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I have a layout that looks like this.
Where:
Blue: rectangle it's a ScrollArea
Orange: rectangles are the widgets from that ScrollArea
My code:
#include <QtWidgets>
///////////////////////////////////////////////////////////////////////////////////////
class RoundedPolygon : public QPolygon {
public:
RoundedPolygon() { SetRadius(10); }
void SetRadius(unsigned int iRadius) { m_iRadius = iRadius; }
const QPainterPath &GetPath() {
m_path = QPainterPath();
if (count() < 3) {
qDebug() << "!! Polygon should have at least 3 points !!";
return m_path;
}
QPointF pt1;
QPointF pt2;
for (int i = 0; i < count(); i++) {
pt1 = GetLineStart(i);
if (i == 0)
m_path.moveTo(pt1);
else
m_path.quadTo(at(i), pt1);
pt2 = GetLineEnd(i);
m_path.lineTo(pt2);
}
// close the last corner
pt1 = GetLineStart(0);
m_path.quadTo(at(0), pt1);
return m_path;
}
private:
QPointF GetLineStart(int i) const {
QPointF pt;
QPoint pt1 = at(i);
QPoint pt2 = at((i + 1) % count());
float fRat = m_iRadius / GetDistance(pt1, pt2);
if (fRat > 0.5f)
fRat = 0.5f;
pt.setX((1.0f - fRat) * pt1.x() + fRat * pt2.x());
pt.setY((1.0f - fRat) * pt1.y() + fRat * pt2.y());
return pt;
}
QPointF GetLineEnd(int i) const {
QPointF pt;
QPoint pt1 = at(i);
QPoint pt2 = at((i + 1) % count());
float fRat = m_iRadius / GetDistance(pt1, pt2);
if (fRat > 0.5f)
fRat = 0.5f;
pt.setX(fRat * pt1.x() + (1.0f - fRat) * pt2.x());
pt.setY(fRat * pt1.y() + (1.0f - fRat) * pt2.y());
return pt;
}
float GetDistance(QPoint pt1, QPoint pt2) const {
int fD = (pt1.x() - pt2.x()) * (pt1.x() - pt2.x()) + (pt1.y() - pt2.y()) * (pt1.y() - pt2.y());
return sqrtf(fD);
}
private:
QPainterPath m_path;
unsigned int m_iRadius{};
};
class PolygonButtonWidget : public QWidget {
Q_OBJECT
public:
explicit PolygonButtonWidget(QWidget *parent = nullptr) : QWidget(parent) {}
~PolygonButtonWidget() override = default;
protected:
void resizeEvent(QResizeEvent *event) override {
float ratioW = 8;
float ratioH = 3;
// ui->scrollAreaWidgetContents->setFixedSize(5000, h);
float thisAspectRatio = (float) event->size().width() / event->size().height();
if (thisAspectRatio < ratioW / ratioH) {
float w = event->size().height() * ratioW / ratioH;
float h = event->size().height();
qDebug() << hasHeightForWidth() << " " << w << " " << h;
this->resize(w, h);
if (m_nrButtons != 0) {
this->move((w + 20) * m_nrButtons, this->y());
}
}
QWidget::resizeEvent(event);
}
int m_nrButtons{};
public:
void setMNrButtons(int mNrButtons) {
m_nrButtons = mNrButtons;
}
protected:
void paintEvent(QPaintEvent *event) override {
int offset = 50;
m_polygon.clear();
m_polygon.emplace_back(0, height()); //DOWN-LEFT
m_polygon.emplace_back(width() - offset, height()); //DOWN-RIGHT
m_polygon.emplace_back(width(), 0); //TOP-RIGHT
m_polygon.emplace_back(0 + offset, 0);
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing);
RoundedPolygon poly;
poly.SetRadius(15);
for (QPoint point: m_polygon) {
poly << point;
}
QBrush fillBrush;
fillBrush.setColor(Qt::darkBlue);
fillBrush.setStyle(Qt::SolidPattern);
QPainterPath path;
path.addPath(poly.GetPath());
painter.fillPath(path, fillBrush);
}
void mousePressEvent(QMouseEvent *event) override {
auto cursorPos = mapFromGlobal(QCursor::pos());
qDebug() << "X: " << cursorPos.x() << " Y: " << cursorPos.y();
inside(cursorPos, m_polygon);
qDebug() << "Pressed";
}
private:
std::vector<QPoint> m_polygon;
bool inside(QPoint point, std::vector<QPoint> polygon) {
auto x = point.x();
auto y = point.y();
auto inside = false;
auto i = 0;
auto j = polygon.size() - 1;
while (i < polygon.size()) {
auto xi = polygon[i].x();
auto yi = polygon[i].y();
auto xj = polygon[j].x();
auto yj = polygon[j].y();
auto intersect = ((yi > y) != (yj > y)) && (x < (xj - xi) * (y - yi) / (yj - yi) + xi);
if (intersect) inside = !inside;
j = i++;
}
qDebug() << inside;
return inside;
}
};
///////////////////////////////////////////////////////////////////////////////////////
int main(int argc, char *argv[]) {
QApplication app(argc, argv);
QWidget root;
QHBoxLayout layout{&root};
for (int i = 0; i < 10; ++i) {
auto p = new PolygonButtonWidget();
p->setMinimumSize(100, 100);
p->setMNrButtons(i);
layout.addWidget(p);
}
root.setStyleSheet("background-color: rgb(19,19,19);");
QScrollArea view;
view.setWidget(&root);
view.show();
app.exec();
}
#include "main.moc"
The problem arises when I'm trying to resize the window. In the moment of resizing, I want my widgets to keep their aspect ratio. But that's not going to happen.
I have scroll list of widgets which is looking like this (if it's expended on X way too much)
If I will scale it on Y-axis it's going to look like this.
After I've changed the resizeEvent now it's going to look something like this
or like this
How can I fix this? For some reason, some of my widgets are going to disappear, what should be my approach in order to fix this issue?
