Add alpha multiplier to QCustom3DVolume api

Change-Id: I856c4166513f6d6f7b73fd52bc46d52ab1b8fdff
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>
Reviewed-by: Mika Salmela <mika.salmela@digia.com>

5 files changed, 216 insertions, 75 deletions

diff --git a/src/datavisualization/data/customrenderitem.cpp b/src/datavisualization/data/customrenderitem.cpp
index 3eb68845..c316fd38 100644
--- a/src/datavisualization/data/customrenderitem.cpp
+++ b/src/datavisualization/data/customrenderitem.cpp
@@ -36,7 +36,13 @@ CustomRenderItem::CustomRenderItem()
       m_textureWidth(0),
       m_textureHeight(0),
       m_textureDepth(0),
-      m_isVolume(false)
+      m_isVolume(false),
+      m_textureFormat(QImage::Format_ARGB32),
+      m_sliceIndexX(-1),
+      m_sliceIndexY(-1),
+      m_sliceIndexZ(-1),
+      m_alphaMultiplier(1.0f),
+      m_preserveOpacity(true)
 {
 }
 
diff --git a/src/datavisualization/data/customrenderitem_p.h b/src/datavisualization/data/customrenderitem_p.h
index e21b6f39..5428ce43 100644
--- a/src/datavisualization/data/customrenderitem_p.h
+++ b/src/datavisualization/data/customrenderitem_p.h
@@ -89,9 +89,13 @@ public:
     inline void setSliceIndexX(int index) { m_sliceIndexX = index; }
     inline void setSliceIndexY(int index) { m_sliceIndexY = index; }
     inline void setSliceIndexZ(int index) { m_sliceIndexZ = index; }
-    int sliceIndexX() const { return m_sliceIndexX; }
-    int sliceIndexY() const { return m_sliceIndexY; }
-    int sliceIndexZ() const { return m_sliceIndexZ; }
+    inline int sliceIndexX() const { return m_sliceIndexX; }
+    inline int sliceIndexY() const { return m_sliceIndexY; }
+    inline int sliceIndexZ() const { return m_sliceIndexZ; }
+    inline void setAlphaMultiplier(float mult) { m_alphaMultiplier = mult; }
+    inline float alphaMultiplier() const { return m_alphaMultiplier; }
+    inline void setPreserveOpacity(bool enable) { m_preserveOpacity = enable; }
+    inline bool preserveOpacity() const { return m_preserveOpacity; }
 
 private:
     Q_DISABLE_COPY(CustomRenderItem)
@@ -120,6 +124,8 @@ private:
     int m_sliceIndexX;
     int m_sliceIndexY;
     int m_sliceIndexZ;
+    float m_alphaMultiplier;
+    bool m_preserveOpacity;
 };
 typedef QHash<QCustom3DItem *, CustomRenderItem *> CustomRenderItemArray;
 
diff --git a/src/datavisualization/data/qcustom3dvolume.cpp b/src/datavisualization/data/qcustom3dvolume.cpp
index cab79ac0..c1a77dba 100644
--- a/src/datavisualization/data/qcustom3dvolume.cpp
+++ b/src/datavisualization/data/qcustom3dvolume.cpp
@@ -112,6 +112,30 @@ QT_BEGIN_NAMESPACE_DATAVISUALIZATION
  */
 
 /*!
+ * \qmlproperty real Custom3DVolume::alphaMultiplier
+ *
+ * The alpha value of every texel of the volume texture is multiplied with this value at
+ * the render time. This can be used to introduce uniform transparency to the volume.
+ * If preserveOpacity is \c{true}, only texels with at least some transparency to begin with are
+ * affected, and fully opaque texels are not affected.
+ * The value must not be negative.
+ * Defaults to \c{1.0}.
+ *
+ * \sa preserveOpacity
+ */
+
+/*!
+ * \qmlproperty bool Custom3DVolume::preserveOpacity
+ *
+ * If this property value is \c{true}, alphaMultiplier is only applied to texels that already have
+ * some transparency. If it is \c{false}, the multiplier is applied to the alpha value of all
+ * texels.
+ * Defaults to \c{true}.
+ *
+ * \sa alphaMultiplier
+ */
+
+/*!
  * Constructs QCustom3DVolume with given \a parent.
  */
 QCustom3DVolume::QCustom3DVolume(QObject *parent) :
@@ -578,84 +602,72 @@ QImage::Format QCustom3DVolume::textureFormat() const
 }
 
