Qt中的直线插值
Line interpolation in Qt?
我正试图通过分割线条的长度来减少画笔笔划的间距(在QPixmap上)。如果我乘以这条线,那么间距会增加,但间距永远不会减少。此外,这条线的最小长度似乎是一。很明显,将其分割会减少——可能会低于允许的金额?不确定这是否会对像素图的绘制产生负面影响。
以下是违规代码:
QLineF line = QLineF(lastPoint, endPoint);
float lineLength = line.length();
qDebug() << line.length();
line.setLength(lineLength / 50.0f);
qDebug() << line.length();
painter.drawPixmap(line.p1().x() - 16, line.p2().y() - 16, 32, 32, testPixmap);
下面是这个特定文件中的所有代码:
#include "inkspot.h"
#include "inkpuppet.h"
#include "ui_inkpuppet.h"
#include "newdialog.h"
#include "ui_newdialog.h"
#include <QtCore>
#include <QtGui>
#include <QWidget>
#include <QPainter>
#include <QPaintEvent>
InkSpot::InkSpot(QWidget *parent) :
QWidget(parent)
{
widget = this;
drawing = false;
}
void InkSpot::mousePressEvent(QMouseEvent *event)
{
if(event->button() == Qt::LeftButton)
{
lastPoint = event->pos();
drawing = true;
}
}
void InkSpot::mouseMoveEvent(QMouseEvent *event)
{
if((event->buttons() & Qt::LeftButton) && drawing)
{
drawLineTo(event->pos());
}
}
void InkSpot::mouseReleaseEvent(QMouseEvent *event)
{
if(event->button() == Qt::LeftButton && drawing)
{
drawLineTo(event->pos());
drawing = false;
}
}
void InkSpot::drawLineTo(const QPoint &endPoint)
{
QPainter painter(&pixmap);
painter.setPen(Qt::NoPen);
painter.setBrush(Qt::NoBrush);
QFile *stencilInput; // file for input, assumes a SQUARE RAW 8 bit grayscale image, no JPG no GIF, no size/format header, just 8 bit values in the file
char *brushPrototype; // raw brush prototype
uchar *brushData; // raw brush data
stencilInput = new QFile("C:/brush3.raw"); // open raw file
stencilInput->open(QIODevice::ReadOnly);
QDataStream in;
in.setDevice(stencilInput);
int size = stencilInput->size(); // set size to the length of the raw file
brushPrototype = new char[size]; // create the brush prototype array
in.readRawData(brushPrototype, size); // read the file into the prototype
brushData = new uchar[size]; // create the uchar array you need to construct QImage
for (int i = 0; i < size; ++i)
brushData[i] = (uchar)brushPrototype[i]; // copy the char to the uchar array
QImage test(brushData, 128, 128, QImage::Format_Indexed8); // create QImage from the brush data array
// 128x128 was my raw file, for any file size just use the square root of the size variable provided it is SQUARE
QImage test2(128, 128, QImage::Format_ARGB32);
QVector<QRgb> vectorColors(256); // create a color table for the image
for (int c = 0; c < 256; c++)
vectorColors[c] = qRgb(c, c, c);
test.setColorTable(vectorColors); // set the color table to the image
for (int iX = 0; iX < 128; ++iX) // fill all pixels with 255 0 0 (red) with random variations for OIL PAINT effect
// use your color of choice and remove random stuff for solid color
// the fourth parameter of setPixel is the ALPHA, use that to make your brush transparent by multiplying by opacity 0 to 1
{
for (int iY = 0; iY < 128; ++iY)
{
test2.setPixel(iX, iY, qRgba(255, 100, 100, (255-qGray(test.pixel(iX, iY)))*0.5));
}
}
// final convertions of the stencil and color brush
QPixmap testPixmap = QPixmap::fromImage(test2);
QPixmap testPixmap2 = QPixmap::fromImage(test);
painter.setBrush(Qt::NoBrush);
painter.setPen(Qt::NoPen);
// in a paint event you can test out both pixmaps
QLineF line = QLineF(lastPoint, endPoint);
float lineLength = line.length();
qDebug() << line.length();
line.setLength(lineLength / 50.0f);
qDebug() << line.length();
painter.drawPixmap(line.p1().x() - 16, line.p2().y() - 16, 32, 32, testPixmap);
//delete all dynamically allocated objects with no parents
delete [] brushPrototype;
delete [] brushData;
delete stencilInput;
lastPoint = endPoint;
}
void InkSpot::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
painter.setPen(Qt::NoPen);
painter.setBrush(Qt::NoBrush);
QRect rect = event->rect();
painter.drawPixmap(rect, pixmap, rect);
update();
}
不要使用QLineF
,使用QPainterPath
-它有几个非常方便的方法:
qreal QPainterPath::percentAtLength ( qreal len ) const
QPointF QPainterPath::pointAtPercent ( qreal t ) const
qreal length () const
因此,不使用QLineF
,而是创建一个绘制器路径,该路径仅由从旧绘制光标位置到新绘制光标位置的一条直线组成,获取该直线的长度,并在长度上按间距递增迭代以获得一个百分比值,从中可以为必须绘制画笔像素图的每个位置获得QPointF
。就这么简单。
编辑:好吧,它在这里,还没有测试过,大脑到终端,但类似这样的东西:
QPointF lastPosition, currentPosition;
qreal spacing;
void draw() {
QPainterPath path;
path.moveTo(lastPosition);
path.lineTo(currentPosition);
qreal length = path.length();
qreal pos = 0;
while (pos < length) {
qreal percent = path.percentAtLength(pos);
drawYourPixmapAt(path.pointAtPercent(percent)); // pseudo method, use QPainter and your brush pixmap instead
pos += spacing;
}
}
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