The problem is caused by the assumption that there's any mechanism that will automatically resize the widgets for you. There isn't. A QScrollArea acts as a layout barrier and any layouts inside of it are isolated from its size, and thus from any resize events.
You must resize the container widget (the one with blue outline on your diagram) yourself anytime the scroll area changes size, and you need first to prepare a test case for the widgets such that their size changes are properly managed when placed in the layout of your choice, and said layout is resized.
Finally, the pet peeve of mine: It's unlikely that you actually need the QMainWindow for anything. It's just a silly Qt Creator template. But unless you want an MDI interface and docking, you shouldn't be using the QMainWindow - and especially not when making a self-contained example. All you need here is QScrollArea as a top-level widget. That's literally all. Any QWidget can be a top-level window!
For future submissions, please provide all the code needed in a single main.cpp file that begins with #include <QtWidgets> and ends with #include "main.moc". You won't need any other includes for Qt classes, and you can write class definitions Java-style, with all the methods defined within the class declaration itself. This provides for short code - after all, a SO question isn't an Enterprise project. It's supposed to be minimal, and that really means that anything not necessary must be removed. No need for header files, multiple includes, nor other fluff - i.e. use Qt containers instead of C++ STL so that you don't need more includes etc.
Your example should look roughly as follows:
#include <QtWidgets>
class PolygonButtonWidget : public QAbstractButton {
Q_OBJECT
/* without seeing the code here, your question is unanswerable */
};
int main(int argc, char* argv[]) {
QApplication app(argc, argv);
QWidget root;
QHBoxLayout layout{&root};
PolygonButtonWidget buttons[10];
for (auto &button : buttons)
layout.addWidget(&button);
QScrollArea view;
view.setWidget(&root);
view.show();
app.exec();
view.takeWidget();
}
#include "main.moc"
Without such an example, your question is hard to answer, since:
How can we debug it? Debugging means using a debugger. If your code cannot be immediately compiled, then it's quite unlikely that someone will bother debugging it, and debugging by inspection is often error-prone.
How can we provide a tested answer if we'd have to first write the entire "test case" for it?
How can we know what's inside your button widget? The behavior of that widget does affect the ultimate solution.
It'd also help if you described a few use cases that you'd expect to work. That is, mock up (with a drawing) the state of the widgets before and after the view is resized, so that we can easily see what it is that you expect to happen. A lot of it is very easy to miss when explaining your needs in words. Use cases are a lingua franca of software specifications. If you don't use them, it's highly likely that you yourself don't know what behavior you expect in all cases.
I have a multiple screen video player, and I just want to keep 16:9 ratio. There is a qgroupbox as a container of a qwidget which plays video in it. I also use qgroupbox to show selected frame by painting border to green. I can't do this on qwidget because rendered video overlaps that. When I have done with resize, I emit a signal with mouseup event to be able to informed about the resize operation completed. Then I calculate new bounds for qwidget to keep 16:9 ratio and apply this values for qwidget. Here is the image to show you how my app looks like:
And here is the code that I use to resize qwidgets:
void playBack::OnWindowResized()
{
float ratio = 16.0f / 9.0f;
float w = playBackplayer_contList.at(0)->size().width(); //qgroupbox's width
float h = playBackplayer_contList.at(0)->size().height();//qgroupbox's height
float currentRatio = w / h;
float newW = 0;
float newH = 0;
if (currentRatio > ratio)
{
newH = h;
newW = h*ratio;
}
else if (currentRatio < ratio)
{
newW = w;
newH = w / ratio;
}
qDebug() << "NEW WIDGET SIZE: " << (int)newW << " x " << (int)newH;
for (int i = 0; i < playBackplayer_widgtList.count(); i++)
{
playBackplayer_widgtList.at(i)->setMinimumSize(newW, newH);
//playBackplayer_widgtList.at(i)->resize(newW, newH);
}
}
This code works perfectly when I enlarge form, but When I want to shrink, It doesn't allow me to do that. Because I set a minimum value for qwidgets. If I don't use setMinimumSize, use resize(w,h) instead, than orientation problems occur. And here is a example for this issue:
This code below shows ctor and this is where I set the layout:
playBack::playBack()
{
playback_player_1_widget = new QWidget;
playback_player_2_widget = new QWidget;
playback_player_3_widget = new QWidget;
playback_player_4_widget = new QWidget;
playback_player_1_widget_cont = new QGroupBox;
playback_player_2_widget_cont = new QGroupBox;
playback_player_3_widget_cont = new QGroupBox;
playback_player_4_widget_cont = new QGroupBox;
playBackplayer_widgtList.append(playback_player_1_widget);
playBackplayer_widgtList.append(playback_player_2_widget);
playBackplayer_widgtList.append(playback_player_3_widget);
playBackplayer_widgtList.append(playback_player_4_widget);
playBackplayer_contList.append(playback_player_1_widget_cont);
playBackplayer_contList.append(playback_player_2_widget_cont);
playBackplayer_contList.append(playback_player_3_widget_cont);
playBackplayer_contList.append(playback_player_4_widget_cont);
int rowcnt = 0;
int colcnt = 0;
for (int i = 0; i < 4; i++)
{
playBackplayer_contList.at(i)->setStyleSheet(QString("border:1px solid #000;background-color:#000;"));
playBackplayer_widgtList.at(i)->setStyleSheet(QString("background-color:#f00;"));
QGridLayout* layout = new QGridLayout;
layout->setRowStretch(0, 1);
layout->setColumnStretch(0, 1);
layout->setRowStretch(2, 1);
layout->setColumnStretch(2, 1);
playBackplayer_widgtList.at(i)->setMinimumWidth(100);
playBackplayer_widgtList.at(i)->setMinimumHeight(100);
playBackplayer_widgtList.at(i)->setMaximumWidth(10000);
playBackplayer_widgtList.at(i)->setMaximumHeight(10000);
layout->addWidget(playBackplayer_widgtList.at(i),1,1);
layout->setMargin(0);
layout->setSpacing(0);
playBackplayer_contList.at(i)->setLayout(layout);
mainLayout->addWidget(playBackplayer_contList.at(i), colcnt, rowcnt);
rowcnt++;
if (rowcnt % 2 == 0)
{
rowcnt = 0;
colcnt++;
}
playBackplayer_widgtList.at(i)->setAcceptDrops(true);
}
}
I have tried various things, I have tried to set size 0 for qwidget before resize, (in mousedownevent) that didn't work, I have tried deleting layout for qgroupbox, after resize happens, create new layout and set it for groupbox, that didn't work, I have tried layout()->adjustSize(), update(), repaint(), all that stuff didn't work. What am I missing? I need helps from you. Any help would be appreciated. Thank you in advance.
