Add colorAtScratchPoint() method

Author: adazem009

src/irenderedtarget.h

@@ -86,6 +86,7 @@ class IRenderedTarget : public QNanoQuickItem
         virtual const std::vector<QPoint> &hullPoints() const = 0;
 
         virtual bool containsScratchPoint(double x, double y) const = 0;
+        virtual QRgb colorAtScratchPoint(double x, double y) const = 0;
 
         virtual bool touchingClones(const std::vector<libscratchcpp::Sprite *> &clones) const = 0;
 };

src/renderedtarget.cpp

@@ -582,6 +582,30 @@ bool RenderedTarget::containsScratchPoint(double x, double y) const
     return containsLocalPoint(mapFromScratchToLocal(QPointF(x, y)));
 }
 
+QRgb RenderedTarget::colorAtScratchPoint(double x, double y) const
+{
+    if (!m_engine || !m_cpuTexture.isValid())
+        return qRgba(0, 0, 0, 0);
+
+    // Translate the coordinates
+    QPointF point = mapFromScratchToLocal(QPointF(x, y));
+    x = point.x();
+    y = point.y();
+
+    const double width = m_cpuTexture.width();
+    const double height = m_cpuTexture.height();
+
+    // If the point is outside the texture, return fully transparent color
+    if ((x < 0 || x >= width) || (y < 0 || y >= height))
+        return qRgba(0, 0, 0, 0);
+
+    GLubyte *data = textureManager()->getTextureData(m_cpuTexture);
+    const int index = (y * width + x) * 4; // RGBA channels
+    Q_ASSERT(index >= 0 && index < width * height * 4);
+    // TODO: Apply graphic effects (#117)
+    return qRgba(data[index], data[index + 1], data[index + 2], data[index + 3]);
+}
+
 bool RenderedTarget::touchingClones(const std::vector<libscratchcpp::Sprite *> &clones) const
 {
     // https://github.com/scratchfoundation/scratch-render/blob/941562438fe3dd6e7d98d9387607d535dcd68d24/src/RenderWebGL.js#L967-L1002

src/renderedtarget.h

@@ -94,6 +94,7 @@ class RenderedTarget : public IRenderedTarget
 
         Q_INVOKABLE bool contains(const QPointF &point) const override;
         bool containsScratchPoint(double x, double y) const override;
+        QRgb colorAtScratchPoint(double x, double y) const override;
 
         bool touchingClones(const std::vector<libscratchcpp::Sprite *> &) const override;
 

test/mocks/renderedtargetmock.h

@@ -71,6 +71,7 @@ class RenderedTargetMock : public IRenderedTarget
 
         MOCK_METHOD(bool, contains, (const QPointF &), (const, override));
         MOCK_METHOD(bool, containsScratchPoint, (double, double), (const, override));
+        MOCK_METHOD(QRgb, colorAtScratchPoint, (double, double), (const, override));
 
         MOCK_METHOD(bool, touchingClones, (const std::vector<libscratchcpp::Sprite *> &), (const, override));
 

test/renderedtarget/renderedtarget_test.cpp

@@ -299,7 +299,7 @@ TEST_F(RenderedTargetTest, DeinitClone)
     ASSERT_EQ(mouseArea.draggedSprite(), nullptr);
 }
 
-TEST_F(RenderedTargetTest, HullPoints)
+TEST_F(RenderedTargetTest, CpuRendering)
 {
     EngineMock engine;
     Sprite sprite;
@@ -392,6 +392,28 @@ TEST_F(RenderedTargetTest, HullPoints)
     ASSERT_TRUE(target.containsScratchPoint(-224.5, 162));    // [3, 3]
     ASSERT_FALSE(target.containsScratchPoint(-224.2, 161.5)); // [3.3, 3.5]
 
+    // Test colorAtScratchPoint()
+    ASSERT_EQ(target.colorAtScratchPoint(-227.5, 165), 0); // [0, 0]
+    ASSERT_EQ(target.colorAtScratchPoint(-226.5, 165), 0); // [1, 0]
+    ASSERT_EQ(target.colorAtScratchPoint(-225.5, 165), 0); // [2, 0]
+    ASSERT_EQ(target.colorAtScratchPoint(-224.5, 165), 0); // [3, 0]
+
+    ASSERT_EQ(target.colorAtScratchPoint(-227.5, 164), 0);             // [0, 1]
+    ASSERT_EQ(target.colorAtScratchPoint(-226.5, 164), 4278190335);    // [1, 1]
+    ASSERT_EQ(target.colorAtScratchPoint(-226.1, 163.75), 4278255615); // [1.4, 1.25]
+    ASSERT_EQ(target.colorAtScratchPoint(-225.5, 164), 4294902015);    // [2, 1]
+    ASSERT_EQ(target.colorAtScratchPoint(-224.5, 164), 4294934656);    // [3, 1]
+
+    ASSERT_EQ(target.colorAtScratchPoint(-226.5, 163), 4278190208); // [1, 2]
+    ASSERT_EQ(target.colorAtScratchPoint(-225.5, 163), 0);          // [2, 2]
+    ASSERT_EQ(target.colorAtScratchPoint(-224.5, 163), 2505545047); // [3, 2]
+    ASSERT_EQ(target.colorAtScratchPoint(-224, 162.9), 9764864);    // [3.5, 2.1]
+
+    ASSERT_EQ(target.colorAtScratchPoint(-226.5, 162), 4286578816); // [1, 3]
+    ASSERT_EQ(target.colorAtScratchPoint(-225.5, 162), 4286611711); // [2, 3]
+    ASSERT_EQ(target.colorAtScratchPoint(-224.5, 162), 4286611456); // [3, 3]
+    ASSERT_EQ(target.colorAtScratchPoint(-224.2, 161.5), 0);        // [3.3, 3.5]
+
     // Cleanup
     context.doneCurrent();
 }