 /*!
- * Renders the slice specified by \a index along \a axis into an image.
- * The texture format of this object is used.
+ * \property QCustom3DVolume::alphaMultiplier
  *
- * \return the rendered image of the slice, or a null image if invalid index is specified.
+ * The alpha value of every texel of the volume texture is multiplied with this value at
+ * the render time. This can be used to introduce uniform transparency to the volume.
+ * If preserveOpacity is \c{true}, only texels with at least some transparency to begin with are
+ * affected, and fully opaque texels are not affected.
+ * The value must not be negative.
+ * Defaults to \c{1.0f}.
  *
- * \sa textureFormat
+ * \sa preserveOpacity, textureData
  */
-QImage QCustom3DVolume::renderSlice(Qt::Axis axis, int index)
+void QCustom3DVolume::setAlphaMultiplier(float mult)
 {
-    if (index < 0)
-        return QImage();
-
-    int x;
-    int y;
-    if (axis == Qt::XAxis) {
-        if (index >= textureWidth())
-            return QImage();
-        x = textureDepth();
-        y = textureHeight();
-    } else if (axis == Qt::YAxis) {
-        if (index >= textureHeight())
-            return QImage();
-        x = textureWidth();
-        y = textureDepth();
+    if (mult >= 0.0f) {
+        if (dptr()->m_alphaMultiplier != mult) {
+            dptr()->m_alphaMultiplier = mult;
+            dptr()->m_dirtyBitsVolume.alphaDirty = true;
+            emit alphaMultiplierChanged(mult);
+            emit dptr()->needUpdate();
+        }
     } else {
-        if (index >= textureDepth())
-            return QImage();
-        x = textureWidth();
-        y = textureHeight();
+        qWarning() << __FUNCTION__ << "Attempted to set negative multiplier.";
     }
+}
 
-    int padding = 0;
-    int pixelWidth = 4;
-    if (textureFormat() == QImage::Format_Indexed8) {
-        padding = x % 4;
-        pixelWidth = 1;
-    }
-    QVector<uchar> data((x + padding) * y * pixelWidth);
-    int frameSize = textureDataWidth() * textureHeight();
+float QCustom3DVolume::alphaMultiplier() const
+{
+    return dptrc()->m_alphaMultiplier;
+}
 
-    int dataIndex = 0;
-    if (axis == Qt::XAxis) {
-        for (int i = 0; i < y; i++) {
-            const uchar *p = textureData()->constData()
-                    + (index * pixelWidth) + (textureDataWidth() * i);
-            for (int j = 0; j < x; j++) {
-                data[dataIndex++] = *p;
-                for (int k = 1; k < pixelWidth; k++)
-                    data[dataIndex++] = *(p + k);
-                p += frameSize;
-            }
-        }
-    } else if (axis == Qt::YAxis) {
-        for (int i = 0; i < y; i++) {
-            const uchar *p = textureData()->constData() + (index * textureDataWidth())
-                    + (frameSize * i);
-            for (int j = 0; j < (x * pixelWidth); j++) {
-                data[dataIndex++] = *p;
-                p++;
-            }
-        }
-    } else {
-        for (int i = 0; i < y; i++) {
-            const uchar *p = textureData()->constData() + (index * frameSize)
-                    + (textureDataWidth() * i);
-            for (int j = 0; j < (x * pixelWidth); j++) {
-                data[dataIndex++] = *p;
-                p++;
-            }
-        }
+/*!
+ * \property QCustom3DVolume::preserveOpacity
+ *
+ * If this property value is \c{true}, alphaMultiplier is only applied to texels that already have
+ * some transparency. If it is \c{false}, the multiplier is applied to the alpha value of all
+ * texels.
+ * Defaults to \c{true}.
+ *
+ * \sa alphaMultiplier
+ */
+void QCustom3DVolume::setPreserveOpacity(bool enable)
+{
+    if (dptr()->m_preserveOpacity != enable) {
+        dptr()->m_preserveOpacity = enable;
+        dptr()->m_dirtyBitsVolume.alphaDirty = true;
+        emit preserveOpacityChanged(enable);
+        emit dptr()->needUpdate();
     }
+}
 
-    QImage image(data.constData(), x, y, x * pixelWidth, textureFormat());
-    image.bits(); // Call bits() to detach the new image from local data
-    if (textureFormat() == QImage::Format_Indexed8)
-        image.setColorTable(colorTable());
+bool QCustom3DVolume::preserveOpacity() const
+{
+    return dptrc()->m_preserveOpacity;
+}
 
