图片缩放与旋转

图片缩放与旋转

图片的缩放与旋转是图像处理的常用功能。QMatrix类提供了坐标系统的2D转化功能，可以使窗体转化变形，经常在绘图程序中使用，QMatrix可以实现坐标系统的移动、缩放、变形以及旋转功能。

1、创建imgprocessor.h

#ifndef IMGPROCESSOR_H
#define IMGPROCESSOR_H

#include <QtGui>

class ImgProcessor : public QMainWindow
{
Q_OBJECT

public :
ImgProcessor();

void createMenus();
void createActions();
void createToolBars();

private:
QImage img;
QLabel *imageLabel;

QMenu *fileMenu;
QMenu *zoomMenu;
QMenu *rotateMenu;
QMenu *mirrorMenu;

QAction *openFileAction;
QAction *zoomInAction;
QAction *zoomOutAction;
QAction *rotate90Action;
QAction *rotate180Action;
QAction *rotate270Action;
QAction *mirrorVerticalAction;
QAction *mirrorHorizontalAction;

QToolBar *fileTool;
QToolBar *zoomTool;
QToolBar *rotateTool;
QToolBar *mirrorTool;

protected slots:
void slotOpenFile();
void slotZoomIn();
void slotZoomOut();
void slotRotate90();
void slotRotate180();
void slotRotate270();
void slotMirrorVertical();
void slotMirrorHorizontal();

};

#endif // IMGPROCESSOR_H

2、创建imgprocessor.cpp

#include "imgprocessor.h"

ImgProcessor::ImgProcessor() : QMainWindow()
{
setWindowTitle(tr("Image Processor"));

imageLabel = new QLabel(this);
imageLabel->setSizePolicy(QSizePolicy::Ignored,QSizePolicy::Ignored);
imageLabel->setScaledContents(true);

setCentralWidget(imageLabel);

createActions();
createMenus();
createToolBars();
}

void ImgProcessor::createActions()
{
openFileAction = new    QAction(QIcon(":/images/openfile.png"),tr("Open"),this);
openFileAction->setShortcut(tr("Ctrl+O"));
openFileAction->setStatusTip(tr("Open File"));
connect(openFileAction,SIGNAL(triggered()),this,SLOT(slotOpenFile()));

// zoom in action
zoomInAction = new QAction(QIcon(":/images/zoomin.png"),tr("ZoomIn"),this);
zoomInAction->setShortcut(tr("PgUp"));
zoomInAction->setStatusTip(tr("Zoom In"));
connect(zoomInAction,SIGNAL(triggered()),this,SLOT(slotZoomIn()));

// zoom out action
zoomOutAction = new QAction(QIcon(":/images/zoomout.png"),tr("ZoomOut"),this);
zoomOutAction->setShortcut(tr("PgDown"));
zoomOutAction->setStatusTip(tr("Zoom Out"));
connect(zoomOutAction,SIGNAL(triggered()),this,SLOT(slotZoomOut()));

// rotate 90 action
rotate90Action = new QAction(QIcon(":/images/rotate90.png"),tr("Rotate90"), this);
rotate90Action->setShortcut(tr("Ctrl+Right"));
rotate90Action->setStatusTip(tr("Rotate 90"));
connect(rotate90Action, SIGNAL(triggered()), this, SLOT(slotRotate90()));

// rotate 180 action
rotate180Action = new QAction(QIcon(":/images/rotate180.png"),tr("Rotate180"), this);
rotate180Action->setShortcut(tr("Ctrl+Down"));
rotate180Action->setStatusTip(tr("Rotate 180"));
connect(rotate180Action, SIGNAL(triggered()), this, SLOT(slotRotate180()));

// rotate 270 action
rotate270Action = new QAction(QIcon(":/images/rotate270.png"),tr("Rotate270"), this);
rotate270Action->setShortcut(tr("Ctrl+Left"));
rotate270Action->setStatusTip(tr("Rotate 270"));
connect(rotate270Action, SIGNAL(triggered()), this, SLOT(slotRotate270()));

// mirror vertical action
mirrorVerticalAction = new QAction(QIcon(":/images/mirrorvertical.png"),tr("MirrorVertical"), this);
mirrorVerticalAction->setShortcut(tr("Ctrl+V"));
mirrorVerticalAction->setStatusTip(tr("Mirror Vertical"));
connect(mirrorVerticalAction, SIGNAL(triggered()), this, SLOT(slotMirrorVertical()));