Do away with the grid layout inside the container group boxes. Instead, align and resize the video widget with setGeometry
Here is a simple subclass of QGroupBox I made that keeps your desired ratio and always stays in the center:
class RatioGroupBox : public QGroupBox{
Q_OBJECT
public:
RatioGroupBox(QWidget *parent = nullptr) : QGroupBox (parent){
setFlat(true);
setStyleSheet("border:1px solid #000;background-color:#000;");
setMinimumSize(100, 100);
setMaximumSize(10000, 10000);
ratio = 16.0f/9.0f;
ratioWidget = new QWidget(this);
ratioWidget->setStyleSheet("background: #f00;");
ratioWidget->setAcceptDrops(true);
}
protected:
void resizeEvent(QResizeEvent *){//or you can use your own resize slot
float w = width();
float h = height();
float currentRatio = w/h;
float newW(0);
float newH(0);
if (currentRatio > ratio){
newH = h;
newW = h*ratio;
}
else if (currentRatio < ratio){
newW = w;
newH = w / ratio;
}
ratioWidget->setGeometry((w-newW)/2, (h-newH)/2, newW, newH);
}
private:
QWidget *ratioWidget;
float ratio;
};
Your entire ctor will become something like:
playBack::playBack()
{
for(int r=0; r<2; r++){
for(int c=0; c<2; c++){
RatioGroupBox* playback_player_cont = new RatioGroupBox;
mainLayout->addWidget(playback_player_cont, c, r);
playBackplayer_contList.append(playback_player_cont);
}
}
}
You can of course access your video widgets by exposing ratioWidget any way you like. Either by making it public or creating a getter function.
I'm trying to figure out how to use QCPLayer to only replot certain items in the plot.
The qcustomplot documentation states this:
If you often need to call a full QCustomPlot::replot only because a non-complex object (e.g. an item) has changed while having relatively static but complex graphs in the plot, consider placing the regularly changing objects onto an own layer and setting its mode (QCPLayer::setMode) to QCPLayer::lmBuffered. This makes QCustomPlot allocate a dedicated paint buffer for this layer, and allows it to be replotted individually with QCPLayer::replot, independent of the other layers containing the potentially complex and slow graphs. See the documentation of the respective methods for details.
Which is what I'm trying to do in the example below:
I am creating a custom qcustomplot by inheriting from QCustomPlot:
QCustomPlot_custom.h
#pragma once
#include "qcustomplot.h"
#define USING_LAYER false
struct QCPCursor{
QCPItemLine *hLine;
QCPItemLine *vLine;
QCPItemText* cursorText;
};
class QCustomPlot_custom :
public QCustomPlot
{
Q_OBJECT
private slots:
void mouseMove(QMouseEvent*);
public:
QCustomPlot_custom(QWidget* parent = NULL);
~QCustomPlot_custom(){}
private:
QCPLayer* cursorLayer;
QCPCursor cursor;
void manageCursor(double x, double y, QPen pen);
public:
void init(QVector<double> xdata, QVector<double> ydata);
};
This class initializes with some data to plot. It also overloads the mouseMove event to control a custom cursor. USING_LAYER set to true means that the custom cursor is added to it's own layer (cursorLayer).
By setting USING_LAYER to false I get the desired effect as seen below:
The cursor is displayed by a horizontal and vertical line and the coordinates.
If I have many graphs in the plot and/or a lot of point in each graph, I will see a delay when moving the cursor. (Which is the reason I want to be able to replot only the cursor by setting it in a layer.)
