From 8ce803db51a28eb662b6271b2b223e0312bdb3d2 Mon Sep 17 00:00:00 2001 From: Jason Garrett-Glaser Date: Sun, 7 Nov 2010 18:04:46 +0000 Subject: [PATCH] Make x11grab cursor drawing suck less This new version: 1. Works on 24-bit and 32-bit input, not just 32-bit. 2. Doesn't try to run on 16-bit or 8-bit, instead of outright crashing. 3. Does proper alpha-blending, so cursor shadows look correct. 4. Doesn't swap R and B. Mostly fixes issue 1997. Fixes issue 2056. Originally committed as revision 25690 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavdevice/x11grab.c | 33 +++++++++++++++++++++++++-------- 1 file changed, 25 insertions(+), 8 deletions(-) diff --git a/libavdevice/x11grab.c b/libavdevice/x11grab.c index 1b58d44f2e..ee3b8e901e 100644 --- a/libavdevice/x11grab.c +++ b/libavdevice/x11grab.c @@ -256,7 +256,16 @@ paint_mouse_pointer(XImage *image, struct x11_grab *s) int x, y; int line, column; int to_line, to_column; - int image_addr, xcim_addr; + int pixstride = image->bits_per_pixel >> 3; + /* Warning: in its insanity, xlib provides unsigned image data through a + * char* pointer, so we have to make it uint8_t to make things not break. + * Anyone who performs further investigation of the xlib API likely risks + * permanent brain damage. */ + uint8_t *pix = image->data; + + /* Code doesn't currently support 16-bit or PAL8 */ + if (image->bits_per_pixel != 24 && image->bits_per_pixel != 32) + return; xcim = XFixesGetCursorImage(dpy); @@ -268,14 +277,22 @@ paint_mouse_pointer(XImage *image, struct x11_grab *s) for (line = FFMAX(y, y_off); line < to_line; line++) { for (column = FFMAX(x, x_off); column < to_column; column++) { - xcim_addr = (line - y) * xcim->width + column - x; + int xcim_addr = (line - y) * xcim->width + column - x; + int image_addr = ((line - y_off) * width + column - x_off) * pixstride; + int r = (uint8_t)(xcim->pixels[xcim_addr] >> 0); + int g = (uint8_t)(xcim->pixels[xcim_addr] >> 8); + int b = (uint8_t)(xcim->pixels[xcim_addr] >> 16); + int a = (uint8_t)(xcim->pixels[xcim_addr] >> 24); - if ((unsigned char)(xcim->pixels[xcim_addr] >> 24) != 0) { // skip fully transparent pixel - image_addr = ((line - y_off) * width + column - x_off) * 4; - - image->data[image_addr] = (unsigned char)(xcim->pixels[xcim_addr] >> 0); - image->data[image_addr+1] = (unsigned char)(xcim->pixels[xcim_addr] >> 8); - image->data[image_addr+2] = (unsigned char)(xcim->pixels[xcim_addr] >> 16); + if (a == 255) { + pix[image_addr+0] = r; + pix[image_addr+1] = g; + pix[image_addr+2] = b; + } else if (a) { + /* pixel values from XFixesGetCursorImage come premultiplied by alpha */ + pix[image_addr+0] = r + (pix[image_addr+0]*(255-a) + 255/2) / 255; + pix[image_addr+1] = g + (pix[image_addr+1]*(255-a) + 255/2) / 255; + pix[image_addr+2] = b + (pix[image_addr+2]*(255-a) + 255/2) / 255; } } }