Qt：在widget的外部进行绘制带有坐标轴的图像

=====================================Widget.h=====================================

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>

namespace Ui {

class
Widget;
}

class
Widget : public
QWidget {
Q_OBJECT
public:

Widget(QWidget *parent = 0
);
~Widget();

protected:

virtual
void

changeEvent(QEvent *e);
virtual
bool

eventFilter(QObject *watched, QEvent *e);
void
paintOnWidget(QWidget *w);

private:

Ui::Widget *ui;
};

#endif
// WIDGET_H

=====================================Widget.cpp=====================================

#include
"Widget.h"
#include
"ui_Widget.h"
#include
<QtGui/QPainter>

Widget::Widget(QWidget *parent) :
QWidget(parent), ui(new
Ui::Widget) {
ui->setupUi(this
);

ui->widget->installEventFilter(this
);
}

Widget::~Widget() {
delete
ui;
}

void
Widget::changeEvent(QEvent *e) {
QWidget::changeEvent(e);
switch
(e->type()) {
case
QEvent::LanguageChange:
ui->retranslateUi(this
);
break
;

default:

break
;
}
}

bool
Widget::eventFilter(QObject *watched, QEvent
*e) {
if
(watched == ui->widget) {
if
(e->type() == QEvent::Paint) {

paintOnWidget(ui->widget);
return
true
;
}
}

return
QWidget::eventFilter(watched, e);
}

void
Widget::paintOnWidget(QWidget *w) {
QPainter painter(w);

QFontMetrics metrics =
painter.fontMetrics();
int
textHeight = metrics.ascent() +
metrics.descent();

int
leftWidth = metrics.width(tr("9000"
)) + 5
;
int
rightWidth = metrics.width(tr("(
日
)"
));
int
width = w->size().width() - leftWidth -
rightWidth;
int
height = w->size().height() - 3
* textHeight;

// 绘制外框

painter.drawRect(0
, 0
,
w->size().width() -1
,
w->size().height() - 1
);

//　移动坐标系

//painter.translate(inset * 2,
ui->yearWidget->size().height() - inset);
painter.translate(leftWidth, 1.75
* textHeight + height);

int
totalCount = 9000
; //
默认每年收入
9000
件衣服

int
count = 10
; //

分成
10
成

float
deltaX = width / 12.0f
; //
x
坐标上每分的宽度

float
deltaY = (float
)height / count; // y
坐标上每分的宽度

// 画横坐标

painter.drawLine(0
, 0
, width,
0
);
for
(int
i =
1
; i <= 12
; ++i) {
QString month = tr("%1
月
"
).arg(i);
int
stringWidth = metrics.width(month);

// 绘制坐标刻度

painter.drawLine(deltaX * i,
0
, deltaX * i, 4
);

// 绘制坐标处的月

int
monthX = deltaX * (i - 1
) + ((deltaX - stringWidth) / 2
);
painter.drawText(monthX,
textHeight, month);
}

// 画纵坐标

painter.drawLine(0
, 0
, 0
, -height);

painter.drawText(-metrics.width(tr("(
件
)"
)),
-(deltaY * count +
textHeight / 2
+ metrics.descent()),
tr("(
件
)"
));
for
(int
i =
1
; i <= count; ++i) {
QString value = QString("%1"
).arg(i * totalCount / count);
int
stringWidth = metrics.width(value);

// 绘制坐标刻度

painter.drawLine(-4
, -i * deltaY, 0
, -i * deltaY);

//

绘制坐标值

//painter.drawText(-stringWidth - 4, -i *
deltaY + stringHeight / 2, value);
painter.drawText(-stringWidth -
4
, -(deltaY * i + textHeight / 2
- metrics.ascent()), value);
}

// // 绘制每个月收到的服饰

// painter.setBrush(Qt::BDiagPattern);

// for (int i = 0; i < yearList.size();
++i) {

// painter.setPen(Qt::black);

// int fineryCount = yearList.at(i); //
第
i + 1个月收到的服饰件数

// int h = fineryCount /
(float)totalCount * height;

// painter.drawRect(deltaX * i + 2, 0,
deltaX - 4, -h);
//

// // 绘制收到的服饰件数

// QString fineryString =
QString("%1").arg(fineryCount);

// int stringWidth =
metrics.width(fineryString);
//

// if (h > height) {

// h = height;

// }
//

// painter.setPen(Qt::red);

// //painter.drawText(deltaX * i +
(deltaX - stringWidth) / 2, -(h + metrics.descent()), fineryString);

// }
}