QCustomPlot_custom.cpp
QCustomPlot_custom::QCustomPlot_custom(QWidget* parent)
{
connect(this, SIGNAL(mouseMove(QMouseEvent*)), this, SLOT(mouseMove(QMouseEvent*)));
QCustomPlot::setInteraction(QCP::iRangeDrag, true);
QCustomPlot::setInteraction(QCP::iRangeZoom, true);
if (USING_LAYER){
this->addLayer("cursorLayer", 0, QCustomPlot::limAbove);
cursorLayer = new QCPLayer(this, "cursorLayer");
cursorLayer->setMode(QCPLayer::lmBuffered);
}
}
void QCustomPlot_custom::init(QVector<double> xdata, QVector<double> ydata)
{
this->addGraph();
this->graph(0)->setData(xdata, ydata);
QColor colorPen(10, 25, 180, 255);
QPen pen;
pen.setWidth(50);
pen.setColor(colorPen);
this->graph()->setLineStyle(QCPGraph::lsLine);
this->graph()->setPen(QPen(colorPen));
this->xAxis->setLabel("X-axis");
this->yAxis->setLabel("Y-axis");
this->rescaleAxes();
this->replot();
}
void QCustomPlot_custom::mouseMove(QMouseEvent* event)
{
//Cursor coordinates:
double x = this->xAxis->pixelToCoord(event->pos().x());
double y = this->yAxis->pixelToCoord(event->pos().y());
manageCursor(x, y, QPen(Qt::DashDotLine));
if (USING_LAYER)
cursorLayer->replot();
else
this->replot();
}
void QCustomPlot_custom::manageCursor(double x, double y, QPen pen)
{
if (cursor.hLine)
this->removeItem(cursor.hLine);
cursor.hLine = new QCPItemLine(this);
cursor.hLine->setPen(pen);
cursor.hLine->start->setCoords(-QCPRange::maxRange, y);
cursor.hLine->end->setCoords(QCPRange::maxRange, y);
if (cursor.vLine)
this->removeItem(cursor.vLine);
cursor.vLine = new QCPItemLine(this);
cursor.vLine->setPen(pen);
cursor.vLine->start->setCoords(x, -QCPRange::maxRange);
cursor.vLine->end->setCoords(x, QCPRange::maxRange);
//Coordinates as text:
if (cursor.cursorText)
this->removeItem(cursor.cursorText);
cursor.cursorText = new QCPItemText(this);
cursor.cursorText->setText(QString("(%1, %2)").arg(x).arg(y));
cursor.cursorText->position->setCoords(QPointF(x, y));
QPointF pp = cursor.cursorText->position->pixelPosition() + QPointF(50.0, -15.0);
cursor.cursorText->position->setPixelPosition(pp);
cursor.cursorText->setFont(QFont(font().family(), 8));
//Add to layer:
if (USING_LAYER){
cursor.hLine->setLayer(cursorLayer);
cursor.vLine->setLayer(cursorLayer);
cursor.cursorText->setLayer(cursorLayer);
}
}
The function that initializes the class member:
void Qt_PlotTest::testPlot(){
//Create some data and initalize plot:
QVector<double> yData, xData;
int imax = 100000;
for (int i = 0; i < imax; i++){
double x = double(i) / imax;
xData.push_back(x);
yData.push_back(pow(x, 2)*( 1.0 + 0.5*cos(20*x) + 0.1*sin(500*x - 0.1)));
}
ui.custom_QWidgetPlot->init(xData, yData);
}
When using the layer method, the cursor doesn't render. I tried understanding the documentation, but it is not clear for me how to correctly use QCPLayers.
How should I do this?
After adding layer
this->addLayer("cursorLayer", 0, QCustomPlot::limAbove);
don't call QCPLayer constructor to get layer pointer. Use provided getters with name of the layer or index:
QCPLayer * QCustomPlot::layer ( const QString & name) const
QCPLayer * QCustomPlot::layer ( int index) const
cursorLayer = this->layer("cursorLayer");
Also every Graph and Item is added to currentLayer and in your case it's not cursorLayer it's the main. You need to change current layer
bool QCustomPlot::setCurrentLayer ( const QString & name)
bool QCustomPlot::setCurrentLayer ( QCPLayer * layer)
I.e.:
this->setCurrentLayer("cursorLayer");
this->addGraph();
...
this->setCurrentLayer("main");
Or you can specify layer for each QCPLayerable
bool QCPLayerable::setLayer ( QCPLayer * layer)
bool QCPLayerable::setLayer ( const QString & layerName)
someGraph->setLayer("cursorLayer);
As #EligijusPupeikis reminded me, I am deleting and re-creating the cursor every time I move it.
I didn't think this would have any effect to my issue, but apparently it is, because reploting a layer which has new items in it requires that the plot has be reploted first (source: will check the qcustomplot doc and add link).
So my code now looks like this:
QCustomPlot_custom::QCustomPlot_custom(QWidget* parent)
{
connect(this, SIGNAL(mouseMove(QMouseEvent*)), this, SLOT(mouseMove(QMouseEvent*)));
QCustomPlot::setInteraction(QCP::iRangeDrag, true);
QCustomPlot::setInteraction(QCP::iRangeZoom, true);
}
void QCustomPlot_custom::init(QVector<double> xdata, QVector<double> ydata)
{
this->addGraph();
this->graph(0)->setData(xdata, ydata);
QColor colorPen(10, 25, 180, 255);
QPen pen;
pen.setWidth(50);
pen.setColor(colorPen);
this->graph()->setLineStyle(QCPGraph::lsLine);
this->graph()->setPen(QPen(colorPen));
this->xAxis->setLabel("X-axis");
this->yAxis->setLabel("Y-axis");
this->rescaleAxes();
this->replot();
if (USING_LAYER){
this->addLayer("cursorLayer", 0, QCustomPlot::limAbove);
cursorLayer = this->layer("cursorLayer");
//cursorLayer = new QCPLayer(this, "cursorLayer");
cursorLayer->setMode(QCPLayer::lmBuffered);
}
//Cursor:
QPen qpen = QPen(Qt::DashDotLine);
cursor.hLine = new QCPItemLine(this);
cursor.hLine->setPen(qpen);
cursor.vLine = new QCPItemLine(this);
cursor.vLine->setPen(qpen);
cursor.cursorText = new QCPItemText(this);
cursor.cursorText->setFont(QFont(font().family(), 8));
//Add to layer:
if (USING_LAYER){
cursor.hLine->setLayer("cursorLayer"); //"cursorLayer"
cursor.vLine->setLayer("cursorLayer");
cursor.cursorText->setLayer("cursorLayer");
}
}
void QCustomPlot_custom::mouseMove(QMouseEvent* event)
{
//Cursor coordinates:
double x = this->xAxis->pixelToCoord(event->pos().x());
double y = this->yAxis->pixelToCoord(event->pos().y());
manageCursor(x, y);
if (USING_LAYER)
this->layer("cursorLayer")->replot();
else
this->replot();
}
void QCustomPlot_custom::manageCursor(double x, double y)
{
cursor.hLine->start->setCoords(-QCPRange::maxRange, y);
cursor.hLine->end->setCoords(QCPRange::maxRange, y);
cursor.vLine->start->setCoords(x, -QCPRange::maxRange);
cursor.vLine->end->setCoords(x, QCPRange::maxRange);
cursor.cursorText->setText(QString("(%1, %2)").arg(x).arg(y));
cursor.cursorText->position->setCoords(QPointF(x, y));
QPointF pp = cursor.cursorText->position->pixelPosition() + QPointF(50.0, -15.0);
cursor.cursorText->position->setPixelPosition(pp);
}
As a test, if I plot 10 000 000 points, and set USING_LAYER to false, I will notice a clear lag on the cursor when moving the mouse. While setting it to true, will result in a smooth cursor movement.