// mirror horizontal action
mirrorHorizontalAction = new QAction(QIcon(":/images/mirrorhorizontal.png"),tr("MirrorHorizontal"), this);
mirrorHorizontalAction->setShortcut(tr("Ctrl+H"));
mirrorHorizontalAction->setStatusTip(tr("Mirror Horizontal"));
connect(mirrorHorizontalAction, SIGNAL(triggered()), this, SLOT(slotMirrorHorizontal()));
}

void ImgProcessor::createMenus()
{
fileMenu = menuBar()->addMenu(tr("File"));
zoomMenu = menuBar()->addMenu(tr("zoom"));
rotateMenu = menuBar()->addMenu(tr("rotate"));
mirrorMenu = menuBar()->addMenu(tr("mirror"));

fileMenu->addAction(openFileAction);

zoomMenu->addAction(zoomInAction);
zoomMenu->addAction(zoomOutAction);

rotateMenu->addAction(rotate90Action);
rotateMenu->addAction(rotate180Action);
rotateMenu->addAction(rotate270Action);

mirrorMenu->addAction(mirrorVerticalAction);
mirrorMenu->addAction(mirrorHorizontalAction);
}

void ImgProcessor::createToolBars()
{
fileTool = addToolBar("File");
zoomTool = addToolBar("Zoom");
rotateTool = addToolBar("Rotate");
mirrorTool = addToolBar("Mirror");

fileTool->addAction(openFileAction);

zoomTool->addAction(zoomInAction);
zoomTool->addAction(zoomOutAction);

rotateTool->addAction(rotate90Action);
rotateTool->addAction(rotate180Action);
rotateTool->addAction(rotate270Action);

mirrorTool->addAction(mirrorVerticalAction);
mirrorTool->addAction(mirrorHorizontalAction);
}

void ImgProcessor::slotOpenFile()
{
QString s = QFileDialog::getOpenFileName(this,
"open image file",
".",
"Image files (*.bmp *.jpg *.pbm *.pgm *.png *.ppm *.xbm *.xpm);;All files (*.*))");
if(s != "")
{
if(img.load(s))
{
imageLabel->setPixmap(QPixmap::fromImage(img));
resize(img.width(),img.height());
}
}
}

void ImgProcessor::slotZoomIn()
{
if(img.isNull())
{
return;
}
else
{
QMatrix matrix;
matrix.scale(2,2);
img = img.transformed(matrix);
imageLabel->setPixmap(QPixmap::fromImage(img));
resize(img.width(),img.height());
}
}

void ImgProcessor::slotZoomOut()
{
if(img.isNull())
{
return;
}

QMatrix matrix;
matrix.scale(0.5,0.5);
img = img.transformed(matrix);
imageLabel->setPixmap(QPixmap::fromImage(img));
resize(img.width(),img.height());
}

void ImgProcessor::slotRotate90 ()
{
if(img.isNull())
{
return;
}
QMatrix matrix;
matrix.rotate(90);
img = img.transformed(matrix);
imageLabel->setPixmap(QPixmap::fromImage(img));
resize(img.width(),img.height());

}

void ImgProcessor::slotRotate180 ()
{
if(img.isNull())
{
return;
}
QMatrix matrix;
matrix.rotate(180);
img = img.transformed(matrix);
imageLabel->setPixmap(QPixmap::fromImage(img));
resize(img.width(),img.height());
}

void ImgProcessor::slotRotate270 ()
{
if(img.isNull())
{
return;
}
QMatrix matrix;
matrix.rotate(270);
img = img.transformed(matrix);
imageLabel->setPixmap(QPixmap::fromImage(img));
resize(img.width(),img.height());
}

void ImgProcessor::slotMirrorVertical ()
{
if(img.isNull())
{
return;
}

img = img.mirrored(false,true);
imageLabel->setPixmap(QPixmap::fromImage(img));
resize(img.width(),img.height());
}

void ImgProcessor::slotMirrorHorizontal ()
{
if(img.isNull())
{
return;
}

img = img.mirrored(true,false);
imageLabel->setPixmap(QPixmap::fromImage(img));
resize(img.width(),img.height());
}

3、创建main.cpp

#include <QApplication>
#include "imgprocessor.h"

int main(int argc,char *argv[])
{
QApplication app(argc,argv);

ImgProcessor *img = new ImgProcessor;
img->show();

return app.exec();
}

4、创建资源文件imgprocessor.qrc

5、运行程序，读取一张图片，可以试一下放大，缩小等功能。



6、资源代码