Add QImage and CV::Mat conversion functions into Frame for better handling alpha channel handling

src/Frame.cpp

@@ -2,6 +2,7 @@
  * @file
  * @brief Source file for Frame class
  * @author Jonathan Thomas <[email protected]>
+ * @author HaiVQ <[email protected]>
  *
  * @ref License
  */
@@ -113,6 +114,7 @@
 	audio.reset();
 	#ifdef USE_OPENCV
 	imagecv.release();
+	brga_image_cv.release();
 	#endif
 }
 
@@ -891,6 +893,13 @@
 	return imagecv;
 }
 
+// Set pointer to OpenCV image object
+void Frame::SetImageCV(cv::Mat _image)
+{
+	imagecv = _image;
+	image = Mat2Qimage(_image);
+}
+
 std::shared_ptr<QImage> Frame::Mat2Qimage(cv::Mat img){
 	cv::cvtColor(img, img, cv::COLOR_BGR2RGB);
 	QImage qimg((uchar*) img.data, img.cols, img.rows, img.step, QImage::Format_RGB888);
@@ -904,11 +913,39 @@
 	return imgIn;
 }
 
-// Set pointer to OpenCV image object
-void Frame::SetImageCV(cv::Mat _image)
-{
-	imagecv = _image;
-	image = Mat2Qimage(_image);
+// Convert QImage to cv::Mat and vice versa
+// Frame class has GetImageCV, but it does not include alpha channel
+// so we need a separate methods which preserve alpha channel
+cv::Mat Frame::QImage2BGRACvMat(std::shared_ptr<QImage>& qimage) {
+	cv::Mat cv_img(
+		qimage->height(), qimage->width(),
+		CV_8UC4, (uchar*)qimage->constBits(),
+		qimage->bytesPerLine()
+	);
+	return cv_img;
+}
+
+// Convert cv::Mat back to QImage
+std::shared_ptr<QImage> Frame::BGRACvMat2QImage(cv::Mat img) {
+	cv::Mat final_img;
+	cv::cvtColor(img, final_img, cv::COLOR_BGRA2RGBA);
+	QImage qimage(final_img.data, final_img.cols, final_img.rows, final_img.step, QImage::Format_ARGB32);
+	std::shared_ptr<QImage> imgIn = std::make_shared<QImage>(qimage.convertToFormat(QImage::Format_RGBA8888_Premultiplied));
+	return imgIn;
+}
+
+// Get BGRA
+cv::Mat Frame::GetBGRACvMat() {
+	if (!image)
+		// Fill with black
+		AddColor(width, height, color);
+	brga_image_cv = QImage2BGRACvMat(image);
+	return brga_image_cv;
+}
+
+void Frame::SetBGRACvMat(cv::Mat _image) {
+	brga_image_cv = _image;
+	image = BGRACvMat2QImage(_image);
 }
 #endif
 

src/Frame.h

@@ -2,6 +2,7 @@
  * @file
  * @brief Header file for Frame class
  * @author Jonathan Thomas <[email protected]>
+ * @author HaiVQ <[email protected]>
  *
  * @ref License
  */
@@ -108,6 +109,7 @@ namespace openshot
 
 #ifdef USE_OPENCV
 		cv::Mat imagecv; ///< OpenCV image. It will always be in BGR format
+		cv::Mat brga_image_cv; ///< OpenCV image. It will always be in BGR format
 #endif
 
 		/// Constrain a color value from 0 to 255
@@ -279,6 +281,18 @@ namespace openshot
 
 		/// Set pointer to OpenCV image object
 		void SetImageCV(cv::Mat _image);
+
+		/// Convert QImage to OpenCV Mat (alpha channel included)
+		cv::Mat QImage2BGRACvMat(std::shared_ptr<QImage>& qimage);
+
+		/// Convert OpenCV Mat to QImage (alpha channel included)
+		std::shared_ptr<QImage> BGRACvMat2QImage(cv::Mat img);
+
+		/// Get pointer to OpenCV Mat image object (with alpha channel)
+		cv::Mat GetBGRACvMat();
+
+		/// Set pointer to OpenCV image object (with alpha channel)
+		void SetBGRACvMat(cv::Mat _image);
 #endif
 	};
 

src/effects/Outline.cpp

@@ -1,8 +1,9 @@
 /**
  * @file
  * @brief Source file for Outline effect class
- * @author Jonathan Thomas <[email protected]>, HaiVQ <[email protected]>
- *
+ * @author Jonathan Thomas <[email protected]>
+ * @author HaiVQ <[email protected]>
+ * 
  * @ref License
  */
 
@@ -60,12 +61,11 @@ std::shared_ptr<openshot::Frame> Outline::GetFrame(std::shared_ptr<openshot::Fra
 	}
 
 	// Get the frame's image
-	std::shared_ptr<QImage> frame_image = frame->GetImage();
-
+	cv::Mat cv_image = frame->GetBGRACvMat();
+	
 	float sigmaValue = widthValue / 3.0;
 	if (sigmaValue <= 0.0)
 		sigmaValue = 0.01;
-	cv::Mat cv_image = QImageToBGRACvMat(frame_image);
 