I'm trying to make an horizontal layout with 3 QLabel scale use all its available space. More specifically, this is what I have
this is what I am aiming for
At the moment, the second image is achieved by changing the stylesheet of the qlabels with a slider. Additionally, since I have the the three labels in a layout inside a groupbox, the groupbox resizes to fit its contents, cool.
Now I wanted to drop the slider approach and instead autofit the space available when moving the splitters. In this question, OP reimplements the resizeEvent, and I've seen other posts suggesting the same, changing point by point with this while( !doesFit ) or something similar.
I tried using this approach, both on the resize event and on the splitterMoved event. However, this approach is way prone to feedback loops and other display errors caused. In the other question, they suggest enabling ignoreSizePolicy to prevent the size policy retriggering the sizeevent, but I like how qt handles the size of the layout, how it keeps a minimum size and then it folds the widget if the user insists. Maybe it would work if the HLayout would ignore the resize events triggered by the QLabels, still IMHO unclean thought.
I was wondering if that's the recommended way of achieving this, and wether a less unstable solution exists, maybe using using stylesheets. There are some behaviours that I could also drop, the minimum size limit (so the user could potentially hide the groupbox).
If that's the recommended way of doing it, how should I use the fontmetrics if I have three separate labels, one of which (the number) changes its text dynamically and rapidly? It should not have an impact on performance, and that while loop makes me wary.
It doesn't sound like the while(!fit) approach is going to cut it. Or does it?
--- Edit regarding the duplicate question
Another post creates an event filter, which might also work if reworked to deal with a layout with 3 labels. I finally used a version of the first mentioned post with the variation of the post mentioned in the comments. I'll post the answer if the question is reopened.
One could apply the Newton's method approach from this answer to work on all widgets in a given layout. It will work on any widget with a settable font, not only on a QLabel.
The Newton's algorithm converges reasonably quickly when given a good starting point, e.g. when resizing interactively. It's not atypical to have the loop execute only once. On the other hand, QWidget::sizeHint is integer-valued and and widgets may round fractional font sizes, thus sometimes the iteration is a bit slower than one would expect. The number of iterations is capped to ensure decent performance.
A custom replacement for the label, that provided a QSizeF sizeHintF(), would work better here.
The minimum sizing for the widgets is a bit of a stretch, as the size is not updated as the widget contents change. This could be remedied easily, though.
// https://github.com/KubaO/stackoverflown/tree/master/questions/label-text-size-vert-40861305
#include <QtWidgets>
class LabelStretcher : public QObject {
Q_OBJECT
static constexpr const char kMinimumsAcquired[] = "ls_minimumsAcquired";
static constexpr const char kStretcherManaged[] = "ls_stretcherManaged";
public:
LabelStretcher(QObject *parent = 0) : QObject(parent) {
apply(qobject_cast<QWidget*>(parent));
}
void apply(QWidget *widget) {
if (!widget) return;
setManaged(widget);
setMinimumSize(widget);
widget->installEventFilter(this);
}
void setManaged(QWidget *w, bool managed = true) {
w->setProperty(kStretcherManaged, managed);
}
protected:
bool eventFilter(QObject * obj, QEvent * ev) override {
auto widget = qobject_cast<QWidget*>(obj);
if (widget && ev->type() == QEvent::Resize)
resized(widget);
return false;
}
private:
void onLayout(QLayout *layout, const std::function<void(QWidget*)> &onWidget) {
if (!layout) return;
auto N = layout->count();
for (int i = 0; i < N; ++i) {
auto item = layout->itemAt(i);
onWidget(item->widget());
onLayout(item->layout(), onWidget);
}
}
void setFont(QLayout *layout, const QFont &font) {
onLayout(layout, [&](QWidget *widget){ setFont(widget, font); });
}
void setFont(QWidget *widget, const QFont &font) {
if (!widget || !widget->property(kStretcherManaged).toBool()) return;
widget->setFont(font);
setFont(widget->layout(), font);
}
void setMinimumSize(QWidget *widget) {
if (widget->layout()) return;
widget->setMinimumSize(widget->minimumSizeHint());
}
static int dSize(const QSizeF & inner, const QSizeF & outer) {
auto dy = inner.height() - outer.height();
auto dx = inner.width() - outer.width();
return std::max(dx, dy);
}
qreal f(qreal fontSize, QWidget *widget) {
auto font = widget->font();
font.setPointSizeF(fontSize);
setFont(widget, font);
auto d = dSize(widget->sizeHint(), widget->size());
qDebug() << "f:" << fontSize << "d" << d;
return d;
}
qreal df(qreal fontSize, qreal dStep, QWidget *widget) {
fontSize = std::max(dStep + 1.0, fontSize);
return (f(fontSize + dStep, widget) - f(fontSize - dStep, widget)) / dStep;
}
void resized(QWidget *widget) {
qDebug() << "pre: " << widget->minimumSizeHint() << widget->sizeHint() << widget->size();
if (!widget->property(kMinimumsAcquired).toBool()) {
onLayout(widget->layout(), [=](QWidget *widget){ setMinimumSize(widget); });
widget->setProperty(kMinimumsAcquired, true);
}
// Newton's method
auto font = widget->font();
auto fontSize = font.pointSizeF();
qreal dStep = 1.0;
int i;
for (i = 0; i < 10; ++i) {
auto prevFontSize = fontSize;
auto d = df(fontSize, dStep, widget);
if (d == 0) {
dStep *= 2.0;
continue;
}
fontSize -= f(fontSize, widget)/d;
fontSize = std::max(dStep + 1.0, fontSize);
auto change = fabs(prevFontSize - fontSize)/fontSize;
qDebug() << "d:" << d << " delta" << change;
if (change < 0.01) break; // we're within 1% of target
}
font.setPointSizeF(fontSize);
setFont(widget, font);
qDebug() << "post:" << i << widget->minimumSizeHint() << widget->sizeHint() << widget->size();
}
};
constexpr const char LabelStretcher::kMinimumsAcquired[];
constexpr const char LabelStretcher::kStretcherManaged[];
int main(int argc, char ** argv) {
QApplication app{argc, argv};
QWidget w;
QGridLayout layout{&w};
LabelStretcher stretch{&w};
QLabel labels[6];
QString texts[6] = {"V", "30.0", "kts", "H", "400.0", "ft"};
int i = 0, j = 0, k = 0;
for (auto & label : labels) {
stretch.setManaged(&label);
label.setFrameStyle(QFrame::Box);
label.setText(texts[k++]);
if (j == 0) label.setAlignment(Qt::AlignRight | Qt::AlignVCenter);
else if (j == 1) label.setAlignment(Qt::AlignCenter);
layout.addWidget(&label, i, j++);
if (j >= 3) { i++; j=0; }
}
w.show();
return app.exec();
}
#include "main.moc"
Althought I consider KubaOber's answer better, I'll post this in case it's helpful to someone who wants a solution in the line of the answers mentioned in the post.