-    return image;
+/*!
+ * Renders the slice specified by \a index along \a axis into an image.
+ * The texture format of this object is used.
+ *
+ * \return the rendered image of the slice, or a null image if invalid index is specified.
+ *
+ * \sa textureFormat
+ */
+QImage QCustom3DVolume::renderSlice(Qt::Axis axis, int index)
+{
+    return dptr()->renderSlice(axis, index);
 }
 
 /*!
@@ -683,7 +695,9 @@ QCustom3DVolumePrivate::QCustom3DVolumePrivate(QCustom3DVolume *q) :
     m_textureHeight(0),
     m_textureDepth(0),
     m_textureFormat(QImage::Format_ARGB32),
-    m_textureData(0)
+    m_textureData(0),
+    m_alphaMultiplier(1.0f),
+    m_preserveOpacity(true)
 {
     m_isVolumeItem = true;
     m_meshFile = QStringLiteral(":/defaultMeshes/barFull");
@@ -705,7 +719,9 @@ QCustom3DVolumePrivate::QCustom3DVolumePrivate(QCustom3DVolume *q, const QVector
     m_textureDepth(textureDepth),
     m_textureFormat(textureFormat),
     m_colorTable(colorTable),
-    m_textureData(textureData)
+    m_textureData(textureData),
+    m_alphaMultiplier(1.0f),
+    m_preserveOpacity(true)
 {
     m_isVolumeItem = true;
     m_shadowCasting = false;
@@ -738,6 +754,103 @@ void QCustom3DVolumePrivate::resetDirtyBits()
     m_dirtyBitsVolume.textureFormatDirty = false;
 }
 
+QImage QCustom3DVolumePrivate::renderSlice(Qt::Axis axis, int index)
+{
+    if (index < 0)
+        return QImage();
+
+    int x;
+    int y;
+    if (axis == Qt::XAxis) {
+        if (index >= m_textureWidth)
+            return QImage();
+        x = m_textureDepth;
+        y = m_textureHeight;
+    } else if (axis == Qt::YAxis) {
+        if (index >= m_textureHeight)
+            return QImage();
+        x = m_textureWidth;
+        y = m_textureDepth;
+    } else {
+        if (index >= m_textureDepth)
+            return QImage();
+        x = m_textureWidth;
+        y = m_textureHeight;
+    }
+
+    int padding = 0;
+    int pixelWidth = 4;
+    int dataWidth = qptr()->textureDataWidth();
+    if (m_textureFormat == QImage::Format_Indexed8) {
+        padding = x % 4;
+        pixelWidth = 1;
+    }
+    QVector<uchar> data((x + padding) * y * pixelWidth);
+    int frameSize = qptr()->textureDataWidth() * m_textureHeight;
+
+    int dataIndex = 0;
+    if (axis == Qt::XAxis) {
+        for (int i = 0; i < y; i++) {
+            const uchar *p = m_textureData->constData()
+                    + (index * pixelWidth) + (dataWidth * i);
+            for (int j = 0; j < x; j++) {
+                for (int k = 0; k < pixelWidth; k++)
+                    data[dataIndex++] = *(p + k);
+                p += frameSize;
+            }
+        }
+    } else if (axis == Qt::YAxis) {
+        for (int i = 0; i < y; i++) {
+            const uchar *p = m_textureData->constData() + (index * dataWidth)
+                    + (frameSize * i);
+            for (int j = 0; j < (x * pixelWidth); j++) {
+                data[dataIndex++] = *p;
+                p++;
+            }
+        }
+    } else {
+        for (int i = 0; i < y; i++) {
+            const uchar *p = m_textureData->constData() + (index * frameSize) + (dataWidth * i);
+            for (int j = 0; j < (x * pixelWidth); j++) {
+                data[dataIndex++] = *p;
+                p++;
+            }
+        }
+    }
+
+    if (m_textureFormat != QImage::Format_Indexed8 && m_alphaMultiplier != 1.0f) {
+        for (int i = pixelWidth - 1; i < data.size(); i += pixelWidth)
+            data[i] = static_cast<uchar>(multipliedAlphaValue(data.at(i)));
+    }
+
+    QImage image(data.constData(), x, y, x * pixelWidth, m_textureFormat);
+    image.bits(); // Call bits() to detach the new image from local data
+    if (m_textureFormat == QImage::Format_Indexed8) {
+        QVector<QRgb> colorTable = m_colorTable;
+        if (m_alphaMultiplier != 1.0f) {
+            for (int i = 0; i < colorTable.size(); i++) {
+                QRgb curCol = colorTable.at(i);
+                int alpha = multipliedAlphaValue(qAlpha(curCol));
+                if (alpha != qAlpha(curCol))
+                    colorTable[i] = qRgba(qRed(curCol), qGreen(curCol), qBlue(curCol), alpha);
+            }
+        }
+        image.setColorTable(colorTable);
+    }
+
+    return image;
+}
+
+int QCustom3DVolumePrivate::multipliedAlphaValue(int alpha)
+{
+    int modifiedAlpha = alpha;
+    if (!m_preserveOpacity || alpha != 255) {
+        modifiedAlpha = int(m_alphaMultiplier * float(alpha));
+        modifiedAlpha = qMin(modifiedAlpha, 255);
+    }
+    return modifiedAlpha;
+}
+
 QCustom3DVolume *QCustom3DVolumePrivate::qptr()
 {
     return static_cast<QCustom3DVolume *>(q_ptr);
diff --git a/src/datavisualization/data/qcustom3dvolume.h b/src/datavisualization/data/qcustom3dvolume.h
index 00733d17..2f95fa5d 100644
--- a/src/datavisualization/data/qcustom3dvolume.h
+++ b/src/datavisualization/data/qcustom3dvolume.h
@@ -40,7 +40,8 @@ class QT_DATAVISUALIZATION_EXPORT QCustom3DVolume : public QCustom3DItem
     Q_PROPERTY(QVector<QRgb> colorTable READ colorTable WRITE setColorTable NOTIFY colorTableChanged)
     Q_PROPERTY(QVector<uchar> *textureData READ textureData WRITE setTextureData NOTIFY textureDataChanged)
     Q_PROPERTY(QImage::Format textureFormat READ textureFormat WRITE setTextureFormat NOTIFY textureFormatChanged)
-
+    Q_PROPERTY(float alphaMultiplier READ alphaMultiplier WRITE setAlphaMultiplier NOTIFY alphaMultiplierChanged)
+    Q_PROPERTY(bool preserveOpacity READ preserveOpacity WRITE setPreserveOpacity NOTIFY preserveOpacityChanged)
 public:
 