 	// Extract alpha channel for the mask
 	std::vector<cv::Mat> channels(4);
@@ -95,25 +95,24 @@ std::shared_ptr<openshot::Frame> Outline::GetFrame(std::shared_ptr<openshot::Fra
 	solid_color_mat.copyTo(final_image, outline_mask);
 	cv_image.copyTo(final_image, alpha_mask);
 
-	std::shared_ptr<QImage> new_frame_image = BGRACvMatToQImage(final_image);
-
-	// FIXME: The shared_ptr::swap does not work somehow
-	*frame_image = *new_frame_image;
+	frame->SetBGRACvMat(final_image);
+
 	return frame;
 }
 
-cv::Mat Outline::QImageToBGRACvMat(std::shared_ptr<QImage>& qimage) {
-	cv::Mat cv_img(qimage->height(), qimage->width(), CV_8UC4, (uchar*)qimage->constBits(), qimage->bytesPerLine());
-	return cv_img;
-}
-
-std::shared_ptr<QImage> Outline::BGRACvMatToQImage(cv::Mat img) {
-	cv::Mat final_img;
-	cv::cvtColor(img, final_img, cv::COLOR_RGBA2BGRA);
-	QImage qimage(final_img.data, final_img.cols, final_img.rows, final_img.step, QImage::Format_ARGB32);
-	std::shared_ptr<QImage> imgIn = std::make_shared<QImage>(qimage.convertToFormat(QImage::Format_RGBA8888_Premultiplied));
-	return imgIn;
-}
+// Moved to Frame.cpp
+// cv::Mat Outline::QImageToBGRACvMat(std::shared_ptr<QImage>& qimage) {
+// 	cv::Mat cv_img(qimage->height(), qimage->width(), CV_8UC4, (uchar*)qimage->constBits(), qimage->bytesPerLine());
+// 	return cv_img;
+// }
+
+// std::shared_ptr<QImage> Outline::BGRACvMatToQImage(cv::Mat img) {
+// 	cv::Mat final_img;
+// 	cv::cvtColor(img, final_img, cv::COLOR_RGBA2BGRA);
+// 	QImage qimage(final_img.data, final_img.cols, final_img.rows, final_img.step, QImage::Format_ARGB32);
+// 	std::shared_ptr<QImage> imgIn = std::make_shared<QImage>(qimage.convertToFormat(QImage::Format_RGBA8888_Premultiplied));
+// 	return imgIn;
+// }
 
 // Generate JSON string of this object
 std::string Outline::Json() const {

src/effects/Outline.h

@@ -1,7 +1,8 @@
 /**
  * @file
  * @brief Header file for Outline effect class
- * @author Jonathan Thomas <[email protected]>, HaiVQ <[email protected]>
+ * @author Jonathan Thomas <[email protected]>
+ * @author HaiVQ <[email protected]>
  *
  * @ref License
  */
@@ -33,19 +34,17 @@ namespace openshot
 	 * with openshot::Keyframe curves over time.
 	 *
 	 * Outlines can be added around any image or text, and animated over time.
+	 * Idea from: https://stackoverflow.com/a/78480103
 	 */
 	class Outline : public EffectBase
 	{
 	private:
 		/// Init effect settings
 		void init_effect_details();
 
-		// Convert QImage to cv::Mat and vice versa
-		// Although Frame class has GetImageCV, but it does not include alpha channel
-		// so we need a separate methods which preserve alpha channel
-		// Idea from: https://stackoverflow.com/a/78480103
-		cv::Mat QImageToBGRACvMat(std::shared_ptr<QImage>& qimage);
-		std::shared_ptr<QImage> BGRACvMatToQImage(cv::Mat img);
+		// Moved to Frame.h
+		// cv::Mat QImageToBGRACvMat(std::shared_ptr<QImage>& qimage);
+		// std::shared_ptr<QImage> BGRACvMatToQImage(cv::Mat img);
 
 	public:
 		Keyframe width;	///< Width of the outline

tests/Frame.cpp

@@ -3,6 +3,7 @@
  * @brief Unit tests for openshot::Frame
  * @author Jonathan Thomas <[email protected]>
  * @author FeRD (Frank Dana) <[email protected]>
+ * @author HaiVQ <[email protected]>
  *
  * @ref License
  */
@@ -160,4 +161,26 @@ TEST_CASE( "Convert_Image", "[libopenshot][opencv][frame]" )
 	CHECK(f1->GetHeight() == cvimage.rows);
 	CHECK(cvimage.channels() == 3);
 }
+
+TEST_CASE( "Convert_Image_Alpha", "[libopenshot][opencv][frame]" )
+{
+	// Create a video clip
+	std::stringstream path;
+	path << TEST_MEDIA_PATH << "sintel_trailer-720p.mp4";
+	Clip c1(path.str());
+	c1.Open();
+
+	// Get first frame
+	auto f1 = c1.GetFrame(1);
+
+	// Get first Mat image
+	cv::Mat cvimage = f1->GetBGRACvMat();
+
+	CHECK_FALSE(cvimage.empty());
+
+	CHECK(f1->number == 1);
+	CHECK(f1->GetWidth() == cvimage.cols);
+	CHECK(f1->GetHeight() == cvimage.rows);
+	CHECK(cvimage.channels() == 4);
+}
 #endif