col = c1; col <= c2; col++) {
p = result.scanLine(r2) + col * 4;
for (int i = i1; i <= i2; i++)
rgba[i] = p[i] << 4;
p -= bpl;
for (int j = r1; j < r2; j++, p -= bpl)
for (int i = i1; i <= i2; i++)
p[i] = (rgba[i] += ((p[i] << 4) - rgba[i]) * alpha / 16) >> 4;
}
for (int row = r1; row <= r2; row++) {
p = result.scanLine(row) + c2 * 4;
for (int i = i1; i <= i2; i++)
rgba[i] = p[i] << 4;
p -= 4;
for (int j = c1; j < c2; j++, p -= 4)
for (int i = i1; i <= i2; i++)
p[i] = (rgba[i] += ((p[i] << 4) - rgba[i]) * alpha / 16) >> 4;
}
return result;
}
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QLabel label;
QImage image("image.png");
image = blurred(image,image.rect(),10,false);
label.setPixmap(QPixmap::fromImage(image));
label.show();
return a.exec();
}
答案 3 :(得分:3)
让我们为这个话题做出贡献。从Qt 5.3开始,以下函数将帮助您将QGraphicsEffect应用于QImage(并且不会丢失alpha)
QImage applyEffectToImage(QImage src, QGraphicsEffect *effect, int extent = 0)
{
if(src.isNull()) return QImage(); //No need to do anything else!
if(!effect) return src; //No need to do anything else!
QGraphicsScene scene;
QGraphicsPixmapItem item;
item.setPixmap(QPixmap::fromImage(src));
item.setGraphicsEffect(effect);
scene.addItem(&item);
QImage res(src.size()+QSize(extent*2, extent*2), QImage::Format_ARGB32);
res.fill(Qt::transparent);
QPainter ptr(&res);
scene.render(&ptr, QRectF(), QRectF( -extent, -extent, src.width()+extent*2, src.height()+extent*2 ) );
return res;
}
他们使用此功能来模糊您的图像非常简单:
QGraphicsBlurEffect *blur = new QGraphicsBlurEffect;
blur->setBlurRadius(8);
QImage source("://img1.png");
QImage result = applyEffectToImage(source, blur);
result.save("final.png");
当然,你不需要保存它,这只是一个有用的例子。 你甚至可以放下一个阴影:
QGraphicsDropShadowEffect *e = new QGraphicsDropShadowEffect;
e->setColor(QColor(40,40,40,245));
e->setOffset(0,10);
e->setBlurRadius(50);
QImage p("://img3.png");
QImage res = applyEffectToImage(p, e, 40);
注意范围参数,它会在原始图像的所有边上添加extent
个像素数,尤其适用于阴影和模糊不能被截断。
答案 4 :(得分:0)
Gaussian blur是一种创建模糊效果的简单方法。
编辑:而且,我遇到了Qt的QGraphicsBlurEffect。在Qt 4.6中引入,似乎完全符合你的要求。
答案 5 :(得分:0)
基于QT 5的@ПетърПетров答案添加python代码。
def applyEffectToImage(src, effect):
scene = QGraphicsScene()
item = QGraphicsPixmapItem()
item.setPixmap(QPixmap.fromImage(src))
item.setGraphicsEffect(effect)
scene.addItem(item)
res = QImage(src.size(), QImage.Format_ARGB32)
res.fill(Qt.transparent)
ptr = QPainter(res)
scene.render(ptr, QRectF(), QRectF(0,0, src.width(), src.height()) )
return res
blur = QGraphicsBlurEffect()
blur.setBlurRadius(8)
source = QImage(r"C:\Users\fran\Desktop\test.png")
result = applyEffectToImage(source, blur)
result.save(r"C:\Users\fran\Desktop\result.png")