     explicit QCustom3DVolume(QObject *parent = 0);
@@ -80,6 +81,11 @@ public:
     void setTextureFormat(QImage::Format format);
     QImage::Format textureFormat() const;
 
+    void setAlphaMultiplier(float mult);
+    float alphaMultiplier() const;
+    void setPreserveOpacity(bool enable);
+    bool preserveOpacity() const;
+
     QImage renderSlice(Qt::Axis axis, int index);
 
 signals:
@@ -92,6 +98,8 @@ signals:
     void colorTableChanged();
     void textureDataChanged(QVector<uchar> *data);
     void textureFormatChanged(QImage::Format format);
+    void alphaMultiplierChanged(float mult);
+    void preserveOpacityChanged(bool enabled);
 
 protected:
     QCustom3DVolumePrivate *dptr();
diff --git a/src/datavisualization/data/qcustom3dvolume_p.h b/src/datavisualization/data/qcustom3dvolume_p.h
index 69dd1eb2..b83e27fb 100644
--- a/src/datavisualization/data/qcustom3dvolume_p.h
+++ b/src/datavisualization/data/qcustom3dvolume_p.h
@@ -40,13 +40,15 @@ struct QCustomVolumeDirtyBitField {
     bool colorTableDirty        : 1;
     bool textureDataDirty       : 1;
     bool textureFormatDirty     : 1;
+    bool alphaDirty             : 1;
 
     QCustomVolumeDirtyBitField()
         : textureDimensionsDirty(false),
           sliceIndicesDirty(false),
           colorTableDirty(false),
           textureDataDirty(false),
-          textureFormatDirty(false)
+          textureFormatDirty(false),
+          alphaDirty(false)
     {
     }
 };
@@ -64,6 +66,7 @@ public:
     virtual ~QCustom3DVolumePrivate();
 
     void resetDirtyBits();
+    QImage renderSlice(Qt::Axis axis, int index);
 
     QCustom3DVolume *qptr();
 
@@ -79,9 +82,14 @@ public:
     QVector<QRgb> m_colorTable;
     QVector<uchar> *m_textureData;
 
+    float m_alphaMultiplier;
+    bool m_preserveOpacity;
+
     QCustomVolumeDirtyBitField m_dirtyBitsVolume;
 
 private:
+    int multipliedAlphaValue(int alpha);
+
     friend class QCustom3DVolume;
 };