I had some issues recently in attempting to capture the entire screen to a jpeg image. I could capture our OpenGL view pretty easily but not the Cascades UI on-top. The main issue was getting a handle to the screen window at the top level. Below is the code I used to achieve the full-screen capture. Not that this is being performed within an custom OpenGL view and so I use the screen context for that to initialise the pixmap, this may not be the case for you. The image is essentially captured as a bmp, the bmp data is stored in a QByteArray and we use the handy QImage save feature to output as a jpeg. There may be some ways to improve this code but it does the trick for me.
screen_pixmap_t screen_pix;
screen_buffer_t screenshot_buf;
char *screenshot_ptr = NULL;
int screenshot_stride = 0;
int usage, format;
int size[2];
screen_create_pixmap(&screen_pix, m_screen_cxt);
usage = SCREEN_USAGE_READ | SCREEN_USAGE_NATIVE;
screen_set_pixmap_property_iv(screen_pix, SCREEN_PROPERTY_USAGE, &usage);
format = SCREEN_FORMAT_RGBA8888;
screen_set_pixmap_property_iv(screen_pix, SCREEN_PROPERTY_FORMAT, &format);
size[0] = width;
size[1] = height;
screen_set_pixmap_property_iv(screen_pix, SCREEN_PROPERTY_BUFFER_SIZE, size);
screen_create_pixmap_buffer(screen_pix);
screen_get_pixmap_property_pv(screen_pix, SCREEN_PROPERTY_RENDER_BUFFERS,
(void**)&screenshot_buf);
screen_get_buffer_property_pv(screenshot_buf, SCREEN_PROPERTY_POINTER,
(void**)&screenshot_ptr);
screen_get_buffer_property_iv(screenshot_buf, SCREEN_PROPERTY_STRIDE,
&screenshot_stride);
screen_read_window(GLOBALS_PTR()->app->app()->mainWindow()->handle(), screenshot_buf, 0, NULL ,0);
QByteArray array;
int nbytes = size[0] * size[1] * 4;
write_bitmap_header(nbytes, array, size);
for (int i = 0; i < size[1]; i++)
{
array.append(screenshot_ptr + i * screenshot_stride, size[0] * 4);
}
QImage image = QImage::fromData(array, "BMP");
QFile outFile("shared/photos/temp1.jpeg");
outFile.open(QIODevice::WriteOnly);
image.save(&outFile, "JPEG");
screen_destroy_pixmap(screen_pix);
You'll also want the write_bitmap_header, here it is:
void write_bitmap_header(int nbytes, QByteArray& ba, const int size[])
{
char header[54];
/* Set standard bitmap header */
header[0] = 'B';
header[1] = 'M';
header[2] = nbytes & 0xff;
header[3] = (nbytes >> 8) & 0xff;
header[4] = (nbytes >> 16) & 0xff;
header[5] = (nbytes >> 24) & 0xff;
header[6] = 0;
header[7] = 0;
header[8] = 0;
header[9] = 0;
header[10] = 54;
header[11] = 0;
header[12] = 0;
header[13] = 0;
header[14] = 40;
header[15] = 0;
header[16] = 0;
header[17] = 0;
header[18] = size[0] & 0xff;
header[19] = (size[0] >> 8) & 0xff;
header[20] = (size[0] >> 16) & 0xff;
header[21] = (size[0] >> 24) & 0xff;
header[22] = -size[1] & 0xff;
header[23] = (-size[1] >> 8) & 0xff;
header[24] = (-size[1] >> 16) & 0xff;
header[25] = (-size[1] >> 24) & 0xff;
header[26] = 1;
header[27] = 0;
header[28] = 32;
header[29] = 0;
header[30] = 0;
header[31] = 0;
header[32] = 0;
header[33] = 0;
header[34] = 0; /* image size*/
header[35] = 0;
header[36] = 0;
header[37] = 0;
header[38] = 0x9;
header[39] = 0x88;
header[40] = 0;
header[41] = 0;
header[42] = 0x9l;
header[43] = 0x88;
header[44] = 0;
header[45] = 0;
header[46] = 0;
header[47] = 0;
header[48] = 0;
header[49] = 0;
header[50] = 0;
header[51] = 0;
header[52] = 0;
header[53] = 0;
ba.append(header, sizeof(header));
}
