Q_GUI_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, bool include_alpha)
{
int w = size.width();
int h = size.height();
QOpenGLFunctions *funcs = QOpenGLContext::currentContext()->functions();
while (funcs->glGetError());
#if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
QImage img(size, (alpha_format && include_alpha) ? QImage::Format_ARGB32_Premultiplied
: QImage::Format_RGB32);
#ifdef QT_OPENGL_ES
GLint fmt = GL_BGRA_EXT;
#else
GLint fmt = GL_BGRA;
#endif
funcs->glReadPixels(0, 0, w, h, fmt, GL_UNSIGNED_BYTE, img.bits());
if (!funcs->glGetError())
return img.mirrored();
#endif
QImage rgbaImage(size, (alpha_format && include_alpha) ? QImage::Format_RGBA8888_Premultiplied
: QImage::Format_RGBX8888);
funcs->glReadPixels(0, 0, w, h, GL_RGBA, GL_UNSIGNED_BYTE, rgbaImage.bits());
return rgbaImage.mirrored();
}
void QSGDistanceFieldGlyphCache::saveTexture(GLuint textureId, int width, int height) const
{
QOpenGLFunctions *functions = QOpenGLContext::currentContext()->functions();
GLuint fboId;
functions->glGenFramebuffers(1, &fboId);
GLuint tmpTexture = 0;
functions->glGenTextures(1, &tmpTexture);
functions->glBindTexture(GL_TEXTURE_2D, tmpTexture);
functions->glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
functions->glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
functions->glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
functions->glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
functions->glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
functions->glBindTexture(GL_TEXTURE_2D, 0);
functions->glBindFramebuffer(GL_FRAMEBUFFER_EXT, fboId);
functions->glFramebufferTexture2D(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D,
tmpTexture, 0);
functions->glActiveTexture(GL_TEXTURE0);
functions->glBindTexture(GL_TEXTURE_2D, textureId);
functions->glDisable(GL_STENCIL_TEST);
functions->glDisable(GL_DEPTH_TEST);
functions->glDisable(GL_SCISSOR_TEST);
functions->glDisable(GL_BLEND);
GLfloat textureCoordinateArray[8];
textureCoordinateArray[0] = 0.0f;
textureCoordinateArray[1] = 0.0f;
textureCoordinateArray[2] = 1.0f;
textureCoordinateArray[3] = 0.0f;
textureCoordinateArray[4] = 1.0f;
textureCoordinateArray[5] = 1.0f;
textureCoordinateArray[6] = 0.0f;
textureCoordinateArray[7] = 1.0f;
GLfloat vertexCoordinateArray[8];
vertexCoordinateArray[0] = -1.0f;
vertexCoordinateArray[1] = -1.0f;
vertexCoordinateArray[2] = 1.0f;
vertexCoordinateArray[3] = -1.0f;
vertexCoordinateArray[4] = 1.0f;
vertexCoordinateArray[5] = 1.0f;
vertexCoordinateArray[6] = -1.0f;
vertexCoordinateArray[7] = 1.0f;
functions->glViewport(0, 0, width, height);
functions->glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, vertexCoordinateArray);
functions->glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, textureCoordinateArray);
{
static const char *vertexShaderSource =
"attribute vec4 vertexCoordsArray; \n"
"attribute vec2 textureCoordArray; \n"
"varying vec2 textureCoords; \n"
"void main(void) \n"
"{ \n"
" gl_Position = vertexCoordsArray; \n"
" textureCoords = textureCoordArray; \n"
"} \n";
static const char *fragmentShaderSource =
"varying vec2 textureCoords; \n"
"uniform sampler2D texture; \n"
"void main() \n"
"{ \n"
" gl_FragColor = texture2D(texture, textureCoords); \n"
"} \n";
GLuint vertexShader = functions->glCreateShader(GL_VERTEX_SHADER);
GLuint fragmentShader = functions->glCreateShader(GL_FRAGMENT_SHADER);
if (vertexShader == 0 || fragmentShader == 0) {
GLenum error = functions->glGetError();
qWarning("QSGDistanceFieldGlyphCache::saveTexture: Failed to create shaders. (GL error: %x)",
error);
return;
}
functions->glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
functions->glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
functions->glCompileShader(vertexShader);
GLint len = 1;
functions->glGetShaderiv(vertexShader, GL_INFO_LOG_LENGTH, &len);
char infoLog[2048];
functions->glGetShaderInfoLog(vertexShader, 2048, NULL, infoLog);
if (qstrlen(infoLog) > 0)
qWarning("Problems compiling vertex shader:\n %s", infoLog);
functions->glCompileShader(fragmentShader);
functions->glGetShaderInfoLog(fragmentShader, 2048, NULL, infoLog);
if (qstrlen(infoLog) > 0)
qWarning("Problems compiling fragment shader:\n %s", infoLog);
GLuint shaderProgram = functions->glCreateProgram();
functions->glAttachShader(shaderProgram, vertexShader);
functions->glAttachShader(shaderProgram, fragmentShader);
functions->glBindAttribLocation(shaderProgram, 0, "vertexCoordsArray");
functions->glBindAttribLocation(shaderProgram, 1, "textureCoordArray");
functions->glLinkProgram(shaderProgram);
functions->glGetProgramInfoLog(shaderProgram, 2048, NULL, infoLog);
if (qstrlen(infoLog) > 0)
qWarning("Problems linking shaders:\n %s", infoLog);
functions->glUseProgram(shaderProgram);
functions->glEnableVertexAttribArray(0);
functions->glEnableVertexAttribArray(1);
int textureUniformLocation = functions->glGetUniformLocation(shaderProgram, "texture");
functions->glUniform1i(textureUniformLocation, 0);
}
functions->glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
{
GLenum error = functions->glGetError();
if (error != GL_NO_ERROR)
qWarning("glDrawArrays reported error 0x%x", error);
}
uchar *data = new uchar[width * height * 4];
functions->glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data);
QImage image(data, width, height, QImage::Format_ARGB32);
QByteArray fileName = m_referenceFont.familyName().toLatin1() + '_' + QByteArray::number(textureId);
fileName = fileName.replace('/', '_').replace(' ', '_') + ".png";
image.save(QString::fromLocal8Bit(fileName));
{
GLenum error = functions->glGetError();
if (error != GL_NO_ERROR)
qWarning("glReadPixels reported error 0x%x", error);
}
functions->glDisableVertexAttribArray(0);
functions->glDisableVertexAttribArray(1);
functions->glDeleteFramebuffers(1, &fboId);
functions->glDeleteTextures(1, &tmpTexture);
delete[] data;
}