Note that the sampletext could be retrieved from the labels as well, the font from the stylesheet, and the code could potentially be placed on a resizeEvent of the groupbox or layout. It wouldn't work on the resizeEvent of the labels since they would compete for the space.
That is one reason why KubaOber answer is superior. Other reasons I can think of is stability given that the 3 labels space differs from the sampletext, thus the font size is not as accurate as it could be. Therefore a resize event could potentially be triggered again by the font change.
static void fitGroupBoxLabels(QGroupBox* groupbox, const QFont &samplefont, const QLayout* const samplelayout)
{
groupbox->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
QString sampletext = "V 1000.0 kts";
QRect availablerect = samplelayout->contentsRect();
if(samplefont.pointSizeF() <= 0) return; //not initalized yet, return
QRect textrect = QFontMetrics(samplefont).boundingRect(sampletext);
if(!textrect.isValid() || !availablerect.isValid()) return; //not initalized yet, return
float factorh = availablerect.width() / (float)textrect.width();
float factorw = availablerect.height() / (float)textrect.height();
float factor = std::min(factorh, factorw);
if (factor < 0.95 || factor > 1.05)
{
float fontSize = samplefont.pointSizeF()*factor;
QString groupBoxStyle = QString("QGroupBox{font-size:8pt} QLabel{font-size:%1pt}").arg(fontSize);
groupbox->setStyleSheet(groupBoxStyle);
}
}
After struggling with this issue, I create DynamicFontSizeLabel and DynamicFontSizePushButton widgets. Hope it helps.
https://github.com/jonaias/DynamicFontSizeWidgets/
This is the output of what I have done till now:
Although this shows only black and white images, the code works for color images too. The code basically populates the larger image using smaller images from a small database.
So this is where I am stuck, rather clueless.
How can I get an effect like this one. or this one.
Qn1 : I need to take another input(large) image*(One for which the effect is to be seen)* and merge them, but how?
Qn2 : How can I evaluate the goodness of the photo-mosaic? I have a genetic algorithm written for this but am unable to fix the fitness function,(mutation and crossover work perfectly).
This is what I could think of(for Qn1):
1. Take alternate pixels of the image shown above and the image for which the mosaic has to be made.
2. Take average of the pixel values of the above and input image for which the mosaic has to be made.
But have no clue to evaluate the goodness.
Below is a self contained sketch. The mosaicing algorithm is mid-way through the algorithms implemented in an excellent reference. It works well enough for two hours of work, I think. I tried for the code to be reasonably correct, with two caveats, left, as they say, as an exercise to the reader.
I'm not tracking the worker threads - if you try to exit the application while workers are active, it is expected to crash on exit. This is not nice, but otherwise benign and doesn't affect the overall functionality. There may be a few corrupt images left on disk, but those should be ignored when reloading.
There is no scaling of the image displayed in the label. The window will resize to the image size.
The tile image database can be filled with random images from imgur, you can also fill it with your own images by storing them on disk yourself. It's located in a standard application data path suffixed by /so-photomosaic/image. The fetched images are added there. Upon startup, the image database is repopulated from disk in the background - that's how your own tile images would be loaded. In fact, all of image processing is done in non-GUI threads. On a rather unassuming 5 year old Core 2 OS X system, disk image loading proceeds at about 5000 images/s. The images requested from imgur are their small size, or 90x90.
The tile matching is done with a 4x4 subdivision grid (divs parameter to calcPropsFor). The images are downsampled to a 4x4 mosaic, and the RGB color values of consecutive pixels in that grid are stored in Props vectors. The squared sums of differences of elements of those vectors are the measure of fit. For each tile to be replaced, the images are sorted according to their fit, and one of the best ones are picked up at random. The randomness parameter is a power-of-to of the sample size from which the image is randomly selected.
It uses Qt 5 and C++11. Length: 300 lines, out of which 64 are the random image source, 25 are the disk image database, and 88 are actually to do with mosaics. The image processing code would probably look and perform better if OpenCV or Eigen was used instead of valarray/QImage, but oh well.
