Basic support for transparency

PdfForQtLib/sources/pdfblendfunction.cpp

@@ -0,0 +1,132 @@
+//    Copyright (C) 2019 Jakub Melka
+//
+//    This file is part of PdfForQt.
+//
+//    PdfForQt is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Lesser General Public License as published by
+//    the Free Software Foundation, either version 3 of the License, or
+//    (at your option) any later version.
+//
+//    PdfForQt 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 Lesser General Public License for more details.
+//
+//    You should have received a copy of the GNU Lesser General Public License
+//    along with PDFForQt.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "pdfblendfunction.h"
+
+namespace pdf
+{
+
+constexpr const std::pair<const char*, BlendMode> BLEND_MODE_INFOS[] =
+{
+    { "Normal", BlendMode::Normal },
+    { "Multiply", BlendMode::Multiply },
+    { "Screen", BlendMode::Screen },
+    { "Overlay", BlendMode::Overlay },
+    { "Darken", BlendMode::Darken },
+    { "Lighten", BlendMode::Lighten },
+    { "ColorDodge", BlendMode::ColorDodge },
+    { "ColorBurn", BlendMode::ColorBurn },
+    { "HardLight", BlendMode::HardLight },
+    { "SoftLight", BlendMode::SoftLight },
+    { "Difference", BlendMode::Difference },
+    { "Exclusion", BlendMode::Exclusion },
+    { "Hue", BlendMode::Hue },
+    { "Saturation", BlendMode::Saturation },
+    { "Color", BlendMode::Color },
+    { "Luminosity", BlendMode::Luminosity },
+    { "Compatible", BlendMode::Compatible }
+};
+
+BlendMode PDFBlendModeInfo::getBlendMode(const QByteArray& name)
+{
+    for (const std::pair<const char*, BlendMode>& info : BLEND_MODE_INFOS)
+    {
+        if (info.first == name)
+        {
+            return info.second;
+        }
+    }
+
+    return BlendMode::Invalid;
+}
+
+bool PDFBlendModeInfo::isSupportedByQt(BlendMode mode)
+{
+    switch (mode)
+    {
+       case BlendMode::Normal:
+       case BlendMode::Multiply:
+       case BlendMode::Screen:
+       case BlendMode::Overlay:
+       case BlendMode::Darken:
+       case BlendMode::Lighten:
+       case BlendMode::ColorDodge:
+       case BlendMode::ColorBurn:
+       case BlendMode::HardLight:
+       case BlendMode::SoftLight:
+       case BlendMode::Difference:
+       case BlendMode::Exclusion:
+       case BlendMode::Compatible:
+            return true;
+
+        default:
+            return false;
+    }
+}
+
+QPainter::CompositionMode PDFBlendModeInfo::getCompositionModeFromBlendMode(BlendMode mode)
+{
+    switch (mode)
+    {
+        case BlendMode::Normal:
+            return QPainter::CompositionMode_SourceOver;
+        case BlendMode::Multiply:
+            return QPainter::CompositionMode_Multiply;
+        case BlendMode::Screen:
+            return QPainter::CompositionMode_Screen;
+        case BlendMode::Overlay:
+            return QPainter::CompositionMode_Overlay;
+        case BlendMode::Darken:
+            return QPainter::CompositionMode_Darken;
+        case BlendMode::Lighten:
+            return QPainter::CompositionMode_Lighten;
+        case BlendMode::ColorDodge:
+            return QPainter::CompositionMode_ColorDodge;
+        case BlendMode::ColorBurn:
+            return QPainter::CompositionMode_ColorBurn;
+        case BlendMode::HardLight:
+            return QPainter::CompositionMode_HardLight;
+        case BlendMode::SoftLight:
+            return QPainter::CompositionMode_SoftLight;
+        case BlendMode::Difference:
+            return QPainter::CompositionMode_Difference;
+        case BlendMode::Exclusion:
+            return QPainter::CompositionMode_Exclusion;
+        case BlendMode::Compatible:
+            return QPainter::CompositionMode_SourceOver;
+
+        default:
+            break;
+    }
+
+    return QPainter::CompositionMode_SourceOver;
+}
+
+QString PDFBlendModeInfo::getBlendModeName(BlendMode mode)
+{
+    for (const std::pair<const char*, BlendMode>& info : BLEND_MODE_INFOS)
+    {
+        if (info.second == mode)
+        {
+            return QString::fromLatin1(info.first);
+        }
+    }
+
+    return "Unknown";
+}
+
+}   // namespace pdf