这个函数文档的意思就是画弧,看了文档也不太明白,自己做了demo终于明白了意思
移动到圆心,画180度半圆
void TestArcTo::paintEvent(QPaintEvent *)
{
QPoint startPt(, );
QRect rect(startPt.x(), startPt.y(), , );
QPainter p(this);
p.setRenderHint(QPainter::Antialiasing); //抗锯齿
p.fillRect(rect, QColor(, , )); int arcR = rect.width()/;
int rectSize = rect.width();
QPainterPath path; path.moveTo(startPt.x() + arcR, startPt.y() + arcR); //先移动到圆心
path.arcTo(rect, 00.0f, 180.0f); //以0度起点,逆时针画180度 p.fillPath(path, QBrush(QColor(, , )));
}
移动到圆心,以90度开始画180度半圆
path.moveTo(startPt.x() + arcR, startPt.y() + arcR); //先移动到圆心
path.arcTo(rect, 90.0f, 180.0f); //以0度起点,逆时针画180度
移动到圆心,以190度开始画180度半圆
path.moveTo(startPt.x() + arcR, startPt.y() + arcR); //先移动到圆心
path.arcTo(rect, 90.0f, 180.0f); //以0度起点,逆时针画180度
移动到某个点可以画弦月
几个点组合
矩形区圆角
void TestArcTo::paintEvent(QPaintEvent *)
{
QRect rect(, , , );
QPainter p(this);
p.setRenderHint(QPainter::Antialiasing);
p.fillRect(rect, QColor(, , )); int cornerSize = ; //调节圆角的大小
int arcR = cornerSize/;
QPainterPath path;
path.moveTo(rect.left() + arcR, rect.top());
path.arcTo(rect.left(), rect.top(), cornerSize, cornerSize, 90.0f, 90.0f); path.lineTo(rect.left(), rect.bottom() - arcR);
path.arcTo(rect.left(), rect.bottom() - cornerSize, cornerSize, cornerSize, 180.0f, 90.0f); path.lineTo(rect.right() - arcR, rect.bottom());
path.arcTo(rect.right() - cornerSize, rect.bottom() - cornerSize, cornerSize, cornerSize, 270.0f, 90.0f); path.lineTo(rect.right(), rect.top() + arcR);
path.arcTo(rect.right() - cornerSize, rect.top(), cornerSize, cornerSize, 0.0f, 90.0f); p.fillPath(path, QBrush(QColor(, , )));
}
底部和右边有黄色边框需要处理,这就需要+1, -1微调了。理解了arcTo函数,都不难处理。
最方便的圆角方法
void TestArcTo::paintEvent(QPaintEvent *)
{
QRect rect(, , , );
QPainter p(this);
p.setRenderHint(QPainter::Antialiasing);
p.fillRect(rect, QColor(, , )); p.setPen(Qt::NoPen);
p.setBrush(QColor(, , ));
p.drawRoundedRect(rect, , );
}