Also, all of this would be probably 50 lines in Mathematica :)
# main.pro
# Make sure to re-run quake once this is set.
TEMPLATE = app
QT += widgets network concurrent
CONFIG += c++11
SOURCES += main.cpp
TARGET = photomosaic
#include <QApplication>
#include <QLabel>
#include <QSlider>
#include <QPushButton>
#include <QCheckBox>
#include <QBoxLayout>
#include <QFileDialog>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QRegularExpression>
#include <QImage>
#include <QPainter>
#include <QColor>
#include <QAtomicInt>
#include <QMutex>
#include <QtConcurrent>
#include <QStandardPaths>
#include <algorithm>
#include <functional>
#include <valarray>
/// Provides random images. There may be more than one response per request.
class RandomImageSource : public QObject {
Q_OBJECT
int m_parallelism;
bool m_auto;
QNetworkAccessManager m_mgr;
QSet<QNetworkReply*> m_replies;
QList<QUrl> m_deferred;
QRegularExpression m_imgTagRE, m_imgUrlRE;
QUrl m_randomGallery;
void get(const QUrl & url) {
if (m_replies.count() < m_parallelism) {
QNetworkRequest req(url);
req.setAttribute(QNetworkRequest::HttpPipeliningAllowedAttribute, true);
m_replies.insert(m_mgr.get(req));
} else
m_deferred << url;
}
void finishReply(QNetworkReply * reply) {
m_replies.remove(reply);
if (reply) reply->deleteLater();
if (! m_deferred.isEmpty()) get(m_deferred.takeLast());
while (m_deferred.isEmpty() && m_auto) get(m_randomGallery);
}
Q_SLOT void rsp(QNetworkReply * reply) {
auto loc = reply->header(QNetworkRequest::LocationHeader);
if (loc.isValid()) {
get(loc.toUrl()); // redirect
} else {
auto ct = reply->header(QNetworkRequest::ContentTypeHeader).toString();
if (ct.startsWith("text/html"))
foreach (QUrl url, parseImageUrls(reply->readAll()))
get(url);
else if (ct.startsWith("image")) {
auto img = QImage::fromData(reply->readAll());
img.setText("filename", m_imgUrlRE.match(reply->url().toString()).captured(1));
if (!img.isNull()) emit rspImage(img);
}
}
finishReply(reply);
}
QList<QUrl> parseImageUrls(const QByteArray & html) {
QList<QUrl> urls;
auto it = m_imgTagRE.globalMatch(QString::fromUtf8(html));
while (it.hasNext()) { auto match = it.next(); // get small images
urls << QUrl("http:" + match.captured(1) + "s" + match.captured(2)); }
return urls;
}
public:
RandomImageSource(QObject * parent = 0) : QObject (parent),
m_parallelism(20), m_auto(false),
m_imgTagRE("<img src=\"(//i\\.imgur\\.com/[^.]+)(\\.[^\"]+)\""),
m_imgUrlRE("http://i\\.imgur\\.com/(.+)$"),
m_randomGallery("http://imgur.com/gallery/random")
{
connect(&m_mgr, SIGNAL(finished(QNetworkReply*)), SLOT(rsp(QNetworkReply*)));
}
Q_SLOT void reqImages(int count) {
while (count--) get(m_randomGallery);
}
Q_SIGNAL void rspImage(const QImage &);
bool automatic() const { return m_auto; }
Q_SLOT void setAutomatic(bool a) { if ((m_auto = a)) finishReply(0); }
int parallelism() const { return m_parallelism; }
Q_SLOT void setParallelism(int p) { m_parallelism = p; if (m_auto) finishReply(0); }
};
/// Stores images on disk, and loads them in the background.
class ImageStorage : public QObject {
Q_OBJECT
QString const m_path;
public:
ImageStorage() :
m_path(QStandardPaths::writableLocation(QStandardPaths::DataLocation)
+ "/images/")
{ QDir().mkpath(m_path); }
Q_SLOT void addImage(const QImage & img) {
QString path = img.text("filename");
if (path.isEmpty()) return;
path.prepend(m_path);
QtConcurrent::run([img, path]{ img.save(path); });
}
Q_SLOT void retrieveAll() {
QString const path = m_path;
QtConcurrent::run([this, path] {
QStringList const images = QDir(path).entryList(QDir::Files);
foreach (QString image, images) QtConcurrent::run([this, image, path] {
QImage img; if (img.load(path + image)) emit retrieved(img);
});
});
}
Q_SIGNAL void retrieved(const QImage &);
};
/// A memory database of images. Finds best match to a given image.
class ImageDatabase : public QObject {
Q_OBJECT
typedef std::valarray<qreal> Props;
typedef QPair<QImage, Props> ImageProps;
QMutex mutable m_mutex;
QList<ImageProps> m_images;
static void inline addProps(Props & p, int i, QRgb rgb) {
QColor const c = QColor::fromRgb(rgb);
p[i+0] += c.redF(); p[i+1] += c.greenF(); p[i+2] += c.blueF();
}
static Props calcPropsFor(const QImage & img, int divs = 4) {
Props props(0.0, 3 * divs * divs);
std::valarray<int> counts(0, divs * divs);
QSize div = img.size() / divs;
for (int y = 0; y < img.height(); ++y)
for (int x = 0; x < img.width(); ++x) {
int slice = x/div.width() + (y*divs/div.height());
if (slice >= divs*divs) continue;
addProps(props, slice*3, img.pixel(x, y));
counts[slice] ++;
}
for (size_t i = 0; i < props.size(); ++i) props[i] /= counts[i/3];
return props;
}
public:
Q_SIGNAL void newImageCount(int);
Q_SLOT void addImage(const QImage & img) {
QtConcurrent::run([this, img]{
Props props = calcPropsFor(img);
QMutexLocker lock(&m_mutex);
m_images << qMakePair(img, props);
int count = m_images.count();
lock.unlock();
emit newImageCount(count);
});
}
ImageProps bestMatchFor(const QImage & img, int randLog2) const {
QMutexLocker lock(&m_mutex);
QList<ImageProps> const images = m_images;
