@@ -19,6 +19,8 @@ Copyright (C) 2021, Linaro
attribute vec4 vertexIn;
attribute vec2 textureIn;
+uniform mat4 proj_matrix;
+
uniform vec2 tex_size; /* The texture size in pixels */
uniform vec2 tex_step;
@@ -47,5 +49,5 @@ void main(void) {
yCoord = center.y + vec4(-2.0 * tex_step.y,
-tex_step.y, tex_step.y, 2.0 * tex_step.y);
- gl_Position = vertexIn;
+ gl_Position = proj_matrix * vertexIn;
}
@@ -9,10 +9,11 @@ attribute vec4 vertexIn;
attribute vec2 textureIn;
varying vec2 textureOut;
+uniform mat4 proj_matrix;
uniform float stride_factor;
void main(void)
{
- gl_Position = vertexIn;
+ gl_Position = proj_matrix * vertexIn;
textureOut = vec2(textureIn.x * stride_factor, textureIn.y);
}
@@ -12,6 +12,7 @@
#include <QByteArray>
#include <QFile>
#include <QImage>
+#include <QMatrix4x4>
#include <QStringList>
#include <libcamera/formats.h>
@@ -464,6 +465,7 @@ bool ViewFinderGL::createFragmentShader()
vertexBuffer_.release();
+ projMatrixUniform_ = shaderProgram_.uniformLocation("proj_matrix");
textureUniformY_ = shaderProgram_.uniformLocation("tex_y");
textureUniformU_ = shaderProgram_.uniformLocation("tex_u");
textureUniformV_ = shaderProgram_.uniformLocation("tex_v");
@@ -509,7 +511,7 @@ void ViewFinderGL::initializeGL()
glEnable(GL_TEXTURE_2D);
glDisable(GL_DEPTH_TEST);
- static const GLfloat coordinates[2][4][2]{
+ const GLfloat coordinates[2][4][2]{
{
/* Vertex coordinates */
{ -1.0f, -1.0f },
@@ -801,6 +803,17 @@ void ViewFinderGL::doRender()
shaderProgram_.setUniformValue(textureUniformStrideFactor_,
static_cast<float>(size_.width() - 1) /
(stridePixels - 1));
+
+ /*
+ * Place the viewfinder in the centre of the widget, preserving the
+ * aspect ratio of the image.
+ */
+ QMatrix4x4 projMatrix;
+ QSizeF scaledSize = size_.scaled(size(), Qt::KeepAspectRatio);
+ projMatrix.scale(scaledSize.width() / size().width(),
+ scaledSize.height() / size().height());
+
+ shaderProgram_.setUniformValue(projMatrixUniform_, projMatrix);
}
void ViewFinderGL::paintGL()
@@ -818,18 +831,14 @@ void ViewFinderGL::paintGL()
close();
}
- if (image_) {
- glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
- glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+ if (!image_)
+ return;
- doRender();
- glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
- }
-}
+ glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-void ViewFinderGL::resizeGL(int w, int h)
-{
- glViewport(0, 0, w, h);
+ doRender();
+ glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
}
QSize ViewFinderGL::sizeHint() const
@@ -51,7 +51,6 @@ Q_SIGNALS:
protected:
void initializeGL() override;
void paintGL() override;
- void resizeGL(int w, int h) override;
QSize sizeHint() const override;
private:
@@ -88,6 +87,7 @@ private:
/* Common texture parameters */
GLuint textureMinMagFilters_;
+ GLuint projMatrixUniform_;
/* YUV texture parameters */
GLuint textureUniformU_;
Mimic the letterbox behaviour of the Qt viewfinder by rendering the image centered. This is done by adding a projection matrix to the vertex shader to scale the rendered rectangle. Another option would have been to keep using glViewport() (which would have needed to be moved to paintGL(), as Qt resets the viewport to span the full widget before calling). Hidpi displays would then need special handling of the device pixel ratio, which is done automatically by Qt when it sets the default viewport. Using a projection matrix avoids this complication. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- src/apps/qcam/assets/shader/bayer_8.vert | 4 ++- src/apps/qcam/assets/shader/identity.vert | 3 ++- src/apps/qcam/viewfinder_gl.cpp | 31 +++++++++++++++-------- src/apps/qcam/viewfinder_gl.h | 2 +- 4 files changed, 26 insertions(+), 14 deletions(-)