qcam: viewfinder_gl: Add support for RGB formats

Add support for 24-bit and 32-bit RGB formats. The fragment samples the
texture and reorders the components, using a pattern set through the
RGB_PATTERN macro. The pattern stores the shader vec4 element indices
(named {r, g, b, a} by convention, for elements 0 to 3) to be extracted
from the texture samples, when interpreted by OpenGL as RGBA.

Note that, as textures are created with GL_UNSIGNED_BYTE, the RGBA
order corresponds to bytes in memory, while the libcamera formats are
named based on the components order in a 32-bit word stored in memory in
little endian format.

An alternative to manual reordering in the shader would be to set the
texture swizzling mask. This is however not available in OpenGL ES
before version 3.0, which we don't mandate at the moment.

Only the BGR888 and RGB888 formats have been tested, with the vimc
pipeline handler.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

3 files changed, 91 insertions, 3 deletions

diff --git a/src/qcam/assets/shader/RGB.frag b/src/qcam/assets/shader/RGB.frag
new file mode 100644
index 00000000..4c374ac9
--- /dev/null
+++ b/src/qcam/assets/shader/RGB.frag
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Laurent Pinchart
+ *
+ * RGB.frag - Fragment shader code for RGB formats
+ */
+
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+varying vec2 textureOut;
+uniform sampler2D tex_y;
+
+void main(void)
+{
+	vec3 rgb;
+
+	rgb = texture2D(tex_y, textureOut).RGB_PATTERN;
+
+	gl_FragColor = vec4(rgb, 1.0);
+}
diff --git a/src/qcam/assets/shader/shaders.qrc b/src/qcam/assets/shader/shaders.qrc
index 86310914..8a8f9de1 100644
--- a/src/qcam/assets/shader/shaders.qrc
+++ b/src/qcam/assets/shader/shaders.qrc
@@ -1,6 +1,7 @@
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 <!DOCTYPE RCC><RCC version="1.0">
 <qresource>
+	<file>RGB.frag</file>
 	<file>YUV_2_planes.frag</file>
 	<file>YUV_3_planes.frag</file>
 	<file>YUV_packed.frag</file>
diff --git a/src/qcam/viewfinder_gl.cpp b/src/qcam/viewfinder_gl.cpp
index cbc13655..5d9b442e 100644
--- a/src/qcam/viewfinder_gl.cpp
+++ b/src/qcam/viewfinder_gl.cpp
@@ -14,21 +14,28 @@
 #include <libcamera/formats.h>
 
 static const QList<libcamera::PixelFormat> supportedFormats{
-	/* Packed (single plane) */
+	/* YUV - packed (single plane) */
 	libcamera::formats::UYVY,
 	libcamera::formats::VYUY,
 	libcamera::formats::YUYV,
 	libcamera::formats::YVYU,
-	/* Semi planar (two planes) */
+	/* YUV - semi planar (two planes) */
 	libcamera::formats::NV12,
 	libcamera::formats::NV21,
 	libcamera::formats::NV16,
 	libcamera::formats::NV61,
 	libcamera::formats::NV24,
 	libcamera::formats::NV42,
-	/* Fully planar (three planes) */
+	/* YUV - fully planar (three planes) */
 	libcamera::formats::YUV420,
 	libcamera::formats::YVU420,
+	/* RGB */
+	libcamera::formats::ABGR8888,
+	libcamera::formats::ARGB8888,
+	libcamera::formats::BGRA8888,
+	libcamera::formats::RGBA8888,
+	libcamera::formats::BGR888,
+	libcamera::formats::RGB888,
 };
 
 ViewFinderGL::ViewFinderGL(QWidget *parent)
@@ -172,6 +179,30 @@ bool ViewFinderGL::selectFormat(const libcamera::PixelFormat &format)
 		fragmentShaderDefines_.append("#define YUV_PATTERN_YVYU");
 		fragmentShaderFile_ = ":YUV_packed.frag";
 		break;
+	case libcamera::formats::ABGR8888:
+		fragmentShaderDefines_.append("#define RGB_PATTERN rgb");
+		fragmentShaderFile_ = ":RGB.frag";
+		break;
+	case libcamera::formats::ARGB8888:
+		fragmentShaderDefines_.append("#define RGB_PATTERN bgr");
+		fragmentShaderFile_ = ":RGB.frag";
+		break;
+	case libcamera::formats::BGRA8888:
+		fragmentShaderDefines_.append("#define RGB_PATTERN gba");
+		fragmentShaderFile_ = ":RGB.frag";
+		break;
+	case libcamera::formats::RGBA8888:
+		fragmentShaderDefines_.append("#define RGB_PATTERN abg");
+		fragmentShaderFile_ = ":RGB.frag";
+		break;
+	case libcamera::formats::BGR888:
+		fragmentShaderDefines_.append("#define RGB_PATTERN rgb");
+		fragmentShaderFile_ = ":RGB.frag";
+		break;
+	case libcamera::formats::RGB888:
+		fragmentShaderDefines_.append("#define RGB_PATTERN bgr");
+		fragmentShaderFile_ = ":RGB.frag";
+		break;
 	default:
 		ret = false;
 		qWarning() << "[ViewFinderGL]:"
@@ -481,6 +512,40 @@ void ViewFinderGL::doRender()
 					       1.0f / (size_.width() / 2 - 1));
 		break;
 
+	case libcamera::formats::ABGR8888:
+	case libcamera::formats::ARGB8888:
+	case libcamera::formats::BGRA8888:
+	case libcamera::formats::RGBA8888:
+		glActiveTexture(GL_TEXTURE0);
+		configureTexture(*textures_[0]);
+		glTexImage2D(GL_TEXTURE_2D,
+			     0,
+			     GL_RGBA,
+			     size_.width(),
+			     size_.height(),
+			     0,
+			     GL_RGBA,
+			     GL_UNSIGNED_BYTE,
+			     data_);
+		shaderProgram_.setUniformValue(textureUniformY_, 0);
+		break;
+
+	case libcamera::formats::BGR888:
+	case libcamera::formats::RGB888:
+		glActiveTexture(GL_TEXTURE0);
+		configureTexture(*textures_[0]);
+		glTexImage2D(GL_TEXTURE_2D,
+			     0,
+			     GL_RGB,
+			     size_.width(),
+			     size_.height(),
+			     0,
+			     GL_RGB,
+			     GL_UNSIGNED_BYTE,
+			     data_);
+		shaderProgram_.setUniformValue(textureUniformY_, 0);
+		break;
+
 	default:
 		break;
 	};