lock.unlock();
Props const props = calcPropsFor(img);
typedef QPair<qreal, const ImageProps *> Match;
QList<Match> matches; matches.reserve(images.size());
std::transform(images.begin(), images.end(), std::back_inserter(matches),
[props](const ImageProps & prop){
return qMakePair(pow(props - prop.second, 2).sum(), &prop);
});
std::sort(matches.begin(), matches.end(),
[](Match a, Match b) { return b.first < a.first; });
randLog2 = 1<<randLog2;
return *(matches.end()-randLog2+qrand()%randLog2)->second;
}
};
QImage getMosaic(QImage img, const ImageDatabase & db, int size, int randLog2)
{
QPainter p(&img);
for (int y = 0; y < img.height(); y += size)
for (int x = 0; x < img.width(); x += size) {
QImage r = db.bestMatchFor(img.copy(x, y, size, size), randLog2).first
.scaled(size, size, Qt::KeepAspectRatio, Qt::SmoothTransformation);
p.drawImage(x, y, r);
}
return img;
}
class MosaicGenerator : public QObject {
Q_OBJECT
QPointer<ImageDatabase> m_db;
int m_size, m_randLog2;
QAtomicInt m_busy;
QImage m_image;
void update() {
if (m_image.isNull() || m_busy.fetchAndAddOrdered(1)) return;
QImage image = m_image;
QtConcurrent::run([this, image]{ while (true) {
emit hasMosaic(getMosaic(image, *m_db, m_size, m_randLog2));
if (m_busy.testAndSetOrdered(1, 0)) return;
m_busy.fetchAndStoreOrdered(1);
}});
}
public:
MosaicGenerator(ImageDatabase * db) : m_db(db), m_size(16), m_randLog2(0) {}
Q_SLOT void setImage(const QImage & img) { m_image = img; update(); }
Q_SLOT void setSize(int s) { m_size = s; update(); }
Q_SLOT void setRandLog2(int r) { m_randLog2 = r; update(); }
Q_SIGNAL void hasMosaic(const QImage &);
};
class Window : public QWidget {
Q_OBJECT
bool m_showSource;
QImage m_source, m_mosaic;
QBoxLayout m_layout;
QSlider m_parallelism, m_cellSize, m_randomness;
QLabel m_imgCount, m_parCount, m_image;
QPushButton m_add, m_load, m_toggle;
MosaicGenerator m_gen;
Q_SIGNAL void newSource(const QImage &);
void updateImage() {
const QImage & img = m_showSource ? m_source : m_mosaic;
m_image.setPixmap(QPixmap::fromImage(img));
}
public:
Window(ImageDatabase * db, QWidget * parent = 0) : QWidget(parent),
m_showSource(true), m_layout(QBoxLayout::TopToBottom, this),
m_parallelism(Qt::Horizontal), m_cellSize(Qt::Horizontal),
m_randomness(Qt::Horizontal), m_add("Fetch Images"),
m_load("Open for Mosaic"), m_toggle("Toggle Mosaic"), m_gen(db)
{
QBoxLayout * row = new QBoxLayout(QBoxLayout::LeftToRight);
row->addWidget(new QLabel("Images in DB:"));
row->addWidget(&m_imgCount);
row->addWidget(new QLabel("Fetch parallelism:"));
row->addWidget(&m_parallelism);
row->addWidget(&m_parCount);
row->addWidget(&m_add);
m_parallelism.setRange(1, 100);
m_layout.addLayout(row);
m_layout.addWidget(&m_image);
row = new QBoxLayout(QBoxLayout::LeftToRight);
row->addWidget(new QLabel("Cell Size:"));
row->addWidget(&m_cellSize);
row->addWidget(new QLabel("Randomness:"));
row->addWidget(&m_randomness);
m_cellSize.setRange(4, 64); m_cellSize.setTracking(false);
m_randomness.setRange(0,6); m_randomness.setTracking(false);
m_layout.addLayout(row);
row = new QBoxLayout(QBoxLayout::LeftToRight);
row->addWidget(&m_load);
row->addWidget(&m_toggle);
m_layout.addLayout(row);
m_add.setCheckable(true);
m_parCount.connect(&m_parallelism, SIGNAL(valueChanged(int)), SLOT(setNum(int)));
connect(&m_add, SIGNAL(clicked(bool)), SIGNAL(reqAutoFetch(bool)));
connect(&m_parallelism, SIGNAL(valueChanged(int)), SIGNAL(reqParallelism(int)));
m_gen.connect(&m_cellSize, SIGNAL(valueChanged(int)), SLOT(setSize(int)));
m_gen.connect(&m_randomness, SIGNAL(valueChanged(int)), SLOT(setRandLog2(int)));
m_parallelism.setValue(20);
m_cellSize.setValue(16);
m_randomness.setValue(4);
connect(&m_load, &QPushButton::clicked, [this]{
QString file = QFileDialog::getOpenFileName(this);
QtConcurrent::run([this, file]{
QImage img; if (!img.load(file)) return;
emit newSource(img);
});
});
connect(this, &Window::newSource, [this](const QImage &img){
m_source = m_mosaic = img; updateImage(); m_gen.setImage(m_source);
});
connect(&m_gen, &MosaicGenerator::hasMosaic, [this](const QImage &img){
m_mosaic = img; updateImage();
});
connect(&m_toggle, &QPushButton::clicked, [this]{
m_showSource = !m_showSource; updateImage();
});
}
Q_SLOT void setImageCount(int n) { m_imgCount.setNum(n); }
Q_SIGNAL void reqAutoFetch(bool);
Q_SIGNAL void reqParallelism(int);
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
a.setOrganizationDomain("stackoverflow.com");
a.setApplicationName("so-photomosaic");
RandomImageSource src;
ImageDatabase db;
ImageStorage stg;
Window ui(&db);
db.connect(&src, SIGNAL(rspImage(QImage)), SLOT(addImage(QImage)));
stg.connect(&src, SIGNAL(rspImage(QImage)), SLOT(addImage(QImage)));
db.connect(&stg, SIGNAL(retrieved(QImage)), SLOT(addImage(QImage)));
ui.connect(&db, SIGNAL(newImageCount(int)), SLOT(setImageCount(int)));
src.connect(&ui, SIGNAL(reqAutoFetch(bool)), SLOT(setAutomatic(bool)));
src.connect(&ui, SIGNAL(reqParallelism(int)), SLOT(setParallelism(int)));
stg.retrieveAll();
ui.show();
return a.exec();
}
#include "main.moc"