From 9ea334d08f42f3c362e86499dc3c0ed658bb428c Mon Sep 17 00:00:00 2001
From: keshavbhatt <keshavnrj@gmail.com>
Date: Mon, 5 Apr 2021 02:11:25 +0530
Subject: src init

---
 src/widgets/scrolltext/scrolltext.cpp | 179 ++++++++++++++++++++++++++++++++++
 1 file changed, 179 insertions(+)
 create mode 100644 src/widgets/scrolltext/scrolltext.cpp

(limited to 'src/widgets/scrolltext/scrolltext.cpp')

diff --git a/src/widgets/scrolltext/scrolltext.cpp b/src/widgets/scrolltext/scrolltext.cpp
new file mode 100644
index 0000000..00696af
--- /dev/null
+++ b/src/widgets/scrolltext/scrolltext.cpp
@@ -0,0 +1,179 @@
+#include "scrolltext.h"
+#include <QPainter>
+#include <QHoverEvent>
+
+ScrollText::ScrollText(QWidget *parent) :
+    QWidget(parent), scrollPos(0)
+{
+
+    staticText.setTextFormat(Qt::PlainText);
+
+    setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding);
+
+    setMinimumHeight(fontMetrics().height()+10);
+    setMaximumHeight(this->minimumHeight()+6);
+
+    leftMargin = 0; //height() / 3;
+
+    setSeparator("        ");
+
+    connect(&timer, SIGNAL(timeout()), this, SLOT(timer_timeout()));
+    timer.setInterval(50);
+}
+
+QString ScrollText::text() const
+{
+    return _text;
+}
+
+void ScrollText::setText(QString text)
+{
+    _text = text;
+    updateText();
+    update();
+}
+
+QString ScrollText::separator() const
+{
+    return _separator;
+}
+
+void ScrollText::setSeparator(QString separator)
+{
+    _separator = separator;
+    updateText();
+    update();
+}
+
+void ScrollText::setLeftMargin(int pixels)
+{
+    leftMargin = pixels;
+    update();
+}
+
+void ScrollText::pause()
+{
+    if(scrollEnabled){
+        timer.stop();
+    }
+}
+
+void ScrollText::resume()
+{
+    if(scrollEnabled){
+        timer.start();
+        scrolledOnce = false;
+    }
+}
+
+void ScrollText::updateText()
+{
+    scrolledOnce = false;
+    timer.stop();
+
+    singleTextWidth = fontMetrics().horizontalAdvance(_text);
+//    scrollEnabled = true;
+      scrollEnabled  = (singleTextWidth > width() - leftMargin);
+
+    if(scrollEnabled)
+    {
+        scrollPos = -64;
+        staticText.setText(_text + _separator);
+        timer.start();
+    }
+    else{
+        staticText.setText(_text);
+    }
+    staticText.prepare(QTransform(), font());
+    //wholeTextSize = QSize(fontMetrics().width(staticText.text()), fontMetrics().height());
+    wholeTextSize = QSize(fontMetrics().horizontalAdvance(staticText.text()), fontMetrics().height());
+
+}
+
+void ScrollText::paintEvent(QPaintEvent*)
+{
+    QPainter p(this);
+
+    if(scrollEnabled)
+    {
+        buffer.fill(qRgba(0, 0, 0, 0));
+        QPainter pb(&buffer);
+        pb.setPen(p.pen());
+        pb.setFont(p.font());
+
+        int x = qMin(-scrollPos, 0) + leftMargin;
+        while(x < width())
+        {
+            pb.drawStaticText(QPointF(x, (height() - wholeTextSize.height()) / 2) + QPoint(2, 2), staticText);
+            x += wholeTextSize.width();
+        }
+
+        //Apply Alpha Channel
+        pb.setCompositionMode(QPainter::CompositionMode_DestinationIn);
+        pb.setClipRect(width() - 15, 0, 15, height());
+        pb.drawImage(0, 0, alphaChannel);
+        pb.setClipRect(0, 0, 15, height());
+        //initial situation: don't apply alpha channel in the left half of the image at all; apply it more and more until scrollPos gets positive
+        if(scrollPos < 0)
+            pb.setOpacity((qreal)(qMax(-8, scrollPos) + 8) / 8.0);
+        pb.drawImage(0, 0, alphaChannel);
+        p.drawImage(0, 0, buffer);
+    }
+    else
+    {
+        p.drawText(QRectF(0, 0, width(), height()), Qt::AlignCenter, text());
+//      p.drawStaticText(QPointF(leftMargin, (height() - wholeTextSize.height()) / 2), staticText);
+    }
+}
+
+void ScrollText::resizeEvent(QResizeEvent*)
+{
+    //When the widget is resized, we need to update the alpha channel.
+
+    alphaChannel = QImage(size(), QImage::Format_ARGB32_Premultiplied);
+    buffer = QImage(size(), QImage::Format_ARGB32_Premultiplied);
+
+    //Create Alpha Channel:
+    if(width() > 64)
+    {
+        //create first scanline
+        QRgb* scanline1 = (QRgb*)alphaChannel.scanLine(0);
+        for(int x = 1; x < 16; ++x)
+            scanline1[x - 1] = scanline1[width() - x] = qRgba(0, 0, 0, x << 4);
+        for(int x = 15; x < width() - 15; ++x)
+            scanline1[x] = qRgb(0, 0, 0);
+        //copy scanline to the other ones
+        for(int y = 1; y < height(); ++y)
+            memcpy(alphaChannel.scanLine(y), (uchar*)scanline1, width() * 4);
+    }
+    else
+        alphaChannel.fill(qRgb(0, 0, 0));
+
+
+    //Update scrolling state
+    bool newScrollEnabled = (singleTextWidth > width() - leftMargin);
+    if(newScrollEnabled != scrollEnabled)
+        updateText();
+}
+
+void ScrollText::timer_timeout()
+{
+    scrollPos = (scrollPos + 2)
+                % wholeTextSize.width();
+    pauseAfterOneRotation(scrollPos);
+    update();
+}
+
+void ScrollText::pauseAfterOneRotation(int scrollPos)
+{
+    if(scrolledOnce == false && scrollPos+2==wholeTextSize.width()){
+        scrolledOnce = true;
+    }
+    if(scrolledOnce){
+        pause();
+    }
+}
+
+
+
+
-- 
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