<div dir="ltr">Hi, without any further investigation, I think that the problem is that <div> </div><div> CAIRO_FORMAT_RGB24</div><div class="gmail_extra"> </div><div class="gmail_extra">is actually 32-bit, not 24-bit.</div><div class="gmail_extra"> </div><div class="gmail_extra">I would start here, hope that helps.</div><div class="gmail_extra"> </div><div class="gmail_extra">Cheers,</div><div class="gmail_extra">Petr <div><div class="gmail_signature"> </div></div><div class="gmail_quote">On Fri, Feb 27, 2015 at 1:22 PM, <<a href="mailto:victorascroft@gmail.com" target="_blank">victorascroft@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello, I am using a Freescale Vybrid module and running the 3.18.5 kernel on it. Vybrid has a framebuffer driver and has the concept of multiple layers. The driver is not in the mainline due to it being a framebuffer driver and not DRM based. <a href="http://thread.gmane.org/gmane.linux.ports.arm.kernel/260784/focus=269349" target="_blank">http://thread.gmane.org/gmane.linux.ports.arm.kernel/260784/focus=269349</a> It allows for setting BPP to 16, 24 and 32 for each of the framebuffer layers. The alpha values of each of the five framebuffer layers can be set by using IOCTL call provided by the driver. The layers have priority with the 0 layer being highest priority and the highest layer having lower priority. Depending on the alpha value of each of the individual layers, these interact to render a blended image. For example, I can set the alpha value of fb0 to 150 and then set the fb1 to have an alpha value of 200. What I write to fb1 will appear blended with what is on fb0. Now to write to the individual fbx I am using Cairo. The cairo version being used is 1.12.16 build using Openembedded. I do have LXDM and X on it but both are disabled and not required for the use of framebuffer which I want. X/LXDM is not much of use here as it does not seem to work with 32 bit bpp. Openembedded build is based on Yocto daisy. On using 16 bit bpp and 32 bit bpp I can write successfully to any of the framebuffers and get the results I am expecting. The alpha value for each of these framebuffers is being controlled by hardware and the driver. At 24 bit bpp, calling cairo_paint crashes. I tried using cairo_paint_with_alpha which also crashes if an alpha value > 0.0 is specified. If I set alpha to 0.0 and then call it, I can see the images being rendered but severely distorted kind of. I used gdb to track and make sure that it is cairo_paint where this crashes, using breakpoints at addresses inside cairo_paint to confirm. I do not have the disassembled output of cairo library with source, but, this is probably at the cr->backend->paint call. I was only able to trace the address based on PLT entries in disassembled output of my cairo application. Not being too well versed with cairo or graphics, can someone point me in the right direction here and give some inputs as to why I am observing this with 24 bit bpp. My code piece is as below: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <fcntl.h> #include <linux/types.h> #include <linux/ioctl.h> #include <linux/fb.h> #include <sys/mman.h> #include <cairo/cairo.h> #define DELAY_IN_SECS 5 #define SCALE_WIDTH 256.0 #define SCALE_HEIGHT 256.0 typedef struct _cairo_linuxfb_device { int fb_fd; char *fb_data; long fb_screensize; struct fb_var_screeninfo fb_vinfo; struct fb_fix_screeninfo fb_finfo; } cairo_linuxfb_device_t; /* Destroy a cairo surface */ void cairo_linuxfb_surface_destroy(void *device) { cairo_linuxfb_device_t *dev = (cairo_linuxfb_device_t *)device; if (dev == NULL) return; munmap(dev->fb_data, dev->fb_screensize); close(dev->fb_fd); free(dev); } /* Create a cairo surface using the specified framebuffer */ cairo_surface_t *cairo_linuxfb_surface_create(const char *fb_name) { int color_input; cairo_linuxfb_device_t *device; cairo_surface_t *surface; /* Use fb0 if no fram buffer is specified */ if (fb_name == NULL) { fb_name = "/dev/fb0"; } device = malloc(sizeof(*device)); if (!device) { perror("Error: cannot allocate memory\n"); exit(1); } // Open the file for reading and writing device->fb_fd = open(fb_name, O_RDWR); if (device->fb_fd == -1) { perror("Error: cannot open framebuffer device"); goto handle_allocate_error; } // Get variable screen information if (ioctl(device->fb_fd, FBIOGET_VSCREENINFO, &device->fb_vinfo) == -1) { perror("Error: reading variable information"); goto handle_ioctl_error; } // Figure out the size of the screen in bytes device->fb_screensize = device->fb_vinfo.xres * device->fb_vinfo.yres * device->fb_vinfo.bits_per_pixel / 8; // Map the device to memory device->fb_data = (char *)mmap(0, device->fb_screensize, PROT_READ | PROT_WRITE, MAP_SHARED, device->fb_fd, 0); if ((int)device->fb_data == -1) { perror("Error: failed to map framebuffer device to memory"); goto handle_ioctl_error; } // Get fixed screen information if (ioctl(device->fb_fd, FBIOGET_FSCREENINFO, &device->fb_finfo) == -1) { perror("Error reading fixed information"); goto handle_ioctl_error; } printf("1. CAIRO_FORMAT_RGB16_565\n"); printf("2. CAIRO_FORMAT_RGB24\n"); printf("3. CAIRO_FORMAT_ARGB32\n"); printf("Enter the color input:\t"); scanf("%d", &color_input); switch(color_input) { case 1: /* Create the cairo surface which will be used to draw to */ surface = cairo_image_surface_create_for_data(device->fb_data, CAIRO_FORMAT_RGB16_565, device->fb_vinfo.xres, device->fb_vinfo.yres, cairo_format_stride_for_width(CAIRO_FORMAT_RGB16_565, device->fb_vinfo.xres)); break; case 2: /* Create the cairo surface which will be used to draw to */ surface = cairo_image_surface_create_for_data(device->fb_data, CAIRO_FORMAT_RGB24, device->fb_vinfo.xres, device->fb_vinfo.yres, cairo_format_stride_for_width(CAIRO_FORMAT_RGB24, device->fb_vinfo.xres)); break; case 3: /* Create the cairo surface which will be used to draw to */ surface = cairo_image_surface_create_for_data(device->fb_data, CAIRO_FORMAT_ARGB32, device->fb_vinfo.xres, device->fb_vinfo.yres, cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, device->fb_vinfo.xres)); break; default: printf("Invalid input. Selecting CAIRO_FORMAT_RGB16_565\n"); /* Create the cairo surface which will be used to draw to */ surface = cairo_image_surface_create_for_data(device->fb_data, CAIRO_FORMAT_RGB16_565, device->fb_vinfo.xres, device->fb_vinfo.yres, cairo_format_stride_for_width(CAIRO_FORMAT_RGB16_565, device->fb_vinfo.xres)); break; } if (cairo_surface_status(surface) != CAIRO_STATUS_SUCCESS) { perror("Error in creating cairo surface\n"); goto handle_ioctl_error; } cairo_surface_set_user_data(surface, NULL, device, &cairo_linuxfb_surface_destroy); return surface; handle_ioctl_error: close(device->fb_fd); handle_allocate_error: free(device); exit(1); } int main(int argc, char *argv[]) { int image_width; int image_height; float cairo_alpha_value; char frame_buffer_number; char fb_node[16] = {0}; cairo_surface_t *surface; cairo_surface_t *image; cairo_t *cr; if (argc != 2) { printf("Usage: ./cairo /path/to/png/image\n"); exit(1); } if (strstr(argv[1], ".png") == NULL) { printf("Only png images are supported with this example\n"); exit(1); } printf("Enter frame buffer number:\t"); scanf("%c", &frame_buffer_number); sprintf(fb_node, "/dev/fb"); fb_node[strlen(fb_node)] = frame_buffer_number; fb_node[strlen(fb_node)] = '\0'; printf("Frame buffer node is: %s\n", fb_node); surface = cairo_linuxfb_surface_create(fb_node); cr = cairo_create(surface); if (cairo_status(cr) != CAIRO_STATUS_SUCCESS) { printf("Error in creating cairo surface\n"); cairo_surface_destroy(surface); exit(1); } printf("Enter the cairo alpha value to paint with:\t"); scanf("%f", &cairo_alpha_value); /* * We clear the cairo surface here before drawing * This is required in case something was drawn on this surface * previously, the previous contents would not be cleared without this. */ cairo_set_operator(cr, CAIRO_OPERATOR_CLEAR); cairo_paint_with_alpha(cr, cairo_alpha_value); cairo_set_operator(cr, CAIRO_OPERATOR_OVER); cairo_select_font_face(cr, "serif", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_BOLD); cairo_set_font_size(cr, 32.0); cairo_set_source_rgb(cr, 1.0, 1.0, 0.0); cairo_move_to(cr, 100, 300); cairo_show_text(cr, "Toradex Cairo Example!"); /* Wait for the result of drawing operation to persist for the user to see */ sleep(DELAY_IN_SECS); /* Clear the surface and prepare for a new drawing operation */ cairo_set_operator(cr, CAIRO_OPERATOR_CLEAR); cairo_paint_with_alpha(cr, cairo_alpha_value); cairo_set_operator(cr, CAIRO_OPERATOR_OVER); image = cairo_image_surface_create_from_png(argv[1]); image_width = cairo_image_surface_get_width(image); image_height = cairo_image_surface_get_height(image); /* Scale the image arbitrarily */ cairo_scale(cr, SCALE_WIDTH/image_width, SCALE_HEIGHT/image_height); cairo_set_source_surface(cr, image, 350, 200); cairo_paint(cr); /* Wait for the result of the drawing operation to persist for the user to see */ sleep(DELAY_IN_SECS); /* Destroy and release all cairo related contexts */ cairo_destroy(cr); cairo_surface_destroy(surface); return 0; } Regards, Victor. -- cairo mailing list <a href="mailto:cairo@cairographics.org">cairo@cairographics.org</a> <a href="http://lists.cairographics.org/mailman/listinfo/cairo" target="_blank">http://lists.cairographics.org/mailman/listinfo/cairo</a></blockquote></div> </div></div>