From 69a7b8c066dd2241cdf5f4b0f12dd66ff48c7e78 Mon Sep 17 00:00:00 2001 From: Frode Langelo Date: Tue, 6 Oct 2015 22:31:58 +0000 Subject: [PATCH] GUAC-1366: Adjust WebP and JPEG image sizes before compressing to avoid artifacts on the edges of the images --- src/common/guac_surface.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/src/common/guac_surface.c b/src/common/guac_surface.c index c2e9e57f..57ea8449 100644 --- a/src/common/guac_surface.c +++ b/src/common/guac_surface.c @@ -98,6 +98,20 @@ */ #define GUAC_SURFACE_WEBP_IMAGE_QUALITY 90 +/** + * The JPEG compression min block size. This defines the optimal rectangle block + * size factor for JPEG compression. Usually 8x8 would suffice, but use 16 to + * reduce the occurrence of ringing artifacts further. + */ +#define GUAC_SURFACE_JPEG_BLOCK_SIZE 16 + +/** + * The WebP compression min block size. This defines the optimal rectangle block + * size factor for WebP compression. WebP does utilize variable block size, but + * ensuring a block size factor reduces any noise on the image edges. + */ +#define GUAC_SURFACE_WEBP_BLOCK_SIZE 8 + /** * Updates the coordinates of the given rectangle to be within the bounds of * the given surface. @@ -1290,6 +1304,14 @@ static void __guac_common_surface_flush_to_jpeg(guac_common_surface* surface) { guac_socket* socket = surface->socket; const guac_layer* layer = surface->layer; + guac_common_rect max; + guac_common_rect_init(&max, 0, 0, surface->width, surface->height); + + /* Expand the dirty rect size to fit in a grid with cells equal to the + * minimum JPEG block size */ + guac_common_rect_expand_to_grid(GUAC_SURFACE_JPEG_BLOCK_SIZE, + &surface->dirty_rect, &max); + /* Get Cairo surface for specified rect */ unsigned char* buffer = surface->buffer + surface->dirty_rect.y * surface->stride + surface->dirty_rect.x * 4; cairo_surface_t* rect = cairo_image_surface_create_for_data(buffer, CAIRO_FORMAT_RGB24, @@ -1327,6 +1349,14 @@ static void __guac_common_surface_flush_to_webp(guac_common_surface* surface) { guac_socket* socket = surface->socket; const guac_layer* layer = surface->layer; + guac_common_rect max; + guac_common_rect_init(&max, 0, 0, surface->width, surface->height); + + /* Expand the dirty rect size to fit in a grid with cells equal to the + * minimum WebP block size */ + guac_common_rect_expand_to_grid(GUAC_SURFACE_WEBP_BLOCK_SIZE, + &surface->dirty_rect, &max); + /* Get Cairo surface for specified rect */ unsigned char* buffer = surface->buffer + surface->dirty_rect.y * surface->stride