aboutdialog: support patreon list

app/dialog/about/scrollinglabel.cpp

@@ -0,0 +1,121 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2021 Olive Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "scrollinglabel.h"
+
+#include <QPainter>
+
+#include "common/qtutils.h"
+
+namespace olive {
+
+const int ScrollingLabel::kMinLineHeight = 5;
+
+ScrollingLabel::ScrollingLabel(QWidget *parent) :
+  QWidget(parent),
+  animate_(0)
+{
+  timer_.setInterval(50);
+  connect(&timer_, &QTimer::timeout, this, &ScrollingLabel::AnimationUpdate);
+}
+
+ScrollingLabel::ScrollingLabel(const QStringList &text, QWidget *parent) :
+  ScrollingLabel(parent)
+{
+  SetText(text);
+}
+
+void ScrollingLabel::SetText(const QStringList &text)
+{
+  text_ = text;
+
+  QFontMetrics fm = fontMetrics();
+  text_height_ = fm.height();
+
+  int width = 0;
+  foreach (const QString& s, text_) {
+    width = qMax(width, QtUtils::QFontMetricsWidth(fm, s));
+  }
+
+  setMinimumSize(width, text_height_ * kMinLineHeight);
+}
+
+void ScrollingLabel::paintEvent(QPaintEvent *e)
+{
+  QImage map(width(), height(), QImage::Format_RGBA8888_Premultiplied);
+  map.fill(Qt::transparent);
+
+  {
+    QPainter p(&map);
+    p.setPen(palette().text().color());
+
+    QFontMetrics fm = p.fontMetrics();
+    int half_width = width();
+
+    for (int i=0; i<text_.size(); i++) {
+      int text_y = fm.ascent() + height() - animate_ + (fm.height()*i);
+      int text_bottom = text_y + fm.descent();
+      int text_top = text_y - fm.ascent();
+
+      if (text_bottom < 0 || text_top >= height()) {
+        continue;
+      }
+
+      const QString& s = text_.at(i);
+
+      int width = QtUtils::QFontMetricsWidth(fm, s);
+      p.drawText(half_width/2 - width/2, text_y, s);
+    }
+
+    for (int y=0; y<text_height_; y++) {
+      double mul = double(y)/double(text_height_);
+
+      SetOpacityOfScanLine(map.scanLine(y), map.width(), 4, mul);
+      SetOpacityOfScanLine(map.scanLine(map.height()-1-y), map.width(), 4, mul);
+    }
+  }
+
+  QPainter wp(this);
+  wp.drawImage(0, 0, map);
+}
+
+void ScrollingLabel::SetOpacityOfScanLine(uchar *scan_line, int width, int channels, double mul)
+{
+  for (int x=0; x<width; x++) {
+    uchar* pixel = &scan_line[x*4];
+
+    for (int c=0; c<channels; c++) {
+      pixel[c] *= mul;
+    }
+  }
+}
+
+void ScrollingLabel::AnimationUpdate()
+{
+  animate_++;
+
+  if (animate_ >= height() + text_.size() * text_height_) {
+    animate_ = 0;
+  }
+
+  update();
+}
+
+}