Add textureContainsPoint() method to CpuTextureManager

Author: adazem009

src/cputexturemanager.cpp

@@ -51,6 +51,12 @@ const std::vector<QPoint> &CpuTextureManager::getTextureConvexHullPoints(const T
         return it->second;
 }
 
+bool CpuTextureManager::textureContainsPoint(const Texture &texture, const QPointF &localPoint)
+{
+    // https://github.com/scratchfoundation/scratch-render/blob/7b823985bc6fe92f572cc3276a8915e550f7c5e6/src/Silhouette.js#L219-L226
+    return getPointAlpha(texture, localPoint.x(), localPoint.y()) > 0;
+}
+
 void CpuTextureManager::removeTexture(const Texture &texture)
 {
     if (!texture.isValid())
@@ -131,3 +137,12 @@ bool CpuTextureManager::addTexture(const Texture &texture)
 
     return true;
 }
+
+int CpuTextureManager::getPointAlpha(const Texture &texture, int x, int y)
+{
+    if ((x < 0 || x >= texture.width()) || (y < 0 || y >= texture.height()))
+        return 0;
+
+    GLubyte *pixels = getTextureData(texture);
+    return pixels[(y * texture.width() + x) * 4 + 3];
+}

src/cputexturemanager.h

@@ -20,10 +20,13 @@ class CpuTextureManager
         GLubyte *getTextureData(const Texture &texture);
         const std::vector<QPoint> &getTextureConvexHullPoints(const Texture &texture);
 
+        bool textureContainsPoint(const Texture &texture, const QPointF &localPoint);
+
         void removeTexture(const Texture &texture);
 
     private:
         bool addTexture(const Texture &texture);
+        int getPointAlpha(const Texture &texture, int x, int y);
 
         std::unordered_map<GLuint, GLubyte *> m_textureData;
         std::unordered_map<GLuint, std::vector<QPoint>> m_convexHullPoints;

test/texture/cputexturemanager_test.cpp

@@ -129,3 +129,44 @@ TEST_F(CpuTextureManagerTest, TextureDataAndHullPoints)
     // Cleanup
     context.doneCurrent();
 }
+
+TEST_F(CpuTextureManagerTest, TextureContainsPoint)
+{
+    // Create OpenGL context
+    QOpenGLContext context;
+    QOffscreenSurface surface;
+    createContextAndSurface(&context, &surface);
+
+    // Paint
+    QNanoPainter painter;
+    ImagePainter imgPainter(&painter, "image.png");
+
+    // Read texture data
+    Texture texture(imgPainter.fbo()->texture(), imgPainter.fbo()->size());
+
+    // Test
+    CpuTextureManager manager;
+    ASSERT_FALSE(manager.textureContainsPoint(texture, { 0, 0 }));
+    ASSERT_FALSE(manager.textureContainsPoint(texture, { 1, 0 }));
+    ASSERT_FALSE(manager.textureContainsPoint(texture, { 2, 0 }));
+    ASSERT_FALSE(manager.textureContainsPoint(texture, { 3, 0 }));
+
+    ASSERT_FALSE(manager.textureContainsPoint(texture, { 0, 1 }));
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 1, 1 }));
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 1.4, 1.25 }));
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 2, 1 }));
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 3, 1 }));
+
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 1, 2 }));
+    ASSERT_FALSE(manager.textureContainsPoint(texture, { 2, 2 }));
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 3, 2 }));
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 3.5, 2.1 }));
+
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 1, 3 }));
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 2, 3 }));
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 3, 3 }));
+    ASSERT_TRUE(manager.textureContainsPoint(texture, { 3.3, 3.5 }));
+
+    // Cleanup
+    context.doneCurrent();
+}